Model 3 Biological Diversity

1. Selection pressures on organism in ecosystems

Key concepts to understand; Favourable characteristics ( adaptations) Evolution by natural selection

Definitions Specie diversity The number of different species and the abundance of each species in

an ecosystem

Ecosystem Any area that contains a community Other living things That interact

with each other and their environments. Ecosystems can be described in terms of The specie they contain

Selection pressures

A combination Abiotic And biotic Factors As well as human activity

Abundance; The number of individuals per Specie In a specific Area At a specific

time

Selection pressures in an ecosystem

Biotic Factors The living Components Or biological features of an environment, Including animals, Plants and microorganisms

abiotic factors The nonliving components of an environment (physical and chemical features)

o Seasonal availability and abundance of food

o The number of competitors o The number of mates available o The number of predators o The number and variety of disease

causing organism

o Temperature à Enzymes in cell o Light availability o Water o Availability of gases ( oxygen and carbon

dioxide) o Soil type o Exposure to natural forces ( wind, tide,

waves)

Inquiry question; How do environmental pressures promote a change in species diversity and abundance?

- Species diversity - Selection pressures à climate, space to live, disease, compotation for food, human

impact, human activity ( e.g pollution and land clearing ) - Ecosystems

Model 3 Biological Diversity

2. Investigation changes in a population of organisms due to selection pressures over time

Organism Change in Abundance and distribution

Selection pressures- change

Cane Toads o Abundance has increases as

they have no predators to kill them

o Destruction; they were introduced from Hawaii in 1935

o Due to having no predators and

natural diseases. The cane toad has become a pest in Aus

o No successful selection pressure o Companion with themselves so

they eat each other

Prickly pears o Introduced in 1800s o Adapted quickly – au’s

diverse environment and dry environment

o No predators o Cactoblastis moth ( biotic

pressure reduced numbers)

3. Conduct practical investigation, and structural, behavioural and physical adaptations

An adaptation may be:

Structural – shape and size of an organism and it’s various body parts eg. kangaroo’s powerful

leg muscles assist it in hopping at high speeds

Physiological – relating to the way the organism functions, how it’s body works eg. human

sweating which assists in heat loss

Behavioural – how an organism responds to its environment eg. penguins huddling together

to stay warm

Inquiry question; how do adaptations increase the organism's ability to survive - Population - Habitat - adaptations

Model 3 Biological Diversity

Results to the experiment below

Leafe Structural adaptation How this aids survival Hakea plant o Waxy coating on upper

surface o Hair on lower surface

o Waxy coating proviants water loss from the STONE MATES on the upper leafed surface

o Hairs on the underside of the leaf prevents water loss, water vapour is trapped in the hairs and creates a hummed environment

Elephant ear

o Large flat leaf ( SA) o Dark green

o Large surface area o Lives in shard ( low light)

needs to capture as much light for photosynthesis

o Dark green – more chorofill in there chloroplast

Eucalyptus

o Waxy coating o Pail colour

o Waxy coating – SONE MATS

o Pale colour to reflect the heat therefore there is less evaporation of water ( less water loss)

Practical : Observation of Structural Adaptations in Plants

Aim

To observe macroscopic structural adaptations of the leaves of five plants and relate these to

increased chances of survival.

Equipment

Disposable gloves

Forceps

Binocular microscope

Camera

Leaf samples of Australian schlerophyll plants such as Hakea, eucalypt, wattles and succulents.

Model 3 Biological Diversity

Risk Assessment

What is the risk? Why is it a risk? How can we minimise the risk?

Plant irritants

Can cause an allergic response Were gloves or wash hands

Plant thorns

Cuts skin and can lead to infection Use forceps to hanndel plant

Method

1. Collect 5 leaves and carefully observe each sample.

2. Place each leaf in turn under the binocular microscope to view structures more closely

3. Record any adaptations that enable the plant to conserve water/obtain light/maintain

temperature

4. Draw or take a photo of each leaf. Label the specific adaptations observed.

5. Construct a table in the space below to include the name of plant, natural environment,

structural adaptation and how each adaptation assists in the plant’s survival.

4. Darwin’s observation and data supporting the theory of evolution by natural selection

The theory of natural selection (Darwin)

1. In any population there are VARITATION between the individuals. More offspring are produced than are needed and there is a constant struggle for survival

2. Those individuals with FAVOURABLE CHARCTERISITICS (ADAPTATIONS) are selected by the environment to survive and reproduce. Those without favourable characteristic are removed from the population

3. The individuals with favourable characteristics REPRODUCE and pass on these

favourable characteristic to their offspring

4. Over time these favourable characteristics become MORE COMMON in the population

Model 3 Biological Diversity Finches - The Galapagos islands

è Finches on the island shows Distinctive

characteristics à beak structure è Only a few finches migrated to the island AND

that each of the different finches had EVOLVED from a COMMON ACESTORS.

è Evolved different beak structures to make use of the different food source’s on the island.

