Chapter 5: Primate Diversity and Ecology
Two Reasons to Study Primates
●Study of nonhuman primates help us understand human evolution
○Closely related species tend to be similar morphologically
■Shared traits thru descent from common ancestor
■Ex: viviparity (birthing live young) and lactation are traits that all placental/marsupial mammals share, and distinguish mammals from other
taxa
■Studying primates give us more insight into our ancestors than other organisms
●This approach is called reasoning by homology
○Nat selection favors similar adaptations in similar enviros
■Assessing patterns of diversity in behavior/morphology in relation to enviro → can see how evolution shapes adaptation in response to diff selective pressures
●This approach is called reasoning by analogy
Primates Are Our Closest Relatives
●Linnaeus first placed humans with apes in 1735; later naturalists put us in our own order;
then Darwin advocated reinstating humans as primates
●Humans and primates share many aspects of morphology, physiology, and development
○Well-developed vision, grasping hands/feet
○Shared life history: extended juvenile development, long lifespan, larger brains
○Similar behaviors due to similar physiologic/cognitive structures
●Nonhuman primates provide useful models for understanding evolutionary roots of human morphology and nature
Primates are a Diverse Order
●Great morphological, ecological, behavioral diversity among species w/in primate order
○Diffs in size, environment, diet, sociality, child-raising, and behavior
●Some primates are nocturnal and others are diurnal
○The fat-tailed dwarf lemur enters torpid state and sleeps for 6 months each year
●Some primates partake in conspecifics, defending territory from incursions by other members of own species
●Phylogenetically similar → typically morphologically, physiologically, and behaviorally similar → can use diffs to determine adaptive responses to diff environments Features That Define the Primates
●All mammals share traits: 4 limbs, hair, live young + milk
●Primates are rather nondescript
○No single derived feature shared by all primates
●Big toe on the foot is opposable and hands are prehensile
○Primates can use feet and hands for grasping
○Humans have lost the opposable big toe
●Flat nails on hands and feet instead of claws
●Sensitive tactile pads w/ fingerprints
○Enhanced dexterity
●Locomotion is hind-limb dominated
○Hind limbs do most of the work and center of gravity is closer to hind limbs than forelimbs
○All nonhuman primates spend at least part of their time in trees
○Some apes swing using brachiation
●Unspecialized olfactory (smelling) apparatus that is reduced in diurnal primates
○Less reliant on sense of smell than other mammals
●Highly developed visual sense
○Large, front-facing eyes w/ stereoscopic vision : each eye sends signal of visual image to both hemispheres in the brain → depth perception
○Most primates can see color and have binocular vision, where vision of the 2 eyes overlap so that both eyes see the same image
●Females have small litters w/ longer relative gestation/juvenile periods
○Longer pregnancies, later maturity, longer lifespan
■Signifies increased dependence on complex behavior, learning, and behavioral flexibility
●Brain is large w/ unique anatomic features
○Use intelligence as a way of life
●Molars are unspecialized, with max 2 incisors, 1 canine, three premolars, and three molars on each side of the upper and lower jaws
○Teeth can be used to gauge age of a skull, see relationships b/n species, inference developmental patterns/diets/social structure
●Not all of these traits apply to every primate but are general rules
Primate Biogeography
●Most nonhuman primates live in Asia, Africa, South America, and nearby coastal islands
●Mainly tropical regions w/ large daily fluctuations in temperature
○Distribution of resources is affected more strongly by seasonal changes in rainfall
rather than changes in temperature
●Nonhuman primates live in extremely diverse set of habitats
○Forests, savanna woodlands, mangroves, grasslands, deserts, etc
●Almost all species live in forested areas Taxonomy of Living Primates
●2 suborders of primates: strepsirrhini and haplorrhini
●Strepsirrhini: nocturnal, well-developed sense of smell, large eyes, independently movable ears
●Haplorrhini: diurnal, increased complexity of behavior, longer life spans, larger brains
○Generally larger than strepsirrhines, more dependent on sight, live in bigger groups
●Exception: tarsiers are included with haplorrhines because they are more closely related to monkeys and apes than to strepsirrhines but they are small-bodied and nocturnal
○Cladistic classification → haplorrhines
○Evolutionary taxonomy classification → strepsirrhines
Primate Diversity
Strepsirrhines
●The infraorder (taxonomic level below suborder) Lemuriformes includes lemurs, only found in Madagascar and Comoro Islands
○Got isolated from the rest of Africa 120mya, evolved in total isolation, and underwent adaptive radiation → once were over 44 species of lemur
○Once humans colonized Madagascar, all larger species of lemur went extinct and
modern lemurs are mostly small/medium arboreal quadrupeds
○Lemur behavior is variable: ~half are diurnal, the rest are either nocturnal or active during day and night
○Females usually dominate males
■Displace them from feeding sites, beat them in fights
■Female dominance is rare in most primate species
●Infraorder Lorisiformes contains small, nocturnal, arboreal animals in Africa and Asia
○2 distinct families w/ diff locomotion and activity patterns
■Galagos: active/agile, leap thru trees
■Lorises and pottos: slow-moving, remain immobile for long periods of time
●Maybe avoid detection from predators
○Lorisiformes feed on fruit, gum, and insects
○Use nests in trees
Haplorrhines
●Infraorder Tarsiiformes includes tarsiers in Borneo, Sulawesi, and Philippines
○Tarsiers are small, nocturnal, arboreal and live in pair-bonded family groups or groups w/ more than 1 breeding female
○Tarsier newborns are 25% of the mother’s weight → must leave babies in hiding places when they forage for insects
○Tarsiers are the only exclusively carnivorous primate (insects, small vertebrates)
