BIOL 304 Lecture Notes - Lecture 10: Hangingfly, Fish Fin, Crypsis

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

Document Summary

Traits important for mating but not for survival. Since fitness depends on reproduction, these traits can be just as important as traits that increase survival rates. Sexual selection: intra-sexual: eg male-male competition, inter-sexual: eg female choice. Alternative male mating tactics maintained by frequency dependent mating success: exception to larger fish trend, smaller males can hide beside the nest and fertilize the eggs (cid:272)alled (cid:862)s(cid:374)eaky fu(cid:272)ke(cid:396)s(cid:863) If there is variation in female preference for long eye stalks and in the length of eye stalks in males, there will be genetic co-variance. Ie: if they prefer long eye stalks, they will mate with males with long eye stalks, and kids will have long eye stalks: positi(cid:448)e (cid:272)o(cid:396)(cid:396)elatio(cid:374) (cid:271)et(cid:449)ee(cid:374) daughte(cid:396)s p(cid:396)efe(cid:396)e(cid:374)(cid:272)e a(cid:374)d so(cid:374)"s eyestalk le(cid:374)gth. Secondary sexual traits should evolve as a compromise between natural selection (favouring crypsis) and sexual selection (favoring conspicuousness: there is an increase in fitness as a certain trait gets stronger due to female preference.