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Primate Behavior

by: Shanie McLaughlin

Primate Behavior ANTHRO 106

Shanie McLaughlin

GPA 3.82

S. Etting

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S. Etting
Class Notes
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This 8 page Class Notes was uploaded by Shanie McLaughlin on Thursday October 22, 2015. The Class Notes belongs to ANTHRO 106 at University of California - Berkeley taught by S. Etting in Fall. Since its upload, it has received 53 views. For similar materials see /class/226670/anthro-106-university-of-california-berkeley in anthropology, evolution, sphr at University of California - Berkeley.


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Date Created: 10/22/15
Anthr0106 Lecture 5 Primate Socioecologyhow ecological factors shapes the way primates organize themselves how it affects the types of groups primates form Primates are unusual in the type of social groups they form 0 each is part ofa home group 0 there are no primates that migrate o occupy relatively stable home ranges 0 always older individuals who are even more familiar with the location of food and water during scarce times live in stable groups ofboth sexes even outside of the breeding season 0 live in groups of male and females throughout the year despite the once a year breeding season I this is unique as most mammals only live among both sexes during the breeding season Primates vary a lot in how they arrange themselves in space This variation ultimately comes down to what is most important to males and females 0 Sexual Selection I Darwin noted 2 types 1 Competition among one sex for the other 2 Differential choice by members of one sex for members of the other 0 1972 9 Robert Trivers o explained why we typically see males competing for females and why females are choosey 0 Why I Female mammals spend a lot of energy on 0 Egg Formation 0 Internal Gestation 0 Lactation 0 Postweaning care I Because of this female reproduction output is primarily limited by access to resources 0 Male mammals are less energetically constrained I Sperm are quite cheap to produce I Paternal care is often not required 0 Therefore male reproductive output is primarily limited by access to females I Also means one male can mate with multiple females Reproductive Constraints 0 Females distribute themselves according to resources and are choosy about mates intersexual selection between sexes inter between 0 Males distribute themselves according to wherefemales are and compete with each other for females intrasexual selection between the same sex intra within MaleMale competition can lead over long periods of time to sexual dimgorghism Sexual Dimporphism 9most obvious traits to observe this 0 Sagittal crest o Brow ridges males tend to have larger brow ridges 0 Body and Canine Size o Coat Length and Color Primate Mating System different from social structure it is who is mating with who 0 Types 0 Monogamy o Polygyny one male mating with multiple females 0 Polyandryrarest type one female mating with multiple males 0 Polygamy males and females both mate with multiple mates Primate Social Structures 0 Things that include o Dispersal Patterns which stay and which individuals leave 0 Group Size and Composition 0 Intragroup Interactions o Intergroup Interactions whether they are territorial and such Dispersal Patterns Individuals leave their natal groups due to lack of reproductive opportunities either related to too many others in the group that won t mate with you or lack of 2 Types 1 Locational Dispersal leave the area that you know with a group of known individuals don t change social circumstances but location Social Dispersalleave an area of known individuals to live with unknown individuals not necessarily the location Advantages to staying within Home Range 0 Familiarity with I Conspecifies kin Individuals of the same speciesknown I Locations of foods I Escape routes shelter from predators I Locations and habits of predators 0 Home Ranges what we re talking about in means of dispersal Costs of Dispersal o Conspecific aggression o Unfamiliarity with novel ranges Different Patterns of Dispersal o Phylopatry 0 Most species show malebiased dispersal meaning that women are Phylopatric baboons 0 Some show femalebiased dispersal chimps9 females leave and males stay very rare 0 And some show dispersal of both sexes howler9 offspring get kicked out at maturity by the samesex parent daughter by motherson by father N Primate Social Structures 0 Types 0 Solitary Foragers I Orangutans o PairLiving I Gibbons o 0nemalemultifemale Multimale multifemale I Stable MMMF groups 0 I Fissionfusion groups 0 Multileveled societies Solitary Foragersexamp1es Nycticebus Pongo Tarsius 0 Females have territoryhome ranges that will typically overlap with other females 0 Typically not too far away from their mothers after being 39kicked out Females travel alone with dependent offspring if they have one Males have territories that overlap those of several females BUT typically don t overlap with other males 0 Sons typically disperse further away than daughters as male territories don t overlap Females travel with dependent