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• Phylum: Echinodermata• I. a) Includes radially symmetrical adult marine organisms

• 1) Class: Asteroidea = starfish (predators)

• 2) Class: Ophiuroidea= brittle stars (detritus feeders) • 3) Class: Echinoidea = sea urchins (grazers) + sand dollars (filter feeders)• 4) Class: Crinoidea= sea lilies or crinoids (filter feeders)• 5) Class: Holothuroidea= sea cucumbers (filter feeders)

– b) deuterostome phylum1) radial cleavage

• 2) indeterminant development• 3) enterocoelous = mesoderm and coelom formed by

outpocketing• 4) blastopore becomes anus• 5) dipleurula or bipinnaria larva c) Although the adult Echinoderms have a pentamerous (5 part) radial

symmetry, the larval stages are definitely bilaterally symmetrical.

d)The question is, how does a bilaterally symmetrical larva become a radially symmetrical adult? To answer the question we need to understand adult anatomy.

e) Echinoderms have a unique system called the water-vascular system. It is derived from a part of the coelomic cavity and it operates by hydrostatic pressure.

f) Because the water vascular system is a coelomic cavity, it is lined with peritoneum.

g) The tube feet can swing forward and back slowly as we ll as lengthen and shorten so several 100 tube feet working together move the starfish along at maybe one meter/hour.

h) Starfish can bend over a bivalve and attach tube feet to both shells and pull it open slightly, or pull chitons or barnacles off rocks.

i) When bivalves open slightly the starfish everts its cardiac stomach and it passes the stomach through a crack as narrow as 0.1 mm into bivalves mantle cavity and starts to digest the live contents of the bivalve.

j) The digestive tract sits in a cavity and is supported by mesenteries.This cavity is also part of the coelom.

II. So how does starfish get two separate coelomic cavity systems? One is the water vascular system and the other surrounds the digestive system and the gonad.a) Early in embryological development the paired coelomic sacs

pinch off into 3 pairs of coelomic sacs.

b) The three sacs on one side degenerate and the dorsal sac on theremaining side forms the stone canal, the middle sac forms therest of the water vascular system and the ventral sac forms the coelom around the gut and gonads.

c) These two cavities reach all parts of the body and t ake care of surface area to volume problems.1)circulation + hemal canal2) respiration + dermal branchiae3) excretion4) diffusion from the branching coelomic cavities is enough

d) Nervous system1) oral nerve ring around the mouth2) nerve net to tube feet and ampullae

e) With radial symmetry there is no cephalization and food can come in any direction1) locomotion in a very slow but coordinated pattern2) They do not try to move in 2 directions at once.

f) Sensory system = not localized as in cephalic organization1) tactile2) olfactory3) light sensitive eye spots in starfish

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g) Reproductive system1) sexes separate2) spawn together for external fertilization probably cued by

pheromone3) great powers of regeneration which is typical for animals

without strong cephalization4) Oyster fishermen used to chop up starfish and throw them back

in the sea until they realized they were helping the starfish toreproduce. Then they threw the starfish on the deck to dry out and die.

h) The outer body wall is covered with living epidermis = ectoderm1) underlying mesoderm secretes CaCO3 ossicles which in sea

urchins and sand dollars make a complete shell except for mouth, tube feet, and madriporite.

2) Internal skeleton like vertebrates can be bent by muscles between ossicles in the star fish and brittle stars.

3) The skeleton can grow continuously without molting

4)In most groups there are also CaCO 3 spines covered with epidermis. Spines project out from the main case or shell ofossicles and give the phylum its name.

Echino dermspine skin

III. Why aren’t these slow moving or sessile animals covered with barnacles or other settling invertebrates the way whales are?

a) Star fish and sea urchins have forceps- or scissor-like groups of spines that are sensitive to small settling invertebrate larvae and pick or cut the settling larvae off. These spines are usually i n pairs with muscles between them that make them cut like scissors. They are called pedicellaria.

Phylum: Hemichordata = acorn worms and pterobranchsI. A small (about 90 species) group of worms once included in th e

phylum Chordataa) pharyngeal gill slits between gut and outsideb) dorsal nerve cord partly hollow in some species

1) but also has a ventral nerve cord\c) anterior projection of the gut was at first thought t o be a notochord

a stiff supportive rod, but later realized to be an extension of the digestive tract

d) typical Deuterstome with a dipleurula-like larva e) Like Echinoderms in having 3 pairs of coelomic cavities, but in

three body regions1) probosis = fleshy projection in front of the mouth2) collar = short raised region between mouth and pharynx3) truck = long narrow extension of the body with pharyngeal gill

slits between the gut and the outside.f) fossils know from 450 x 106 years ago so this is probably an ancient

separate line of evolution.

f) The acorn worms are deposit feeders in marine sediments but filter out food at gill slits and pterobranchs gather food on tentacle around the mouth and then filter it on pharyngeal gills after swallowing it.

Phylum: ChordataSubphylum: Urochordata = tunicates or sea squirtsSubphylum: Cephalochordata = lancelets or AmphioxusSubphylum: Vertebrata = vertebrates = fish, amphibians, reptiles,

birds, and mammalsI. All subphyla have

a) dorsal hollow nerve cord and no ventral nerve cordb) pharyngeal gill slits = from gut to outsidec) dorsal notochord = flexible but supportive rod just below the

nerve cordd) postanal tail

II. Most chordates also havea) Deuterostome pattern of development, although dipleurula larval

stage is skipped

b) segmental somite developmental musculature except in tunicates

c) internal skeleton of notochord, cartilage, or bone allowing rapid movement

Subphylum: Urochordata = tunicates or sea squirtsI. Adults very unlike other chordates because sessile filter feeders

through greatly enlarged pharynxII. Only the larval stage shows the chordate affinity. Even the larva

has no coelom

a) larva settles on its chin and reabsorb its tail with notochord and most of the nervous system

b) evolution of other chordates may be by neotony orpaedomorphosis = attaining sexual maturity in a larval or earlier developmental stage.

c) Adults can concentrate the rare earth metal vanadium a millionfold, perhaps as a defensive chemical. Rare earth metals in someplants are poisonous to terrestrial herbivores.

