BIEB 166 Lecture 2 (WI13)

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Biol/Ecology, Behavior, & Evol
BIEB 166
James Nieh

Lecture 2 Four questions of Tinbergen 1. Proximate - Immediate, moment of the behavior a. Causation ○ Neurons ○ Something developed during the lifetime of animal b. Development 2. Ultimate - Deeper, ultimate purpose of the behavior a. Function b. Evolutionary History Why is the dog barking? 1. Proximate a. Air flow over the larynx b. Learned from other dogs or innate (or both) 2. Ultimate a. Defending its territory b. Barking was advantageous, prevented injurious encounters Evolution and Natural Selection 1. Evolution: descent with modification - There is no goal in evolution 2. Natural selection: Darwin's hypothesis for the principal agent of evolutionary change - Inevitable consequence of certain conditions: a. Heritable variation b. Differential reproductive success c. Accumulation of successful variations ○ Some variants will have greater fitness, then come to predominate ○ Change in gene frequencies over time ○ As a consequence of natural selection, organisms become adapted to their environment Example of evolutionary adaption: adaptations of finches - The finches basically come from 1/2 ancestors - They had a different form, radiated out to fit the differences of niches ○ Morphology adapted ○ Behavior adapted Does evolution have a goal? - Not true - We cannot assume something is going to be more complex - Tapeworms are evolved to extreme simplicity Lemming self-sacrifice - When the population is too high, the lemmings would commit suicide. They would run off the cliff. - The lemmings remain would have more food and the population grow again In fact they are selfishly behaving, trying to migrate to a place with more food - Approaches to natural selection 1. In general, individual selection is a much stronger force than group selection - The selfish individual 2. Modern interpretations - George Price and David Sloan Wilson: Model of multi-level selection with "group selection" approach ○ Evolution of trait groups ○ Evolution of trait groups ○ Within-group cost of altruism is offset by a group benefit - Sacrificing the reproduction ability to the family - Created by genetic variation - When altruism first appears, altruists produce fewer offspring than selfish individuals □ Altruists do not initially sacrifice all their reproduction □ They can partly help their reproductive group and partly reproduce their own genes - Eusocial behavior: complete give up their reproduction ability to help their mother (the queen) ○ Reproduction occurs within the trait group ○ Mixing phase - Individuals leave their family, they mate and start a new family - S=selfish individuals - A=altruists - Increases the number of altruists offspring by spreading their altruistic gene -
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