young Male ranges overlap those of several females Female territoriality varies this helps scientists determine tolerance by looking at how much ranges overlap Both sexes disperse males usually farther Pair Livingexamp1es Aotus Hylobates Indrl39 0 Male and Female with dependent offspring SHARE range territory 0 Territorial 0 Very little overlap and very little tolerance between pairs 0 Offspring wait until a territory opens up before dispersing not many opportunities for disp ersal 0 Both Sexes disperse 0 Variable paternal care Onemale Multifemale groupsexamp1es Colobus Gorilla Erythrocebus 0 Female and offspring share a home range with one male traveling together 0 Males have to disperse 0 Male aggressive toward other males bachelor groups where males hang out together for safety 0 When one group runs into another group males will be very protective and aggressive Typically malebiased dispersal some female transfer Highly sexually dimorphic Infanticide commonkilling of babies 0 Most sexually dimorphic primates have this sexual selection Stable multmale mutlifemale groups examples Lemur Papio Sal39ml39rl39 0 Lots of females and offspring with Lots of males 0 Most of the time in primates males are the ones that disperse o Males form dominance hierarchy within group 0 Some males will have greater access to females than other males Typically malebiased dispersal some exceptions Degree of sexual dimorphism varies 0 Doesn t vary according to sexual selection but rather lineageancestory FissionFusion Communities Ateles Pan paniscus Pan troglodytes 0 Live in VERY large area 0 Females and offspring have their own ranges within the large ranges 0 Travel around roughly by themselves within the big community rangearea I 9 Core areas Females disperse and males stay FemaleBiased Dispersal Males are related to each other and females are not FissionFusion9 core areas used by females and males cooperatively defend the whole large area and go in and out of core areas and occasionally subgroups form this is the fission and fushion Animals fission and fuse not together all the time Related males cooperate to defend communal range More subtle forms of malecompetition 0 Still dominance hierarchies but the males also compete in more subtle Sperm competition is one subtle form of malemale competition in these groups 0 Large testes high sperm volumekeeps them from having to physically fight I See picture on slide of chimp brain vs chimp teste Most extreme sexual dimorphism is found in Singlemalemultifemale groups Multileveled Societies o Onemale group HOWEVER the males will gather together temporarily while foraging or at sleeping sites 0 Many of the species that do this are not well studied homodryas baboons are one of the few groups studied 0 May occur due to rarity of sleeping sites 0 May reduce costs of female dispersal 0 Because female are changing location 0 Mating patterns occur as in 1M MF groups 0 Polygynous o Seems to be little social interaction in large groups Primate Social Systems Summary underlined are social organizations NOT mating situation 0 Food is rare dispersed then females dispersed o If one male can defend only one female range then you get pair livingnot necessarily monogamous groups as this is a tricky definition 0 If one male can defend ranges of multiple females then you get solitary foragers o If multiple males can defend ranges of multiple females then you get fissionfusion societies 0 Food is clumped Predation risk is high 0 Females Clumped small groups I Then one male can defend group of females and you get singlemaleI multi female groups 0 Females clumped large groups I Then one male cannot defend large group of females you get multimale multifemale groups Food and Primates Ranging o The distribution of food in the landscape is important 0 It affects how females distribute themselves 0 The space daily travel needed to get enough food also affects ranging and the economics of territoriality Terms 0 Home Range HR 0 Daily Path Length DPL Daily Travel Distance Relative size of HR and DPL will depend on 1 What the animals are eating 2 Distribution of foods in the habitat a Example baboons eat fruit and have to travel quite far and have a large home range to acquire food i Gorillas live in a quotsalad bowl so their home range and travel is small Groups 0 Contest competition will be observed as 1 Territoriality over ranges if defensible 2 Aggression over food patches if not defensible basically aggressive over the tree you are eating in at that moment TerritorialityDefensible whether a home range is defended depends on the economics of defense Bene ts exclusive access to resources and mates Costs take time energy can be dangerous yelling a lot to each othervery vocal can be dangerous Economics of Defense 0 Depend on relationship between DPL and HR 0 HR diameter lt DPL Defensible 0 HR diameter gt DPL NOT defensible 0 To be territorial you need to be able to travel to your range boundaries in a day Scramble competition will be observed as 0 Increase in home range size 0 Increase in daily travel distance 0 Faster patchdepletion time Why do primates live in groups 0 Primary Hypotheses o Predation 0 Safety in numbers Hamilton 