Graphical summary

Primate Social Behavior 2

Anthropology 2200

Non-residential pattern aspects primate behavior

• Competition • Cooperation • Culture • Parenting behaviors • Tool use • Language

Social Strategies

Male Competition

• Male reproductive strategy  competition for mates

• Produce lots of offspring • Prevent other males from doing

the same thing • Intimidation • Fighting • Leads to sexual selection

• Body size / canine dimorphism

Mandrill: Coloration = health Tooth size

Uakari: Color = health and dominance

Male Competition

• Sperm competition

• Relationship between:

• Testes size

• Penis size

• More competition = larger size

Female Competition

• Female reproductive strategy  competition for resources

• Ensure the survival of offspring

• Dominance relationships • Access to resources

Female Baboon hierarchy

Competition

• Aggressive behaviors • Direct eye contact • Raising eyebrows • Baring canines • Charging

Gelada Baboons

Competition

• Subordination • Ritualized behavior

• Showing backside • Cowering • Presenting to groom • Greeting with friendly facial

expressions and vocalizations

• Intended to ease tension • Prevent conflict

Unequal Pay – Primate Jealousy

• Differences in food quality • Personal jealousy?

Capuchin monkeys and equity

Cooperation

• Affiliative behaviors • Promote group

cohesion • Assurance • Pleasure • Reciprocity

Cooperation

• Form of Altruism • Behavior that benefits others while being a

disadvantage to the individual • Grooming/playing • Hunting/Food sharing • Caregiving • Attacking predators • Giving warning calls

• Kin selection • Behavior that increases the fitness of those

closely related to the individual • Usually the focus of altruistic behavior • Increases the donor’s inclusive fitness

• Reproductive success of organism and close kin

Cooperation

• Grooming to remove parasites and dead skin

• Maintains close contact between family members and non-related group members

• Eases tension • Promotes group cohesion

Chimpanzee grooming

Cooperation

• Playing • Maintains close contact between family

members and non-related group members • Eases tension • Promotes group cohesion

Bonobos Playing

Cooperation

• Caring for young that are not yours • Alloparenting

• Individual other than parent cares for the infant

• Usually done by females (in some species, males also contribute)

Capuchin Monkey

Squirrel Monkey

Cooperation

• Attacking predators and giving warning calls • Allows other members of the group to

escape

• Might lead to injury or death

Vervet Monkey did not survive….

Baboon did survive

Cooperation

• Group Hunting/Foraging • Find food more efficiently • Might find food/hunt prey that you

could not get as an individual • Have to share • Might get injured during hunt

Chimpanzee hunting

Cooperation

• Warfare • Observed in chimps • Group fights between chimps over

territory • Often kill neighboring males • Territory = access to food resources

Chimpanzee patrol composed of primarily

males

Chimpanzee raids

Chimpanzee politics

So where do these behaviors come from? Parenting

• Prolonged period of development • Prolonged period of parental care • Allows parents to teach offspring how to succeed

socially/in environment • Parents VERY important!

Parenting • 1950s psychological experiments (Harry Harlow)

• Demonstrated parenting = not just nourishment • Monkey’s taken from mothers shortly after birth • Raised alone in cages: wire “nourishing” mother, cloth

mother, no mother • Preferred cloth mother = warmth, comfort, security • No mother = distressed, refused to eat, died

Parenting

• Specifics – what do primates learn from their parents?

• Non-verbal and verbal communication

• Social behavior: competition and cooperation

• Tool use • Parenting behavior • Culture!

How do we know its culture and not just inborn behavior?

• Harlow’s Experiments • Japanese Macaques

• Beach of Koshima • Wash sweet potatoes in salt water • 1 decade idea spread • From very few to most

Japanese macaques

The unique side of bonobos

Culture: Examples • Tool use: Chimpanzees

• Spears and their use for hunting bush babies • Termite fishing • Chewed leaves as sponges • Rocks for breaking open nuts

Chimps spearing

Termite fishing

Culture: Examples

• Chimp grooming traditions • Differ depending on the group

• Gombe National Park, Tanzania • Groom each other by holding an overhead branch with one hand

and grooming a partner with the other • Mahale National Park, Tanzania

• Clasp hands while grooming

Gombe Mahale

Communication

• Voluntary (intentional) • e.g. postures,

vocalizations, and facial expressions

• Autonomic (unintentional)

• e.g. estrus

Voluntary Communication Example: Gorilla

• Sharp grunting: a sign of disapproval. • Chuckling: a sign of playfulness. • Screaming: a sign of alarm or warning. • High-pitched barking: a sign of curiosity. • Roaring: a sign of aggression. • Belching: a sign of contentment

Language

• Significant human development

• Communication in non- human primates:

• Emotional • Only in the present • Predator alarm system • Establish territories

