E volution of Species

1. Evolution of Species

2. Microevolution vs. Macroevolution • Microevolution: • Survival through the inheritance of favorable characteristics • Changes occur in gene pools due to mutation, natural selection, genetic drift, etc. • Gene pool changes cause more VARIATION in individuals in the population e.g. anitbiotic resistant • Macroevolution: • Progression of biodiversity through geological time e.g. Speciation, extinction DO Antibiotic resistance worksheet

3. Mutation Gene Flow Non-random mating Genetic Drift Selection 5 Agents of evolutionary change

4. 1. Mutation & Variation • Mutation creates variation • new mutations are constantly appearing • Mutation changes DNA sequence • changes amino acid sequence • changes protein’s: • Structure • function • changes in protein may change phenotype & therefore change fitness

5. 2. Gene Flow • Movement of individuals & alleles in & out of populations • seed & pollen distribution by wind & insect • migration of animals • sub-populations may have different allele frequencies • causes genetic mixingacross regions • reduce differences between populations

6. Human evolution today • Gene flow in human populations is increasing today • transferring alleles between populations Are we moving towards a blended world?

7. The changing face of America

8. 3. Non-random mating • Sexual selection

9. Nonrandom mating • Inbreeding • Impacts the entire genome, not just certain alleles • Individuals are more likely to mate with neighbors than distant members of the population  increases chances of genetically similar individuals mating • Common in plants (self-fertilization an extreme example) • In animals it often causes inbreeding depression, where offspring are less fit

10. Nonrandom mating • Assortative mating • Mates are chosen based on a particular phenotype • Only impacts the genes involved in the selected phenotype • Positive  select mate with the same phenotype • Negative  select mate with the opposite phenotype

11. Do sexual selection worksheet

12. Warbler finch Tree finches Ground finches 4. Genetic drift • Effect of chance events • founder effect • small group splinters off & starts a new colony • bottleneck • some factor (disaster) reduces population to small number & then population recovers & expands again

13. Founder effect • When a new population is started by only a few individuals • some rare alleles may be at high frequency; others may be missing • skew the gene pool of new population • human populations that started from small group of colonists • example:colonization of New World

14. Distribution of blood types • Distribution of the O type blood allele in native populations of the world reflects original settlement

15. Distribution of blood types • Distribution of the B type blood allele in native populations of the world reflects original migration

16. Bottleneck effect • When large population is drastically reduced by a disaster • famine, natural disaster, loss of habitat… • loss of variation by chance event • alleles lost from gene pool • not due to fitness • narrows the gene pool

17. Cheetahs • All cheetahs share a small number of alleles • less than 1% diversity • as if all cheetahs are identical twins • 2 bottlenecks • 10,000 years ago • Ice Age • last 100 years • poaching & loss of habitat

18. Conservation issues Peregrine Falcon • Bottlenecking is an important concept in conservation biology of endangered species • loss of alleles from gene pool • reduces variation • reduces adaptability Breeding programs must consciously outcross Golden Lion Tamarin

19. Do genetic drift, founder effect and bottle neck effect worksheet

20. 5. Natural selection • Differential survival & reproduction due to changing environmental conditions • climate change • food source availability • predators, parasites, diseases • toxins • combinations of allelesthat provide “fitness”increase in the population • adaptive evolutionary change

21. Modes of Natural Selection

22. Modes of Natural Selection • Directional Selection • Favors individuals at one end of the phenotypic range • Most common during times of environmental change or when moving to new habitats • Disruptive selection • Favors extreme over intermediate phenotypes • Occurs when environmental change favors an extreme phenotype • Stabilizing Selection • Favors intermediate over extreme phenotypes • Reduces variation and maintains the current average • Example: Human birth weight

24. Directional Selection Neck of Giraffe Antibiotic resistance of bacteria Moth color (melanin) Camouflage/Mimics Many sexually selected traits Do industrial Melanism worksheet

25. Disruptive Selection Causes divergence within the species Occurs when two different types of resources in one area Results in specialization for each branched group May lead to formation of new species E.g. Darwin’s Finches

26. Stabilizing Selection When the extremes of the trait aren’t as well suited Examples bird clutch size Elk Antlers size Giraffe neck length Tail length in birds Do selection for human birth weight worksheet

27. Examples of selection pressures... • Predators - variants with adaptations allowing them to escape predators have more offspring - e.g. speed, defensive weapons, camouflage, mimicry • Prey/Food - variants with adaptations allowing them to obtain food have more offspring - e.g. Speed, senses for finding prey/food, weapons for killing prey or obtaining food, camouflage for stealth • Climate - those who can survive new climate best have more kids - e.g. ice age, change in climate due to migration. • Mates - variants with adaptations allowing them to attract a mate to have offspring - e.g. strong, attractive, good provider

28. DO selection and speciation POGIL