BIO 200 Lecture Notes - Lecture 8: Disruptive Selection, Genetic Drift, Frequency-Dependent Selection

• School: University at Buffalo
• Department: Biological Sciences
• Course: BIO 200
• Professor: Lindqvist Charlotte

Document Summary

Finches are an example of bottle neck effect. Cha(cid:374)ges i(cid:374) their (cid:271)eaks (cid:449)as(cid:374)"t fro(cid:373) ge(cid:374)eti(cid:272) drift (cid:271)ut fro(cid:373) (cid:374)atural sele(cid:272)tio(cid:374) Both genetic drift and natural selection can shape evolution. Common selective forces: predation, climatic factors, parasitism, mate attraction, resource acquisition. Predation: the (cid:271)etter a(cid:374) a(cid:374)i(cid:373)al (cid:373)ay (cid:271)le(cid:374)d i(cid:374), the (cid:271)etter they (cid:449)o(cid:374)"t (cid:271)e predated. One version of a trait works best with a species: when the environment changes: directional selection. Moving toward a smaller size**: disruptive selection. Negative frequency dependent selection- rare individuals have a higher fitness, common have a lower fitness. Rare will start to become more common, common becomes more rare. Reproductive strategy: mate choice, mating frequency, mate guarding, long term mating behavior, parental care, offspring spacing. Females are choosy: time- longer for females than males, females cannot have as many offspring as males, choosing the right parent is extremely important. Male/male competition: penguins: males and female"s cares for the young, sexual dimorphism: feathers, showy features.