Language

• Non-human primates • Many have been taught ASL

• Don’t have vocal range for human language/no syntax

• Teach others ASL • Can make references to external

objects • E.g. “go get ball outside”

• Can identify images of things in addition to the things themselves

Koko with All Ball

Koko’s sign language

Primate Taxonomy 1

Anthropology 2200

Examine primate classification Pygmy Marmosets

• SIZE DIVERSITY IN PRIMATES

Mouse lemur (Microcebus berthae) 3.6 inches, 1.1 oz

Adult Gorilla (Gorilla gorilla) 440 lb

loris gibbon

aye aye gorilla

chimpanzee

tarsier

capuchin orangutan

spider monkey baboon

ring tailed lemur

Japanese macaque bonobo

howler monkey

mouse lemur

Primates • What is a Primate?

• Kingdom  Animalia • Phylum  Chordata • Class  Mammalia • Order  Primates • Suborders:

• Strepsirhines (Lemur, Loris, Galago) • Infraorder: Lemuriformes

• Haplorhines (Tarsiers, Monkeys, Apes, and Humans)

• Infraorders: • Tarsiiformes • Anthropoidea (Parvorders =

Platyrrhini and Catarrhini) • Slender Loris

Taxonomy

Cladistic Taxonomy: Haplorhini/Strepsirrhini Nomenclature preferred by many

• Places Tarsiers in with Haplorhines • Many believe this system is more evolutionarily accurate!

Tarsiers

Strepsirhines vs. Haplorhines

• Strepsirhines: lemurs, lorises, galagos

• Haplorhines: everything else (tarsiers, New World Monkeys, Old World Monkeys, Apes, humans)

• They split around 55-80 million years ago

Slender Loris Galago/Bush Baby Ring Tailed Lemur

Strepsirhines

Ring-tailed lemur

Strepsirhines

• Found in Africa and Asia (13% of Primates)

• Retain many primitive characteristics

• This does not mean that they are the ancestors of monkeys!!!

High rates of nocturnality • Primitive Trait

• Tapetum lucidum • Layer behind the

retina • Reflects visible light

back through the retina

• Improves vision in low light conditions

Sportive Lemur Retina

Post Orbital Bar: No Closure

Primitive Trait

Partially stereoscopic vision (primitive)

Lack color vision (primitive)

Reliance on Olfaction • Communication for nocturnal animals

• Ancestral trait • Scent glands

• Marking • Messages

• Large olfactory bulb • Part of brain for scent

• Rhinarium  moist nose • readily picks up

scents

Mouse Lemur

Ring Tail Lemur

Grooming claw • Primitive Trait

• Lemurs, Galagos, Lorises: 2nd Toe (Aye-Aye = 2-5)

• Purpose: • Grooming • Extracting insects

Ruffled Lemur

Galago

Tooth comb

• Derived Trait • Used for:

• Grooming • Extracting resin

from trees Ring Tailed Lemur

Lemuroidea : Lemurs

• Only found on the island of Madagascar

• Only non-human primate found there

• Lots of diversity • 20 mya split from Africa • Adaptive radiation • Represent 21% of primate

genera worldwide

Lemuroidea : Lemurs

• Ring-tailed lemur • More terrestrial • Black and white ringed tail • Omnivorous • Diurnal • Forest and spiny scrub • Highly social • Female dominant

• Common in Lemurs • Sent marking • Stink Fighting

Having Trouble Meeting Your Deadline?

Get your assignment on Graphical summary completed on time. avoid delay and – ORDER NOW

Get a 20% Discount

Lemuroidea : Lemurs

• Mouse lemur • Smallest primate • < 1 lb. • Eat insects, small vertebrates,

gum, fruit, flowers, nectar, leaves

• Nocturnal

Grey mouse lemur

Additional Traits

Tend to have more specialized diets and behaviors than anthropoids (derived)

• Often fill very specific niches • Lemurs on Madagascar

Vertical clinging and leaping Often solitary

Sifaka Clinging

Sifaka

Lemuroidea : Aye-aye

Aye-aye • Nocturnal • Mainly insectivorous • Thin middle finger to forage for

grubs  Taps to find grubs  Gnaws bark  Uses finger to pull out grubs

• Solitary

Aye-aye

Lorisoidea: Lorises

• Lorises • Tropical Africa and

Southeast Asia • Nocturnal • Slow-moving,

deliberate stalkers of small prey

Lorisoidea: Lorises

• Slow loris • Toxic bite

• Lick gland on their arm • Secretion activates with

saliva (adult/baby) • Communicate by sent

marking • Eat small animals, fruit, gum,

vegetation • Hunted for exotic pet trade

The Bite of a Slow Loris How poisonous is the slow

loris? • Allergen similar to Felid 1  Cat allergen in dander  Anaphylactic shock  Red blood cells in urine

Depends how allergic you are!

