Evolution 4 - 1 Today: A note on the debate over social vs....

Info iconThis preview shows pages 1–12. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 Today: A note on the debate over social vs. sexual selection Wrap-up adaptation Review 4 modes of natural selection Speciation Roughgarden on Social Selection One way to think about it: What limits an organisms reproductive success? If access to mates Sexual Selection If survival of young Social Selection Collared Flycatchers Great Frigatebirds 2 All over the world, cormorants are great flyers 3 except in Galapagos! (where they are flightless) Reduced wing: May well be a localized adaptation for foraging 4 Now consider cormorants black plumage: An adaptation for thermoregulation after swimming in cold Galapagos waters? Exaptation A character previously shaped for another function for another function is coopted for a new use! Conolophus Amblyrhyncus 5 Conolophus Amblyrhyncus Exaptation A character previously shaped for another function is coopted for a new use! No history of selection for current function 6 In most circumstances, Darwin may well have been right But differential replication can occur on different levels: Group 7 A lot to be said for gene-level selection: Dawkins: Natural selection acts by the preservation of genes responsible for favorable variation, and the elimination of unfavorable genes unfavorable genes. The result, says Dawkins, is reproductive selfishness Selection works against any measure of reprod. altruism Back to Tambopata Rain Forest 8 Meet the cordyceps fungus! Amazing degree of selfishness!! 9 But many organisms show a measure of self-sacrifice Is it altruism ? Beldings Ground Squirrel Consider Beldings Ground Squirrel P. Sherman 1977 Science 197: 1249 Alarm Call! Why dont males do more alarm calls? 10 As ground squirrels mature, males are chased off (prevents inbreeding) Result: groups of closely related females live in close proximity Relatives share genes identical by descent! The proportion shared depends on the relationship: r is coefficient of relationship r measures proportion of shared genes r Individual fitness Effectiveness of design for (your own) survival and reproduction 11 But because genes are shared, theres a probablility that copies of...
View Full Document

Page1 / 25

Evolution 4 - 1 Today: A note on the debate over social vs....

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online