Mammalogy Unit 3

Anisogamy

Differentiation of gamete production between sexes

Reproductive success

Number of offspring surviving to reproductive age

Female reproductive success

Limited by food and condition

Male reproductive success

Limited female scarcity

Elephant seals

Males rarely mate beyond one season

Red-deer

Create harems, mate many seasons

Bateman gradient

Correlation between mating success and reproductive success.

Females in Bateman gradient

Only need to produce one young annually

Males in Bateman gradient

Some males outcompete others, creates pressure on reproductive genes

Operational sex ratio

Abundant sex competes for scarce sex

Operational sex ratio inventors

Trivers and Willard

Mother/daughter competition at natal site

Creates male skew

Daughters and mothers equal

Creates female skew

Sexual selection

Process that creates heritable traits that affect mate acquisition

Sexual dimorphism

Females choose fittest males

Runaway hypothesis

Females select trait, becomes more common. Females produce young that exhibit/prefer trait

Runaway limitation

Preference must balance with practicality

Handicap hypothesis

Body condition displays health, potentially indicating genes/environment

Fluctuating asymmetry

Can reflect genes/environment, “unattractive”

Asymmetry prominence

More prominent in sexually selected traits

Sperm compeition

One female, multiple males. First come, first serve

1st males to mate

Guard females and can create copulatory plug

2nd males

Copious sperm capable of flushing plug

Post-copulation competition

Bruce effect or infanticide

Parental investment

Creates competition for care

Silver-backed jackals

Males aid in young feeding

Allee effect

Investment in care for related individuals helps one’s genes

Semelparity

1 mating in ones whole life

Iteroparity

Multiple mating events

Monogamous taxa (partially)

Carnivora and Primates

Facultative monogamy

Can only have one mate at low population densities

Obligate monogamy

Male investment required!

Monestrous

One reproductive event per year

Polyestrous

Multiple reproductive events per year

Polygamy

Multiple males and females

Polyandry

Multiple males, one female

Polygyny

Multiple females, one male

Resource defendant polygyny

Males defend females as resource

Male dominance polygamy

Males demonstrate on leks

Scramble polygamy

Males are nomadic

Display

Behavior conveying a message

Signals

Physical form of a message

Response

Reaction to receiving a message

Deceit

Sender purposefully misleads receiver

Discrete signals

Binary, yes/no

Graded signals

Exist on spectrum (sort of)

Short distance signals

High frequency alarm calls

Long distance signals

Elephants

Short signal duration

Alarm calls

Long signal duration

Antlers/pelage

Composite

Multiple signals together

Syntax

Sequence of signals

Context

Situation signal is given in

Olfactory

Easily detectable and long-lasting, number of signals limited

Pheromones

Chemical signals that illicit responses

Priming pheromones

Generalized responses

Signaling pheromones

Specific responses

Flehmen response

Sniffing privates or urine, urine contains fat-soluble pheromones telling ID and social status

Auditory communication

Rapid, includes most predator warnings

Visual communication

Displays time and location

Flagging

Distracts predators and warns others

Tactice communication

Primates and gregarious carnivores, removes parasites and reinforces bonds

Group spacing

Auditory and olfactory

4 types of spacing communication

Increase distance, maintain distance, reduce distance, and proximal

Increase distance signal

Lowers competition and creates space

Maintain distance signal

Maintain comfortable distance

Reduce distance signal

Encourages collaboration

Proximal signals

Enhance bonds

Recognition

Individual specific signals prevent inbreeding and reinforces dominance hierarchies

Hunting signals

Vocal and tactile signals encourage pack collaboration

Ritualized combat

Weapons clash harmlessly

Station keeping

Local movements within one’s home range

Ranging

Movement outside one’s home range

Natal philopatry

Breeding near one’s birthplace

Proximate responses

Parent pressure, hormonal changes

Ultimate cause

Resource competition, inbreeding

Heterozygosity

Dampens accrual of negative alleles in inbred competitions

Long outbreeding

Inbreeding effects happen quickly

Recent inbreeding

Inbreeding more tolerable, deleterious alleles selected again

Outbreeding depression

Breeding between distant groups produce less fit offspring

Hairy footed gerbils

Exhibit less activity on nights of full moons (environmental)

Deer mice

Habitat preference determined by genotype

Ungulates

Habitat selection is behavioral (tradition)

3 habitat selection influences

Genotype, environment, tradition

Homing

Returning to one’s home range

Path-integration

“Dead-reckoning”: Homing after feeding in a circuitous route

Distance landmarking

Mental map of terrain in one's home range

Sun-compass

Angle of sun determines direction. Requires internal clock

Hippocampus

Large forebrain in part involved in learning

Hippocampus between genders

Males have larger hippocampus

Promiscuity and spatiality

Promiscuous species are better spatially

Fecundity concentration

Concentrates at distinct ages

Natural selection chooses

Successful offspring

Reproductive opportunism

Some individuals will strategically abstain from reproducing

Senescence

An age related decrease in fecundity and increasing mortality

Mammals of temperate/Arctic areas

r-selected

Tropical mammals

k-selected

Liebig’s law of the minimum

Population cycles

3-4 years per cycle, driven by climate/predators

BIDE

Birth, immigration, death, emigration