13- Tarsiers and platyrrhines Flashcards
tarsiers (1)
group of Southeast Asian primates - Present-day distribution limited to
Indonesian archipelago and Philippine Islands
Survivors of a much more diverse and widespread group of Eocene tarsiiforms
New species continue to be
discovered
Current species count ~14
3 genera
tarsiers (2)
50-130 g
HUGE eyes
Head can turn 180 each way (360 total)
No tapetum
Emit and hear ultrasound
Exclusively arboreal
Pronounced leaping behaviour
Exclusively faunivorous, preying on arthropods and small vertebrates - The only primates who don’t eat any plant food
tarsiers (3)
Produce a single, exceptionally large (25% of
maternal weight) infant
Secondarily nocturnal—descendants of a diurnal
ancestor
Diverse social organisation:
- Solitary
- Pair-living - Some ‘pairs’ include a second female
- Spectral tarsiers observed in small groups in some populations
Platyrrhine phylogeny (genus level)
Primate radiation with long evolutionary history independent from those of catarrhines and strepsirrhines
3 major monophyletic groups
Extant families diverged rapidly
Number of species and even genera debated
platyrrhine biogeography
south and Central America-
exclusively in tropical and subtropical americas
Northern Mexico to northern Argentina
monophyletic group that originated from Africa
platyrrhine ecology
Narrower ecological range than catarrhines – all arboreal
Less adaptive diversity than other primate radiations
Several unique morphological and
behavioural features
Substantial variability in social systems - some unique
platyrrhine body size and morphology
Body mass
- 100g in pygmy marmosets
- >10 kg in atelids
Marmosets & tamarins are ‘phylogenetic dwarfs’
Callitrichids (re)evolved claws
Prehensile tail evolved twice
- Atelids and capuchins
- Also in six mammalian, one amphibian, and two reptilian
families
what do platyrrhines eat?
Broad diet with some specialised taxa
Callitrichine claws and dentition allow them to exploit gums, saps, and embedded insect prey
Some callimico commonly eat fungi
- very rare in other primates
- patchy, ephemeral and low density
- massive home range
No digestive specialization for folivory, unlike in some
lemurs and some catarrhines
Some atelids (howlers, muriquis) have dental and
behavioural adaptations for folivory (semifolivores)
Stone tools improve
diet quality in
capuchins
No effect on amount of food
eaten
Improved nutrition by
providing more consistently
balanced diet
Diets obtained with tools
- higher levels of fat,
carbohydrate, and energy
- lower levels of nutrient-
diluting fiber
what eats platyrrhines
Constricting & venomous snakes
Tayras
Felids
Domestic animals
Raptors
Other monkeys
Likely to depend on body size
Hard to study predation risk
platyrrhine locomotion and activity patterns
All almost exclusively arboreal
Lots of open habitats in S America so lack of open habitat doesn’t explain lack of terrestrial modern platyrrhines
Diurnal, except night monkey
(Azara’s night monkey is cathemeral)
life history
relatively slow compared to other mammals
needs long term study
callitrichines twin - associated with small body size, male involvement in offspring care, high-quality food sources
platyrrine social organisation
Great variation, despite limited ecological range -
variation within genera and within species in some taxa
- No solitary platyrrhines
- Pairs
- One-male, multi-female groups
- Multi-male, one-female group
- Multi-male, multi-female groups
Fission-fusion: Spider monkey females and dependent offspring often travel independently, but regular contact with males and mixed-sex parties common
‘Bachelor’ groups less common than in catarrhines
atelids
muriquis,
spider monkeys
woolly monkeys
howlers
atelids social organisation
One-male, multi-female or multi-male, multi- female
Howler monkeys:
- Groups of 10-15, up to 40
Wooly monkeys, spider monkeys, muriquis:
- Large multi-male, multi-female groups
- Some fissioning
- Spider monkeys have high fission-fusion dynamics (flexible), like chimpanzees & bonobos
- Female dispersal, unlike cercopithecines
pitheciids
titis, sakis, bearded sakis, uakaris
pitheciids social organisation
Titi monkeys
- Adult pair, 2-4 young
- Coordinate activities
- Both sexes disperse
Sakis
- Not well understood
Bearded sakis & uacaris
- Even less well understood!
- Large, loosely structured, multimale, multi-
female groups
- Can be >100
- Fission-fusion?
cebids
marmosets, tamarins, squirrel monkey, capuchins, night monkeys
cebids social organisation
Diverse social systems, group size, mating behavior, and dispersal patterns
Capuchins
- usually multi-male, multi-female groups of 3-30
- dispersal mainly males
Squirrel monkeys
- multi-male, multi-female groups of 25-50
- dispersal patterns vary (males and females in different species)
Owl monkeys
- adult male-female pair, few young
- defend territories
- both sexes disperse
Marmosets & tamarins
- small, territorial groups of 3-12
- 1-3 adults of each sex
- both sexes disperse
mating systems vary a lot
Atelids
- Spider monkeys, woolly monkeys, muriquis mate
promiscuously, little overt competition among males
- Some howler monkeys show rank-based mating skew in males
Pithecids ???
Cebids
- Capuchins promiscuous, variable skew in males
- Squirrel monkey males ‘fatten’ in mating season
- Night monkeys (serial) monogamy
- Callithricines vary! :
Monogamy, polygyny, polyandry, polygynandry
Strong female competition and physiological suppression
social structures also very variable
Great variation in all relationships
- Male-male
- Female-female
- Male-female
Dominance hierarchies
- difficult to discern among males or females in large multi-male, multi-
female groups
- Overt competition rare
- Unlike most catarrhine monkeys
- Some capuchins have clear hierarchies
Allogrooming
- Extremely rare or nonexistent in some group-living platyrrhines
- Howler monkeys groom
- Callitrichids groom a lot
egalitarian muriquis
No dominance hierarchies
No fighting over food or sex
None of the competitive and
aggressive behaviours thought to prevail in primates (in the ‘classic’ literature)
(But males can kill outsiders)
cooperative breeding and parental care
Unlike in other primate radiations, most reproduction n groups concentrated in a single female in many taxa
- titi monkeys & sakis (pitheciids)
- night monkeys & callitrichines (cebids)
Associated with unusual patterns of infant care
Many taxa have intensive offspring care by group
male
- putative father
- carrying & food sharing
Cooperative breeding the norm in callitrichines
- additional alloparental care
callitrichines
Parents, other relatives (e.g.,
older siblings), even unrelated group members share offspring care
Compete for opportunity to carry young
Only cooperatively breeding
primates
- Except humans?
- Rare in mammals
allocare
non-mothers also often care for infants in capuchins & squirrel monkeys
males, older sisters, unrelated females may nurse infants
cooperative mate defence
rare in primates
- only some platyrrhines and chimpanzees
limited overt competition among males in a group
-some atelids, some cebids, maybe some pitheciids
males in same group tend to be more affiliative than in most catarrhines
cooperate to defend the females in their group