Australian Flora and Fauna

Darwin Noticed è Platypus are similar to water rats in England è Magpies and crows are similar to jackdaws in England è Potoroos ( rat kangaroos) are similar to rabbits

è unrelated animals- living in the same environment

• shared similar adaptation • meaning environment pressures play a large role • selecting those that survive.

5. Modern day examples that demonstrate change

Cane toads – describe in Dawns theory of evolution

è Invasion on new territory from 10-15km per year è Faster hopping style è Cane toads witch had a favourable characteristic – survived è Those reproduced- passing on to the offspring è This became more common

Antibiotic resistant strains of bacteria

è Vernation in bacteria, same resistant to anti- biotic è Resistant bacteria with favourable characteristic survive, non- resistant bacteria die è Resistant bacteria reproduce pass on resistance to offspring è Resistant in bacteria are more common

Model 3 Biological Diversity

6. Explaining biological diversity in terms of the theory of evolution

Biological diversity or biodiversity refers to the variety of life forms on earth • Diversity of characteristics • Variety of ecosystems they inhabit

We depend on biodiversity to substance us

• Oxygen • Carbon dioxide • Food

• Medicine • Fuel • Water

Biodiversity exists on 3 different levels Genetic diversity The total number of genetic characteristics

in the genetic makeup of a species ( this can change due to selection pressures)

Species diversity Measure of diversity of different species in an eco-logical community

Ecosystem diversity Variations of different eco-system found in a region

Timeline about life on earth

Inquiry question; what is the relationship between evolution and biodiversity? - All organisms have developed from pre-existing organism - A common organ - Over billions of years, change in life on earth causes the biological diversity (

biodiversity)

Model 3 Biological Diversity 7. How microevolutionary changes can drive evolutionary changes and speciation

è Evolution at both micro and Macro levels establish evolution change, including

natural selection è Natural selection evolves over time

• the environment constantly challenges organisms • Selecting those characteristics that best adapt to the environment • Only the ‘ fittest’ will survive

Key terms Microevolution Evolution changes on a small scale within a single population, a

change in gene frequency over a short period of time Macroevolution Evolution on a large scale that takes place over millions of years

and results in new species Speciation The process which produces two or more species, often because

of geographical isolation

Speciation

è Diversification of species and branching into two or more species

• occurs as group adapt to different environments.

è Isolation occurs a species may form into distinct breeding populations.

• Selection pressures are often not the same when the population are in different environments.

• As a result, the environments select for different adaptations.

Evolution of the horse- Microevolution

è Horse is traced using • fossil records of lower leg bones • hooves • teeth

è horse evolution is believed to have been driven by

• Environmental selection pressures • Cool and drying climate

Model 3 Biological Diversity

è horses were once more abundant and diverse than they are today • Hyracotherium

§ flexible 4 towed feet • Medium sized ( mesohippus and merychippus)

§ grinding surfaced in their teeth § Eating grass § Became faster to flee predators

• Modern horse and piohippus § running on hard surfaces § elongated foot bones for longer stride

Evolution of the platypus- microevolution

è The platypus is a monotreme (an egg- laying mammal) è relationships between members of the platypus family

• ornithorhynchus platypus ( 100 000 years to

present) § toothless living platypus § (60cm long) smaller

• obdurodon tharalkooschild platypus ( largest

species of platypus found) § toothed platypus § feed on wide range of

animals

• Obdurodon may be a closer relative of the living platypus

§ toothed with fully rooted molars

• modern day platypus § duck billed § toothless § semi aquatic § webbed feet § tail like a beaver § covered in short waterproof fur

Model 3 Biological Diversity 8. Darwin and Wallace’s theory of evolution by natural selection

è Evolution of a species involes a CHANGE in CHARACTERISTICS ( GENETIC MAKEUP) OF

A POPULATION OVER TIME • Isolation ( GEOGRAPHICAL) • MUTATION and or SEXUAL REPRODUCTION ( PROVIDING a SOURCE OF

VARITATION IN A SPECIES) • NATURAL SELECTION

Divergent Evolution occurs when different species arise from a common ancestor

due to isolation from one another and adaptation to different enviroments

Natural selection can result in changes within a species If a population is ISOLATED in two different environments. If the changes in these isolated population becoming so different a new species may be formed ( SPECIATION)

Splitting A species could SPLIT FAIRY EQUALLY into TWO POPLUATIONS that evolve differently until they eventually become separate species

Budding

A small part of the SPECIES POPULATION COULD “bud off” from the MAIN PART and EVOLVE RAPIDLY ( in geological time ) to form a NEW SPECIES while leaving MOST OF THE ORGINAL SPECIES POPULATION UNCHANGED.

Convergent Divergent Parallel evolution

Model 3 Biological Diversity Convergent evolution Is a process that leads to SUPERFICIAL SIMILARITIES IN DIFFERENT

SPECIES that are NOT closly related. This is due to these ORGANISM LIVING in the SAME HABITAT or having the SAME LIFESTYLE so they are exposed to the SAME ENVIROMENTAL SELECITION PRESSURES. Natural selection can explain why they have similar characteristics even though they are distantly related.