Subphylum: Cephalochordata

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I. More fish-like than tunicatesa) filter feeders using pharyngeal gill slits for filtering foodb) retain notochord in adult for muscles to work against for undulating

swimming like a fishc) retains hollow dorsal nerve cord in adultd) segmented somite musculature in adult works against notochord

for swimminge) live with front end out of the sand or silt to take i n a stream of

water to filter in pharyngeal gill slitsSubphylum: vertebrata = life in the fast lane

I. The trend in the Deuterostome line of evolution is from filter feeding by catching small organisms on mucus on extended arms ortentacles to filter feeding on pharyngeal gill slits.a) the major switch in the gill filter feeding line comes when the tunicate

line developed a stronger larval state that can potentially feed and feed and swim with the help of a stiff but flexible rod = the notochord b) When the larval stage becomes a swimming feeder it has the

potential for a new niche by becoming sexually mature while stillin the larval form = neotony or paedomorphosis.

c) This potential was exploited early in the marine envi ronment byAmphioxus.

d) However, the line giving rise to the vertebrates does not show up at all in the fossil record until1) Ordovician 430 x 106 years ago and then only as scatter scales 2) Silurian 360 x 106 years ago as complete skeletons.

e) The reason for the late showing is that vertebrates apparentlyevolved in fresh water and there were no good fresh water fossil -bearing sediments until the late Silurian.

f) The evidence that vertebrates did evolve in fresh water is that theosmotic concentration of their body fluids (i.e. blood, lymph,coelomic fluid, cell cytoplasm) is much lower than sea water.1) Marine invertebrates all have the same osmotic concentration

sea water. They do not have to expend energy to maintain salt and, therefore, osmotic concentrations of their body fluids, i.e. they are isotonic with sea water.

2) Most vertebrates have an osmotic concentration much below sea water. They are hypotonic to sea water. This could be

expected if there had been selection to reduce the difference between body fluids and fresh water.

3) The vertebrate kidney is a series of tubules into which fluid isfiltered from the blood as though the function of the kidney is to get rid of excess water which is what it does in fresh waterenvironments.

4) Fish must have some essential materials dissolved in their blood so that their blood is hypertonic to fresh water , but for most materials they are hypotonic to sea water.

5) When fish later (Devonian Period) invaded the sea they were very hypotonic to sea water and their tissues would be destroyed if they had the same osmotic concentration as seawater.a) Sharks (Class Chondrichthyes ) have solved the problem by

accumulating urea in their body fluids and are isotonic with sea water and have also evolved a tolerance to concentrations of urea that would kill other vertebrates.

b) Bony fish (Class Osteichthyes) have evolved salt secretingglands in their gills which keep removing salt from theirbody keeping it hypotonic to sea water.

c) Marine birds have salt secreting glands near the mediancorner of their eye to keep their body hypotonic to sea water.

d) Terrestrial tetrapods maintain the same ancestoral osmotic concentration and mainly have to worry about water loss.

II. Taxonomic classificationSubphylum: Vertebrata = vertebrae present to form a back bone

which in part replaces the notochord which is left as intervertebral discs.

fishClass: Agnatha = jawless fish = lamprey, hagfish and extinct

OstracodermsClass: Placodermi = extinct armored fish with jaws and lateral finsClass: Chondrichthyes = cartilaginous fish = sharks and raysClass: Osteichthyes = bony fish

tetrapodsClass: Amphibia = frogs, salamanders, and apodansClass: Reptilia = crocodiles, turtles, lizards, snakes, and many

extinct groupsClass: Aves = birds Class: Mammalia = mammals

III. In the early Paleozoic some chordates entered fresh wa ter.a) They became stronger swimmers by developing a harder dorsal

support structure that maintained flexibility by being in sectio ns, one to each somite or segment. These were the vertebrae(singular = vertebra) that give the subphylum its name.

b) When good fossils show up in the Silurian Period, the fish are already covered with hard protective plates giving it the nameOstracoderm = plate skin1) Ostracoderms were dorso-ventally flattened2) still filter feeders on gill slits3) no jaw, no lateral appendages (fins) only medial fins

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4) heavy armor thought to be a defense against Eurypterids =large aquatic scorpions

5) living Agnatha = lamprey and hagfish have lost most of theirskeletons

6) Living Agnatha filter feed as Ammocoetes larvae of lamprey, but are external parasites as adults. They hold on to other fish with their sucker-like mouth and rasp their flesh with a file-liketongue. This is not representative of the primitive fish.

IV. The basic vertebrate body plan

a) nervous system1) dorsal hollow nerve cord2) anterior brain with cavities as enlargement of hollow nerve

cord3) obvious cephalization

b) Sensory system1) cephalization of most sense organs2) olfactory = depression later connected to mouth and pharynx

a) most anterior sense organ connected to the forebrain3) visual = a pair of eyes connected to the midbrain4) balance = semicircular canals connected to the hindbrain5) auditory = ears connected to the semicircular canal and

hindbrain6) proprioception = also connected to the hindbrain cerebellum7) taste in mouth = chemical and related to olfaction8) lateral line = not anterior = detects currents in fish and larval

amphibians 9 touch = diffuse over the whole body

c) respiratory system1) gills in most fish and larval amphibians2) lungs in some fish in stagnant fresh water and adult tetrapods

a) outgrowth of the back of the pharynx = endoderm linedd) circulatory system

1) closed system = capillary beds2) ventral heart in its separate coelomic cavity

e) excretory system

1) kidney built of many tubules or nephrons2) kidney works by filtration of blood by blood pressure created

by the heart and then selective reabsorption of dissolved materials

3) has different ducts to the outside added during vertebrate evolution and old ducts were taken over by the male reproductive system

4) kidneys are in the dorsal wall of the coelom on either side ofdorsal aorta to give high blood pressure for filtration

f) Reproductive system1) undifferentiated gonad in the dorsal wall of the coelom

becomes ovary or testes dependent on genetic sex in most a) in some fish and reptiles the environment determines sex

2) oviduct in female develops as a new structure in the dorsal body wall

3) nephric ducts in males are used to move sperm

g) digestive system1) mouth = ectoderm2) pharynx3) esophagus4) stomach5) intestine

a) liver = digestive gland to detoxify food and produce bileb) pancreas = produce digestive enzymes

6 rectum = store feces7 cloaca = the common exit of the last three systems

a) from stomach on supported by mesenteriesb) feeding first filtering and then use of teeth and jaws

The evolution of fishI. Changes as modern fish evolved from Ostracoderms

a) Ostracoderms were small, slow, dorso-ventrally flattened, bottom-dwelling, filter-feeding vertebrates that were armored against Eurypterids, the largest and top predators of their time.

b) The trends in Ostracoderm evolution that led to Placoderms were1) increase in size2) to faster motion by lateral compression allowing body

undulation as the means of progression3) reduction of body (but not head) armor to allow body

undulation4) development of lateral fins to correct any tendency to roll

when off the bottoma) some Placoderms had as many as 7 pairs of lateral finsb) the high number of lateral fins led to a theory that the fins

developed from lateral fold on the side of the body (real origin of fin is not known)

c) pairs of lateral fins rapidly reduce to two (pectoral + p elvic)

