animal behavior final part 3

sex allocation

the allocation of an individual's resources (such as energy, time, and nutrients) to male versus female reproductive functions in sexually reproducing species.

sex determination system

biological system that determined development of sexual characteristics in an organism

what are some methods of sex determination across species

hermaphrodites and parthogenesis

what is it called when both male and female reproductive organs are posses at the same time

simultaneous hermaphrodites (this is more rare)

what is sequential hermaphrodites

when an organism posses female and male reproductive organs but not at the same time during their life (they can switch genders)

what animal is an example of hermaphroditism

some fish

what are the two types of sequential hermaphrodites

protandry and protogyny

what is protandry

when an organism is first male and later develops into female (ex clown fish)

what is a protogyny

when an organism is first female and later in life develops into a male (ex. wrasse)

what often cues the change in gender In sequential hermaphrodites

changes in social structure or environment

is parthenogenesis common

no it is rare

what does it mean to be parthenogenic

young develop directly from unfertilized eggs of female (no DNA from males) – young are “clones” of female. (seen in sharks and rays)

in birds who determines sex and how

the female does. it works very similarly to how it does in humans but revered so the female has ZW chromosomes and the male has ZZ chromosomes. (some fish and butterflies also do this)

how is sex determined in ants, bees and wasps

among ants, bees, and wasps, it is number of chromosome sets that an individual has that determines individual’s sex.

explain sex determination in wasps

• Males haploid, having only single set of chromosomes, and females diploid, carrying two full sets of chromosomes.

• Females produce haploid eggs via meiosis.

• Then mate with males and store sperm in special sac.

• As each egg is produced, female can allow it to be fertilized by some of sperm she has stored, in which case offspring will be diploid and female.

  • Alternatively, she can lay unfertilized egg, which can develop into haploid, male individual.

how is sex determined by turtles, many lizards and few snake species

egg incubation temperature. Hot eggs become female

what is fishers theory of equal investment

• predicted that parents will invest resources equally between each sex of offspring, because each sex supplies exactly half genes of all future generations

  • as result, those genes that cause parents to invest unequally in sexes will tend to be selected against

  • thought that equal investment would be favored in both sexes

what did fishers theory of equal investment say about sex ratio

as long as all else is equal 1:1 sex ratio will be favored by natural selection and if it strays from this it will eventually evolve back to this point

what was one way to test fishers theory

by altering sex ration away from 1:1 and then seeing if it evolves back to even

what did fishers theory assume about related individuals

that related individuals do not interact with (cooperatively or competitively)

• if they do interact then individuals can be favored to bias their offspring ratios to reduce competition between relatives or increase cooperation (idk if this is part of what fisher assumes)

what are two things that can explain sex ratio variation within species or population

local resource competition and local mate competition

what are two main reasons local mate competition occurs

• When sons compete for mates, value to their mother is reduced (so mom should bias her ratio of investment towards daughters).

• If sons able to mate with their sisters then female-biased sex ratio has bonus of providing more mates (daughters) for sons, and so higher proportion of daughters/mother produces greater value of each son produced.

in terms of sex allocations who should be expected to show more variable behavior

animals who live in more variable environments

what may offsprings occasionally do

they may remain in group and help parents rear further offspring

in seychelles warblers when is having helpers (such as daughter staying) beneficial

when they have high quality territories with high density of insect prey so they do not compete for food

what is local resource enhancement

when relatives help one another instead of competing with one another

how does maternal condition affect sex allocation

females in better condition can be selected to preferentially produce sons

• red deer adjust their offspring sex ratios in responses to maternal condition, with mothers in better condition more likely to produce sons

how does male attractiveness affect sex allocation

females who mated with attractive males can be selected to preferentially produce sons

explain how environmental sex determination can affect sex allocation

if one sex gains greater benefit from developing under certain conditions,

then this can lead to sex being determined by environment (remember turtles?).

• Time of year can be very important environmental factor, because it is cue of how long there is to grow before next breeding season

how can sex change affect sex allocation

if being old and big provides greater benefit to one sex then sex change can be favored

when may sex change to male be favored

When old, large males can monopolize mating with females, then individuals may be selected to mature as females, and then changes sex later in life to males.

when may sex change to female be favored

when males not able to monopolize matings then sex change can be favored from male to female

explain selfish sex ratio distorters

Some genes can act selfishly. Instead of helping the whole animal reproduce as successfully as possible, they increase their own chances of being passed on.

For example, a gene might cause an animal to produce more daughters than sons if that makes the gene more likely to end up in the next generation.

But the rest of the animal's genes may be harmed by this imbalance. Since most genes benefit when the sex ratio is closer to the optimal balance (often around 50:50), they are favored by natural selection to stop or suppress the selfish gene.

sociobiology

applies evolutionary theory to study and

interpretation of social behavior to explain how social

behaviors:

• are adaptive.

• could have evolved by natural selection.

what are the three components if phenotype matching

a.Begins with cue or label.

b.Cue compared to

template.

c.Response to individual

in question is made.