EEB2244%Lecture%Guide% Lecture%12:%Behavioral%Ecology% Page%1%%1%%Behavioral Ecology Territory and dominance Groups and social behavior Helping behavior Eusociality Behavior – way an organism acts or responds to others & to signals. Social behavior – within species - Ranges from antagonism to cooperation - Genetically determined with varying levels od decision-making. Territory - area defended against intraspecific intrusion Costs of defense < benefits of exclusive resources Dominance hierarchy - organizes within-group access to resources Groups - purposeful joining of individuals Increase the chances of surviving, feeding, or finding a mate But increased rate of resource depletion Optimal group size balances these factors What is one potential cost to group behavior? -Increased detectability by predators of the group Natural Selection and Social BehaviorEEB2244%Lecture%Guide% Lecture%12:%Behavioral%Ecology% Page%2%%2%%Spitefulness (-, - ) Spiteful behavior is maladaptive no known natural systems exhibit spitefulness Selfishness (+, -) Most behaviors are selfish Individual fitness often high in selfish behavior. e.g., blue-footed boobies and siblicide e.g, bears and infanticide Cooperation (+,+) Benefits to both Cooperation is common Eventually both parties involved receive benefits e.g., spotted hyenas and ________ __________ e.g., musk oxen and _________________ _______ Altruism ( cost to actor, benefit to recipient) Altruism in nature is “selfish” is rare _________________ What prevents cheating in a cooperative group? Cheating causes long term individual fitness Paradox of altruism 1. Evolution maximizes individual fitness 2. Selection for selfish behavior 3. But apparently “altruistic” behaviors found in nature Most “apparent altruism” is probably __________________ e.g., vampire bats and _____ ___________ e.g. reciprocity in primates Altruism among relatives Kin selection – altruistic behavior increases the fitness of a relative and in so doing indirectly increases the fitness of the altruist “I'd lay down my life for two brothers or eight cousins.” J.B.S. Haldane Relatedness – relatives have specific probabilities of sharing copies of the same gene copyEEB2244%Lecture%Guide% Lecture%12:%Behavioral%Ecology% Page%3%%3%% If an altruistic act is favored by kin selection depends on three things: 1. C = the cost to the altruist 2. B = the benefit to the recipient 3. r = the coefficient of the relatedness between the giver and the receiver Inclusive fitness – total fitness of a behavior gene Fitness (Wi) = Hamilton’s rule An altruistic behavior is favored if: > or < . A selfish behavior is favored if: > or < . Altruism and extended families Altruistic behavior occurs in proportion to degree of relatedness Individuals distinguish _____________________ E.g., meerkats Altruism outside of families Altruism among unrelated individuals is rareEEB2244%Lecture%Guide% Lecture%12:%Behavioral%Ecology% Page%4%%4%% Conflict reduce fitness of selfish individuals below that of cooperators When most individuals cooperate, a selfish individual can have highest fitness Game Theory Predicts optimal behavior (“strategy”) when fitness is 1. frequency dependent 2. each individual maximizes its fitness Pay-off grid e.g., 4-way stop sign Eusociality Highest grade of sociality Offspring help parents rear siblings rather than reproduce themselves Some organisms have no individual fitness, only inclusive fitness Characterized by: 1. several adults living together in groups 2. overlapping generations 3. Cooperation among individuals 4. Reproductive dominance & sterile castes Found only in termites, bees, ants and the naked mole rat Organization of insect societies Typically one or a few queens, which are egg-laying females Non-reproductive female progeny of queen gather food and care for brothers and sisters Male offspring become sexually mature & leave the nest. Why? %EEB2244%Lecture%Guide% Lecture%12:%Behavioral%Ecology%