Fall 2024 Living Non-human Primates Review Slides PDF

2/23/24 6.5 The Living Non-Human Primates Kingdom – Animalia – Multicellular, m...

2/23/24 6.5 The Living Non-Human Primates Kingdom – Animalia – Multicellular, mobile, consumer – ~ 950 mya Phylum – Chordata – Notochord, pharyngeal slits, dorsal neural tube – Sea squirts, lancelets – ~ 650 mya Subphylum – Vertebrata – Vertebral column, cephalization – Fish, amphibians, mammals, reptiles, birds – ~ 615 mya Class – Mammalia – ~ 310 mya Order – Primates – ~ 80 mya 1 2 Mammalian Traits Primate Characteristics Relatively generalized limb structure. Hair or fur. Relatively generalized dentition. Live birth (2 exceptions). Grasping hands and feet. Nurse their young. Nails instead of claws. Heterodont dentition (some exceptions). Postorbital bar or postorbital closure. Endothermy. Increased reliance on vision; stereoscopic vision enables depth Increased brain size relative to most perception, color vision enables identifying ripe fruit at a distance as other vertebrates. well as other benefits (it must be beneficial to offset the costs). Reduced reliance on smell (less important in the trees). Relatively large brains are related to... Extended gestation, infancy, and juvenile period, and... Highly social behavior. 3 4 Non-Human Primate Distribution A Note on Human Taxonomy Order Primates (primates) – Suborder Haplorhini (haplorhines) Infraorder Catarrhini (catarrhines) – Superfamily Cercopithecoidea (cercopithecoids) – Superfamily Hominoidea (hominoids) » Family Hylobatidae (hylobatids) » Family Hominidae (hominids) - Subfamily Ponginae - Subfamily Gorillinae - Subfamily Homininae (hominines) - Tribe Panini (panins) - Tribe Hominini (hominins) - Genus Homo - Species Homo sapiens (humans) 5 6 1  2/23/24 Mouse Lemur Locomotion Categories of primate locomotion – Quadrupedalism; terrestrial and arboreal. – Vertical clinging and leaping (VCL). – Brachiation. – Bipedalism. Gorilla Very large range of body weights. 100 grams - over 200 kg (male gorilla). Even smaller and larger if extinct species are included. 7 8 Generalized Limb Structure Locomotion Arboreal quadrupedalism is the most common mode of locomotion in primates. The common ancestor of all primates was probably an arboreal quadruped. 9 10 Long tail. Mobile shoulder and elbow joints. Forelimb and hindlimb are relatively short and of Many Old-World monkeys and several “apes” are terrestrial quadrupeds. similar length. This mode of locomotion is - in living primates - seen only in the Cercopithecoidea and Hominoidea. Moderately long phalanges on the hands and feet with moderate curvature. 11 12 2  2/23/24 Reduced tail. Forelimbs and hindlimbs Restricted shoulder are relatively long and of and elbow joints. similar length. A number of strepsirrhine primates are vertical clingers and leapers, including most of the galagos and the Malagasy indriids. Robust metapodials and short, straight phalanges on the hands and feet. The tarsier is the only haplorrhine vertical clinger and leaper. 13 14 There are three species of indriids - all vertical clinger and leapers - from different parts of Madagascar. They are the largest Indri living lemurs. Sifaka Large hands. There were many larger lemurs (one was almost gorilla-sized) Short slender forelimbs. that are recently extinct due to human’s arrival about 1,500 years ago; until then they had no natural Woolly Long powerful hindlimbs. enemies. lemur Long lumbar region. Large feet. 15 16 Long curved phalanges on the hand Mobile wrist Long forelimbs Mobile shoulder Mobile hip Hominoids and New World ateline primates (howling monkeys & Short hindlimbs spider monkeys) often use a suspensory mode of locomotion called brachiation. Hylobates (gibbon) skeleton shown (show video of gibbon and langur, which shows differences in locomotor behavior between arboreal quadrupeds and suspensory species) 17 18 3  2/23/24 Slightly longer forelimbs Shorter hindlimbs Features of the knuckle, wrist, and elbow for stabilization at full extension Long curved phalanges on the hand The African apes – chimpanzees, bonobos and gorillas - locomote by knuckle-walking when they are on the ground. 