Lorisoidea: Galagos

• “Bush-babies” – Subfamily of Lorises

• Sub-Saharan Africa • Nocturnal • Vertical clingers and leapers • Insectivorous

Lorisoidea: Galagos Can turn its head over 180

degrees Index finger more widely

spaced • Feeding • Gripping branches

Nocturnal • Large Eyes • Large Ears

Haplorhini

Tarsiers, monkeys, apes, and humans

• Larger body • Larger brain-to-body size ratio • More sexually dimorphic • Less specialized dentition (fewer premolars) • Greater reliance on vision than on smell • Post-orbital closure • Diurnal rather than nocturnal

Differ from Strepsirhines in a variety of ways

Tarsiers vs. all other Haplorhines

• Tarsiers are taxonomically problematic

• Prosimian/anthropoid

• Strepsirhine/haplorhine • They possess a mixture of

primitive and derived traits • Divergence time of ca. 50-

70 Million years ago?

Infraorder: Tarsiiformes (Tarsiers) • Tarsiers

• Southeast Asia • Nocturnal

• eye larger than brain • Vertical clingers and

leapers • Grooming claw: 2nd and 3rd

Toes • Highly carnivorous

• Lizards, frogs, insects

Tarsiiformes: Tarsiers

Name refers to two elongated tarsals – extra leverage for leaping

Tarsiers

Primate Taxonomy 2

Anthropology 2200

Infraorder: Anthropoidea

Infraorder: Anthropoidea Two Parvorders

Platyrrhini “Broad-nosed

Catarrhini “Hook-nosed”

2:1:3:3/2 2:1:2:3

Anthropoids: Platyrrhini • Central/South American

Monkeys

• Latin and South America

Platyrrhini: Ceboidea

• Central/South American monkeys • Arboreal quadrupeds

• Suspensory locomotion • Many = Prehensile tail • Not in African/Asian Monkeys

• Diverse diet • Leaves, fruit, insects

Spider Monkey

Platyrrhini: Ceboidea

• Two Families • Atelidae

• Howler, Owl, Spider, Titi, and Woolly monkeys, Uakaris, and Sakis

• Cebidae • Marmosets, Tamarins,

Capuchins, Squirrel Monkeys

Platyrrhini: Ceboidea: Cebidae

• Marmosets/Tamarins • Retain claws instead of

nails • Smallest Platyrrhini • Twin (Chimerism) • Insectivores • Unusual dental

formula • 2:1:3:2

Golden Lion Tamarin Silvery Marmoset

Emperor tamarin

Platyrrhini: Ceboidea: Cebidae

• Capuchin monkeys • Name from Order of Friars

Minor Capuchin • Often in Movies!

White Fronted Capuchin

Platyrrhini: Ceboidea: Atelidae

• Includes subfamilies: • Aotidae • Pitheciidae • Atelidae • Alouattinae

Platyrrhini: Ceboidea: Atelidae

• Owl/Night Monkey • Only truly nocturnal monkey

• Vocal calls/Sent Marking • Susceptible to human forms of

Malaria • Used for malaria research

Platyrrhini: Ceboidea: Atelidae

• Pitheciidae • Titis • Sakis • Uakaris

White Faced SakiUakari

Titi Monkeys (morning calls) Uakari Saki

Bald uakari monkey

Platyrrhini: Ceboidea: Atelidae

• Spider monkeys • Wooly monkeys

• Only monkeys with prehensile tails (aside from Howler)

Spider MonkeyWooly Monkey

Platyrrhini: Ceboidea: Atelidae

• Howler monkey • Prehensile tail • Make loud

vocalizations

Howler monkey

Platyrrhini: Ceboidea: Cebidae

• Howler monkey • Male hyoid enlarged

• resonating chamber • Loudest land animals • Protect territory,

resources, females

Anthropoids: Catarrhini

• Asian and African monkeys • Apes • Humans

Catarrhini: Cercopithecoidae

• African and Asian Monkeys

• Colobinae • Cercopithecinae

Catarrhini: Cercopithecoidae

• African and Asian monkeys • Diverse range of habitats • Some are arboreal while

others are terrestrial • No prehensile tail • High level of sexual

dimorphism (canines, body)

Catarrhini: Cercopithecoidae

• Ischial Callosities • Sitting Pad • Thickened calluses on

Backside • Only in Af/As monkeys • Help monkeys to sleep on thin

branches away from predators

Ischial Callosity

Catarrhini: Cercopithecoidae

• Visual Estrus • Hormonally influenced period of sexual receptivity in females • Skin around genitals becomes inflated/red • Advertises fertility and receptivity

Catarrhini: Cercopithecoidae: Colobinae

• Includes: • Langurs • Colobus Monkeys • Proboscis Monkeys

• Mostly folivorous • Sacculated stomachs • Bilophodont teeth

Langur Black and White Colobus Monkey

Catarrhini: Cercopithecoidae: Colobinae

Proboscis monkey

Large nose may be due to sexual selection!