è Convergent evolution has led to a dophin ( mammal), shark ( fish) and penguin ( bird) all having a streamlined shape due to the environmental SELECTION PRESSURES of the aquatic enviroment.

Shark Dolphin Similarities Streamlined

o body shape o colour

o fins and flippers Differences o Fish

o Cartilaginous skeleton o Ectothermic o Produce eggs

o Mammal o body skeleton o Endothermic o Produce live young

Model 3 Biological Diversity 9. The difference between punctuated equilibrium and the gradual process of natural

selection.

The rate of evolution has been much debated , with two model being proposed è Punctuated equilibrium – proposed by Stephen Jay Gould in 1970s è Gradualism – Dawins

Punctuated equilibrium A model of evolution that is backed by sufficient fossil

evidence which shows that some species remained essentially the same way for millions of years and then underwent short periods of very rapid major change.

è This means that most of a SPECIES existence is spent in STASIS and little time is spent

in ACTIVE EVOLUTIONARY CHANGE è The STIMULUS for rapid evolutionary change is when some crucial factor in the

environment changes • Volcanic activity • Glaciation

è The fact that there are VEARY FEW TRANSITIONAL FORMS in the fosil record supports the idea

Gradualism Dwain’s long- held view that evolutionary change occurred gradually over a long period of time

è There is evidence in the FOSSIL RECORD TO

SUPPORT GRADUALISM. • The evolution of the horse

Model 3 Biological Diversity

10. Evidence supporting Darwin and Wallace’s theory of evolution by natural selection?

The Theory of evolution

è The theory of evolution states that LIFE FORMS ON EARTH HAVE GENETICCALLY CHANGED WITH TIME.

• Different species have GRADUALLY developed in response to changing environments.

• These changes have usually occurred SLOWLY over millions of years. è Over time species have not remained constant- they have changed.

• New species have arisen • others have become extinct

è There has been a general change of SIMPLE TO MORE COMPLEXT forms of life

Biochemical evidence Involves the study of the structure and function of the many chemicals that are found in living organisms.

è The FEWER the differences in base sequence ( order) the more CLOSELY related the

organism is.

è In this technique the EXACT order of NUCLEOTIDE BASES in the gene ( DNA) of one species is COMPARED with the SEQUENCE in a similar DNA section of a second species.

Advantages of Biochemical evidence Limitations of Biochemical evidence o It allows comparison of organisms o The results are quantitative and the

degree of difference can be measured • Allowing judgment based on

scientific critter rather than observation

o DNA revels the most detailed information

o Techniques are • complex • expensive • rely on highly specialised

technology • can only be performed in labs

Inquiry question; what is the evidence that supports the theory of evolution by natural selection?

- Studies of fossils - Geology - Living organisms - Biochemistry - Comparative - Embryology - biogeography

Model 3 Biological Diversity Comparative anatomy Similar anatomy across different species provide evidence of a

common origin

è compare the anatomy of different organisms we find examples where • different species have similar basic structures

è it provides evidence of a COMMON ANCESTOR

è Similar anatomy actors different species is referred to as HOMOLOGOUS STRUCTURES • Frogs, whales, lions, humans and bats have

similar structure § All have humours bone § Radius bone § Ulna bone

• Proportionate length of these bones varies

depending on how they have been modified as adaptions to different environments

§ Swimming § Flying § Walking § grasping

Comparative embryology Provides evidence for evolution since the embryonic forms of divergent groups are extremely similar

è if we compare the embryos of many different species in the early stages of

development they are very similar è provides evidence of a common ancestor

è Example

• all vertebrate embryos have § gills slits § arches § notochords § spinal cords § primitive kidneys

• fish embryos and human embryos both have gill slights § in fish they develop into gills § In human they disappear before birth

è Depending on the species the skin then deveopls into • Fish scals • Bird feathers or hair • Clasws • Nails of mammals

This is an example of how the structure of embryo’s in the early stages of development appears to be similar

Model 3 Biological Diversity But

The structure carries out different functions as they develop into organs.

Biogeography Is the study of distribution of species in different geological regions on the earth

è Earth has a number of biogeographical

regions each with its own environmental features ( selection pressures)

• each regions contains species with specific adaptions that increase there survival

è distribution patterns provide evidence that species have originated from a COMMON ACESTOR and when ISOLATED, have evolved into NEW SPECIES

è evolution is in conjunction with the moment of tectonic plates over time

Fossils Any preserved remains of past organisms

è The development of techniques to date fossils provides scientist with a more accurate picture of

• How life on earth was formed • Which species evolved first and the evolutionary order of species • How species evolved to occupy diverse and changing ecosystems • Timescale of evolution • When certain major events occurred

Fossils

Relative dating techniques

Provides evidence of the sequence of geological events but not the exact dates of an event.

Absolute dating techniques

Eliminates that decay spontaneously at a defined rate; the rate of decay is used to date the formation of igneous rocks

Radioactive dating techniques

For fossils less then 6000 years old. Involves measuring the amount of C-14 isotopes to provide evidence of the data of organic material in fossils