BIOL 304 Lecture Notes - Lecture 4: Directional Selection, Allele, Zygosity

• School: McGill University
• Department: Biology
• Course: BIOL 304
• Professor: Graham Bell

Document Summary

Dryer conditions = less plant reproduction, fewer seeds. Thus less rain, only seeds are the ones on the ground: more quickly depleted. In dry seasons, it becomes more important what beak size you have. If this trait is heritable, next generation should have deeper beaks. Heritability parent/offspring regressions: heritability for beak size is extremely high (0. 72-0. 97, large-beaked g. fortis parents produce large-beaked offspring. Evolutionary change- one generation: upward shift of almost 1mm in beak size after 1 generation passed post-drought, shows strong evolutionary adaptation due to environmental condition after one generation. Evolutionary change long term on daphne major: red line: rapid evolution occurring due to drought, then beak size slowly decreased back through time, selection and evolution vary dramatically through time, evidence for rapid evolution, reversals, stability. Seed-eating ground finch: medium ground finches vary from small to large beaked morphs, the larger beaked birds of fortis (medium finch) are due to the allele from g.