Lecture 2: Evolutionary approach Flashcards
5 assumptions of natural selection
- Within a species there is variation among individuals.
- Variations is heritable, natural selection operates on phenotype, and offspring resembles their parents.
- organisms produce surplus offspring
- competition occurs among individuals
- reproductive success differs among individuals. Fruitful individuals are favored.
4 levels of selection
gene
individual
group/ interdemic
species
gene
selection favors a unit of gene, natural selection favors phenotype.
group/ interdemic
selection favors group to avoid overpopulation, limit reproduction or commit suicide. (honey bees sting to protect group)
Major problem with group selection
individuals may cheat, cheaters will prosper.
Major problem with group selection
individuals may cheat, cheaters will prosper.
What is self-sacrificing behavior?
kin selection
altruistic
Behavior for the benefit of closely related kin . the behavior act decrease it’s own fitness but increase the fitness of closely related relatives.
species
removes species within a group of species rather than genes within a species.
which level of selection has the strongest evolutionary effect?
individual
selection acting on differences among individuals
2 factors causing behavior
ultimate and proximate factors
ultimate factors
longterm causes
resources –> food, water, territory
“why” questions
proximate factors
immediate factors
photoperiod, rainfall, olfaction
“how” questions
EX: Why do birds migrate?
ULTIMATE factors: not enough food at certain temperature, less competition for food.
PROXIMATE factors: increasing or decreasing photoperiod will trigger hormones.
Methods of study
comparative and experimental method
ethogram
an inventory of behaviors performed by a species of animal.
ethogram
an inventory of behaviors performed by a species of animal.
comparative method
- behaviors compared between 2 or more species
- hypothesis tested to compare similarities or differences between species.
experimental method
one or more variables controlled under natural or lab conditions
independent variable
factor to condition, treatment in experiment, blue gene around the glove
dependent variable
observed or measured behavior, amount of venom injected.
control group
unmanipulated set of subjects
experimental group
manipulated set of test subjects
null hypothesis
no differences, either accepted or rejected.
6 Test hypothesis step
- observe behavior
- ask question about the behavior
- form hypothesis and alternative hypothesis
- generate testable predictions for each hypothesis.
- test the hypothesis by matching the predictions with reality
- hypothesis supported by data
sexual competition hypothesis
infant delay estrus in female, male kill infant to reproduce sooner.
sexual competition hypothesis
infant delay estrus in female, male kill infant to reproduce sooner.
cannibalism hypothesis
due to pride killer male kills and consume
social pathology hypothesis
lose contact, start killing, human interference
aggression hypothesis
kill to defeat dominant male and overcome resistance
certainty and science
no absolute certainty in conclusions, old ideas are replaced and modified.