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5) developed jaws from anterior gill arch = bony supports of gill slits

6) Placoderms became the most feared predators of their time,replacing the Eurypterids

II. Skeletal changes involved in fish evolutiona) Vertebrate skeletal system

Dermal Skeleton (dermal bone)

Axial Skeleton

Somatic Skeleton Appendicular

Endoskeleton Skeleton(endochondral bone) Visceral

Skeleton

b) Dermal skeleton1) The dermal skeleton started with the armored bony plates

formed in the surface mesoderm just under the ectoderm of the Ostracodermskin. (dermal = skin)

2) reduction of different parts of Ostracoderm dermal armor leftdifferent structuresa) reduction of most of the deep dermal bone left

1) teeth of all fish and tetrapods except Agnatha2) shark dermal denticles

b) reduction of the surface hard denticles left deeper dermal bone that became1) surface elements of the skull of vertebrates2) most of the lower jaw of vertebrates3) parts of the pectoral girdle = shoulder bones of

vertebrate4) these the trends carry on through Osteichthyes and

tetrapodsc) The only remnants of the dermal skeleton in Chondrichthyes

is teeth in the jaws and the teeth-like dermal denticles in theskin

c) endoskeleton = endochondral bone1) endochondral bone starts deeper in the mesoderm of the

embryo as cartilage and is replaced by bone during development of all vertebrates except living Agnatha andChondrichthyes

2) It forms from mesenchymal connective tissue deeper in the mesoderm of vertebrates than dermal bone. It is, therefore,not functional in surface protection, but instead as structural support for muscles to work against in primitive fish and all extant (not extinct) vertebrates in most parts of their bodies.

3) Visceral skeleton = gill arches that support the pharyngeal gillslitsa) The most anterior gill arches of Ostracoderms were

gradually modified to shut the mouth and in so doing became jaws in Placoderms and later vertebrates.

b) Gill arches support the gills for respiration and includeextensions = gill rakers for straining food from the watercurrent through the gill slits. They at for filter feeding.

c) All that is left in mammals is cartilage to support the t ongue= hyoid cartilage, voice box = larynx, and trachea

4) Somatic skeleton = endochodral skeleton not connected to gillsa) Axial skeleton =

1) vertebrae, ribs, and sternum = the major support for the muscles that move the trunk

2) brain case = the floor of the skull upon which sits the brain

b) Appendicular skeleton =1) all of the pelvic girdle = hip bones and the part of the

pectoral girdle = shoulder bones that are not dermal in origin

2) the skeleton of pectoral and pelvic fins of fish and thefore and hind legs of tetrapods

III. Reproduction in modern fishesa) Chondrichthyes = have evolved few large young rather than

many small young

1) Sharks and rays have male pelvic fins with projections calledclaspers that allow sperm to be passed to females for internal fertilization.a) Skates and rays are dorso-ventrally flattened, kite-shaped

fish that feed on invertebrate fauna of sediments and havelarge crushing teeth to break up bivalve mollusks. They lay large eggs protected by hard cases where development is completed before young emerge.

b) sharks go one step further and have young born alive at several inches long

b) Most Osteichthyes have small eggs that are spawned just beforea male spawns sperm over the eggs.1) In pelagic forms like mackerel (that live in the open ocean far

from the bottom) millions of tiny eggs are spawned and the young go through a very long period of development where they are relatively helpless.

2) In some coastal benthic forms, larger eggs are laid in bottomnests where they are fanned and turned to keep oxygenated.

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c) Nesting behavior in fish1) A surprising thing in fish is that parental care of eggs is more

often the work of males rather than females. A well studiedexample is the 3 -spined stickledback which can be anadromous (come from marine to fresh water to breed like salmon do). The males have bright red bellies and have elaborate displays in areas where they defend territories aroundnests of algae. The interesting question is why males do th e parental care? a) The answer relates to the “battle of the sexes”: the first sex

to be able to leave puts the other sex in a cruel bind of deciding whether to stay and care for the zygotes or leave and find another mate that is more helpful.

b) With internal fertilization the female had the young inside her and the male can leave.

c) With external spawning, the heavier eggs are spawned firstbecause they are less likely to be scattered by the current. The male is second to spawn while the female can leave.

d) Mates are usually not related to each other, so they are notinterested in the success of each others genes, only their own. Long courtships are usually necessary for monogamyand long cooperation.

2) The stickleback proves the selfish interests of the sexes. Malesare stuck on their small territories and can’t go feed withoutdanger of having other fish eat the developing zygotes they guard in their nest. So the male eats a few of the zygotes in his nest that females worked so hard to provide the energy for. A female is at a disadvantage if she is the only female to lay the eggs for a males. Usually a male takes care of the eggs of 4 or 5 females. Females don’t like to lay their eggs in empty nests.Males put a roof on their nest so the contents can’t been seenfrom a distance. Males also sneak and steal fertilized eggsfrom other males’ nests to put in his nest apparently to attract a first female to lay eggs for him to fertilize in his nest.

3) Other strange reproductive patterns occur in other bony fish.

a) Some deep sea fish may not have genetic sex determination .Rather, a small larval fish that is undifferentiated will settlein the reproductive tract of a young normal developing fish and the small one becomes a small parasitic male and thelarge one becomes normally feeding female. In the deep sea it may be so difficult to find the opposite sex when he or she is needed that the female can gain by having a small male feed in and from her reproductive tract so that she willhave a male when she needs one to fertilize her eggs.

b) In some species of coral reef fish, several fish live togetherin a social group similar to a harem with one large male andand several smaller females whose eggs he fertilizes. Thesurprising thing is that when the male dies the largest femaleturns into a male and the group goes on as before. This is adefinite case of environmental sex determination with the social environment being critical. It assures effectiveoutbreeding .

Class: Amphibia = from amphibious = active on land and waterI. Amphibians first show up in the fossil record at the end of the

Devonian Period a little over 300 X 106 years ago. They were the first vertebrates to enter land.a) Why leave water to enter land?

1) to breath air – no, the Crossopterygian fish they arose from had lungs and could breath air at the surface of the stagnant water they lived in.

