primates Flashcards
homology
Close relatives share similar traits due to common ancestry
phylogenic contraints
Evolutionary history limits the variation observed in current populations/species
vestigial traits
‘Legacies’ from ancestors that are not functional at present
convergence
Traits of unrelated or more distantly related groups appear similar due to common selective pressures – rather than common ancestors
fossil homindes
fossils that no longer are avlive however relate to humans
socioecology
the relatonship of primate social behaviour and social organisation to the envionment
Linnaeus
anatomical similarties between monkeys, apes and humans
Darwin
if man had not been his own classifer he ould never have thought of founding a seperate order for his own reception
2 reasons to study primates
1- homology: closley related species tend to be similar morphologically becauase they share traits acquired through decent from a common ancestor
2- anaology: natural selection leads to similar organisms in similar environments by assesing the diversity in behaviour and morphology of organisms in relation to their envionment
examples of primate evolution
1- warfare:
chimps: lethal intergroup aggression
humans: warfare
2- culture and traditions:
humans: chinease eat with chopsticks austrlians use cuttlery
Chip: use stone hammers in africa but not in east africa
3- prosocial behaviour:
humans: act out of self interest but also act on the welfare of others
chimp: spontaneous helping
classification
hierachy of levels for grouping primates in larger units based on relationship
taxonomic groups
similar characterstics
ancestral traits
retained from ancestral groups
derived traits
newly arising in focal taxon
prehensile
grasping of hands and feets (opposable big toe)
steroscophic vision
each eye sends a signal of the visual image to both hemispheres in the brain to create an image with depth
binocular vision
fields of vision of the 2 eyes overlap so that both eyes perceive the same image
colour vision
all diurnal primates have it, nocturnal primates don’t
Postorbital plate/bar
anthropidea: postorbital plate
Prosimii: postorbital bar
olfactory apparatus
reliance on sense of small
- reduction in sensory areas of brain and in snout
– especially in diurnal primate
unspecialised teeth
Utility – processing food – weapons in conflicts • Primates have generalized dentition • Teeth tell us something about – dietary preferences – age of individuals and developmental patterns – phylogenetic relationships – social structure
dental formulas
top jaw/lower jaw
2123
2123
primate evloution: large brain
Primates generally evolved larger body size • Brain increases with increase in body size • Primate brains increased in size more rapidly than body size
themes of evolutionary diversification within order
- mode of locomotion
- dentiton and diet
- sociality
- brain development
prosimians
- Prosimii (‘before monkeys’) • Earliest primate group 55+ MYA • More reliance on olfaction – long snout – moist, fleshy pad (rhinarium) at end of nose – use scent marking – “split” upper lip – Dental comb – Unfused mandible (lower jaw bones) – Post orbital bar, not plate – Many nocturnal • Tapetum lucidum • reflective layer in eye that maximizes use of light • Quadrupedal & mostly arboreal
prosimii lorisoidea
• 2 families – Lorises (Lorisisdae) – Galagos (Galagidae) • Africa and SE Asia • 2133/2133 • Quadrupedal climbers • Nocturnal, arboreal, solitary • Leave their dependent offspring in nests
family lorisidae
Nycticebus coucang (Slow loris): SE Asia • 400 grams • Nocturnal • Diet: tree gum Loris tardigradus (Slender loris): S India • 200 grams • “Banana on stilts” • Slow and cryptic • Powerful grasp • Nocturnal • Diet: fruit and insects
family Galagidae
Continental Africa • Long bushy tails • Large ear pinna • Nocturnal • Leapers • Diet: fruit, gum, animal
Prosimii: lemuroidea
Madagascar • Diverse taxon • Most nocturnal • Most arboreal • Some torpor – state of decreased physiological activity • Females dominant
lemuridae:
Madagascar • 3 kg • Monomorphic – males & females alike • Diurnal, partly terrestrial • Diet: fruit, leaves • Social • Females dominant • Scent mark vegetation • Males display waving ‘scented’ tails (‘stink fight’)