Catarrhini: Cercopithecoidae: Cercopithecinae • Includes:

• Baboons • Macaques • Vervet Monkeys

• Frugivores (fruit-eaters) • Low, rounded molar

cusps • Cheek pouches

Vervet

Baboon

Baboons

Anthropoids: Catarrhini: Hominoidea

• Lesser apes • Great apes • Humans

Catarrhines: Hominoidea

Bonobo

Gibbon

Orangutan

Gorilla

Chimpanzee

Anthropoids: Hominoidea

• Differ from monkeys in various ways:

• Absence of an external tail • Larger brains • Extended period of infant development

and dependency • Y-5 lower molar pattern • Canine-premolar honing complex

Anthropoids: Catarrhini: Hominoidea

• Two Families: • Hylobatidae

• Gibbons, Siamangs • Hominidae

• Orangutans, gorillas, chimpanzees, bonobos, humans

Anthropoids: Hominoidea: Hylobatidae  Lesser apes

 Southeast Asia  Tropical and

subtropical forests  Frugivores  Highly territorial  Siren songs

 Arboreal  Brachiation

Anthropoids: Hominoidea: Hylobatidae

• Siamang • Sexual dichromatism

Anthropoids: Hominoidea: Hominidae

• Great apes and Humans • Orangutans, gorillas, chimpanzees,

and bonobos (pygmy chimpanzees) = Great Apes

• More terrestrial • Various forms of locomotion • Dietary diversity • Great Apes are Knuckle walkers –

aside from Orangutans

Anthropoids: Hominoidea • Three Subfamilies:

• Ponginae (Orangutans) • Gorillinae (Gorillas) • Homininae (Humans,

Chimps, Bonobos)

• Homininae has two Tribes: • Panini (Chimps, Bonobos) • Hominini (Humans)

Anthropoids: Hominoidea: Hominidae: Ponginae

• Orangutan • Borneo and Sumatra • Sexually dimorphic

• Males weigh up to 200 lbs. • Twice the size and weight

of adult females • Arboreal

• Slow climbers • Frugivores • Solitary lives

Orangutan

Anthropoids: Hominoidea:

Hominidae: Ponginae

Orangutan

Anthropoids: Hominoidea: Hominidae: Gorillinae

• Gorilla • Equatorial Africa • Largest living primate

• Males weigh up to 400 lbs.

• Sexually dimorphic • Knuckle-walkers • Folivorous • Highly cohesive groups

Anthropoids: Hominoidea: Hominidae: Gorillinae

• Gorilla

Female Male

Anthropoids: Hominoidea: Hominidae: Gorillinae

• Gorilla

differences in size and shape based on sex

Anthropoids: Hominoidea: Hominidae: Gorillinae

• Gorilla • Exclusively vegetarian diet

• Large canines are to fend off other males • Shy and gentle • Only violent when threatened or in competition for

females • 1 male multi-female

Gorilla

Anthropoids: Hominoidea: Hominidae: Homininae: Panini

• Chimpanzee • Equatorial Africa • Various modes of locomotion • Less sexually dimorphic than

orangutans and gorillas • Omnivores • Complex social behaviors

• Highly territorial • Genetically closer to humans than

to gorillas

Anthropoids: Hominoidea: Hominidae: Homininae: Panini Chimpanzee

Anthropoids: Hominoidea: Hominidae: Homininae: Panini

• Bonobo • Congo (Central Africa) • Smaller than the “common”

chimpanzee • Longer legs and differently shaped

chest • More arboreal

• Lowland rain forest habitat • Less excitable/aggressive • Unique sexuality

Anthropoids: Hominoidea: Hominidae: Homininae: Panini Bonobo

Bonobos

Anthropoids: Hominoidea: Hominidae: Homininae: Hominini

 Habitual bipeds  Omnivores

 Spoken language  Large, complex brains

Primate Social Behavior 1

Anthropology 2200

Primate Behavior

Why do we care? • Primate behavioral ecology • Social behavior

• Types of social groups

Stress, Social Hierarchy, and Baboons • Robert Sapolsky

• Neurobiologist at Stanford • Studies Olive Baboons

• East Africa • 30 + years

• Takes blood samples • Tests levels of cortisol and epinephrine

• Neurotransmitters that trigger brain activity • Found that higher stress levels were present in

lower ranking individuals • Whitehall UK government study found the same in

humans • Study went further when aggressive dominant

male baboons died of TB • Changed culture in affected baboon troop

Social change in baboons

The Beginning: Louis Leakey • Discovered human ancestors

• Olduvai Gorge, E. Africa • Can we use modern great apes to understand

human behavior?