2) to escape enemies – no, the Crossopterygians were the largest carnivores in fresh water

3) to get between pools in a drying stream to eat the smaller fish trapped in the poolsa) This was the answer given in text books until about 1996

when fossils of fish that already had fingers and toes on their pectoral and pelvic fins were found in Devonian swamp deposits in Greenland. The ribs of these animals were too fine to support the weight of an animal on land so they h ad to have evolved in water with hands to help the animal to

navigate through the sticks in the water of the swamp forest.b) The red sedimentary rock of the late Devonian had been

interpreted as showing dry climate, but further analysis of the rock changed the opinion to wet swampy conditions.

4) The reason for leaving water is now given as using food on land.

II. One problem faced by lung fish and the amphibians that evolved from them is getting oxygen rich blood to all their tissues. The basis of the problem is that the original fish circulatory pattern wasdependent on getting O2 from water by gill actiona) One disadvantage of circulation in lungless fish is that 2

capillary beds must be passed before the blood is returned to the heart and once it has passed the first capillary bed it has lost mostof the blood pressure from the heart.

b) An advantage of fish circulation and respiration is t hat blood in the gills flows in the opposite direction to the water passing o verthe gills. This creates the counter current principle of gas exchange where more O2 is gained and CO2 is lost. If they

flowed in the same direction they would come to equilibrium at an intermediate concentration.

c) A second advantage is that there is no mixing of O2 rich and poor blood.

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III. In amphibians and lung fish some of the blood leaving the heart goes to the lungs and some to the rest of the body.

a) One improvement and advantage is that blood only pass es through one capillary bed between trips to the heart’s pump.

b) One disadvantage is that the lungs are blind sacs and there is nochance for counter current gas exchange.

c) Another disadvantage is that O2 rich blood from the lungs and O2

poor blood from the systemic capillaries in the rest of the bodyare mixed in the one ventricle of the heart.

IV. In mammals a 4-chambered heart evolved.a) The advantage gain by the 4 -chambered heart is the separation

of O2 rich blood from the lungs and O2 poor blood from thesystemic capillaries.

b) There is still the advantage of passing only one capillary bed between trips to the heart.

c) The lung is a blind sac and there is the disadvantage of no chancefor counter-current gas exchange in the lungs.

V. In birds, air sacs allow the lungs to have air flow through them in the same direction at all times + 4 -chambered hearta) This pattern of air flow allows the advantage of counter-current

gas exchange between air flowing one way through the lungs andblood flowing the opposite direction in the capillaries of the l ungs.

b) Birds have a 4 -chambered heart and no mixing of blood.c) Birds have one trip through capillary beds before returning to the

heart.

Characteristics of Respiratory and Circulatory Systems

Counter–current Mixing O2 rich Capillary beds per gas exchange and poor blood trip to the heart

Gilled fish yes = + no = + 2 = -

Lung fish +Amphibians no = - yes = - 1 = +

Mammals no = - no = + 1 = +

Birds yes = + no = + 1 = +

+ = advantage- = disadvantage

VI. Primitive amphibians were tied to living near water. Although they attained the size of crocodiles and were the dominant land animals during the Carboniferous Period, they were out-competedby reptiles as soon as reptiles evolved a terrestrial egg.a) All but 3 groups were extinct by the mid Triassic 175 x 106 years

ago.b) The 3 living groups are

1) Order: Caudata = salamanders = mainly temperate and absent from the tropics. Common in Smoky, Ozark, and Cascade Mountains.

2) Order: Anura = frogs and toads = greatest radiation in the tropics, although found further north than salamanders

3) Order: Apoda = apodans = tropical legless group in soilsc) The three modern groups have thin moist skins and much of their

respiration is done by surface blood vessels in the skinexchanging O2 for CO2. 1) all are more common in moist habits2) Plethodont salamanders lost lungs over evolutionary time.

VII. Salamanders are often brightly colored and distasteful to some predators. Those species found together often have the same brightcolor patterns forming a mimicry complex.a) an example from the Ozark Mountains

1) cave salamander = Plethodont without lungs live near streams2) dark-sided salamander = Plethodont3) central newt = lungs

b) in all three species there is1) larval stage in water with external gills2) juvenile terrestrial form without gills and nonreproductive3) adult reproductive form without gills

c) newt1) larval stage lives in ponds where eggs hatch = cryptic green2) juvenile on land in forest litter, red with black spots, full

granular poison glands3) adult in pond = yellowish green cryptic and no functional

granular glands

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d) 2 Plethodont species1) larval stage in streams often near caves = cryptic light green2) juvenile on land but near streams or humid environment to

keep skin moist = yellow to orange to red with black spots asgranular glands develop and fill with poison

3) adults on land near streams = red with black spots = have largegranular glands

4Development of Granular Glands holding toxins

e) predators 1) young birds peck red-and-black forms, but leave them after 1

or 2 pecks and don’t try again2) mice, shrews, and wood rats turn them over and eat them from

the belly leaving the dorsal surface untouched3) raccoons wash them until the granular glands are discharged

and contents washed away and then eat the whole salamander.4) garter and water snakes eat whole salamander without effect5) Therefore, defenses are mainly against birds which are the

most common and active diurnal (day time) predators wholearn the bright color pattern.

6) toxin in granular gland killed blue jay and lumber jack7) toxin is water soluble and not effective in aquatic habitat, i.e.

adult newt in pond is not defended or brightly colored8) aposematic coloration (bright colors of terrestrial stages)

educate young birds quickly. Tail of salamander is waved overit back and is first thing young bird peck and most concentratedgranular glands and is least vulnerable part of the salamander.

VIII. Mimicry complexa) Mullerian mimicry = 2 distasteful species or forms having the

same appearance.1) Each species gains by losing fewer individuals in educating

the naïve predators2) Both potential prey species converge in appearance over

evolutionary time.3) Predators are selected to generalize the avoidance of color

patterns.b) Batesian mimicry = a tasty species gains in predator avoidance

by looking like and being mistaken for a distasteful species1) Mimic gains by resembling the distasteful model and

converges on the model’s appearance through selection for better mimics.

2) Model loses by resemblance and diverges from mimicthrough selection for poorer models.

3) Predators are selected to discriminate between species.c) Juvenile newt in drier forest must acquire protection at once

because no other salamander model is present in the habitat to mimic. Plethodont adults by streams can serve as Mullerianmodels.

d) Juvenile Plethodonts can mimic juvenile newts and adult Plethodonts and can acquire their granular glands more slowly than newts because of the protection. They can divert energy togain body size faster than newts. The juvenile Plethodonts areBatesian mimics of juvenile newts and adult Plethodonts.

