evolution test 4

How might MHC genes be used in kin recognition? Discuss empirical evidence that such a mechanism exists in animals (be specific).

*complex vocal cues in emperor penguins* these genes are able to be identified through odor cues; determine which mate to choose; can asses the degree of genetic relatedness depending on the smell of the other individual - communal nesting in female mice

A parent's decision regarding how much aid to give any particular offspring is a function of . . .

1. how related individuals are, and 2. how high or low the costs & benefits assoc. w/ the trait turn out to be

the 4 paths to the evolution and maintenance of cooperative activities are:

1. kin selected cooperation 2. reciprocity 3. byproduct mutualism 4. group selection

what 3 possibilities dictate hybrid zones?

1. when hybrids are more fit than purebreds, the fate of the hybrid zone depends on the size/extent of the environment in which hybrids have an advantage 2. if hybrids achieve higher fitness in environments outside the ranges of the parental species, then a new species may form in the new habitat 3. if hybrids have an advantage on the boundary if each parental population's range, then a stable hybrid zone may form

What is an "alliance"? Describe the types of alliances that exist in dolphin herding behavior.

An alliance is when coalitions exist for a long period of time In dolphins, all males group together and herd females to increase their chances of mating (first order is when trios of males keep females by their side, where second order alliances aggressively attack other males in order to steal their claimed females)

Describe the "parent-offspring conflict" that occurs between a women and her developing fetus during pregnancy (be specific). Explain the costs and benefits to the fetus and Mom.

David Haig hypothesized that fetal cells 'invade' the maternal endometrium, and that

Provide an evolutionary explanation for the sex difference in alarm calling frequency observed in Beldings's ground squirrel populations.

Females are often surrounded by their relatives, whereas males travel, so females are more inclined to protect those to pass on and preserve their genes

What are hybrid zones?

Region where interbreeding between diverged populations occurs and hybrid offspring are frequent

Human babies weighing over 9 lbs are at greater risk of developing gestational diabetes as adults. Given what we have learned in class about the condition and its development, how might we explain the statistic above? Hint: Start by addressing the question of how babies might get so big before birth.

Some babies have a genetically based ability to manipulate the insulin of the mother; if the mother has high blood glucose levels, then their baby will as well fat babies will get fat babies

Can inclusive fitness theory be used to understand conflicts within families? Explain.

Yes, inclusive fitness theory can be used to understand conflicts with families; inclusive fitness theory predicts that parents should go to great lengths to help their offspring (r value of 0.5)

Define "reciprocal altruism".

a behavior whereby an organism acts in a manner that temporarily reduces its fitness while increasing another organism's fitness, with the expectation that the other organism will act in a similar manner at a later time individuals benefited from exchanging acts of cooperative and altruistic behavior

Define "inclusive fitness" and Hamilton's rule and provide an example.

a theory in evolutionary biology in which an organism's genetic success is believed to be derived from cooperation and altruistic behaviour.

cooperation is...

an outcome from which 2+ interacting individuals each receives a net benefit from their joint actions, despite the potential costs they may pay for undertaking such actions

How might communal nesting female mice be "cheated" by other females in the group? How do they solve this problem? Include in your answer an evolutionary explanation for WHY this would likely solve the problem.

any one female may be nursing their own and others' pups, while some females may get the benefits of being in a safer environment, but not nurse the other pups to avoid this, these nests are with close relatives where kin selection provides the added benefit of decreased risk of cheating

The "b" & "c" terms of Hamilton's model are particularly difficult to measure in nature. How have Ethologists solved this problem? Explain with an example.

because b and c are hard to measure, there is the offspring rule, where we use the number of offspring that were born and survived as the means of measuring ex: if an ethologist wanted to know the positive effects that young 'nest helpers' have on raising their children, they could examine the difference in the average # of chicks that survive with or without them

Why would an alarm caller do anything to attract a predator in its direction and make itself the predator's most likely next meal?

because of genetic kinship - protection of the rest of the ground squirrel population

Explain (in evolutionary terms) the "zone of conflict" between Mom and offspring X with regard to parental care.

between how much offspring X wants a parent to give him/her and how to much a parent is willing to give (the former always being greater than the later) ZONE OF CONFLICT***

A parent could "dispense every ounce of energy it has to provide offspring X with all the benefits at its disposal". Make a case for why natural selection should or should not favor such a parental strategy.

doing this could kill the parent or severely hamper the parent's ability to produce more offspring, so NS may not favor giving all energy and resources to one offspring. It may not maximize the TOTAL # of offspring the parent is able to produce over the course of their lifespan

What advantage do specialist species have over generalist species? What advantage to generalists have over specialists?

generalist can live in many diff places, tolerate a wide amount of env. conditions specialist species have fewer competitors and less overlap

What are cryptic species?

groups that were and/or are actually independent of one another, but appear to be members of the same species based on morphological similarity

The parent-offspring conflict predicted in any population is in part a function of the mating system that exists in that population. Explain and provide an example to illustrate your point.

in a LONG TERM MONOGAMOUS SPECIES current genetic offspring have an average genetic relatedness of r = 0.5, as they're likely to have the same mother and father in POLYANDROUS SPECIES where a female mates with several males, NS will favor offspring who attempt to extract more in the way of parental assistance; as genetic relatedness varies from r= 0.25 (same mom diff dad) and 0.5 (same mom and dad)

Discuss sibling rivalry in resource poor vs. resource rich environments.

in scarce resource environments: we expect intense and lethal competition to emerge among siblings in resource rich environments: sibling interactions are less competitive

Distinguish between pre- and postzygotic isolation. State and describe the 4 forms of reproductive isolation which prevent/avoid the needless loss of gametes (eggs & sperm).

pre zygotic = isolation BEFORE fertilization post zygotic = isolation AFTER fertilization 4 forms of isolation = geographic, temporal, mechanical, behavioral/ecological; figured out that 'oh that isn't a member of my species' before sex/wasting eggs and sperm.

Define the terms "r", "b", "A" and "c" in Hamilton's inclusive fitness model. How does each variable impact the decision to aid family members?

r = measure of relatedness b = the benefit that others receive c = the cost accrued to the individual expressing the trait A = number of individuals affected by the trait of interest the decision of aiding family members is a function of how related individuals are and how high/low the cost /benefits of the trait are

Summarize the basic premise of the "rule of thumb" model of kin recognition. Provide some "pros" and "cons" of using such a kin recognition strategy.

the rule of thumb model of cognition states that "if it's in my nest, I am going to feed it/treat it like kin" pros: cons: subject to cheating in a major way ("nest parasites" with cowbirds and cuckoos)

Summarize Robert Trivers' parent-offspring conflict theory.

this theory arises when parents must decide how much aid they give any particular offspring