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Climate Change and Speciation

Climate Change and Speciation. How Do New Species Evolve?. Speciation : one species splits into two or more species Geographic isolation : happens first; physical isolation of populations for a long period

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Climate Change and Speciation

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  1. Climate Change and Speciation

  2. How Do New Species Evolve? • Speciation: one species splits into two or more species • Geographic isolation: happens first; physical isolation of populations for a long period • Reproductive isolation: mutations and natural selection in geographically isolated populations lead to inability to produce viable offspring when members of two different populations mate

  3. Speciation Example • population of fruit flies laying eggs on several bunches of rotting bananas • hurricane washes the bananas and the immature fruit flies out to sea • bunch washes up on an island off the coast of the mainland • fruit flies mature and emerge on new island • populations, mainland and island, are now too far apart for gene flow to unite them. Speciation has not occurred yet—reunited, they could produce viable offspring. • conditions are different on the island with different selective pressures • another storm reintroduces the island flies to the mainland but changes in courtship or mutations in genes prevent reproduction

  4. Climate Change • What factors change? • Weather patterns, water, overall temp • What trophic levels are initially impacted? • Plants and herbivores • Any species with narrow niche requirements • Impact up food chain

  5. Example • Horses in Oregon

  6. Punctuated Equilibrium

  7. Migration

  8. Behavior Change • Reindeer expected to disappear from current range by end of century • Marmots end hibernation 3 weeks earlier than they did 30 years ago • Canadian red squirrels breeding about 18 days earlier • Red foxes spreading north -- territory occupied by their arctic cousins • Polar bears thinner than those of 20 years ago • Elephant seal pups leaner because prey is migrating to cooler waters • Loggerhead sea turtles laying eggs 10 days earlier than 15 years ago • Rising temp affect the sex of Hawkbill turtle hatchlings—more females • Warm water organisms (barnacles, mollusks, tidal snails) moving north • Fish species moving north in search of cooler waters • Tree swallows laying eggs about nine days earlier 40 years ago • Common murres breeding 24 days earlier than a decade ago • Plants thriving in areas where growth was limited before • Plants like columbines and wild geraniums blooming earlier • Edith's checkerspot butterflies are moving northward

  9. Adaptation • Requires: • Genetic variety • Time • Common Misconceptions • Not “for” anything • Predicting the future • “Survival of the fittest” is not “survival of the strongest” • Organisms do not develop traits out of need or want • No grand plan of nature for perfect adaptation

  10. Climate Change and Catastrophes Affect Natural Selection • Ice ages followed by warming temperatures • Collisions between the earth and large asteroids • New species • Extinctions

  11. Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years Fig. 4-9, p. 89

  12. Geographic Isolation Can Lead to Reproductive Isolation Fig. 4-10, p. 91

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