Class: ReptiliaI. The change that made terrestrial life possible for reptiles and

allowed them to finally cut the vertebrate tie to water was

a) The advance is the result of 4 fetal membranes (3 new to reptiles)1) Amnion is a thin membrane that holds a water environment

to physically protect the embryo and give it room to grow without drying up. The function is similar to the coelom in relation to the organs in it. Some muscles in the amnion wall contract rhythmically to give movement to the water around theembryo and prevent adhesion (mesoderm outside ectoderm)

2) The chorion functions with the allantois as a lung for gas exchange through the porous egg shell (ectoderm outsidemesoderm)

3) The yolk sac provides the material and energy for growth of the embryo and the fetal membranes (mesoderm outsideendoderm)

4) The allantois provides the vascular tissue for the gas exchangethrough the chorion. It serves as a site of deposit of uric acid,the water free nitrogenous waste. (mesoderm outsideendoderm)

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b) The fetal membranes result from a huge expansion of t he coelomwall. The cavity inside the chorion and outside the amnion, yolksac and allantois is an extension of the coelom lined by mesoderm

c) All developmental activity goes on inside the shell as long as thetemperature is right and the shell is not in water. Oxygen exchange is dependent on air, not water, on the shell.

d) Surprisingly, in many species of turtles and some lizards the sex of the offspring that hatches depends on the temperature of the\ground where the eggs are laid and left. Apparently, the distribution of nest sites is such that the sex ratio is 50:50. Whyenvironmental sex determination is adaptive in some reptiles isis not known.

e) The earliest reptiles were amphibious in their habitat use. They laid terrestrial eggs for the same reason that some tropical frogs carry their eggs;1) to get them away from concentrated aquatic predators2) to allow the eggs to survive seasonal dry periods

II. Phylogenetic radiation of reptilesa) The stem reptiles = cotylosaurs radiated into a wide variety of

forms both aquatic and terrestrial. Of these forms, 5 groups ofreptiles and birds and mammals are still extant.

REPTILE PHYLOGENY Order: Testudines = turtlesOrder: Crocodylia = crocodiles, alligators, and caimansOrder: Squamata = lizardsOrder: Squamata = snakes

sphenodons (islands off New Zealand)birdsmammals

b) One of the major clues to reptile phylogeny is where holes develop in the dermal bones of the skull to allow increase in thesize of the temporal jaw muscles

1) anapsid = no hole develops2) synapsid = one pair of holes below the connection of the

postorbital and squamosal bones3) parapsid = one pair of holes above the connection of those

bones4) diapsid = two pairs of holes = above and below the connection

of those two bones.

c) Turtles have the primitive anapsid skull structure, but the fossil record shows that they were diapsid and then went back to being anapsid as they developed body armor.1) head is solid anapsid 2) ribs and backbone expand to form a solid carapace and the

sternum expands to form the plastron making a shell like bodyarmor with tough scales over the fused skeleton.

3) teeth are replaced by horn-like beak on the upper and lower jaw

4) retain the primitive straddle walking with feet not below thebody

d) Crocodiles were the one group of large reptiles not t o go extinctat the end of the Cretaceous Period 70 X 106 years ago.1) although derived from the early diapsid ruling reptiles

(Thecodonts) which were biped, they secondarily evolved back to walking on all fours and became amphibious reptiles with alife style very much like the first amphibians and reptiles

2) almost complete separation of circulation by a 4 -chamber heart

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3) still ectothermal (cold-blooded)4) diapsid skull but not highly modified

e) lizards1) small, mainly insectivorous tending to fill the bird niche in

warm dry habitats (i.e. deserts)2) ectothermal, but very active in warm environments where high

body temperature is maintained behaviorally3) kinetic skull like birds allows mouth to act like forceps

f) Snakes

1) evolved from lizards (probably burrowing forms because of lack of eyelids and ears) 30 to 40 million years ago when mammals and birds were well established and dinosaurs were long extinct

2) not only is the skull kinetic, there is a joint in the lower jaw and the jaws are held together in front by a ligament that allows them to separate even more.

3) several of the more derived families have become poisonous a) coral snakes are relatives of cobras, but are only in Western

Hemisphere where coati replaces mongoose as the forager i n the litter

g) diapsids include all the dinosaurs and their close relatives the birds as well as lizards, snakes, crocodiles, and sphenodons.

h) parapsids gave rise to the Plesiosaurs and Ichthyosaurs = 2 linesof marine reptiles that went extinct with the dinosaurs.

i) synapsids gave rise to the Therapsid reptiles which in turn gave rise to the mammals

j) While the diapsids (especially lizards, birds and snakes) developed kinetic skulls with a quick bite that made them goodinsectivores, the Therapsid reptiles developed a very solid nonkinetic skull and a solid lower jaw that allowed them to become mammals with a very powerful bite and the ability to grind food without disarticulating the skull and the jaw.

III. Temperature regulationa) endothermic = homeothermic = warm blooded = metabolically

generated heat maintaining a high constant body temperatureb) ectothermic = poikilothermic = cold blooded = cannot regulate

internal body temperature with metabolic heat, but can regulateinternal body temperature behaviorally with environmental heat.

c) Today only birds and mammals are endothermic, but there are some scientists that argue that some of the dinosaurs were also endothermic. The evidence they use is1) some fossil dinosaurs had bone structure with Haversian canals

like birds and mammals.2) Therapsid reptile ancestors of mammals were found in cold

polar regions 3) in dinosaur fossils the ratios of carnivore to herbivore biomass

was close to the 2% typical of endotherms rather than the 20 to 40% typical of ectotherms .

Class: AvesI. The main distinguishing characteristic of birds is feathers.

a) The ruling reptiles also gave rise to a separate line of flying reptiles, the pterodactyles = Pterosuria (no feathers)

b) Some dinosaurs were bipedal and had legs and pelvic girdles essentially the same as birds.

c) Several dinosaurs lost teeth and had horny beaks lik e birds.d) The reduction of finger number to three was found in some

dinosaurs like birdse) There is some evidence that some dinosaurs, therapsid reptiles

that gave rise to mammals, and probably pterodactyles wereendothermic.

f) Many, if not most, biologist and paleontologists thi nk that dinosaurs are not extinct, some just evolved feathers and we call them birds.

