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Chapter 5

This document defines key terms related to evolution such as evolution, homologous structures, and adaptive evolution. It then summarizes several topics related to evolution including the incompleteness of the fossil record, evidence for evolution from homologous structures like the pentadactyl limb, distinguishing between analogous and homologous structures, types of evidence that support evolution, different types of evidence for evolution, the process of speciation, and an example of adaptation by natural selection in moths.

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116 views2 pages

Chapter 5

This document defines key terms related to evolution such as evolution, homologous structures, and adaptive evolution. It then summarizes several topics related to evolution including the incompleteness of the fossil record, evidence for evolution from homologous structures like the pentadactyl limb, distinguishing between analogous and homologous structures, types of evidence that support evolution, different types of evidence for evolution, the process of speciation, and an example of adaptation by natural selection in moths.

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Term Definition

Evolution A cumulative change in the genetically controlled characteristics of a population

Homologous Similar structures found in animals with a common ancestry

Adaptative Evolution The rapid evolutionary diversification of a single ancestral line

Species A group of organisms that interbreed to produce fertile offspring

Define Evolution
- Change in genetic characteristics of a population
- New species arise from pre-existing species
- Adaptation of a population due to natural selection

Outline the incompleteness of the fossil record and the resulting


uncertainties about human evolution
- Few hominid fossils have been found
- Most organisms are not preserved
- Only teeth and bones remain
- Require certain conditions for preservation
- Earlier cultures did not bury the dead
- Acids dissolves teeth and bones
- Many missing intermediate stages of fossils
- Difficult to get conclusive evidence
- Theories change radically with few discoveries

Describe the evidence for evolution provided by the vertebrate


pentadactyl limb
- Comparative anatomy provides evidence for evolution
- Pentadactyl limb is limb-bone pattern found in vertebrates
- Adapted to different functions
- Organs having similar basic structure
- Development as structures in other species said to be homologous
- Homologous anatomical structures derived from a common ancestor
- Are examples of adaptive radiation
- Seal’s forelimbs adapted for swimming, human’s for manipulating

Distinguish between analogous and homologous structures


- Same function/Different function
- Differ in structure/Similar in structure
- Convergent evolution/Divergent evolution
Outline the types of evidence that can be used to support the theory of
evolution
- Fossils: Show species changed over time
- Selective breeding of animals
- Shows selection can cause rapid change
- Homologous structures
- Pentadactyl limbs show common ancestry
- DNA sequences show species diverged

Describe the different types of evidence for evolution


- Geographical distribution: Ring species
- Biochemistry: Cytochrome C
- Fossils: Fossilised horse ancestors
- Homologous structures: Pentadactyl limb
- Recent observed evolution: Resistance to antibiotics

Outline the process of speciation


- An existing population is split
- Reproductive isolation
- Ecological isolation
- Isolation due to geography
- Polyploidy can cause isolation
- Gene pools separated
- Differences in selection cause gene pools to change
- Eventually can no longer interbreed

Describe one example of adaptation by natural selection shown by moths


- Black variety of moth arose as a result of a mutation
- Called polymorphism
- Black form caused by a dominant allele
- Black caused by production of melanin
- Industrial pollution caused death of lichens on trees and rocks
- Many buildings, rocks, and tress became blackened
- Melanic variety became better camouflaged than light form
- Results in less predation by birds
- Black variety increased at the expense of the light variety
- As pollution decreased the lichens recovered and conditions favoured the light form
- Light variety increase at the expense of the dark variety

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