Transcript Chapter 5 Overview of Living Primates

Overview of Living Primates
I.
II.
III.
IV.
V.
Primates as Mammals
Primate Evolutionary Trends
Primate Origin Theories
Specific Primate Traits
Survey of the Living Primates (Taxonomy)
I. Primates As Mammals
Primates belong to one of five vertebrate classes
(Mammalia) and are one of +/- 30 placental orders
B. Primates share a number of traits with other placental
mammals:
A.
1.
2.
3.
4.
5.
6.
Fur (body hair)
Long gestation period followed by live birth
Homeothermy, the ability to maintain a constant body temperature
Increased brain size
Capacity for learning and behavioral flexibility
Presence of the placenta in the mother
I. Primates as Mammals
C.
D.
Nonhuman primates (prosimians, monkeys,
and apes) fall into in two major suborders
(Prosimii & Anthropoidea)
Further divided into infraorders, families,
genera, and about 190 total species
II. Primate Evolutionary Trends
Primates retain many primitive mammalian traits and
cannot be defined by one or two traits alone.
Primates are defined by evolutionary trends that
characterize the entire order to one degree or another.
Traits we will focus on:
A.
B.
C.
1.
2.
3.
4.
Limbs and Locomotion
Diet and Teeth
Senses and the Brain
Maturation and Learning Behaviors
1. Limbs & Locomotion
a. Primates have a tendency towards erect
posture.
b. Hands and feet possess a high degree of
prehensility or grasping ability.
c. Features of the hands and feet include:
i. 5 digits on hand and feet
ii. Opposable thumb/great toe
iii. Tactile pads enriched with
sensory nerve fibers at the ends
iv. Fingernails
2. Diet and Teeth
a.
Primates lack dietary specialization and tend to eat a
wide variety of foods.
i.
ii.
iii.
b.
c.
Some primates kill and eat small mammals.
Some primates are dietary specialists on leaves.
Most eat a combination of fruits, leaves, and insects.
Primates are generally omnivorous and this is
reflected in their generalized dentition.
Most primates have four types of teeth:
incisors, canines, premolars and molars.
d.
Dental formulae vary
2123, 2132, 2133, 3143, more
3. Senses and the Brain
a.
b.
c.
d.
Color vision in all diurnal primates. Nocturnal
primates lack color vision.
Depth perception or stereoscopic vision is made
possible by eyes positioned forward on the front of
the face and by an incomplete
cross at the optic chiasma.
Decreased olfaction.
Increased complexity.
4. Maturation, Learning, & Behavior
a.
b.
c.
d.
e.
f.
g.
h.
Longer periods of gestation.
Reduced numbers of offspring (called kselection).
Delayed maturation.
Extension of the entire life span.
Dependence on flexible, learned behavior.
Tendency to live in social groups.
Males are permanent members of many
primate social groups.
Regular shows of affection, play, and
emotion.
III. Primate Origin Theories
Two competing theories
A. Arboreal Hypothesis
1. Arboreal (tree) living was the most important factor in
the evolution of primates.
2. Prehensile hand is adapted to climbing in the trees.
3. A variety of foods led to the omnivorous diet and
generalized dentition.
III. Primate Origin Theories
B.
Visual Predation Hypothesis
1. Flowering plants may have influenced primate evolution.
2. Primates may have first adapted to shrubby forest
undergrowth and the lowest tiers of the forest canopy,
where they captured insects through stealth.
3. Forward facing eyes enabled primates to judge distance
when grabbing for insects.
IV. Specific Primate Traits
Habitats
A.
1.
2.
3.
4.
Most living nonhuman primates live in the tropical or
semitropical areas of the new and old worlds.
Most primates are arboreal, living in forest or woodland
habitats.
Some old world monkeys have adapted to life on the
ground and gorillas and chimpanzees spend
considerable time on the ground.
No nonhuman primate is adapted to a fully terrestrial
environment; all spend some time in the trees.
IV A. Habitats
IV B. Locomotion
1.
2.
3.
4.
5.
6.
7.
8.
Suspensory w/ prehensile tail
Brachiating
Arboreal Quadrapedalism
Vertical Clinging & Leaping
Habitual Bipedalism
Slow Quadramanous Climbing
Knuckle Walking
Terrestrial Quadrapedalism
V. Overview of Living Primates (Taxonomy)
A.
Taxonomic Naming: Binomial Nomenclature
Homo sapiens; Pan paniscus; P. troglodytes
B.
Taxonomic Systems
1. Phenetics
•
Based on gross morphological similarity
2. Cladistics
•
Based on shared, derived traits
3. Evolutionary Taxonomy
Shared, derived traits AND genetic similarity
C.
Survey of extant suborders and their families
Suborder Prosimii
(Lemurs, Lorises, Tarsiers)
The most primitive primates
Retention of some claws
Reliance on olfaction
Laterally placed eyes w/postorbital bar
Shorter gestation and maturation
Dental specialization called the "dental
comb”
Presence of the tapetum lucidum
Elongated snouts
Strepsirhine rhinarium (wet nose)
Unfused mandible
Lemurs
Lemurs are found on the island of Madagascar
and other islands off the coast of Africa.
They became extinct elsewhere in the world.
Characteristics:
Larger lemurs are diurnal and eat vegetable foods:
fruit, leaves, buds, and bark.
