1 / 24

Bellringer – March 13, 2014

Bellringer – March 13, 2014. Green color (G) is dominant to white color ( g ) in turtles. In a population of 200 turtles , 13% are white. A) What are the allele frequencies? B) What percentage of each genotype are in this population? C) How many turtles are heterozygous?.

enye
Download Presentation

Bellringer – March 13, 2014

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bellringer – March 13, 2014 • Green color (G) is dominant to white color (g) in turtles. • In a population of 200 turtles, 13% are white. A) What are the allele frequencies? B) What percentage of each genotype are in this population? C) How many turtles are heterozygous?

  2. ANSWER KEY • G= Green g= white • White = 13% = 0.13 = gg= q2 • √0.13=√q2 A)q= 0.36 then p = 0.64 B) GG = p2= (0.64)2=0.4096= 40.96% • Gg = 2pq= 2(0.64)(0.36)=0.4608= 46.08% • gg = q2= (0.36)2= 0.1296= 12.96% C) (.4608)(200) = 92 turtles are heterozygous

  3. Practice Problem #2 • A scientist has studied the amount of PTC tasters in a population. PTC tasting is dominant. From one population, 500 individuals were sampled. The scientist found the following individuals: AA = 110, Aa = 350; aa = 40. • Calculate the genotypic and allelic frequencies for the PTC gene at this population. • Determine the genotypic and allelic frequencies expected at Hardy-Weinberg equilibrium using the homozygous recessive. Is this population in Hardy-Weinberg equilibrium? Is the population evolving?

  4. A) Actual population • AA = 110, Aa = 350; aa = 40. • AA = 110/500 = 0.22; Aa=350/500 = 0.70 ; aa= 40/500= 0.08 • A=110 + 110 + 350 = 570/1000 = 0.57; • a = 40 + 40 + 350 = 160/1000 = 0.43

  5. b) Hardy-weinberg • p=A= PTC taster q= a = PTC non-taster • 40/500= 0.08 = PTC non-taster = aa= q2 • √0.08=√q2 • q = 0.28 then p = 0.72 • RR = p2 = (0.72)2 = 0.52 = 52.00% • Rr = 2pq = 2(0.72)(0.28) = 0.40= 40.00% • rr = q2 = (0.28)2 = 0.08 = 8.00%

  6. Evolution and Zygotic Barriers (Macroevolution part 2) Ms. Kim H. Biology

  7. Why don’t similar species interbreed?? • Geographic isolation • Reproductive barriers (isolation) • Change in chromosome numbers through mutation • Adaptive radiation (example of divergent evolution) • Speciation = formation of NEW species

  8. Hello over there  A. leucurus A. harrisi Geographic Isolation

  9. Two general modes of speciation determined by the way gene flow among populations is initially interrupted:Geographic and Reproductive Isolation Speciation can occur in two ways: • Geographic:Allopatricspeciation (means “other”) • a genetic isolation WITH a geographical barrier; new group isolated from its parent population • Reproductive: Sympatric speciation (means “together”) • genetic isolation WITHOUT a geographical barrier; a reproductive barrier isolates population in SAME habitat

  10. http://bcs.whfreeman.com/thelifewire/content/chp24/2402001.htmlhttp://bcs.whfreeman.com/thelifewire/content/chp24/2402001.html Allopatric speciation Sympatric speciation

  11. http://www.pbs.org/wgbh/nova/evolution/evolution-action-salamanders.htmlhttp://www.pbs.org/wgbh/nova/evolution/evolution-action-salamanders.html

  12. Reproductive Isolation • biological factors (barriers) that stop 2 species from producing viable, fertile hybrids • Two types of barriers • Postzygotic “after the zygote” • Zygote can NOT develop • Prezygotic “before the zygote” • Sperm and egg can not fuse

  13. Pre-Zygotic Barriers

  14. Sympatric: Habitat Isolation 2 species encounter each other rarely, or not at all, because they live in different habitats, even though not isolated by physical barriers

  15. Sympatric: Temporal Isolation Late Summer Late Winter Species that breed at different times of the day, different seasons, or different years cannot mix their gametes

  16. Sympatric: Behavioral Isolation http://wps.aw.com/bc_campbell_biology_7/26/6661/1705356.cw/index.html Courtship rituals and other behaviors unique to a species are effective barriers

  17. Sympatric: Mechanical Isolation Mating organs don’t fit Morphological differences can prevent successful mating Related species may attempt to mate but CAN’T anatomically incompatible Sperm = transfer

  18. Sympatric: GameticIsolation Sperm of one species may not be able to fertilize eggs of another species Ex: specific molecules on egg coat adhere to specific molecules on sperm

  19. Post-Zygotic Barriers

  20. Reduced Hybrid Viability Salamander hybrid shows incomplete development Genes of the different parent species may interact and impair the hybrid’s development Hybrids are very weak and/or underdeveloped

  21. Reduced Hybrid Fertility Even if hybrids may live and be strong, they may be sterile

  22. Polyploidy • Polyploidy is presence of EXTRA sets of chromosomes due to accidents during cell division • ex: “nondisjunction” • It has caused the evolution of some plant species • More common in plants than in animals

More Related