Biology 2483A Study Guide - Reproductive Isolation, Agrostis, Habitat Fragmentation

• School: Western University
• Department: Biology
• Course: Biology 2483A
• Professor: Hugh Henry

Document Summary

Human impact- trophy hunting- large permits to prevent (), pay big; hunt big, avg size of males & horns decreased. Elephants poached for ivory = less elephants with tusks. As pop"n accumulates difference, it forms another species (with same characteristics, some diff) Mutation- very rare, given time, drives evolution because forms new alleles. Mechanisms of evo"n: natural selection- heritable traits survive, reproduce more successfully, increase in freq. Only mechanism that consistenly causes adaptive evolution. : both extremes favoured, (not intermediate: genetic drift- chance event determines what alleles passed on (not necess. good ones). Genetic variation reduced- some alleles lost- bad- can"t respond to enviro changs. Freq. of bad alleles increases- esp. if only mildly deleterious- bad- bad survival. Differences between pop"s increase: gene flow- alleles move between pop"n (individuals or gametes) New alleles introduced in a population e. g. resistance genes- freq will increase rapidly in populations exposed to insecticides (using insecticide = strong selection pressure for r genes)