Smaller lemurs are nocturnal and insectivorous
(insect -feeding).
Lorises
Loris are found in tropical forests and
woodlands of India, Sri Lanka,
southeast Asia, and Africa.
Characteristics:
Lorises use a climbing form of
quadrupedalism.
Some lorises are insectivorous; others
supplement their diet with fruit, leaves,
gums, and slugs.
Females frequently form associations
for foraging or in sharing the same
sleeping nest.
Tarsiers
Tarsiers are small nocturnal
primates found on the islands
of southeast Asia.
Characteristics:
Tarsiers eat insects and small vertebrates which they catch
by leaping from branches.
The basic social pattern appears to be a family unit
consisting of a mated pair and their offspring.
Anthropoidea
(Monkeys, Apes and Humans)
Common traits:
Larger brain and body size
Reduced reliance on the sense of smell
Greater degree of color vision
Bony plate at the back of the eye socket
Longer gestation and maturation periods
Fused mandible
Only has nails
Monkeys
Monkeys represent about 70% of all primates
Monkeys are divided into two large groups
separated by geographic area as well as several
million years of evolutionary history:
New world monkeys (Platyrhini)
Old world monkeys (Catarhini)
New World Monkeys
Almost exclusively arboreal and found in southern Mexico and
central and south America.
Two families:
Callitrichidae give birth to twins, have claws, live in families
composed of a mated pair or a female and two adult males, plus the
offspring. Males are involved with infant care.
Some of the cebidae family possess prehensile
tails and most live in groups of both sexes and
all ages, or as monogamous pairs with subadults
Old World Monkeys
Habitats range from tropical forests to semiarid desert
to snow-covered areas in Japan and China.
Characteristics:
Most old world monkeys are quadrupedal and arboreal;
others have adapted to life on the ground.
All old world monkeys belong to one family, the
Cercopithecidae, which is divided into subfamilies,
the cercopithecines (terrestrial and
omnivorous) and the colobines (arboreal
and vegetarian).
Hominoids (Apes and Humans)
Characteristics that distinguish hominoids from
monkeys:
Larger body size
Absence of a tail
Shortened trunk
Long arms relative to legs (except humans)
More complex behavior
More complex brain and enhanced cognitive abilities
Increased period of infant development and dependency
Gibbons and Siamangs
Found in tropical southeast Asia.
Locomotor adaptations for brachiation may be related to
feeding behavior while hanging from branches.
Diet is largely fruit with supplements of leaves, flowers,
and insects.
Basic social unit is a monogamous pair and their
dependent offspring.
Males and females are territorial and delineate their
territories with whoops and “songs”.
Orangutans (Pongo pygmaeus)
Found in heavily forested areas of Borneo and Sumatra.
Slow, cautious climbers and almost completely arboreal.
Large animals (males = 200 pounds, females = 100
pounds) with pronounced
sexual dimorphism.
Solitary
Principally frugivorous (feed-eating).
Gorillas (Gorilla gorilla)
The largest of the living primates confined to forested
regions of central Africa.
Exhibit marked sexual dimorphism; Males can weigh up
to 400 pounds, females 200 pounds.
Primarily terrestrial, employing a semi-quadrupedal
posture called knuckle -walking.
Live in groups that consist of one large silverback male,
a few adult females, and their subadult offspring.
Chimpanzees (Pan troglodytes)
Found in equatorial Africa.
Anatomically similar to gorillas particularly in limb
proportions and upper-body shape.
Locomotion includes knuckle-walking on the
ground and brachiation in the trees.
Eat a variety of plant and animal foods.
Large communities of as many as 50 individuals.
Bonobos (Pan paniscus)
Only found in an area south of the Zaire river.
Their population is believed to only number a few
thousand individuals.
Exploit many of the same foods as chimps, including
occasional small mammals.
Male-female bonds constitute the societal core.
Bonobo sexuality includes frequent copulations and
occur throughout the female's estrous cycle.
Humans (Homo sapiens)
The only living species in the family Hominidae.
Characteristics:
Primate heritage is evident in anatomy, genetic makeup and
aspects of behavior.
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•
•
•
Human teeth are typical primate teeth.
Dependence on vision for orientation to the world
Flexible limbs and grasping hands
Omnivorous diet
Cognitive abilities are the result of dramatic increases in brain
size.
Bipedal
Endangered Primates
Greatest challenge facing primatologists is the urgent
need for conservation.
Over half of all living primates are endangered and
many face immediate extinction.
Habitat destruction - most primates live in tropical rain forests
that are being destroyed for their natural resources.
Hunting of primates for their meat.
Live capture for the pet trade or export to collectors.
Hunting of Primates
In west Africa the most serious problem is
hunting to feed the growing human population.
Estimated that thousands of primates, including
gorillas and chimpanzees, are killed and sold for
meat every year.
Primates are also killed for commercial products.
Live Capture
Primates have been live captured for zoos,
biomedical research, and the exotic pet trade.
Live capture has declined dramatically in recent
years with the implementation of the convention
on trade in endangered species of wild flora and
fauna (CITES) in 1973.
87 countries have signed this treaty.
Conservation Efforts
Many developing countries such as Madagascar and
Costa Rica have designated areas as national parks or
reserves.
Private organizations, such as the rain forest
information center in Ecuador, have
purchased land to set up biological reserves.
Through conservation and educational programs,
primate species may have a chance at escaping
extinction.