A4. 1 Evolution

Darwin’s Evolution

The theory of evolution by natural selection

Linnaean Society

1858

Darwin and Wallace

Evolution

Process of cumulative change in the heritable characteristics of a population over generations

World heritable

Changes must be passed genetically from generations

Evolution does not happen overnight

Speciation

New populations will be different enough from the pre existing population that they will no longer be able to inter-breed

Modern genetics/ neo-Darwinism

Combination of Darwin ideas with newer ideas of genetics

Fundamental insight = common ancestry

Lamarckism

organisms acquire characteristics through lifetime and are passed down to their offspring

Kangaroos: limbs and tail are strong

Atrophy in forelimbs due to unused

Use of biochemical evidence

examine evolutionary relationships

→ allows comparison of nucleic acids and protein data

→ explains gills in embryos

Cons of using DNA for examining sequences

→ not helpful for seeing which animals are most closely related

Phylogenic tree

only maps 1 gene

outlines the differences of the genes in mammals and which species are most closely related in that gene

Selective breeding

Controlling reproduction to predict offspring characteristics to choose agriculturally desirable genetic characteristics

Artificial selectio

Farmer and breeder choice of survival

Teosinte

100,000 years ago, farmers saved seeds with most desirable characteristics

Artificial selection = corn

Homologous Structures

Derived from same body part of common ancestor

Specific function of the limbs may be very different

Same body part

Prove that organisms in question share a common ancestor they have evolved from

Analogous Structure

Parts may have same function but not necessarily same body part

DO NOT indicate common ancestor

Wings = evolved from different body parts but have same morphology, all animal kingdom but not same taxon

Phylogeny

Process of speciation, ways species split from another species

Convergent Evolution

Independent evolution of similar features in species of different periods or epochs in time

Analogous features provide this as it is the evolution of specific body parts for a similar function but do not indicate common ancestor

Divergent evolution

What occurs when two groups of the same species evolve different traits within those groups in order to accommodate for differing environmental and social pressures

Speciation by divergence of isolated population

If a subgroup of reproducing population is separated from main population it might evolve differently

e.g iguana adaptation

Extinction

When last individual of a species dies out

Factors of reproductive Isolation

Barriers reventing isolation

• geographical

• temporal

• behavioral

Reproductive isolation

Evolution of 2 different species in different ways preventing reproduction to produce fertile offspring

Bonobos & Chimps

Prevented by geographical barriers, (Congo River) to reproduce

Different habitats lead to different food availability and behavioral traits