II. There is also disagreement about the first function of feathers.a) One idea is that they functioned first as insulation as down

feathers do today. However, the period when birds first evolved

was very warm and there would be little need for insulation.b) Others think that they were first used for gliding and then later

helped in flight when they were well developed. These differences of opinion are part of a general argument about thesteps in the origin of birds and of flight for birds.

c) Archaeopteryx is the oldest fossil that biologists agree was a bird that probably could fly, but it differed in many ways from modern birds by having1) teeth2) a relatively long tail with many similar vertebrae3) the absence of an expanded sternum with a keel which we

call the breast bone.4) the absence of a large breast bone means that it was a weak

flier at best and maybe could only glide5) it had three fingers with curved claws like a squirrels, which

indicate that they climbed trees before flying rather than flying up into trees

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6) Other biologist think that birds came from running dinosaursthat used feathers on their arms to trap insects and then used to fly when they were running fast like an airplane taking off.There is no general agreement over whether they started as running dinosaurs or a separate group of arboreal reptiles.

IV. Feathers are made of the protein keratin like hair and reptile scales, but the keratin in feathers is chemically different than the keratin in hair and scales.a) We will discuss 4 general types of feathers

1) contour feathers = flight feathers which cover the outer surface of birds and stick out from the posterior margin of t hewings and tail to increase the surface area of the bird for flighta) the quill is the base of the feather that is held in the skin by

muscles b) the vane is the broad flat part of the feather that make the

feather flat to cover the bird with a smooth surface.1) the shaft is the center of the vane and is a continuation of

the quill

FEATHER TYPES

2) the first branch off the shaft is a barb3) barbules branch off the barbs and the shaft and cross each

at nearly right angles4) The barbules coming off the distal side of barbs have y et

another branch called a barbicel which hook onto the proximal barbules coming off the next barb. This wholeweb of structure gives the feather strength with a light weight.

2) down feathers have a quill with no shaft and a few barbs radiating from the quill. Its function is insulation.

3) filoplumes are very small and have a quill and shaft with a few small barbs at at the enda) found around the base of the main flight feathers in the wings

and tailb) their function is to sense the movement of the main flight

feathers that is causes by the wind and not by musclesc) they are an additional aid to the proprioceptors in muscles to

tell the brain the position of the wing and its feathers.

4) bristles are small feathers that have a tactile sensory function like whiskers in mammalsa) they have a quill and a naked shaft with a few barbs at the

baseV. Birds are specialized for the extreme activity of flight.

a) Flight requires on the order of 10 times as much metabolic energy as resting, something that mammals can sustain for only ashort time if at all.

b) separation of circulation by a 4-chambered heart1) The aorta in birds goes to the right of the heart rather than the

left as in mammals. This difference shows that in birds the aorta is formed by the right systemic arch of a fish gill or frog systemic arch. The left systemic arch becomes the aorta in mammals.

c) Birds have a very high body temperature from endothermy = 40o to 42o C = 104o to 108 o F (i.e. lethal in mammals)

d) Birds can migrate over oceans without stopping for wa ter because of the efficiency of the lungs in supplying oxygen.

e) Lung efficiency also allows birds to fly at over 20,0 00 feet without going into oxygen debt.

BIRD BACKBONE, RIBS, AND STURNUM

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BIRD AIR SAC AND LUNG ACTION e) The efficiency of the lung is a consequence of one way flow ofair through the lung and counter current flow of blood in the lung so that even at 20,000 feet the bird can pick up 80% of theO2 in the blood that it would have at ground level. A mammal would get about half of that.

VI. How do bird determine where to fly?a) built in compass in the brain using the sun during the day and

star constellations at night. The compass must be combine with a clock which is a circadian or 24-hour rhythm in body metabolism

b) California bird watchers find a few eastern migratory birds each year with a defective compass. The birds concentrate on the off-shore island before they fly further west to die in the Pacific.

c) Birds also have the ability to sense a magnetic field and thus havea built in magnetic compass. The compass was first suspected when homing pigeon were seen to become disoriented when flying over an atomic reactor.

VII. Behavioral orientationa) Most birds have their visual and auditory senses most acute.

Mostly birds that feed on dead and therefore smelly flesh have anacute sense of smell. Turkey vultures in Manhattan and albatrosses at sea are the best examples. It makes sense that b irds moving fast off the ground do not track their food by smell like a wolf or nocturnal mouse or shrew.

b) The lack of response to odor allows researchers to handlenestling birds without the parents abandoning themas many mammal species mothers do. 1) Some researchers interested in what parents feed their nestling

birds tie pipe cleaners around the nestlings neck loose enoughthat they can breath but not swallow. The researchers wait u ntilthe parents leave and then remove the food from the nestlingsmouth.

2) These types of techniques have allowed researchers to learn what limits the number of eggs a female will lay in a clutch.

3) Four hypotheses on what limits clutch sizea) maximum number of eggs a female can lay – rejected

because a species that usually lays five eggs will lay 20 ormore eggs if the third egg laid and lying in the nest is removed each day for 20 days

b) maximum number of eggs a parent can cover to keep warm during incubation – reject because a species that usually lays and hatches 5 eggs can hatch many more if added to the 5.

c) enough eggs to just replace last year’s mortality – rejected because if a female could lay more eggs and raise them shewould leave more genes in the next generation, i.e. natural selection would be for the individual that raised more young

d) the maximum number the parents can raise to maturity –accepted because clutches larger than average usually havemore young die by starvation and predation and fewer reachmaturity than in the average sized clutch

4) Most birds form monogamous pair bonds because both parents can feed the young and thus raise more young than if a female is willing to become the second mate of a male who is already mated.

Class: MammaliaI. The characteristics used to distinguish mammals from other

vertebrates area) for extant mammals

1)mammary glands – function to produce milk as nutrition for newly born or hatched young

2) hair – at least in the form of whiskers at some stage of development

b) The class name comes from mammary glandsc) mammary gland evolution is thought to be derived from sweat

glands connected to hair follicles.1) In Monotremes (egg laying mammals), mammary glands are

diffuse and connected with hair. The young lick milk from hair.d) But neither hair nor mammary glands usually leave fossil imprint

and the definition of what is a mammal in fossil history is dependent on the articulation of the lower jaw to the skull.1) reptiles + birds = articular bone to quadrate bone in the skull2) mammals = dentary bone to squamosal bone in the skull

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e) Trends in the evolution of Therapsid reptiles to mammals1) increase in jaw musculature2) reduction of surface dermal bone3) fusion of dermal bone to deeper endochondral bone to

strengthen the skull and make a solid case around the brain =the brain case

4) reduction of all the bones in the lower jaw except the dentarybone to which most muscles are attached and all the teeth areinserted

5) differentiation of the teeth for biting, stabbing and chewing6) attachment of the skull to the vertebral column in two places.

