1. Evolution – a change in the genetic makeup of a population over time.

2. Charles Darwin English naturalist.
Took a five year journey on the HMS Beagle.
Developed the theory evolution based on natural selection.

3. You can see the concepts of evolution at work.
Visible evolution
Medicine: flu vaccine and antibiotics resistance
Agriculture: hybrid plants and pest resistance
Biotechnology: transgenic organisms

4. Populations of species are changing.
Descendent
Ancestor
Descendent

5. Mechanisms for evolutionary change.
Artificial Selection
Commonly called selective breeding.
Selecting organisms with desired traits when breeding livestock, pets, or crops.

6. Natural Selection “Survival of the fittest”
Proposed by Charles Darwin as the mechanism of evolution.
In order for natural selection to occur:
There must be heritable variation in a population
More organisms are born than can survive
Some forms have a better chance of surviving than others
Over time, populations share more traits with the organisms that survive.

7. Terms
Adaptation – heritable trait that increases an organism’s ability to survive and reproduce.
Fitness – the ability to survive and reproduce in a specific environment.

8. Evidence for Evolution
Biogeography – the geographical distribution of species.
Many islands have species found nowhere else (indigenous).
Closely related species are often found on nearest island mass.
Similar environments on opposite ends of the earth do not have closely related species.
Tropical animals of South America are more closely related to desert animals of South America than Tropical African animals

9. Evidence for Evolution
Comparative Anatomy
Forelimbs of closely related animals have similar anatomy (even though they have different functions).
These are called homologous structures.

10. Homologous vs. Analogous
Analogous structures – Structures that have the same function, but different structures (ex. Fly wing, bird wing bat wing).

11. Evidence for Evolution
Fossil record – shows chronological appearance of different species.

12. Evidence for Evolution
Vestigial organs – organs that have no function.
Historical remnants
Ex. Whale has remnants of leg bones, appendix in humans, leg bones in snakes.

13. Dolphin with legs?

14. Evidence for Evolution
Comparative Embryology
Closely related species go through similar developmental stages.
Ex. Gill pouches and tail are found in most vertebrates.

15. Evidence for Evolution
Molecular biology
DNA and protein analysis show relationships between species.
Closely related species have similar sequences of bases in DNA and have similar proteins.
Ex. Humans and chimpanzees have 96 – 98% identical DNA.
Humans share less DNA similarities with dogs, and even less with lizards.

16. Speciation Speciation – the formation of a new species
Species – a population or group of populations that can mate and produce fertile offspring.
Population – a group of the same species in an area.

17. Overview of How a New Species Can Occur
Variation exists within all populations (due to mutations and sexual reproduction)
Variations in a population may be selected for (good) or selected against (bad) depending on the situation.
Different populations of the same species are sometimes separated genetically, and are exposed to different circumstances.
Because of this, the populations may change differently (due to different natural selection pressures).
If the changes are significant enough, a new species may occur.

18. Ways to isolate species:
Geographic isolation - separating by physical barriers such as rivers or mountains.
Behavioral Isolation– habitats overlap but behaviors prevent mating (ex. Different mating songs.
Temporal isolation – habitats overlap, but mating times do not.

19. The idea of evolution is often misunderstood…

22. There is no perfect organism
Organisms that are most fit for one environment might not be fit for another.
The environment is constantly changing.
Evolution only works with what is already there.

23. Mammals adapted to water:

24. Webbed Feet

25. Nocturnal Mammals

26. Mechanical protection

27. Adaptations to cold:

28. Mammals Blending in

29. Fish catching mammals

30. Desert mammals

31. Flying mammals

32. Convergent Evolution
Relatively unrelated organisms developing similar characteristics due to similar environmental characteristics

33. Gene pool Gene pool – the total collection of genes in a population.
New genes can be added to a population by mutation or new members moving in from outside.

34. The gene pool (allele frequency) will change (evolve) if any of the following happen:
Natural selection
Immigration or emigration
Mutation.
Nonrandom Mating.
Small Population size.

35. Small Population Size
Cause differences in the percentage (or frequency) of alleles in a population due to chance.
Statistics require large sample sizes to regularly obtain expected results.

36. Small population size
The bottleneck effect – environmental conditions (natural disaster etc.) causes the survivors’ allele frequencies to be different than the original population.

37. Small population size
The founder effect – a small portion of a population becomes isolated from a larger population to make a new population.
The gene pool of the new population is not the same as the original (by chance).
Can occur when a new area is colonized.

38. The community is closed.
Microevolution
4/27/2017
The Founder Effect
Old Order Amish populations are derived from a few dozen colonists who escaped religious persecution in Germany in 1719 to settle in Pennsylvania.
The community is closed.
Allele and genetic disease frequencies in Amish are significantly different from the German ancestral and the surrounding local populations.
G. Podgorski, Biol. 1010