ZOL 313 Week 15
ZOL 313 Week 15 ZOL 313
Blue Mountain State
Popular in Animal Behavior
Popular in Animal Science and Zoology
This 7 page Class Notes was uploaded by Elaine Foster on Saturday May 2, 2015. The Class Notes belongs to ZOL 313 at Michigan State University taught by Dr. Dyer in Fall. Since its upload, it has received 185 views. For similar materials see Animal Behavior in Animal Science and Zoology at Michigan State University.
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Date Created: 05/02/15
ZOL 313 Animal Behavior Group Living amp Cooperation 0 Sociobiology o Paradox of cooperation why help ls cooperation for the good of the group 0 Reproductive restraint by Great Tits continued from Week 14 0 Experiment 0 Vary clutch size by adding or removing eggs The bigger the nestbrood the lower the average weight of young 0 Thus it is in the individual s best interest to hold back 0 Levels of Selection Group selection 0 Thinking of large populations as smaller subpopulations 0 Selection against groups with negative phenotypes Individual selection 0 Success among individuals that matters Genic selection 0 Homologous chromosomes each in a different individual 0 Why cooperate Roles donors amp recipients of help General Hypothesis donor should cooperate when its benefits exceed costs Hypotheses for cooperation 0 H1 Mutualism 0 Features Both donor amp recipient benefit from interaction 0 Examples intraspecific Grooming coalitions Selfish herd Cooperative hunting Mate sharing 0 H2 Manipulation 0 Features Donor gains no benefit recipient wins Explains helping of nonrelatives amp other species Donor should be selected to avoid 0 Examples Brood parasitism cuckoostarlings Egg dumping Deceptive alarm calls eg tufted capuchin 0 Production of RRDAs Resource Related Deceptive Alarms ZOL 313 Animal Behavior 0 H3 Kin Selection 0 Features Donor pays cost recipient gains benefit Explains helping of relatives Extreme selfsacrifice can be evolutionarily stable 0 Examples Cooperative breeding helping at the nest Cooperative defense Reproductive division of labor eusociality 0 H4 Reciprocity 0 Features Costs and benefits to donor depend on whether or not recipient returns favor Explains helping of nonrelatives 0 Examples See book p 432434 0 How Kin Selection works 0 Gardenvariety natural selection heritable trait can spread in a population if it enhances the fitness of the individuals carrying the genes that produce the trait o Kin selection is an extension of this idea Heritable altruistic trait can spread in a population if it enhances the fitness of other individuals carrying copies of the genes that produce the trait 0 Both offspring amp nonoffspring kin o Kin selection can be thought of as favoring selfish genes rather than selfish individuals 0 Quantifying effects on Kin Selection 0 Ecological predispositions high benefit relative to cost where Benefit Br Cost Cd 0 Genetic predispositions high degree of relationship between donor amp recipient Coefficient of relatedness r o Calculating relatedness Diploid case fW pm eihehililar elf allele wf dad gin5 Emmy Whammy eaf allele wf mum ing ZOL 313 Animal Behavior lluloirlnl Dad Tm P ria mm PE a nd If 1f21f2 112 14 1Q 15 Haplodiploid case Ilul ll39ll39lli Dad TM PEP mm P i dad If 3 lfg1fg 1 3 it firm P ria mom I 3 12 1L 0 Thus females are more closely related to their full sisters than to their brothers or even their own offspring ZOL 313 Animal Behavior 0 Putting it together Hamilton s Rule William Hamilton in groundbreaking papers in 1964 outlined the conditions under which altruistic traits could evolve by kin selection Hamilton s Rule an allele coding for altruistic tendency should increase in frequency in a population if BrCd gt 11 rBr gt Cd Here Benefits amp Costs are measured in terms of lives saved or sacrificed Consider alarm call with Cost 1 to donor 0 How high does benefit have to be to repay cost 0 Depends on relatedness of donor to recipient For siblingsoffspring r 05 benefit must be gt2 For grandchildren r 025 benefit must be gt4 For greatgrandchildrenothers r 0125 benefit must be gt8 0 Another way of expressing Hamilton s Rule An allele coding for altruistic tendency should increase in frequency in a population if B1 gt rdonorown offspring C d rdonorrecipient39s offspring Br 7quotdonorrecipient39s offspring gt Cd rdonorown offspring Here Benefits amp Costs are measured in terms of offspring produced or forgone 0 Hamilton argued that we have to consider an animal s inclusive fitness direct fitness indirect fitness 0 Can Kin Selection explain altruism 0 Helping at the nest in birds eg Florida scrub jays Males upon fledging often do not go off to establish their own territories but instead stay on parental territory helping parents to rear more offspring defend territory fight off predators