19 20 Primate Diet Prehensility (Grasping Ability) PrimatesPrimate Morphology are eclectic & Ecology eaters, relatively unspecialized, opportunistic. – Although most primates specialize to a greater or lesser degree, they eat fruit, leaves,diet stems, nuts, seeds, flowers, tree gum, fungi, insects, eggs, small vertebrates. I primates are eclectic eaters, relatively unspecialized Some general classifications are I fruit, leaves, stems, based nuts, on thefungi, seeds, flowers, majority of food consumed insects, and their teeth are eggs, small adapted for vertebrates their preferred diet: I some rough classifications: – Frugivore – fruit (most primates). I frugivore—fruits (any primate) – Folivore – leaves (tend to be I folivore—leaves large-bodied). (tend to be large-bodied) insectivore—insects – Insectivore –I insects (tend to be(tend to be small-bodied) small-bodied). Opposable pollex (thumb) and hallux (big toe). Nails, not claws. Dermal ridges (fingerprints). frugivore teeth, low round cusps Enhanced sense of touch. folivore teeth, high shearing crests insectivore teeth, spiky cusps Anthro 2050/2051: Describing Primate Morphology & Ecology 20 21 22 Senses and the Brain Primate Vision Increased emphasis on vision: Decreased reliance on smell: Eyes in front of head, facing forward. Sharp vision in front. A small pit in the middle of the retina (the fovea) has a dense concentration of cones. Color vision (cones); rods have better light gathering ability but lack color discrimination. Binocular stereoscopic vision provides depth perception. 23 24 4  2/23/24 The Primate Brain Allometry Reptile Domestic dog Human Increased size and complexity relative to other mammals. 25 26 Why big brains? Long Time to Maturity Ecological hypothesis – adaptation to foraging, cognitive maps of the environment. Social hypothesis – help primates navigate complex social networks. – Needed to establish & maintain relationships. – Primates know other individuals and how they will probably react. – Third party relationships. – Redirected aggression. – Form coalitions to gain position and/or resources. Primate social interactions are very complex. – Mating strategies. This requires high cognitive ability and a relatively large and complex brain. It takes a long time to learn how to be a primate and the social rules that govern interactions with other members of the group; “how to behave.” 27 28 Much to Learn Female Reproductive Strategy “Strategy” does not imply conscious decisions; it simply means behaviors that have been favored by natural selection as advantageous. Females invest much more time and resources in infants than males do. Before and after birth females need to maximize resources which leads to competition with other group members. Gestation and nursing reduces fitness: As a result primates have more flexible, learned behavior and relatively less – Females need more resources. “programmed” behavior. – Acquiring the needed resources takes more time Social groups and their interactions are crucial. and energy. Primates must learn how to “read” the other members of their social group. – This makes them more vulnerable to predators, malnutrition, and disease. What defines a social group, as opposed to a group or herd? 29 30 5  2/23/24 Male Reproductive Strategy Territoriality What determines whether a species is territorial; i.e., defends a particular territory for its exclusive use? Distribution of resources; clumped (e.g., fruit) or diffuse (e.g., insects or leaves). Territorial behavior requires defending a known and relatively safe territory. Benefits: prevents outsiders from exploiting resources. Reproductive success is determined by their ability to produce as many Costs: vigilance, time and energy spent on defense (can be patrolling, offspring as possible (i.e., access to fertile & receptive females). displays, vocalizations, etc.) and possible injury. Sexual selection (Darwin 1871): Competition with other males for access Reduced time and energy for finding food, resting, and social interactions. to females takes two forms: – By direct conflict with other males. – By maximizing attractiveness to females as a potential mate. 31 32 What are the Determinants of Social Groups? Group Living Under some circumstances groups will be favored by natural selection. Females distribute themselves based on the distribution of Being in a group can reduce predation risk and increase resource acquisition. the resources needed for producing and nourishing their However, being in a group causes competition for resources and status offspring (essentially food): among members of the group. – Fruit: the most important as fruit is a clumped resource. Groups will only be stable if the benefits of reduced predation risk or – Leaves are dispersed. resource acquisition outweigh the costs of within-group competition. – Insects are dispersed. Therefore (contrary to a commonly held belief) Natural Selection will favor Males distribute themselves based on where the females behaviors that help to resolve within-group conflict: are (remember that the limiting resource for a male’s Friendly interactions. reproductive success is access to females). Dominance hierarchies. Cooperative behaviors. Altruism. 