• Sent three untrained women to study ape behavior: • Jane Goodall • Diane Fossey • Birute Galdikas

Jane Goodall

• Studied Chimpanzees at Gombe National Park (20 years)

• Noted similarities between chimps and humans:

• Emotions • Intelligence • Family and social behavior • Aggression • Tool use

• Termite fishing • Dispelled “man the tool maker” • https://www.janegoodall.org/

Dian Fossey

• Studied Gorillas in Rwanda (18 Years) • Demonstrated that Gorillas were not as

fierce as people assumed • Helped save Mountain Gorillas from

extinction • Social relations, feeding behavior,

infanticide, vocalization • Murdered in 1985 – Unsolved

Birute Galdikas

Primate Behavioral Ecology • Understanding the ecological

and evolutionary reasons for primate behavior

Social Behavior

Group living: Residential Patterns • One aspect of social behavior • Group living is a balance between

competition for resources and the benefits associated with social behavior

• In general, primates are highly social • Exceptions = some nocturnal

prosimians and Orangutans

Group Living: Residential Patterns

Advantages Disadvantages ● Protection from predators ● Competition for resources ● Locating and protecting resources

● Opportunity for violence

● Access to mates ● Competition for mates ● Long-term bonds (e.g. child rearing, learning)

● Increased spread of disease

Constant struggle between competition and cooperation

Group living: Residential Patterns • Residential patterns related to reproductive

success • Evolutionarily, the goal is to have offspring. • Females

• Limited by access to resources • Males

• Limited by access to females

Its all about the babies!

So …

Types of Social Groups: Residence Patterns

One-male, multifemale (polygynous)

One-female, multimale (polyandrous)

Multimale, multifemale

All-male

One-male, one-female (monogamous)

Solitary

One-male, multifemale

• Polygyny • Most common type of social group • One male, multiple females, and

their immature offspring

• Sexual dimorphism • Ensures reproductive rights to

females • Females select males • Leave if not suitable

One-male, multifemale

• Females stay in their natal (birth) group

• Males leave the group as juveniles – before reproductive maturity

• Females = close social network • Allomothering in some cases • Males marginalized

One-male, multifemale

• Infanticide common • The killing of nursing

young • Foreign male drives

out dominant male • Females try to protect

young • Males larger, kill young • Females resume

ovulation • New baby belongs to

new male • Old male’s genetic

contribution reduced

Male Gorilla interaction with infants

One-male, multifemale

Langur

Howler monkey

Gelada baboon?

Gorilla

One-female, multimale

• Polyandry • One female, multiple males, and

their immature offspring

• Most rare type of social group • Female reproduction

consumes more time and energy

• Need only a few males • Only NWM – Callitrichidae

One-female, multimale

• Communal breeding • Males help with parenting • These groups raise twins

• Small primates • Die often due to predators • More offspring =

reproductive strategy • Increase reproductive output

Common Marmoset – Babies on Father Emperor tamarin

One-female, multimale

Multimale, multifemale • Large troops – OWM, NWM,

Chimpanzees/Bonobos

• Males, females, and their offspring • Promiscuous mating • Male competition relatively low • Sexual dimorphism = Low • Advantages:

• Protection from predators • More effective food acquisition • Lots of genetic variability

Chimpanzee family

Multimale, multifemale

• Dominance relationships (male and female)

• Determined by: • Sex • Age • Aggression • Intelligence • Mother’s position • Time in group

Macaque

Multimale, multifemale

• Impose a degree of order • Reduction of violence

• Dominant individuals = greater reproductive success • Access to food • Access to females

• Complicated and flexible rather than simple and linear • “Know your role” • Learned socially

Multimale, multifemale

• “Common” chimpanzee (fission- fusion)

All-male • Temporary all-male groups formed

before joining groups that include M/F • Commonly exist together with

multimale, multifemale groups

• “Bachelor” groups • Exist together with one-male,

multifemale groups • Consist of males who are not

able to obtain females • May attack one-male groups

and attempt to evict the resident male from his females (infanticide)

Baboon

One-male, one-female • Monogamy • Male knows his offspring

• Invests more time in supporting his own offspring

• Protection/food acquisition • Less sexual dimorphism than other

types of social systems • Lower degree of competition

• Uncommon • Gibbons, Siamangs, Night

monkey, some Marmosets, some Prosimians

One-male, one-female

• Males and females share defense of the territory

• Social interactions limited (small groups)