Lemuroidea: Indridae
Madagascar • Diurnal, arboreal • Ca 7 kg • Vertical clinging & leaping • Diet: leaves, fruit • Monogamous
Tarsioidea
• East Asia • Nocturnal and arboreal • 110 grams • Dental formula 2133/1133 • Diet: 100% animal prey • Incomplete post orbital plate • Grooming claws (2) • Eye larger than brain • Rotate head almost 180 degrees • Clinging and leaping • Solitary (except females + young)
anthropoidea
• Single clade (all from one ancestor) • No grooming claw (all nails) • No tapetum lucidum (only 1 nocturnal genus) • Largely diurnal • Fused lower jaw • Short snout / reduced olfactory reliance • Continuous hairy dry upper lip • Postorbital plate • Larger relative brain size than prosimians
Platyrrhini (‘flat noses’):
Ceboidea (New World
Monkeys)
• Only Ceboidea (but not all) have prehensile (grasping) tails • Dental usually 2133/2133 • Sideways-facing nares (nostrils) • Completely arboreal • Diurnal (except 1 genus) • Two large families – Cebidae – Callitrichidae
Cebidae
Diverse family • 5 subfamilies • Dental 2133/2133 • >3-8 kg • All nails • Many with prehensile tail • Diurnal • Leaves, fruit, animal matter
Callitrichidae
All < 1 kg • Dental = 2132/2132 (molar reduction!) • Claw-like nails (reversal) except 1 st toe • Quadrupedal • Diurnal • Diet: fruit, gum, animal • Family groups of 5- 10 • Most twin
Catarrhini (‘narrow noses’):
Cercopithecoidea
• 1 family (Cercopithecidae) = Old World monkeys • Dental: 2123/2123 • Bilophodont molars • Ischial callosities near tail • Some with sexual swellings • Tail never prehensile • Wide variety of habitats • 2 subfamilies • Cercopithicinae – largely fruit eating • Colobinae – largely leaf eating
Colobinae
Africa, Asia • Arboreal (most) • Leaf and seed eaters, lichen (some) • Have complex stomachs • Often found in ‘harems’
Cercopithecinae
Africa & Asia • Variable in size • Typically live in medium or large bisexual groups (multimale-multifemale)
Examples of Cercopithecinae
- Patas (Erythrocebus)
- Mandrill (Mandrillus)
- Japanese macaque
Catarrhini: Hominoidea (apes and humans)
Larger body (usually) • No tails • Limb arrangement reflecting brachiation – rotation of shoulder & scapula – ventral-dorsal flattening of trunk (shallow chest) – wrist joint flexibility • Longer forelimb than hindlimb – human reversal • Y-5 molars on mandible • Relatively even larger brains • Prolonged dependency of young
Hominoidea: Hylobatidae
SE Asia • Diurnal, arboreal • 6-8 kg • Brachiators • Ischial callosities • Monomorphic body size (but some dichromatism) • Mostly fruit • Monogamous • Territorial • Vocal duets
Hominoidea: Pongidae
Orangutan (Pongo) – 2 species • Borneo & Sumatra • Ca 37-77 kg • Males 2x female body weight • No ischial callosities • Quadrumanous • Cheek flanges in dominant males • Diurnal, arboreal • Fruit, leaves, animal • Most solitary • Slowest life history of all primates – age at first reproduction: 15 yrs – inter-birth interval: 9 yrs
Hominoidea: Hominidae
Gorilla (Gorilla) • 70-170 kg; males = 2x females • No ischial callosities • Knuckle walk • More terrestrial • Mainly folivorous • Typically in one-male groups
Hominoidea: Hominidae
2 species – chimpanzee – bonobo • 31-60 kg; sex dimorph varies • Knuckle walk • Quadruped; climbing • Fruit, leaves, animals
Behavioural peculiarities of chimps and bonobos
- large mixed sec communities
- chimps modify natural objects for use as tool in the wild
- chimps co-operativley hunt other primates
- bonobos: ‘make love not war’ ape
evolution of primate traits
• Natural selection → increased efficiency of behaviours in particular environments
- Some individuals better able to produce more offspring →left
more copies of their genes
behavioural ecology
- the study of behaviour from an evolutionary and ecological perspective
- Behaviour is a product of
natural selection on ancestral populations resulting in increased adaptation to particular habitat
• Anatomical traits and
behaviour linked
socioecology
• Social system evolves in response to ecological conditions • Availability and distribution of resources → – competition – grouping – social behaviour – mating patterns • Social behaviour is a suite of adaptations to the ecological and social environment
