10/16 Daily Catalyst

1. 10/16 Daily Catalyst • 1. If 9% of the population has blue eyes, what percent of the population is hybrid for brown eyes? Homozygous for brown eyes? • 2. Why are the peppered and charcoal moths an example of directional selection? • 3. Explain the term balanced polymorphism.

2. 10/16 Daily Catalyst Answers • 1. If 9% of the population has blue eyes, what percent of the population is hybrid for brown eyes? Homozygous for brown eyes? • 42% • 49% • 2. Why are the peppered and charcoal moths an example of directional selection? • The allele frequency of the peppered coloring shifted to the coloring of charcoal. • .

3. 3. Explain the term balanced polymorphism: • Is the presence of two or more distinct phenotype forms. • Example: light and dark shell • Each morph is adapted in a different area

4. 10/16 Class Business • Dress like a boss extra credit • Parent afternoon TOMORROW • 12:40-3:20pm • Extra Credit • Evolution Exam is MONDAY • Come see me for tutoring!

5. 10/16 Agenda • Daily Catalyst • Class Business • Hardy-Weinberg problem • Speciation notes • Patterns of evolution reading

6. Hardy-Weinberg problem

7. Macroevolution Allopatric Speciation

8. Looks Can Be Deceiving! • These meadowlarks look very similar yet they are not the same species. • By contrast, these brittle stars look very different from one another, but they are the same species.

9. Definition of Species • Species: A group of interbreeding organisms that produce viable, fertile offspring in nature. • Members of a species will interbreed with one another but not other organisms outside of the species. (At least most of the time!)

10. Tigers and lions will interbreed in captivity, but they do not interbreed in nature. • Lions form groups or prides and live in the grasslands. • Tigers are more solitary and live in the forests. • Tiglon are products of male tigers and female lions. • Ligers are the opposite cross.

11. Macroevolution vs. Microevolution • Macroevolution is evolution on a scale of multiple gene pools. • Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.

12. What is speciation? • When a species is ___________ physically or reproductively, the group of genes become isolated from one another. • The two group will begin to evolve differently. • The two groups will evolve so differently that if brought back together, they would not interbreed again. • A new species has been created • =SPECIATION

13. Allopatric and sympatric speciation are two modes of specitation due to a type of ISOLATION

14. Allopatric vs. Sympatric Speciation Allopatric speciation- is caused by geographic isolation. I.e.: mountain ranges, canyons, rivers, lakes, glaciers, altitude or longitude. Sympatric speciation-speciation occurs even though the two groups are still living in the same area.

15. Allopatric Speciation • First, geographic isolation occurs. This is an extrinsic isolating mechanism. • The two populations must become isolated geographically from one another. • If the groups become sympatric again one of two things result…

16. Allopatric Speciation • They become separate species, as evidenced by the fact they can no longer interbreed. • They can still interbreed, thus they remain the same species. Islands produce some of the most profound examples of speciation due to geographic isolation.

17. Why does speciation occur after geographic isolation? The population that left the original group will have a different allelic make-up than the original species, thus experiencing the “founder effect”. The two groups will continue to experience different mutations. The two groups will now experience genetic drift and different selection pressures due to living in separate and perhaps different environments.

18. Allopatric vs. Sympatric Speciation Allopatric speciation-Speciation occurs because a given group has been separated from the parent group, usually because of a geographic separation as time goes by. Sympatric speciation-speciation occurs even though the two groups are still living in the same area. Without geographic isolation.

19. Types of Speciation: A Review • Allopatric speciation is the evolution of geographically isolated populations into distinct species. There is no gene flow, which tends to keep populations genetically similar. • Parapatric speciation is the evolution of geographically adjacent populations into distinct species. Divergence occurs despite limited interbreeding where the two diverging groups come into contact. • Sympatric speciationhas no geographic constraint to interbreeding. • These categories are special cases of a continuum from zero (sympatric) to complete (allopatric) spatial or geographic segregation of diverging groups.

20. Sympatric Speciation • Sympatric Speciation occurs without geographic isolation, thus it occurs at a local level. • There is something within the environment that keeps a single species separated into two or more distinct groups. • The end result is that the two groups evolve into separate species.

21. Sympatric Speciation • Suppose that a certain species feeds on a particular host and only that host. • Next, suppose a mutation occurs that allows it to feed upon a different host. • Eventually, the species is divided into two groups that are separated from one another. Given enough time, speciation can occur. • The species of treehoppers pictured above are host specific. The first lives on bittersweet while the second lives on butternut.

22. Polyploidy • Habitat isolation • Behavioral isolation • Temporal isolation • Reproductive isolation

23. Sympatric Speciation: Polyploidy • Polyploidy refers to instant speciation which occurs in most often in plants. • Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes. • Polyploidy may occur due to abnormal cell division, either during mitosis, or commonly during metaphase I in meiosis.

24. Sympatric Speciation: Polyploidy • Autopolyploidy refers to the occurrence in which the number of chromosomes double in the offspring due to total non-disjunction during meiosis. • This was discovered by Hugo deVries when studying primroses. • He noticed some of them were larger and very hardy.

25. Sympatric Speciation: Polyploidy • The normal primrose is diploid with 14 chromosomes. 2N = 14 • In this species there was a total nondisjunction event resulting in primroses that are tetraploid. 4N = 28 • These primroses cannot successfully mate with the diploid species.

26. Habitat Isolation • Two organisms live in the same areas, but rarely encounter one another. • Example: Two species on one genus of snake found in the same area. One lives in the water and the other lives on land.

27. Behavioral Isolation • Mating behavior • For example: small saltwater fish males change in color and develop a red underbelly. The male builds a nest and court the female with a dance. If at any time this ritual fails, then no mating occurs and no offspring is produced.

28. Temporal Isolation • Isolated by time • For example: a flowering plants colonizes a region with areas that are warm and sunny and areas that are cool and shady. Flowers in the warm region become sexually mature sooner than the cooler areas. This separates the flowers.

29. Reproductive Isolation • Closely related species may be unable to mate because of a variety of reasons. • For example: difference in flower shape may prevent pollination and the difference in the structure of genitalia may prevent insemination.

30. Prezygotic barriers: • Barrier to mating. • For example: small male dog and large female dog • Postzygotic barriers: • Once mating has occurred, fertile offspring cannot be produced. • For example: zygote is not viable

31. Reading • Patterns of Evolution: • Divergent Evolution • Convergent Evolution • Parallel Evolution • Coevolution • Adaptive radiation