• Infants will engage in solitary play unless siblings are present

• Parents play with the infants

• Gibbons: aggregate at territorial borders

• Infants from different families play

• Best understood as female reproductive strategy

Pygmy Marmoset: a monogamous Callitrichidae

One-male, one-female GibbonSiamang

Gibbons in the wild

Solitary

• Noyau • One male range encompasses several female ranges • Individuals forage separately and socialize for

reproduction • Less successful males = more solitary

• Orangutans, some prosimians • Marked sexual dimorphism

• Large territory = increased male reproductive success

Solitary

Orangutan

Many Nocturnal prosimians

Aye-aye

Mouse lemur

• Males = 2x females • Large canines • Large cheek pads • Very loud calls

Watch from 5:30 until 10:00

Factors influencing the type of residence pattern

• Food distribution • Type of food • Seasonality

Fruit

Leaves

Insects

Factors influencing the type of residence pattern • Food is abundant = large groups

• Multimale-multifemale • One male-multifemale • Leaves • Fruits

• Food in small clumps = small groups • Monogamous pairs • One female-two males

• Food is very limited = individuals • Solitary • Insects

Factors influencing the type of residence pattern

• Predation • If predation = high • And body size = small • Large group may help fend off

predators • Large bodied primates are not

preyed on as often • Nocturnal species not preyed

on as often • Solitary tend to be

large/nocturnal

Humans

• What residential pattern do humans have?

Species Concepts, Modes of Speciation, and phylogenetics

Anthropology 2200

Primate classification

What is a Species?

Definition of a Species • Biological species

concept

• Ecological species concept

• Morphological species concept

Biological Species Concept

• “Groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups” – Ernst Mayr (1942)

• Complications • So what do we mean by “reproductively

isolated”?

Lion

Tiger

Liger or Tigon

Reproductive Isolating

Mechanisms

Any factor that prevents a male and female of two different “species” from hybridizing

Reproductive isolation causes “species” to be recognized as distinct biological species

• Example: Lions and tigers do not naturally mate with one another at present, but their territories overlapped in the past

• Are they separate species today? In the past?

So, what exactly do we mean by Reproductive

Isolating Mechanisms?

Pre-Mating RIMs

Post-Mating RIMs

1. Habitat Isolation 1. Sperm-egg incompatibility

2. Temporal Isolation 2. Zygote inviability

3. Behavioral Isolation 3. Embryonic inviability

4. Mechanical Incompatibility

4. Offspring inviability

5. Offspring sterility

Reproductive Isolating Mechanisms

• Natural selection favors pre-mating reproductive isolating mechanisms

• Hybrid mating in most cases would be a wasted reproductive effort (due to inviability or sterility) and natural selection promotes mechanisms to prevent such matings.

• Not mating uses less energy than mating, wasting reproductive resources (eggs/sperm), and producing Non-viable offspring

Ecological Species Concept

• Defines species based on the uniqueness of their ecological niche • Formation of discrete species

because of adaptation to exploit the resources in nature

• Based on the competitive exclusion principle

• Two species competing for the same resources can not both survive

Morphological Species Concept

“Classic” way of defining species

Linnaeus

Descriptive rather than theoretical concept

Defines species based on shared phenotypic characteristics

If one group of organisms consistently differs from other organisms, it will be defined as a separate species

Ring Species – defined as separate based on Morphology .

Species Concepts

• Biological, environmental, and morphological species concepts will generally recognize many of the same “species”, although not always.

How do we study extinct species? Paleospecies

• Species defined using fossil evidence • What concept of species do you think applies

best to fossils?

Morphological? Biological?

How do we study extinct species? Paleospecies

• Use morphological species concept to infer biological species concept

gene exchange species similarity CAUSE CAUSE

gene exchange species similarity INFERENCE INFERENCE

Paleospecies: Problems

• Allometry  Study of the change in proportion of various parts of an organism as a consequence of growth

Paleospecies: Problems • Allometry: Humans

Paleospecies: Problems

• Allometry: Orangutans

Growth comparison

H um

an

Ch im

pa nz

ee

Paleospecies: Problems • Sexual dimorphism • Pronounced

morphological differences between Males and Females

• Must differentiate between Sex. Dimorphism and morphological differences between species in the fossil record

Gorilla – Male Gorilla – Female

Paleospecies: Problems

• Sexual dimorphism: Mandrills

Paleospecies: Problems

• Variation • Intraspecific (within species) • Interspecific (between species) • Pathological conditions • At what point do we define a new

species? • Lumpers vs. splitters

How Are Species

Formed?

• Two general modes of evolutionary change • Anagenesis

• Evolution of a trait or a species into another over a period of time

– Cladogenesis • Evolution through the branching of a species or a

lineage (ancestor species may/may not = new array)

Evolution does not need to be gradual

What is Speciation?

• Speciation = radiations that occur through cladogenesis

• Results in one species diverging into multiple species

• Ancestor species may or may not persist over the long term

What is Speciation?

