Transcript 06_prughNS
2 WORK-STUDY JOBS 1. Endangered species and biodiversity Duties: - collect data on endangered species traits - enter data into Access database 2. Plant-insect ecology Duties: - survey seedheads for bio control insects - enter data into Excel spreadsheet spotted knapweed Qualifications: majoring in Biology interest in conservation good work ethic good computer skills To apply: www.students.ubc.ca/workstudy Project # 1235 Centaurea maculosa REVIEW QUESTION # children Education level ♦ Women with more education have fewer children ♦ Should society become dumber over time??? FITNESS The relative reproductive success of a gene in the long term variant of a gene: allele e.g., eye color: SELECTION VS. EVOLUTION Selection is a process Selective agents (weather events, predators, competitors) favor one form of a trait over another (larger beaks, longer legs, stronger horns) Evolution is an outcome Change in allele frequencies in the population GENETIC DRIFT Random changes in the frequency of alleles from generation to generation Equivalent to sampling error 2 main effects: 1. Changes allele frequencies 2. Decreases genetic variation GENETIC DRIFT Small populations can lose genetic varation because of drift Bottleneck: population crash causes loss of alleles GENETIC DRIFT Example: the cheetah (Acinonyx jubatus) Fastest land mammal: 110 kph Went through severe genetic bottleneck 10,000 years ago: lost nearly all variation GENETIC DRIFT Founder effect: a few individuals colonize a new area New population has different allele frequencies (and less diversity) because of “sampling error” Example: Amish in Pennsylvania - descended from 200 Germans - commonly have Ellis-van Creveld syndrome - inbreeding makes impact of bottlenecks and founder effect worse INCLUSIVE FITNESS ½ ½ + ½ =1+ ¼ + ¼ = 1.5 KIN SELECTION: traits that increase inclusive fitness are favored INCLUSIVE FITNESS Relative reproductive success of a gene in an individual plus its close relatives Ex., you have the “helpful” gene “helpful” gene will spread if: rxb>c r = relatedness b = benefit c = cost Hamilton’s rule KIN SELECTION Classic case: Eusocial insects Eusocial animals have sterile worker caste - Evolved 11 times in Hymenoptera - Also termites, crustaceans, 1 mammal (naked mole rat) How could this evolve? Haplodiploidy: are haploid (unfertilized) are diploid (fertilized) = ¾ genes shared More related to sisters than own offspring! ALTRUISM What if r = 0? rxb >c 0 Reciprocal altruism: helping another individual in expectation of receiving help in the future Robert Trivers (1971) RECIPROCAL ALTRUISM Vampire Bats 3 species in central and south America Live in large groups, often unrelated to bats around them If no meal, may die within 24 hours Bats will often regurgitate blood to hungry neighbors RECIPROCAL ALTRUISM Necessary conditions: 1. cost << benefits 2. recipient and donor are recognizable 3. roles are changed occasionally