etc To test kin selection hypothesis answer the following questions 0 Q1 Do helpers really help Yes 0 Correlational evidence numbers of nestlings fledglings and independent young are higher 0 Experimental evidence experimental territories had helpers taken away and number of offspring went down 0 Q2 Do helpers help relatives Yes 0 In Florida scrub jays yes helpers are typically rearing full siblings r 05 0 Because of EPCs by female siblings are sometimes 12 siblings r 025 but average relatedness is still pretty high r 043 ZOL 313 Animal Behavior 0 Q3 Do helpers help enough to repay costs of being helpers o The cost lost reproductive opportunity Cd rdonorown offspring number of offspring produced by firsttime breeders rparentoffsprmg 124 05 062 o The benefit to break even by helping helpers would have to Add to the productivity of parents 0 This added productivity is discounted by relatedness to these extra fledglings Net payoff due to helping should be 2 0 62 0 Actual payoff to helpers average Avg extra fledglings per helpers Br 2 033 Avg relatedness of helpers to fledglings 043 rdonorrecipient39s offspring I Net payOff Br rdonorrecipient s offspring 033 043 014 NOT ENOUGH 0 So does Kin Selection explain helping Key Questions 0 Do helpers really help 0 Do they help relatives 0 Does this help lead to net genetic profit If kin selection isn t enough then why help 0 Limits on breeding opportunities 0 Being helper has 2 selfish benefits Breeder o Inherit breeding male s territory direct fitness payoff enforces 0 Help rear kin indirect fitness payoff o For species in which helpers help nonrelatives only the longterm payoffs apply 0 Other evidence altruism is targeted Examples 0 Stinging insects workers more likely to sting when near nest o Mate amp food sharing lion 0 Alarm calls Belding s Ground Squirrel females call more often 0 Cooberation in social insects 0 Origin of eusociality genetic amp ecological predispositions Incidence in haplodiploid clades Influence of relatedness on patterns of helping within eusocial colonies o Inferring phylogenetic history of eusociality Mole rats 0 Damaraland mole rats amp naked mole rats gt 2 roots origins ZOL 313 Animal Behavior Cockroaches o Termites are eusocial cockroaches gt single root origin Origins of eusociality within diploid lineages o Termites 1 o Mole rats 2 o Snapping shrimp 3 o Ambrosia beetles 1 Origins of eusociality within haplodiploid lineages o Hymenoptera at least 8 o Aphids 1 o Thrips 1 Assume constant Haplodip0idy HypotheSIs Diploid r 05 BY Hamilton s mile 4 Haplodiploid r 05 Br 7quotdonorrecipient39s offspring gt Cd rdonorown offspring For diPIOidS rdonorrecipient39s offspring 0395 For hapIOdipIOidS rdonorrecipient39s offspring 03975 0 So Br doesn t have to be as big to favor helping 0 Too simplistic to say that haplodiploidy is explanation for eusociality o Haplodiploidy is not necessary eg termites naked mole rats 0 Haplodiploidy is not sufficient most bee amp wasp species are nonsocial Siblings r 05 Offspring r 10 o Other related evidence Rmales 0 Who helps Haplodiploid species gt workers are female Diploid species gt male female workers 11 0 Ecological biases BC Haplodiploid species gt eusocial species gt evolved from ancestors that built nests amp had parental care Termites amp mole rats diploid gt have to process cellulose gt economy of scale Refined hypothesis haplodiploidy biases kin selection 0 All else being equal cooperation evolves more easily in lineages where relatedness is high 0 If B gt C cooperation can evolve without genetic predisposition o Organizing Work 0 Social insect colonies achieve complex patterns of organization through cooperation communication and mass action Ex termite nests serve functions ZOL 313 Animal Behavior 0 A Factory Enclosed in a Fortress Edward O Wilson Challenges to survival 0 Acquiring resources 0 Processing resources 0 Defense against predators 0 Defense against pathogens 0 Regulating climate temperature humiditiy o Producing offspring All organisms face these problems eusocial species face them on a colony level Three principles 0 Division of labor 0 By size leaf cutter ants gt Big soldier Med foragers Small tend queenride shotgun o By form morphology gt termites o By age gt honeybees 0 Communication 0 Direct info signals Trophallaxis in ants formica Natural selection acted to shape communicative phenotype 0 Chemical touch vibration sound etc 0 Indirect info cues Information left in environment Other workers use this to guide behavior 0 Decentralized distributed control 0 No leaders No generals architects foremen supervisors choreographers etc Ex starlings baitfish 0 Instead Local information Simple rules for responding Responses may include communicative signals IL food water nutrients
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