• 4 geographic modes of speciation • Allopatric • Peripatric • Parapatric • Sympatric

Allopatric Speciation

• Speciation occurring via geographic isolation • Common in nature • Geographic barriers = mountains, rivers, etc. • Divergence = drift, dif. Mutations, dif. Selective pressures

Allopatric Speciation • Geographical features divide groups over time • Ex. Grand Canyon Squirrels • Albert Squirrel

• South rim • White bellies • Dark tails

• Kaibab squirrel • north rim • black bellies • White Tails

• Warming after last Ice age = isolated high elevation Ponderosa Pine forests

• Allopatric speciation occurred

Has been different species, now subspecies!

Peripatric Speciation

Subform of Allopatric Speciation

Subpopulations can migrate to a new location outside the range of the

original population

e.g., a few individuals colonize an island away

from the mainland populations

Population at the edge of the main range of a species = peripheral

isolate

Related to Founder’s effect

Parapatric Speciation • Speciation occurring when two populations are

geographically contiguous • “Stepped cline” pattern of geographic variation

• Caused by abrupt environmental changes • Species A adapted to one side of boundary,

species B adapted to the other side • Hybrid Zone in the middle • Conditions for parapatric speciation are particularly

great if the hybrid zone is a tension zone (exists when the hybrids between the forms on either side of the boundary are selectively disadvantageous)

Sympatric Speciation

• Speciation occurring in the same geographic location • Polymorphism in the

population does not depend on space (in contrast to the stepped cline of parapatric speciation)

Sympatric Speciation

• Ex. Speciation of Cichlids of Lakes Nabugabo, Victoria, Tanganyika, in East Africa

• Rapidly evolved (1 million years) • Over 500 very different species • Thought to be due to sexual selection

Speciation Comparison

Speciation Events

• Adaptive radiation – The diversification of an ancestral

group of organisms into new forms that are adapted to specific ecological niches

– Ex: • The radiation of mammals

following the extinction of the dinosaurs

• Darwin’s finches

Phylogenetics and Cladistics

Phylogeny

• Phylogeny – The study of the

branching relationships of populations as they give rise to multiple descendant populations over evolutionary time

– Aimed at reconstructing evolutionary histories

What is Phylogenetics?

– Practice of creating “phylogenetic trees” – Shows the pattern of evolutionary relationships

among species – Can be created using living or fossil species

• This is a HYPOTHESIS!

How do we develop phylogenies?

• Rests on our observations of traits displayed by organisms

• Traits: • Any observable characteristics of

an organism • Anatomical features • Developmental or

embryological processes • Behavioral patterns • Genetic sequences

How do we read a phylogenetic tree?

• Traits are used to determine the relationship between species

• Taxon Group of related organisms that share one common ancestor

• Node Point where tree splits

• Outgroup Taxon that is related to the groups of interest but that branched off earlier in evolutionary history

• Root Base of tree Common lineage from which all species in the tree are derived

What is Cladistics?

• A phylogenetic method that uses shared derived traits to create ancestor-descendant trees – Shared derived traits

(synapomorphies) • Trait that is shared by two

or more taxa and their most recent common ancestor

• Species of organisms are grouped into clades

• Clade: group that consists of an ancestor organism and all its descendants

How Do We Determine Clades?

• To determine clades we need to determine which traits are shared derived traits (synapomorphies)

• Shared derived trait (synapomorphy) – Homologous trait that is shared

by two or more taxa and their most recent common ancestor but not ancestors that existed prior to this

• Homoplasy (analogous trait) – Same trait – Trait not present in a

common ancestor

How Do We Determine

Synapomorphies? • Try to determine whether a trait is homologous

or analogous – Homologous Trait

• In two or more species • Inherited from a common ancestor

– Analogous Trait • In two or more species • Evolution independently fashioned

similar traits in each species • Not from a common ancestor

• Homologous traits are then used to determine clades

Homology

Analogy

Divergent vs.

Convergent Evolution

Divergent vs. Convergent Evolution

Issues for reconstructing

phylogenetics of past species

What features are variation within a species? What features distinct to species?

How do you know a trait is homologous?

Are sample sizes large enough?

What is a Primate? Anthropology 2200

What is primatology?

• The study of the behavior, ecology, anatomy, and evolution of non-human primates

Primatology and Anthropology?

• Why study primates in an anthropology class? • Cross-species perspective • Evolutionary implications • Evolutionary modeling • Insight into human behavior, morphology,

culture

For example….

• Morphology and behavior of extant primates can help us understand:

• Relationship between morphology and behavior • Use this to infer behavior in the fossil record • Better understand human evolution

• Bipedalism – Orangutan Brachiation

• Can also help us understand additional aspects of human behavior

• Elevator avoidance • Alcoholism • Stress

Taxonomy • Kingdom Animalia • Phylum Chordata • Class Mammalia • Order Primates

What unites the primates?