Two Reasons to Study Primates
●Study of nonhuman primates help us understand human evolution
○Closely related species tend to be similar morphologically
■Shared traits thru descent from common ancestor
■Ex: viviparity (birthing live young) and lactation are traits that all placental/marsupial mammals share, and distinguish mammals from other
taxa
■Studying primates give us more insight into our ancestors than other organisms
●This approach is called reasoning by homology
○Nat selection favors similar adaptations in similar enviros
■Assessing patterns of diversity in behavior/morphology in relation to enviro → can see how evolution shapes adaptation in response to diff selective pressures
●This approach is called reasoning by analogy
Primates Are Our Closest Relatives
●Linnaeus first placed humans with apes in 1735; later naturalists put us in our own order;
then Darwin advocated reinstating humans as primates
●Humans and primates share many aspects of morphology, physiology, and development
○Well-developed vision, grasping hands/feet
○Shared life history: extended juvenile development, long lifespan, larger brains
○Similar behaviors due to similar physiologic/cognitive structures
●Nonhuman primates provide useful models for understanding evolutionary roots of human morphology and nature
Primates are a Diverse Order
●Great morphological, ecological, behavioral diversity among species w/in primate order
○Diffs in size, environment, diet, sociality, child-raising, and behavior
●Some primates are nocturnal and others are diurnal
○The fat-tailed dwarf lemur enters torpid state and sleeps for 6 months each year
●Some primates partake in conspecifics, defending territory from incursions by other members of own species
●Phylogenetically similar → typically morphologically, physiologically, and behaviorally similar → can use diffs to determine adaptive responses to diff environments Features That Define the Primates
●All mammals share traits: 4 limbs, hair, live young + milk
●Primates are rather nondescript
○No single derived feature shared by all primates
●Big toe on the foot is opposable and hands are prehensile
○Primates can use feet and hands for grasping
○Humans have lost the opposable big toe
●Flat nails on hands and feet instead of claws
●Sensitive tactile pads w/ fingerprints
○Enhanced dexterity
●Locomotion is hind-limb dominated
○Hind limbs do most of the work and center of gravity is closer to hind limbs than forelimbs
○All nonhuman primates spend at least part of their time in trees
○Some apes swing using brachiation
●Unspecialized olfactory (smelling) apparatus that is reduced in diurnal primates
○Less reliant on sense of smell than other mammals
●Highly developed visual sense
○Large, front-facing eyes w/ stereoscopic vision : each eye sends signal of visual image to both hemispheres in the brain → depth perception
○Most primates can see color and have binocular vision, where vision of the 2 eyes overlap so that both eyes see the same image
●Females have small litters w/ longer relative gestation/juvenile periods
○Longer pregnancies, later maturity, longer lifespan
■Signifies increased dependence on complex behavior, learning, and behavioral flexibility
●Brain is large w/ unique anatomic features
○Use intelligence as a way of life
●Molars are unspecialized, with max 2 incisors, 1 canine, three premolars, and three molars on each side of the upper and lower jaws
○Teeth can be used to gauge age of a skull, see relationships b/n species, inference developmental patterns/diets/social structure
●Not all of these traits apply to every primate but are general rules
Primate Biogeography
●Most nonhuman primates live in Asia, Africa, South America, and nearby coastal islands
●Mainly tropical regions w/ large daily fluctuations in temperature
○Distribution of resources is affected more strongly by seasonal changes in rainfall
rather than changes in temperature
●Nonhuman primates live in extremely diverse set of habitats
○Forests, savanna woodlands, mangroves, grasslands, deserts, etc
●Almost all species live in forested areas Taxonomy of Living Primates
●2 suborders of primates: strepsirrhini and haplorrhini
●Strepsirrhini: nocturnal, well-developed sense of smell, large eyes, independently movable ears
●Haplorrhini: diurnal, increased complexity of behavior, longer life spans, larger brains
○Generally larger than strepsirrhines, more dependent on sight, live in bigger groups
●Exception: tarsiers are included with haplorrhines because they are more closely related to monkeys and apes than to strepsirrhines but they are small-bodied and nocturnal
○Cladistic classification → haplorrhines
○Evolutionary taxonomy classification → strepsirrhines
Primate Diversity
Strepsirrhines
●The infraorder (taxonomic level below suborder) Lemuriformes includes lemurs, only found in Madagascar and Comoro Islands
○Got isolated from the rest of Africa 120mya, evolved in total isolation, and underwent adaptive radiation → once were over 44 species of lemur
○Once humans colonized Madagascar, all larger species of lemur went extinct and
modern lemurs are mostly small/medium arboreal quadrupeds
○Lemur behavior is variable: ~half are diurnal, the rest are either nocturnal or active during day and night
○Females usually dominate males
■Displace them from feeding sites, beat them in fights
■Female dominance is rare in most primate species
●Infraorder Lorisiformes contains small, nocturnal, arboreal animals in Africa and Asia
○2 distinct families w/ diff locomotion and activity patterns
■Galagos: active/agile, leap thru trees
■Lorises and pottos: slow-moving, remain immobile for long periods of time
●Maybe avoid detection from predators
○Lorisiformes feed on fruit, gum, and insects
○Use nests in trees
Haplorrhines
●Infraorder Tarsiiformes includes tarsiers in Borneo, Sulawesi, and Philippines
○Tarsiers are small, nocturnal, arboreal and live in pair-bonded family groups or groups w/ more than 1 breeding female
○Tarsier newborns are 25% of the mother’s weight → must leave babies in hiding places when they forage for insects
○Tarsiers are the only exclusively carnivorous primate (insects, small vertebrates)
