Chapter 5

Figure 5.2 (a)

Figure 5.2 (b)

Figure 5.3

Figure 5.4 (a)

Figure 5.4 (b)

Figure 5.6 (a)

Figure 5.6 (b)

Species and Speciation

• Fundamental unit of classification is the species.

• Species = a group of populations in which genes are actually, or potentially, exchanged through interbreeding.

• Problems– Reproductive criterion must be assumed based on

phenotype and ecological information.– Asexual reproduction– Fossil – Geographical isolation

Reproductive isolation leads to Speciation- the formation of new species

• Requirement – Subpopulations are prevented from interbreeding– Gene flow does not occur (Reproductive isolation)

• Reproductive isolation can result in evolution

• Natural selection and genetic drift can result in evolution

Allopatric Speciation

• geographical isolation

• Adaptation to different environments

• Genetic drift

• Results in members not being able to mate successfully

• Most common type of speciation

• i.e. Galapagos island Finches

Geographic barrier divides a population3 subpopulation of Freshwater fishA, A1, and A2

Fig 5.7 Allopatric Speciation:

Genetic exchange occurs between A and A1 and between A1 and A2.Exchanges less likely in A and A2

Rise in water forces the breakup of A1 and makes A and A2 separate populations.

Genetic drift and different selection pressures result in B and C

Sympatric Speciation

• Occurs within a single population

• Even though populations are together (sympatric) they may be reproductively isolated

To demonstrate sympatric speciation

Researchers

• Demonstrate species share a common ancestor

• Arose without geographical isolation

• i.e. studies of indigobirds from Africa

Morphological variation between indigobird species

Nestling mouth markings in V. camerunensis (a) and V. chalybeata (b) mimic the young of their firefinch hosts, L. rara and L. senegala, respectively. Dark wing and plumage in V. chalybeata from West Africa (c). Pale wing and green plumage in V. raricola (d). White bill and blue plumage in V. camerunensis (e). Red bill and orange feet in V. chalybeata from southern Africa (f).

Figure 5.8

Rates of Evolution

Fig 5.1 Speciation of Darwin’s Finches

Warbler

Fig 5.1 (b) Large ground finch

EOC Figure

Opener Chapter 7

Chapter 7

Animal Classification, Phylogeny, and Organization

Common names• Crawdads, crayfish, or crawfish?• English sparrow, barn sparrow, or a house sparrow?

Problem with common names• Vary from region to region• Common names often does not specify particular species

Binomial system of Nomenclature brings order to a chaotic world of common names

• Universal

• Clearly indicates the level of classification

• No two kinds of animals have the same binomial name

• Every animal has one correct name International Code of Zoological Nomenclature

• Genus begins with a Capital letter

• Entire name italicized or underlined

• Homo sapien or H. sapien

Kingdom of Life

1969 R. Whittaker- five kingdom classification

System of classification that distinguished b/w kingdoms according to

• cellular organization

• mode of nutrition

Monera- bacteria and cyanobacteria are prokaryotic

• Protista- single or colonies of eukaryotic cells (Ameoba, Paramecium)

• Plantae- eukaryotic, multicellular, and photosynthtic. Have cell wall, and usually nonmotile

• Fungi-eukaryotic and multicellular. Have cell wall and nonmotile. Mode of nutrition distiguishes fungi from plant- fungi digest extracellularly and absorb the breakdown products

• Animalia- eukaryotic and multicellular, usually feed by ingesting other organisms, cell lack cell walls, and usually motile

Figure 7.2 (a)

Challenge of the five class system

• Ribosomal RNA excellent for studying evolution

• rRNA changes very slow (evolutionary conservation)

• Closely related organisms have similar rRNAs

• Comparison of rRNA of different organisms concludes

• All life shares a common ancestor

• Three major evolutionary lineage (domains) and supersedes the kingdom as the broadest taxonomic grouping

The three domains

• Arhaea- prokaryotic microbes live in extreme environments, inhabit anaerobic environments

• Reflect the conditions of early life

• Archaea the most primitive life form

• Archaea give rise to two other domains– Eubacteria- true bacteria and are prokaryotic

microorganisms– Eukarya- include all eukaryotic organisms, diverged

more recently thus more closely related to archae (protists, fungi, plants and animals)

Figure 7.2 (b)

Text devoted to animals

• Except for Chapter 8 Animal like protists (Amoeba and Paramecium)

• The inclusion of protozoa is part of a tradition

• Once considered a phylum (Protozoa) in the animal kingdom

Pattern of Organization

• Symmetry

• Asymmetry

• Radial symmetry

• Bilateral symmetry

Figure 7.7 Asymmetry red encrusting sponge

Figure 7.8

Radial symmetry tube coral pulp

Part 2

Acoelomate Bilateral Animals

• Consist of phyla:– Phylum Platyhelminthes

– Phylum Nemertea

– Others…

Bilateral animals

• Bilateral symmetry = important evolutionary advancement– Important for active, directed movement