33 34 Aggression Quick Review Why do primates have relatively large brains? Aggressive – unfriendly behaviors: Primates have a long period of infancy and “childhood.” – Can be disruptive within the group. Primates take a long time to learn how to be a primate. – Often shown by signals or displays that can serve to prevent physical confrontations. For females, the limiting factor for reproduction is access to resources, Often due to resource competition. especially food. Negative consequences: For males, the limiting factor for reproduction is access to females. – May cause injury or death. Territoriality is largely determined by the distribution of resources. – Can lower survival and reproductive success. Group formation. Can be within a group (usually ameliorated) or between groups (often more Aggression. extreme). 35 36 6  2/23/24 Affiliative Behaviors Cooperation Affiliative –friendly interactions: Altruism is behavior that benefits another at cost/risk to performer. – serve to enhance group cohesion. Reciprocal Altruism is performing an act that benefits another with a cost – serve to cause and maintain friendships. to the performer in the (not necessarily conscious) expectation of a returning beneficial act from the recipient in the future. – are required for sex. This requires the mental capability to remember past interactions, not Hugging, kissing, GROOMING. necessarily consciously. Provide comfort. This has led to the ability to identify cheats and the concept of fairness; Allows reconciliation after conflicts. both of which have been shown to exist in many non-human primates as Promotes and maintain alliances. well as in humans. Largely kin-based. 37 38 Explanations for “Altruism” Reproductive Strategies At first altruism seems to make no sense in terms of Natural Selection. R-selected species William Hamilton (1936-2000) provided an evolutionary explanation: – produce relatively large numbers of offspring Inclusive Fitness: a performer’s reproductive success is enhanced by – provide relatively less care. altruistic acts if the actor is related to the recipient. k-selected species Kin Selection: “altruistic” behavior is favored when the actor is related to – have relatively few, widely spaced, offspring. the recipient and the cost to the actor is less than the degree of relatedness – have relatively high parental investment (care), especially from the mother. times the benefit to the recipient recipient. The terms R-selected and k-selected are relative: Hamilton’s Rule: C < (r x B) In general, mammals & birds are k-selected, but not equally: – C = cost to actor E.g., humans are k-selected relative to cats. – r = genetic relatedness But cats are k-selected relative to lizards. – B = benefit gained by recipient But lizards are k-selected relative to clams. Reptiles & fish are R-selected relative to birds and mammals. 39 40 Reproduction Strepsirrhines Estrus refers to behaviors and visual cues that indicate when females are sexually receptive. Receptivity is linked to ovulation. Often females in estrus are proactive; actively seeking sexual interactions. Estrus behavior is determined by the species and type of social group. Consortships (during estrus); e.g., chimpanzees. Homo sapiens have concealed ovulation, so how does this affect our behavior and interactions? Lemurs Lorises Galagos (bushbabies) Most species are nocturnal. A tapetum lucidum increases vision in low light. Female estrus swelling Nostrils have a rhinarium. Dental formula (usually) 2.1.3.3 No species is fully terrestrial. Body sizes range from very small to medium, ~22 lbs. 41 42 7  2/23/24 Strepsirrhines Tooth comb Moist rhinarium, continuous upper lip and nostrils. The tooth comb is used to groom (self & others), get food (useful for scraping gum from tree trunks). A shared derived trait (synapomorphy). It’s diagnostic; i.e., if we see it on a primate mandible we know it’s a strepsirrhine. 43 44 Tarsiers Tarsiers One genus, Tarsius. A haplorrhine, originally classified as a “prosimian” along with the strepsirrhines. Small vertical clinger and leaper. Nocturnal; large eyes but no tapetum lucidum. Insectivorous. 