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NATS 1550 (1)
Lecture 15

NATS 1550 - Lecture 15

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York University
Natural Science
NATS 1550
Alexander Mills

Lecture 15th - Evolution of Migration Overview: • Review few traits about migration • Idea of sedentary ancestral population • Sedentary population must change to a migratory one and migration must be adaptive • If indiv. in that area is to be successful, it has to be adaptive • Instinctive components show that there is a genetic basis to migration (some learning too) • Evolution is change in the genes of a population • The main idea for evolution by genetic change is "natural selection" How does it begin? • Often leave summer homes long before food is scarce (long distance migrants) • Suffer great morality during migration (Sillett and Holmes study) • Have to cope with very diff. env. and must be adaptable "generalists" • Ex. Palm Warbler: found in Spruce Bog/ Muskeg, then palm scrub; must be adaptable • Ex. Eastern Kingbird: found in beaver ponds, eats dragonflies, then in winter, in rain forest, fruit eaters Migrants: • Travel on mysterious schedules that do not match conditions • Suffer great mortality • Equipped to cope with great ecological variability 2 main ideas of origins: 1.The northern breeding range is the ancestral home 2.Southern winter range is the ancestral home • For both: starting point is an ancestral population that is sedentary • Individual/ populations born in one place, it will spend its life in the same region - never leaving if their needs are met there • Many populations of organisms are sedentary • If they begin to migrate: due to large populations, low food source -- individuals will start to move Migration abilities have genetic basis: • Must be a genetic basis: • Main idea: organisms with genes or gene combination that favours migration adaptions including behaviours will achieve greater success and reproduction • Migration adaptations: flight, feathers, wings • 2 ways to be successful: 1. Survive - pass on genes 2. Reproduce • Migration adaptive behaviours: • Location of breeding ranges • Location of wintering - winter ranges • Routes • Timing of migration • Non-adaptive/ less adaptive behaviours get 'weeded' out 1.How adaption is thought to evolve 2.What kinds of environmental events can cause a sedentary species to become a migratory one Evolution of Adaption • Adaption - evolutionary concept of "natural selection" • Idea by Charles Darwin in 1859 in "Origin of Species" • Evolution explains diversity of life • Remains a major mechanism of modern evolutionary analysis HMS Beagle and Caption Fitzroy (1831-1836) - Darwin's Journey • Darwin fo
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