Biology of Mammals
Biology of Mammals ZOL 365
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This 6 page Class Notes was uploaded by Marlon Brown on Saturday September 19, 2015. The Class Notes belongs to ZOL 365 at Michigan State University taught by Barbara Lundrigan in Fall. Since its upload, it has received 39 views. For similar materials see /class/207228/zol-365-michigan-state-university in Animal Science at Michigan State University.
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Date Created: 09/19/15
Social Organization amp Mating Systems 3242011 10100 PM Social Organizations Sociobiology study of the evolution of social behavior in all animals o Founded by EC Wilson o Assumptions 0 Genetic Basis o Affects the reproductive success of an individual All mammals exhibit some social behavior o Femalesmales must get together to mate o Females must interact wtheir young at least until weaning 0 But most mammals are solitary most of the time o Eg Subclass Prototheria all extant are solitary o Metatheria most solitary o Eutheria most solitary c We don t always know if they are social due to lack of study o Variation within many species Society group of individuals belonging to the same species and organized in a cooperative manner o Sociality has evolved many times in mammals o Solitary is the primitive feature Benefits of Group Living o 1 Increased acquisition of resources 0 Mountain sheep benefit from the memory of others Young benefit from elder sheep memory 0 Baboons benefit from a group search If something is found they all get to have some 0 Bring down largerfaster prey African wild dogs stalking an antelope o 2 Improved defense of resources 0 African Lions Defend territory 0 Banded Mongoose Defend territory from other banded mongoose n Mostly during females are in estrous o 3 Reduces susceptibility to predation 0 Alarm calls Alerts other members to presence of predators Prairie Dogs have advanced system 0 Signals of Alarm Stotting stiff legged bounding gait n In deer and antelope o Defending against predators Muskoxen a Make ring and make young go to the center and adults make up the outside of ring 0 A form of cover Selfish herd all animals try to get to the center of herd to stay alive n Wildebeest Costs of Group Living o 1 Increased visibility 0 problem for both predators and prey Spotted hyenas amp Pronghorn n Refinements in hunting techniques and anti predator techniques o 2 Increased competition for resources 0 establishment of dominance hierarchies o 3 Increased opportunity for transmission of parasites and disease 0 fidelity to the social group excluding outsides reduces probability to bring outside diseasesparasites into the group Mating Systems o Monogamy mating between one male and female o Polygyny one male mates with more than one female o Promiscuity both malesfemales have multiple partners o Polyandry one female mates with more than one male 0 Most mammal species are polygynous Why Females usually make a much larger investment in their young than males have As a result a Females tend to be choosy about mates n Males are not choosy mate with as many females as possible 0 Many species do not fall cleanly into any one category 0 Most are not well enough studied to place into a category Monogamy o Less than 5 of mammal species are monogamist o It is evolved widespread o Obligate monogamy females requires assistance Strong pair bond Welldeveloped male parental care 0 Facultative monogamy male presence not required Male holds territory that is needed for offspring to be successful Weak pair bond Little or no male parental care a Alarm call is about all they do o Cooperative breeding 0 Young animals forego reproduction amp help breeding pair Wolves Meerkats Alpine marmots Polygyny o 1 Resource defense Polygyny males defend resources that females want 0 Tend to be neststerritories o 95 of the young were fathered by the territory male o 2 Female defense Polygyny males defend the females themselves from other males 0 Harems o Occurs in bats Perissodactyla o 3 Dominance Polygyny males establish a dominance hierarchy which determines their access to females 0 When females are not in estrous then no males will be in the group but once they become in heat males will begin to fight and show dominance o Hammerheaded bat o Lek a communal courtship area where males congregate and compete for dominance Not very common 6 of the males secured 80 of the matings Promiscuity Polyandry o Very rare o Saddlebacked tamarin 0 Have twins and male helps the females carry them around Eusociality a specialized caste reproduces in a colony of mostly non reproductive animals o Very rare in mammals o Naked Mole Rats 0 Live in underground colonies o 3 Castes frequent infrequent nonworkers 0 Queen only reproductive female and mates with select group of nonworkers Food Resources Social Organization and mating systems o Jarman 0 Group 1 Browsersfeed very selectively Small group Permanent territory Monogamous 0 Group 5 Grazers not a selective feeder Large groups No permanent territory Highly polygynous c When you need to make predictions about social structure or mating systems look at the distribution of critical resources starting with FOOD What happens to the offspring of social species when they mature o Females are usually philopatric they stay home and males usually disperse What happens to the adult males that are excluded from breeding by Polygyny o 2 Decisions 0 Accept subordinate position 0 Leave the group o Males usually have a shorter lifespan than female conspecifics 3242011 10100 PM
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