i.e. the atlas attaches to the skull at two occipital condylesa) allows the skull to move up and down relative to the

vertebrae, but not to turn from side to sideb) side to side motion of the mammalian head come from

movement of the 7 cervical (neck) vertebraef) All of these trends tend to make the force of a bite by the lower

jaw stronger without endangering the vertebrae in the neck.1) the mammalian neck, skull, and lower jaw act like a monkey

wrench with only the lower jaw moving. The skull is not kinetic as in birds, lizards, and snakes where the skull and lower jaw both move like tweezers.

g) In the Permian and early Triassic, which were cool periods, the Therapsid reptiles were the biggest terrestrial carnivores and seemed to be the dominant group of reptiles. They probably hadhair and nurse their young.1) Fossils had whisker pits in the lower jaws as evidence of hair.2) Small fossil individuals were found curled up next to large

individuals under volcanic ash.h) As the temperature warmed for the length of the Mesozoic Era,

the Therapsids lost out to the Thecodonts and dinosaurs whichwere called the ruling reptiles. Only rat-sized or smaller Therapsid reptiles were found during this time and they were thought to be nocturnal which would explain their olfactory specialization with a long nasal part of the skull. The trends in Therapsid evolution continued until by the end of the Triassic there were fossils with only a dentary bones in the lower jaw which made the animals mammals by definition.

i) Most of the bones of the lower jaw were lost, but the articular bone with the quadrate from the skull became new ear ossicles.

reptile bone mammal boneArticulation jaw {articular = malleus } all are

skull {quadrate = incus } middle earMiddle ear ossicle {stapes = stapes } ossicles

j) The middle ear ossicles allow the amplification of the vibration ofthe tympanic membrane to reach the oval window of the inner earwhere the sensory neurons are that transmit sound to the brain.

II. Mammals have radiated into more life styles than any other group ofvertebrate.a) The skull, jaw, and teeth show the great diversity of feeding

evolved by different mammal speciesb) There are 4 general types of teeth from front to back of mouth

1) incisors = biting off pieces of food2) canines = stabbing prey or enemies3) premolars = for chewing or grinding food into smaller pieces,

especially in young animals4) molars = for chewing in adults

c) the first set of incisor, canines, and premolars are called milk teeth and are replaced by a second set of adult teeth

d) the first set of molars are not replacede) tooth formulas give the number of these 4 types of teeth on one

side of the skull and lower jaw1) The human tooth formula is 2/2 1/1 2/2 3/3 and thus we have

two incisors on the left side or our skull and two on the left side of our jaw, one canine on the left side of our skull and one on left side of our jaw, two premolars on the left side of our s kull and two on the left side of our jaw, and three molars on the leftside of our skull and three on the left side of our jaw. Thus we have 16 teeth on the left side of our head (skull and jaw) and another 16 on the right side for a total of 32 teeth in our h ead.

f) The shape of the teeth denotes their function1) incisors = chisel shape to cut off food2) canines = long cone shape to deeply pierce and stab prey3) premolars and molars are the teeth that vary most depending

on the type of foods being broken up into smaller pieces.

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a) scissor-shaped carnassials in carnivores to cut meatb) mound shaped cusps to hold and crush food in omnivores

like humans, pigs, and bearsc) high crowned teeth with ridges to grind up tough plant

material for herbivoresd) cone-shaped molars to hold fish in dolphins and sealse) lost or reduce molars in anteaters

g) Not only the teeth but the jaw and skull evolve to fit the food requirements of the species of mammals

1) The main force on the lower jaw of a carnivore comes from a struggling prey that pulls on the canine teeth and tends to disarticulate the lower jaw from the skull. This force is best resisted by the pull of the temporalis muscle inserted on the coronoid process of the lower jaw and originating from the top of the back of the skull. The long moment armbetween the coronoid process and the articular process that attaches the jaw to the skull gives the temporalis muscle more force like a child being further out on a see saw. The masseter muscles pulling partly forward from the angular process to the middle of the skull are small and have a small moment arm because by pulling partly forward they would help to disarticulate the jaw to the detriment of the carnivore.2) The main force on the lower jaw of a herbivore is the resistance of the plant food to being ground up between thepremolars and molars of the skull and lower jaw. The force is being resisted by the masseter muscles pulling up and partly forward to hold the teeth of the jaw against the teeth of the skull.

The angular process in herbivores is far from the articular processcreating a big moment arm for the stronger action of the massetermuscles. The temporalis muscles inserted on the coronoid process are unimportant because plant material does not strugglewhen it is bitten off by the incisor teeth at the front of the j aw.

3) Note the position of the articular process in both jaws. It gives a larger mechanical advantage to the most important muscle in each case.4) Note the shape and firmness of the articulation in each case.For the carnivore the articular process is a transverse bar that fits

in a transverse groove in the skull so that it will not slip out whenthe struggling prey pulls to one side or the other. The bar in groove of carnivore jaw articulation also keeps the carnassial molars in line so that they cut like scissors that have their blades held in line by a tight screw. In herbivores the articular process fits loosely in the skull so that the jaw can be pulled from side to side by muscles that help to grind the food between ridges that run from the front to the back of the molar teeth.

III. Mammals all have the three unique characteristics of h air,mammary glands, and dentary-squamosal jaw articulation, but theyevolved a bewildering diversity of forms and food suppliesa) marine forms

1) whales = carnivores + filter feeders on small animals2) seals = varied carnivores and walrus feed on bivalves3) sea cows = grazing herbivores

b) flight = bats1) blood ectoparasite = vampires2) insectivores = most species using sonar

3) fish eating = tropical streams4) frugivores (fruit eaters) = tropical forests 5) nectar and pollen = pollinators in tropical forests and deserts6) carnivores on other bats caught on the wing

c) large terrestrial herbivores1) elephants2) odd-toed ungulates = horses, rhinos, tapirs3) even-toed ungulates = pigs, hippos, deer, bovines4) kangaroos5) gorillas

d) small terrestrial herbivores1) rabbits2) hyrax3) some rodents = voles

e) ant eaters = ants and termites1) ardvark2) edentates = New World anteaters3) pangolins

4) spiny anteaters = egg-laying Monotremef) large carnivores = cats, dogs, hyenas, weasels, etc.g) seed eaters = most rodentsh) arboreal herbivores

1) sloths2) some primates3) koala

i) general omnivores = bears, pigs, humansf) bark feeders = porcupines, beavers

IV. Mammalian sensory behaviora) mainly olfactory and auditory from their nocturnal ancestryb) bats, whales, and some seals have auditory specialization for

echo location (sonar) to find objects in air or water when lightlevels are low

c) The main exceptions are squirrels and primates which are visual and auditory probably in relation to arboreal habitats

V. Social behaviora) Mating behavior

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1) mainly polygamous (1 male bonds with >1 female) or promiscuous with no pair bondinga) male mammals cannot supply milk

2) monogamous exceptions are canines, beaver, and some primates

a) a prolonged parental care beyond nursing allows male parentto be involved in parental care

b) control of detrimental effects of competition by social behavior1) territorial behavior = individual or group defense of an area

a) found where defensible limiting resources are evenly spacedand in short supply

2) social hierarchies (peck orders) = established order of dominance based on individual recognition of members of a permanent groupa) found where resources are either not defensible on territories

because clumped, or unpredictable in space and/or time. Also found in members of a herd that stay together for protection.

