36. What is the difference between a discrete (Mendelian) trait and a continuous (polygenic) trait? 37. Be able to calculate relative fitness and selection coefficients.Relative fitness (W) = actual survival/largest survival Selection coefficient = 1-W38. Be able to use the equations h2= vg/vp, and R = h2S to calculate heritabilitiesresponses to selection and selection differentials for polygenic traits. , Handout Sociobiology 12
Altruism - behavior by an individual that increases the fitness of another individual while decreasing the fitness of the individual itself. Kin selection - evolutionary force favoring helping behavior by relatives/kin • Individuals increase their inclusive fitness by helping increase the survival and reproduction of genetic relatives that are not offspring • Tend to help kin that are more closely related versus more distant kin Haplodiploidy - system where males develop from unfertilized eggs and are haploid (N), while females develop from fertilized eggs and are diploid (2N) • Inheritance system found in leafcutter ants • Consequence: worker ants within a colony can be very similar genetically (75% genetic similarity) - drone workers more related to their sisters than their offspring Group selection - sociality in diploid organisms- not as strong as individual selection Prides - female lions live in groups of related individuals • 2 males, 3+ females, 4+ subadults, numerous cubs • Males ejected after 2 years, must take over new pride as brothers - kill cubs of old males • More than 2 males requires kin selection • Higher ranked males sire more cubs than lower ranked males • Male coalitions of 2-3 - often unrelated Large male coalitions - rarely unrelated Helpers at the nest - “ Colonial nesters ”—most common habitat is open woodlands with trees large enough to provide cavities for nesting and roosting and providing protection from climate and predation • Cooperative breeders - siblings help provide for young rather than dispersing • Limiting cavities - kin selection favors cooperation rather than dispersal • Higher rainfall during the dry season reduces reproduction of green woodhoopoe flocks • Reproduction was higher in high quality territories • Red-cockaded woodpeckers= colonial nesters in longleaf forests o 2 breeding adults + up to 4 helpers (usually sons) o Nest cavities in larger trees are limiting o Better to inherit your parents nest is nests are limiting— natal territories o Birds colonized 18 of 20 experimentally drilled tree holes • Positive relationship between large trees and the openness and grass cover •
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