Anthropology test 2

Chapter 6

Mating system

The way animals find reproductive partners and care for offspring.

Primate mating systems rules

Strategies (Adaptation terminology)

Set of evolved traits that solve an adaptive problem

Tactics (Adaptation terminology)

Specific behaviors that aid in the success of a strategy

Costs and benefits (Adaptation terminology)

Trade-offs in reproductive success

Mating effort

Activities related to conception

Parenting effort

Activities related to offspring care

Female investment

More in parenting

Male investment

More in mating

Variation in parental care in frogs

Very little

Variation in parental care in birds

Variable

Variation in parental care in mammals

Female care is critical, a function of gestation and lactation, male care varies

Males will put energy into maximizing number of mates if…?

Finding mates is relatively easy, offspring can be raised by one parent

Males will put energy toward helping his offspring survive if…?

Offspring survival depends on care from btoh parents, females are harder to come by

The limiting factor for males is…?

Access to mates (Females)

Females invest heavily in offspring due to biology, because of…?

Long pregnancies (Brain growth energentically expensive), Lactation (Long infant periods)

The limiting factor for females is…?

Access to resources (food), large investment favors fewer offspring

How does access to resources affect females reproductive success?

More food leads to more offspring, short inter-birth interval, offspring mature earlier

How does age affect reproductive success in terms of young mothers?

Still allocating energy towards their own growth, 50% higher infant mortality rate, lack experience

How does age affect reproductive success in terms of older mothers?

More experience but less time to raise offspring, eggs have higher incidence of defects

Senescene

The biological process of aging/gradual deterioration with age

Other influences on female reproductive success

Longevity, group size, rank(greater access to resources) and sociality(get help raising offspring)

Reproductive trade-offs - Weaning

A time when infants become more indpendent, nursing is gradually reduced, energy is available for the mother to concieve again

Sexual selection

A form of selection that arises through the preference by one sex for certain traits in members of the opposite sex, often stronger than natural selection

Sexual dimorphism

Males and females of a species show distinct physical or behavioral differences

Intrasexual selection

Male-male conception, dominant males gain access to females, primary driver of sexual dimorphism

Intersexual selection

Female choice, female selects most “attractive” male

How does sexual dimorphism and mating systems connect?

Sperm competition in multi-male, multi-female systems

A form of male competition in which sperm from two or more different males compete to fertilize the same egg inside a females reproductive tract, females in estrus mate with many males, males with larger sperm volume have greater chance of fathering offspring

Pair bonding (Male reproductive tactics)

Mate guarding, increased parental investment

Cooperative breeding (Male reproductive tactics)

Males and other individuals in group help raise young, marmosets and tamarins for example often have twins and the mother can increase fertility by having helpers, humans are another example

Alloparenting

Care provided to young by individuals other than parents

Male-male competition (Male reproductive tactics)

Highest in one-male, multi-female mating systems

Infanticide

Killing of offspring by (usually) males, a male reproductive strategy, sexual selection infanticide hypothesis, lactational amenorrhea (death of infant accelerates return of female to sexual receptivity

Paternity confusion (Female counterstrategies to infanticide)

Females obscure information about the timing of ovulation, mate with multiple males

Spontaneous abortion of pregnancy (Female counterstrategies to infanticide)

The bruce effect

Male-female friendships (Female counterstrategies to infanticide)

Male protects female, female grooms male

Naturalistic fallacy

The flawed idea that if something is ‘natural’ it muyst be good or correct, confuses what ‘is’ with what ‘should be’, what we see in nature is not neccessarily “right”

How were primates studied?

Discovered by Linnaeus and Darwin through DNA, morphology, behaviour, and fossils.

What specific characteristics do primates share?

Grasping hands and developed vision, long juvenile periods and relatively large brains, physiological and cognitive structures, nails instead of claws, small litters

How are primates diverse?

Body size, habitat and diet, social organization, and activity patterns.

Reasoning in homology

Considers similarities in anatomy and behaviour that result from common ancestry

Reasoning by analogy

Considers similarities and differences that result from different groups responding to similar adaptive or evolutionary problems

Primate dentition

All primates have four kinds of teeth; Incisiors (I), canines (C), premolars (P), and molars (M)

Dental formula

I-C-P-M for upper and lower, 2:1:2:3

Primate biogeography (Primate distribution)

Tropical animals, mostly forest-dwelling, arboreal animals

Modern range (primate distribution)

Americas, africa, asia

Ancient range (Primate distribtution)

Included north america, Europe

Homo sapiens (Primate distribution)

The only primate to ever reach Australia, greenland, and Antartica

Primate species abundance

Relative to other animal order

Primate taxonomy

Not all equally related to one another, using genetic and morphological data, scientists can split the primate order into two suborders; Strepsirrhini and Haplorrhini

Strepsirrhine (Twisted nose)

‘Wet’ nose with rhinarium, tooth comb, tapetum lucidum, 2:1:3:3 (dental formula)

Lemuriformes (Infraorders from strepsirrhini)

Lemurs, madagascar, resulted from an adaptive radiation, big diversity

Lorisiformes (Infraorder from strepsirrhini)

Haplorhine (Simple nose)

‘Dry"‘ nose with no rhinarium, can’t manufacture Vit C, Complete orbital plate, no tapetum and have fovea

Tarsiiformes (Infraorder of Haplorrhini)

Live in asia, small and nocturnal insect eaters, vertical clingers and leapers, no toothcomb or tapetum

Platyrrhini(Simiiformes parvorder of Infraorder of Haplorrhini)

New world monkeys, five families, ‘flat nose and nostrils face out, live in tropical forests in south and Central America, arboreal, quadrupedal, and some suspensory climbers, 2:1:3:3 dental formula

Family Callirichidae (Marmosets/tamarins)

Pair bonders, co-operative breeders

Atelidae (Howler, wooly, and spider monkeys)

Suspensory climbers, prehensile tails

Family Cebidae (Capuchin and squirrel monkeys)

Highly social, omnivorous

Family aotidae (Night and owl monkeys)

Only nocturnal anthropoid

Family pithecidae (Saki, titi monkeys and uakaris)

Dinural, aboreal and polygamous

Catarrhini(Simiiformes parvorder of Infraorder of Haplorrhini)

‘Downward-facing’ nostrils, africa and eurasia, larger body size and more diverse habitats than platyrrhines, no prehensile tail, 2:1:3:3 (dental formula), split into two superfamilies

Cercopithecoidea (Superfamily)

Old world monkeys, two subfamilies; Colobines and Cercopithecines, 150 species, africa and asia, have tails, ischial callosities, bilophodont molar pattern, very diverse in size, habitats and diets.

Hominoidea (Superfamily)

Hominoids (Apes), relatively large brains, tailless, suspensory and orthograde climbers, separated into two families; hylobatidae and hominidae

Hylobatidae (family of hominodea)

Gibbons and Siamangs