45 46 Platyrrhines New World Monkeys New World “monkeys.” Nostrils widely separated, “flat nose.” Dental formula 2.1.3.3 Tail is prehensile in some larger species. No terrestrial species. Body size ranges from very small to medium, ~22 lbs. 47 48 8  2/23/24 Catarrhines Cercopithecoidea: Old World Monkeys Old World “monkeys, “apes,” & humans. Nostrils narrowly separated, “downward nose.” Dental formula 2.1.2.3. Tail is not prehensile; hominoids are tailless. Some species are terrestrial, partially or fully. Body size ranges from small to large; cercopithecoids > 70 lbs, hominoids > 400 lbs. Two subfamilies: Cercopithecinae (cheek pouch monkeys). Colobinae (leaf-eating monkeys). 49 50 Hominoids (“apes” and humans) Types of Social Groups Noyau (solitary) One male/ one female (pair-bonded) One female/multi-male (polyandry) One male/multi-female (polygyny) Multi-male/multi-female Orangutans Fission-fusion Gorillas Gibbons * The basis for all social groups and learning is a mother and her offspring. Kids learn first from interacting with their mothers and also by observing her interactions with others. * “Range” is the area covered by a group’s usual travel. * “Territory” is the actively defended part of a range. Chimpanzees 51 52 Noyau (solitary) Pair-bonded Offspring Offspring Female A male and female pair with their offspring. Typically no sexual Female Male dimorphism. A females with her offspring has a small range; a male’s range overlaps several female ranges. Male Because a male must defend his resources (females) he is typically much larger than females. 53 54 9  2/23/24 Polyandry One-Male Group Offspring Offspring Female Female One male with several females and their offspring; this Male One female with more than one males (usually two) also produces all-male groups. and their offspring. Usually little or no sexual dimorphism. Male Because of male-male competition males are much larger than females. 55 56 Multimale/multifemale Group Fission-Fusion Society Offspring Female Offspring Female Several males, several females, and their offspring. Subgroups break off and reform from day to day; often They travel, feed, and sleep as a group. Male females with offspring and males together. Male Males are usually slightly larger than females. Males are usually slightly larger than females. 57 58 Non-human Primates in danger: Threats to Non-human Primates Habitat loss: In the last 20 years about 2 million square kilometers of forest How many species of primates are has been lost; this is an area the size of Mexico and more than 5 times the there? size of Germany. This is due to: This graph lists 504. – Agriculture, private & commercial. Populations of more than 75% of – Urban Development. primates are declining. – Deforestation: Logging, Roads. More than 60% of all primate species – Mining. are threatened with extinction, many of them critically. Other causes are: – Habitat fragmentation and pollution. – Hunting: Bushmeat, Trophies. – Illegal Pet Trade. – Human diseases. All these are the result of human demands on land and resources driven by human population growth. 59 60 10  2/23/24 Deforestation: Hunting Cutting down trees to satisfy demand for wood for construction, firewood, and farmland. Bushmeatt: meat of wild animals. Now the biggest threat to non-human primates. 61 62 Hunting Bushmeat Preparation Bushmeat: wild animals are hunted, butchered, and their meat sold in (usually urban) markets. This is now the biggest threat to non-human primates. 63 64 Preservation Illegal Pet Trade Preservation is essentially absolute: – No “development.” – No “use” (farming, logging, etc.). – Requires guarding and protecting (legally, physically, etc.). 65 66 11  2/23/24 Conservation Non-human primates are especially susceptible Conservation: – Guarding & protecting but also ”managing.” Primates are often large bodied and require large ranges. – Legal protection; national parks, enforcement of laws. – Controlled & sustainable use; e.g., selective logging, ecotourism, etc. Primates are slow-reproducing (k-selected). – Education and public awareness of the value of the property. Primates are typically sensitive to habitat disturbance. – Must be community-based to succeed. The terrible impact of hunting or capture: – Must be economically beneficial to the local population. – Directly reduces populations. – Needs to provide alternative protein sources to replace bushmeat. – Community development (schools, medical care, sanitation, water, etc.). – Disrupts social groups. Conservation Programs – Produces orphans. – Zoos are used to keep some animals alive. – Capturing an infant usually involves killing many adults. – Captive Breeding & Reintroduction Very expensive and labor intensive. – The vast majority of captured infants do not survive. High risk, not often successful: tameness, no survival skills, disease. Another danger is the perceived reduced need for habitat preservation. 67 68 12