1971 o More eyes looking out Pulliam 1974 Lima 1990 0 None of these explain variability or why they live in kin groups 0 DispersalForaging Efficiency 0 Infanticide o Feeding competition Food Competition Model to explain grouping By Wrangham 1980 0 Group living increases intragroup feeding competition larger groups benefit members of intergroup feeding competition 0 Larger groups do better than smaller groups Groups form through coalitions of related females also gaining inclusive fitness benefit of cooperating with kin Bigger groups can outcompete smaller groups over defensible foods Cooperative defense of food femalebonded groups Su ortin evidence two rou s of rimates 1 Many primates live in quotfemalebondedquot groups I Tend to be frugivorous I Strong dominance hierarchies I Aggressive toward other groups 2 quotNonfemale bonded groups I tend to be folivorous I weak or nonexistent dominance hierarchies I Non aggressive toward other groups I Some studies show that 0 Females in larger groups have greater survival fecundity offspring survival and reproductive rates 0 Larger groups displace smaller groups 0 Criticisms and Limitations 0 Based on limited data set 0 Now known there are more than 2 types of females 0 Doesn t explain solitary foraging or variation in group composition 0 Some femalebonded species found to have lower RS reproductive success in larger groups suggest more intragroup competition 0 Van Schaik 1983 o Feeding efficiency will always be lower in groups 0 Intergroup competition lt intragroup competition disagrees with Wrangham o Primates form groups to avoid predators but will suffer from intragroup competition 0 SO I Predation 9 Increased Group Size I Intragroup feeding competition 9 decreased group size 0 Supporting evidence I Smaller groups may occur in the absence ofpredators I Some evidence predators give up sooner ifprimates are living in bigger groups I PSA s polysistic associations 6 see yesterday s lecture may form response to predators Criticisms and limitations I Doesn t necessarily explain solitary foragersvariations in group competition I Fewer infants per female in larger groups used as evidence due to greater infanticide in larger singlemale multifaceted groups 0 Infanticidle males are more attracted to the larger groups of females 0 o Sterck 1997 o Infanticide I Realted to the predation hypothesis but addresses group composition issue I Predation risk 9 females live in groups quotLike predation infanticide enhances the formation of female groups I Females get protection from infanticidal males by grouping with protective males Infanticide killing of infants can be adaptive when males increase their reproductive success by killing dependent offspring of females in order to bring the females into estrus sooner than waiting Hrdy 19705 I Spcies characteristics that increase likelihood ofinfanticide 1 N onseasonal breeders bringing the females into estrus 2 Live in singlemale groups 3 Long interbirth intervals 4 Short male tenure Supporting Evidence I Infanticide happens I Happens more often in singlemale multifemale groups Criticisms and limitations I There should be more multimale multifemale groups if Hrdy s theory is the case I Doesn t explain solitary foragers or group compositions other than singlemale multifemale groups Primate sociali Dis ersal Fora in Efficienc Model I Isbell 2004 argues o Kin groups form when costs of dispersing are great and mothers can tolerate them staying I Low dispersal costs Females may may not disperseIndifterent females variable female kin groups I High Dispersal Costs 0 Energetically Constrained goaldirected I Stingz Mothers no female kin associations 0 Less Energetically Constrained some wandering travel I Wandering gt GoalDirected o Generous Females no kin groups I GoalDirectedgtWandering o Incomplete Suppressors small female kin groups 0 Allows to keep track of other females so she doesn t go to a tree already usedwithout fruit I Wandering gtgtgt GoalDirected o Facilitators large female kin groups Dispersal Costs I Ifmothers can tolerate daughters may be better to move together within home range I Variation in grouping depends on how much females can expand home ranges to accommodate breeding daughters I Which depends on exploratory foraging Why Do primates live in groups Pros I Reduced risk of predation I More eyes looking out for predators I Greater success in intergroup feeding contests I Better protection from infanticidal males I Minimize dispersal costs Cons I Greater intragroup feeding competition 0 Longer daily travel scramble competition 0 Dominance Hierarchies context competition I More conspicuous to predators I More attractive to infanticidal males What you need to know I What primate socioecology is I Reproductive contraints and implications I Primate mating systems 0 What are they 0 How are they different from social systems I Primate Social Systems 0 What is dispersal Costs Benefits 0 What are the different types of social systems 0 General characteristics of each I Understand economics of territoriality when and when you can not I Be familiar with theories on why primates live in groups 0


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