Bioee 1780 1st Edition Lecture 17Outline of previous lectureI. AnnouncementsII. Life history evolutionIII. FitnessIV. Tradeoffs and constraintsA) Senescence as a life history tradeoffOutline of current lectureI. Types of selectionA) Kin selectionB) Individual selectionC) Group selectionII. Behaviors are traitsIII. SociabilityA) Cost and benefit of sociabilityB) DarwinIV. Kin selectionA) Hamilton’s ruleB) Cornell crowsC) Maternity assuranceCurrent lectureI. Types of selection A) Kin selection*Bee Eater Birds:-If conditions are bad, parents of Bee Eaters force their children to come back home and take care of their kin-The more related organisms are the more likely they are to help*African Wild dogs-Dogs are packs in 8-16 or so individuals-Cooperative hunting allow dogs to be more successfulB) Individual selection *Differential performance (fitness) of individuals causes some genotypes to replace other genotypesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.*We know that selection work on individuals on a basic level (virtually if not all is this)C) Group selection *Differential performance of groups of individuals causes some groups to out compete and replace other groups*Many biologists debate on whether group selection exist*Group selection is extremely rare and only happens in certain conditions because this selection is extremely unstable*After all, self-sacrifice is generally selected against*However, if every organism in the group agrees to cooperate group selection can occur *Yet if there are some “cheaters” who go against this cooperation, group selection breaks down*Ex. Bees and their hives*Ex. Dogs hunting together-amount of food per dog goes up as the pack goes up (to a certain point)-therefore their situation favors group selectionII. Behaviors are traits*We are so culturally influenced that perhaps we feel that many things are “learned”*Many behaviors are genetically selected*Ex. Aggressive mice selected in artificial environments pass on their aggressiveness to their offspring III. SociabilityA) Cost and benefits of sociability*Benefits include smaller chance to be predated upon, etc.*Costs included vulnerability to diseases, etc.*Altruism: behaviors that decrease the fitness of the individual but increase their kin’sB) Darwin*Thought that altruism is fatal to his theory of natural selection*For altruism to be consistent with natural selection, there has to be a benefit that outweighs the cost (not truly just altruistic)*Ex. Ground squirrels-Sometimes a squirrel gives an alarm call when a predator approaches-However, this leaves that squirrel more vulnerable to predation-More females give calls, since females stay at home and do not migrate. They are more related to those around them.IV. Kin selection *Selection arising from the indirect fitness benefits of helping relatives*We can probably say that altruism is not truly altruistic but more like kin selection*Inclusive fitness (total fitness) = direct fitness + indirect fitness-(own success at genetic contribution + success of other individuals that share alleles) *Not all relatives are equal*r = coefficients of relatedness-every time a node passes in relation to one point on a pedigree relation decreases by .5 times-remember to add total number of pathsA) Hamilton’s rule*rB > C*A “helping” behavior can spread in a population if the cost to the donor is smaller than the benefit*B = benefit (difference between choices)*C = Cost (difference between choices)*Natural selection will favor this if benefit > cost in a long termB) Cornell crows*Cornell crows are cooperative (live in large groups)*They are marked and tagged *Many crows stay home and help raise younger siblingsC) Maternity assurance*Mother give birth to offspring and ensures that the mother is definitely related to the offspring*However, it is not sure that a male individual’s offspring is definitely his*Therefore, it is a better strategy to help one’s sister than