social organization
group compositon and spatiotemproal cohesion
social structure
social interactions and relationships
mating system
whos mates with whom and what are the genetic consequences
what is needed to survive
Find food – Find and co-ordinate with mate – Have offspring & rear offspring – Avoid parasites – Avoid predators
pros of living in a group
defense of territory/food
resources & mates from
competitors
– lower risk of predation
cons of living in a group
Costs – increased competition for resources (food, mates) – increased likelihood of disease and parasite transmission – increased consp
benefits of sociality
lower risk of predation Detection • more eyes to detect predators Deterrence • more individuals to mob or chase predators away Dilution • smaller chance that any one individual is the prey of the day when group is larger-
what is the optimal group size
The size and composition of groups reflects a compromise between the costs and benefits of sociality for individuals
what is reproductive success limited by?
females: access to resources
males: access to females
ecological pressures: influnce the distrabution of females, and males distribute themselves to maximize their access to females
explain/define the food that is needed
• Supplies energy requirements for survival, growth & reproduction • Dietary specializations drive numerous specializations – body size – teeth form and number – gut length – hand (shape, function) – locomotor and suspensory systems – brain size • Different kinds of foods in different kinds of habitats are distributed differently in space and time
what are the major adaptations to the digestive tract in primates and colobines
Primates unable to digest cellulose → microorganism for cellulose digestion
Colobines: complex multi-chambered stomach with cellulose-digesting bacteria
effect of resource distrabution
High-quality food such as fruits have patchier distributions than low quality foods such as leaves
what are the types of competition and how does this affect resources
- scramble: “first come first serve”
- Food is evenly distributed
- Amount of food available per individual decreases with increasing group size
- contest: Food is found in defensible clumps
– Individuals compete
aggressively over access to
resources
why do animals disperse
Avoid inbreeding – reason in many cases for natal dispersal but does not explain secondary dispersal • Seeking better resources – plays important role secondary dispersal • Result of intrasexual competition- – but does not explain species where individuals leave voluntarily
solitary
males defend home ranges tha encompass home ranges of several females
monogamous pairs
when females are dispersed males may associate permanently with one of them
polyandry
several males associate with one repoductive female
polygyny
if females are clumped in groups one male may be able to monopolize access to a group
male infanticide
Infanticide by males is major source of infant mortality in primates
– especially in single-male groups
• Most cases of infanticide follow changes in male residence (eg. takeovers) or dominance rank
human mating system and the types of mating that i allowed
• Majority of human societies allow polygyny
• but its frequency depends on subsistence
style:
– monogamy predominates in forager societies
– pastoralists and agriculturalists show significant
polygyny
sexual dimorphism
Correlation between sexual size dimorphism and polygyny in many mammalian groups
• Pronounced body size dimorphism is suggestive of
high levels of male–male competition
how does testis size affect the mating system
Primate species in promiscuous mating systems have much larger testes relative to body size than primates in single-male groups
• Humans: mild level of promiscuity
sprem competition in humans
- Male ejaculate volume reflects risk of extra-pair copulation (EPC)
- Ejaculate volume from copulations correlated with length of time for which couple were apart – effect independent of time since last copulation
- → Functions to maximise probability of conception by swamping any rival sperm