Tropical distribution

• Almost all non-human primates live in the tropics of South or Central America, Asia, or Africa

Order: Primates

• Four prominent evolutionary tendencies • Arboreal adaptation

• Behaviors • Anatomical Characteristics

• Dietary Plasticity • Eat a wide variety of foods

• Larger brains • More complex behaviors

• Parental investment • Fewer offspring • More time invested

Arboreal Adaptations

• A generalized body structure • Bones of shoulders, limbs,

hands, feet are separate • Clavicle

• Keeps upper limbs at sides of body

• Flexibility/highly mobile joints • Equal length of front and hind

limbs • Long tail

• prehensile in some primates

Arboreal Adaptations • Generalized skeletal structure  Hand

• Opposable thumb • Thumb  4 fingers • Grasping

• Precision grip • Fine manipulation

• Power grip • Fist-like grip around object

Arboreal Adaptations

Arboreal Adaptations

Arboreal Adaptations

• Generalized skeletal structure  Foot

• Many = opposable big toe (hallux)

• Grasping • Humans

• Terrestrial • Bipedal

Arboreal Adaptations

• Generalized skeletal structure  Vertebral column

• 4 types of vertebrae • Bending • Twisting • Humans

• Coccyx = Tail • S-Shape vs. C-

Shape

Arboreal Adaptations • Enhanced sense of touch

• Dermal ridges (finger/toe prints)

• Primitive = Strepsirhines

• Derived = higher primates = better grasp

• Nails • Protection • Gripping

Grasping hands and feet

Prehensile tails

Arboreal Adaptations

• Enhanced sense of vision • Stereoscopic vision

• Both eyes see at the same time

• Depth perception = locomotion

• Color vision = insects/prey/fruit

Arboreal Adaptations

• Post-orbital bar • Product of eyes

moving forward!

Arboreal Adaptations

• Forms of locomotion • Quadrupedalism

• Arboreal • Typical arboreal quadrupeds • Suspensory locomotors

• Terrestrial • Typical terrestrial quadrupeds • Knuckle walkers

• Bipedalism

Trend towards diurnality

Benefits of diurnality

Diurnal and arboreal

• Reduced sense of smell • Due to enhanced vision • Smaller and less projecting snouts • Most higher primates have lost:

• Rhinarium (external wet nose) • Long snout

• Primitive primates have rhinarium • Loris/Lemur

• Baboons have large snouts • Massive canine roots

Dietary Plasticity

• Primates eat a wide range of foods

• Omnivorous • Fruit, nuts,

seeds, leaves, insects, meat

• Some specializations • Frugivore

• Mainly fruit • Folivore

• Mainly leaves • Insectivore

• Mainly insects

Dietary Plasticity • Generalized Heterodont dentition = wide range of foods

• Primitive dental characteristics

• Four functionally distinctive tooth types

• Incisors • Canines • Premolars • Molars

• 3.1.4.3 • Ancestral dental formula

Primate Characteristics

Heterodont dentition

Incisors:Canines:Premolars:molars

Dental formula

(# of upper) Incisors:Canines:Premolars:Molars

(# of lower) Incisors:Canines:Premolars:Molars

Primate Characteristics

Heterodont dentition

Incisors:Canines:Premolars:molars

Dental formula

(# of upper) Incisors:Canines:Premolars:Molars

(# of lower) Incisors:Canines:Premolars:Molars

Primate Characteristics

Heterodont dentition

Incisors:Canines:Premolars:molars

Dental formula

(# of upper) Incisors:Canines:Premolars:Molars

(# of lower) Incisors:Canines:Premolars:Molars

Primate Characteristics

Heterodont dentition

Incisors:Canines:Premolars:molars

Dental formula

(# of upper) Incisors:Canines:Premolars:Molars

(# of lower) Incisors:Canines:Premolars:Molars

Primate Characteristics

Heterodont dentition

Incisors:Canines:Premolars:molars

Dental formula

(# of upper) Incisors:Canines:Premolars:Molars

(# of lower) Incisors:Canines:Premolars:Molars

Dietary Plasticity

• General reduction in the number of teeth

• Dental formula = evolutionary relationships

• Mammals  3.1.4.3 (ancestral)

• New World Monkeys  2.1.3.3

• Old World Monkeys  2.1.2.3

• Great Apes  2.1.2.3

Exceptions to Dietary Plasticity

• Specialized adaptations • Canine-premolar honing complex • Tooth comb

• Lemurs • Bilophodont vs. Y-5

• Old World

Larger and more complex brains

Brain Size and Complexity in Primates

Big Brain and behavior flexibility

Parental Investment

• Greater investment in young • Longer gestation period • Reduced number of offspring • Time, energy, and intensive

care

• Extended length of each stage of the life cycle

• Social groups • Learned behaviors

Extended care of infants

These are all traits that unite primates

But primates are also incredibly diverse