• Anterior, posterior ends

– One side of body kept up (dorsal) vs. down (ventral)

Directed movement evolved with anterior sense organs cephalization

Cephalization– specialization of sense organs in head end of animals

Bilateral Symmetry

• Divided along sagittal plane into two mirror images– sagittal= divides bilateral organisms into right and left

halves

• Anterior= head end

• Posterior= tail end

• Dorsal= back side

• Ventral= belly side

• Symmetry, fig. 7.9– Median= sagittal

Other Patterns of Organization may reflect evolutionary trends

• Unicellular (cytoplasmic)- organisms consist of single cells or cellular aggregates, – provide functions of locomotion, food acquisition,

digestion, water and ion regulation, sensory perception and reproduction in a single cell.

– Cellular aggregates consist of loose association, cells that exhibit little interdependence, cooperation, or coordination of function

– Some cells may be specialized for reproduction, nutritive or structural function

• Diploblastic Organization– Cells are organized into tissues in most animal phyla– Body parts are organized into layers derived from two

embryonic tissue layers.– Ectoderm- Gr. ektos, outside + derm, skin gives rise to

the epidermis the outer layer of the body wall– Endoderm- Gr. Endo, within, gives rise to the

gastrodermis that lines the gut

Mesoglea- between the ecto and endo and may or may not contain cells

– Derived from ecto and/or endo– Cells form middle layer (mesenchyme)

– Layers are functionally inderdependent, yet cooperate showing tissue level organization i.e. feeding movements of Hydra or swimming movements of a jellyfish

Figure 7.10

The Triploblastic (treis, three +blaste, sprout)

• Animals described in chapters 10-22

• Tissues derived from three embryological layers

• Ectoderm- outer layer

• Endoderm- lines the gut

• Mesoderm- meso, middle, Third layer between Ecto and Endo– Give rise to supportive cells

Figure 7.11

• Most have an organ system level of organization

• Usually bilaterally symmetrical or evolved from bilateral ancestors

• Organized into several groups based on the presence or absence of body cavity and for those that posses one, the kind of body cavity present.

• Body cavity- fluid filled space in which the internal organs can be suspended and separated from the body wall

Body cavities are advantageous

1. Provide more room for organ development

2. Provide more surface area for diffusion of gases, nutrients, and waste into and out of organs

3. Provide area for storage

4. Often act as hydrostatic skeletons (supportive yet flexible)

5. Provide a vehicle for eliminating wastes and reproductive products from the body

6. Facilitate increase in body size

What does acoelomate mean?

No coelom

Acoelomate a, without+ kilos, hollow

• Mesoderm relatively solid mass

• No cavity formed between ecto and endo

• These cells within mesoderm often called parenchymal cells

• Parenchymal cells not speciallized for a particular fnc.

What’s a coelom?

• coelom= – true body cavity– Fluid-filled– lined by mesoderm-derived epithelium

Earthworm

• Acoelomates lack a true body cavity– Solid body

– no cavity b/w the digestive tract and outer body wall

Do these questions now…

• Think about aceolomate bilateral animals: – To what domain do they belong– “ ” kingdom ” ” ”– What phyla include these organisms

• What is bilateral symmetry, and why was it an important evolutionary advantage

movie

Acoelomate Bilateral Animals

Reproductive and osmoregulatory systems

1. Simplest organisms to have bilateral symmetry

2. Triploblastic

3. Lack a coelom

4. Organ-system level of organization

5. Cephalization

6. Elongated, without appendages

Acoelomate Bilateral Animals

Reproductive and osmoregulatory systems

1. Simplest organisms to have bilateral symmetry

2. Triploblastic

3. Lack a coelom

4. Organ-system level of organization

5. Cephalization

6. Elongated, without appendages

Triploblastic Pseudocoelomate pseudes, false

• Body cavity not entirely lined by mesoderm

• No muscle or connective tissue associated with gut

• No mesodermal

The Triploblastic Coelomate Pattern

• Coelom is a body cavity completely surrounded by mesoderm

• Peritoneum- mesodermal sheet that lines the inner body wall and serosa (outer covering of visceral organs)

• Having mesodermally derived tissue (muscle, connective tissue) enhances the function of all internal body systems.

Figure 7.12

Figure 7.3

Fig 7.3 Evolutionary groups

All descendants of a single ancestor

Includes some but not all of a members of a lineage

Groups traced to separate ancestors

Figure 7.4

Fig 7.4 Vertebrate Phylogenetic tree depicts the degree of divergence from a common ancestor

Figure 7.5

Fig 7.5 Interpreting Cladograms Five taxa (1-5) and characteristics (A-H)

Symplesiomorphies- common characters in a group

Figure 7.6

EOC Figure