Human BiologyI. Taxonomic position

Kingdom AnimaliaPhylum ChordataSubphylum VertebrataClass MammaliaOrder PrimatesFamily HominidaeGenus HomoSpecies sapiens

a) We are easy to place as animals, chordates, vertebrates, and mammals. However, as primates we are fairly distinct from thethe other primates1) upright posture2) general reduction of body hair3) large brain = at least double the size relative to body size4) extreme development of acquired characters = culture5) a well developed sense of morality, i.e. judgment about the

value of the actions of other humans6) self awareness

b) Does biology deal with these subjects at all?1) In recent years ecologists, behaviorists, anthropologists, and

psychologists have all studied the other members of the orderPrimates in hopes of understanding the evolutionary steps leading up to humans

2) How can you study the behavior and ecology of fossils?c) Primates are a unique group because most if not all o f the major

steps in their evolution have some members still extant and at least morphologically like the common ancestor.1) In order of first being found in the fossil record the general

groups go lemurs, new world monkeys (NWM), old worldmonkeys (OWM), anthropoid apes, hominids

d) The following chart will relate the social behavior o f groups to their diet, especially their main source of protein

Source of protein insects leaves vertebrate fleshBody size small large largeLitter size 1 – 3 1 1Gestation period 1.5-3 mo. 4 -8 mo. 9 mo.Care of young in nest or mother carries male and female

father carries parental carePredatory defense fleeing troop aggression troop aggressionMating system promiscuous promiscuous polygynous to

monogamous polygynous protandrous bondmonogamous 1st

Home range small small largeTaxonomic groups lemurs lemurs humans

small NWM large NWMgibbon OWM

chimps gorillaorangutan

e) Notice that taxonomic grouping does not follow phylogeneticlines. i.e. all major groups are split except old world monkeys

f) the grouping follows the ecological factor of the food source ofprotein

g) Primates start out similar to arboreal shrews in1) having a rich protein diet allowing2) rapid growth and large litters3) food supply has low density and is hard to catch with large

effort allowing only a small body size4) individuals are not in large social groups because it would

inhibit catching insects5) small size and small social unit prevents joint aggression

against predators as a predator defense6) young in nest nursed by mother in promiscuous mating system

or male carries young in a pair bond with mother leading to monogamy

7) home range small because individuals and groups are small =often monogamous pairs defend territories

h) The switch to an increased amount of fruit as an energy source of carbohydrates and finally to young leaves as a source of protein.

1) more food needed because plants are less digestible and morefood available because in a lower trophic level.

2) lower relative ratio of protein to carbohydrate leads to slower development rate and lower litter size.

3) young carried by female because less of a problem when mother is feeding on plants rather than trying to catch insects

4) Plant diet allows or even forces larger body size for big gut. Large body size allows predator defense by joint aggressionespecially by large males freed of participating in parental care and are more likely to be sexually dimorphic by fighting for breeding rights. Also, individuals group in the few trees infruit leading to troop social structure.

5) Mating system is polygynous or promiscuous depending on how many males in a troop.

6) Home range is not much larger because food is more plentifulin the lower trophic level.

7) The switch is not phylogenetic, but has occurred withina) lemurs on Madagascar where nocturnal lemurs are small and

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insectivorous and diurnal lemurs are large and eat plant material

b) New World monkeys include small monogamous insectivorous marmosets where the males carry the young andlarge troop-living howler monkeys that eat leaves and fruit and are promiscuous

c) The anthropoid apes include monogamous gibbons that eat mainly fruit and some leaves and gorillas that are herbivores

i) The steps that led from eating plant protein to protein from largevertebrates include1) Anthropoid apes brachiate in locomotion, i.e. use their arms

for locomotion separate from their legs and can swing throughthe trees with the arms. Brachiating is best developed in gibbons, but also used in other anthropoid apes. The hominidline that developed from this ancestry but invaded open savannah habitat used the hind legs more for locomotion freeing the fore legs for tool use.

2) Both baboons and chimpanzees use the flesh of young ungulates for food when they chance on a new born. Chimps beg from each other and share pieces of the animal as though itwas their favorite food. For a primate in a savannah habitatthere would be much more food.

3) Australopithicus are the first fossils in the hominid line showing up in the fossil record about 3 million years agoleaving a 3 to 4 million year gab to the common ancestor withchimpanzees if the DNA clock is correct. Australopithicus walked upright, but was still mainly vegetarian on the basis ofit teeth.

4) Homo erectus was the first hunting hominid using crude stone tool and having large amounts of animal remains in deposits with its remains. It is in the evolution of Homo erectus that thesize of the brain doubles and human intelligence and probablyspoken language become important.

5) Hunting is thought to have favored a) division of labor between males hunting meat and females

gathering plant materials still important in the diet.b) large home ranges in which to hunt food at a higher trophic

level.c) pair bonding between a male and a female providing food for

each other and their offspring. Mating systems were monogamous before the advent of agriculture.

d) interdependence and reciprocal altruism, or returning favors with “friends”, was dependent on1) long life2) living with the same individuals over a long time3) giving large benefits with small cost4) opportunity for reciprocation5) lack of strong dominance order

e) reciprocal altruism is thought to be the pressure for increasedbrain size, self awareness, and the interest in moral codes which are uniquely human. You had to be able to put yourself in your friends place to see if he or she was cheating you in reciprocation of your altruism.

f) All of this consideration of reciprocal altruism is based onmeat as too large for one individual to effectively use all at once and the small cost of doing the large favor of sharing. Also, the sharing of male hunting products with femalegathering products would be an important base for reciprocalaltruism.

j) A final major change in resource base came with agriculture andanimal husbandry.1) resources much more concentrated2) children would become of value in resource exploitation at a

much younger age3) Polygamous mating systems more prevalent as material wealth

could be more effectively accumulated by individual males allowing males to support more wives and children

4) All changes would be basically cultural rather than genetic i n last 10,000 year.