Two important terms Fitness ◦ Survival and reproduction Adaptation ◦ A relative increase in fitness.

Fitness◦ Survival and reproduction

Adaptation◦ A relative increase in fitness

What it isand

What is NOT

A. TrueB. False

A. TrueB. False

A. TrueB. False

Increase in complexity, organization or specialization may occur

No specific end goal in mind, however There is no trend toward more advanced

forms, could just as easily go in reverse (oscillating selection).

The following claim is often made: “Of course individuals with favorable

variations are the ones that survive and reproduce because the theory defines favorable as the ability to survive and reproduce.”

What is wrong with this argument?

A. TrueB. False

Where does variation come from? How are traits inherited from parents?

Mayr article discussion

A. GeneticistsB. Naturalists

•Studied biodiversity and origin of new taxa•Macroevlolution•Properties in individuals are objects of selection•Speciation is a gradual accumulation of changes

Genetics◦ Based on small changes within populations◦ Microevolution◦ Gene is the object of selection◦ Mutations lead to saltational speciation

Naturalists◦ Studied biodiversity and origin of new taxa◦ Macroevlolution◦ Properties in individuals are objects of selection◦ Speciation is a gradual accumulation of changes

First what was well accepted? ◦ Change in organisms occurs over time◦ The branching theory implying common descent

What had difficulty being accepted?◦ That evolution was a gradual process◦ That species multiplied (increase in diversity)◦ That natural selection was the means

Scientists worked in isolation in different countries. Beliefs in each country were dictated by the most powerful scientists.

Scientists in different branches of biology had different prevailing ideas

Each group thought that the other group had no flexibility in their beliefs.

Geneticists◦ Worked in labs and studied the processes in single

populations◦ Only examined changes within a population-

microevolution ◦ Believed each mutation led to a new species◦ Believed speciation was saltational◦ Gene is the object of selection

Developed mutation theory Any new variation caused by mutation was

actually a new species Emphasized random genetic variation (no

guidance by selection) Speciation abrupt and spontaneous

◦ Studied biodiversity and the origin of new species and higher taxa - macroevolution

◦ Changes occur gradually as Darwin said◦ Individual is object of selection not the gene◦ New species are formed by geographic isolation

A. NaturalistB. Geneticist

Geneticists also called mutationists◦William Bateson and Hugo DeVries ◦ Other geneticists who also believed evolution was

gradual were not as well known to naturalists. Edward East and Sergei Chetverikov.

◦ Moritz Wagner ◦ Karl Jordan◦ Edward Poulton◦ Sergei Chetverikov◦ Erwin Stresemann◦ Ernst Mayr and ◦ Julian Huxley

A. Thomas Hunt MorganB. Theodosius DobzhanskyC. Ledyard StebbinsD. Ernst MayrE. R. A. Fisher

Thomas Hunt Morgan – his research was a key factor in the synthesis◦ He showed (working with Drosophila) that

mutations occurred in every generation and that the resulting populations were reproductively

isolated and were not new species. Mutations simply increased the variability of a

population. Theodosius Dobzhansky – was a naturalist in

Russia, came to US and worked in Morgan’s lab◦ He saw how they were complimentary to each other.

Mutations provide the new alleles that increases variation in populations.

◦ Geographically separated populations can then respond to different environments

gradually, become separate species. Over more time new higher taxa can emerge.

Selection acts on individuals but has its effects in populations.

Population genetics and microevolution. ◦ R.A. Fisher – mathematician showed variability in

populations could be explained using Mendel’s laws Genetical Theory of Natural Selection Believed selection was favored in large populations because

variability remains high due to mutation and genetic recombination

Selection acts uniformly and slowly◦ J.B.S. Haldane

Same basic understanding as Fisher but he emphasized the use of practical examples for his models ( e.g industrial melanism and moths)

Sewall Wright Mathematical techniques to show that evolution could

proceed in isolated groups Developed the ideas of genetic drift. (based on the work of

William Castle)

John Maynard Smith◦ Extended the Darwinian theory to explanation of animal

behavior Ledyard Stebbins –

◦ did for plant evolution what Dobzhansky with his fruit flies had done for animal evolution

George Gaylord Simpson◦ Reinterpreted the fossil record◦ Major responsibility for paleontologists embracing

Darwin's ideas.

Showing the same trend only in opposite direction

1. Direct Observation of Change Through Time

Anatomical

2. Evidence from vestigial structures

Embryonic or developmental

Embryonic Vestigial structures

Vestigial Genes

Gene for CMAH enzyme (processes a sugar found on surface of chimp cells) ◦ DNA sequence for the gene is found in both humans

and chimps◦ However the gene is disabled in humans by a deletion

Causes a different biochemical signature on the surfaces of human and chimp cells.

Gene in humans is leftover from a common ancestor that humans share with chimps

Evidence against a separate origin for humans.

A test for interpretation of vestigial molecular traits Can anyone relate this story on page 43? Heavy plating in marine Light plating in fresh water Cresko and colleagues identified that most of the

control for this trait was due to 2 Mendelian-inherited genes

Predicted rapid evolution from marine to fresh water form

This was later demonstrated by the experiments of Michael Bell

1. Extinct species

The fossil record provides many examples of species that once lived on the earth but are now extinct.

Irish Elk

2. The Law of Succession

Armadillo

Wombat

Glyptodont

Diptotodon

Connection made by Richard Owen

Connection made by Charles Darwin

3. Transitional Fossils

Discovered about 1860

Discovered about 1997

More feathered dinosaurs discovered in the late 1990s

Another of Darwin’s premises

Ring Species

1. Ring Species

Siberian Greenish Warbler

Pg. 53

Homology

2. Homology from 3 areas

Structural Homology

Developmental Homology

1. Genetic Code is identical in essentially all species

2. Shared flaws in genetic makeup 3. Psuedogenes (CMAH in humans)

Page 57

Shared genetic flaws found in Chimps and Bonobos but not ion Gorillas and Orangutans also

Flaw leads to mistakes

Pseudogenes (Pg 58) shared among species

Age of pseudogenes is determined by the number of mutations they contain.

Relationships among species

Relationships among species

Discussed on Page 60

1. Principle of Uniformitarianism2. Geologic time scale\

1. Younger rocks on top of older ones2. Originally in horizontal position3. Rocks that intrude into seams are younger4. Boulders, cobbles are older than the host rock5. Earlier fossil life forms are simpler, more recent

are most similar to extant forms. 3. Radiometric dating4. Dating the earth’s actual age from its

molten state.