Comparative Animal Behavior Exam 3

enhance

Sexual selection favors characteristics that ______ reproductive success

sexual selection

a subset of natural selection that acts through heritable traits. It involves mate competition and mate choice that often result in the evolution of exaggerated traits, ornaments, and weapons that increase mating success

the advantage certain individuals have over others of the same sex and species solely in respect of reproduction

Sexual selection represents…

primary sexual characteristics

Genitalia and organs of reproduction are what?

Secondary sexual characteristics

morphological difference between the sexes that are not directly involved in reproduction

a situation in which members of the same sex compete for access to the other sex for reproduction (intrasexual competition)

Describe mate competition

selection by one sex for members of the other sex for reproduction (intersexual competition)

Describe mate choice

Anisogamy

the existence of differently sized gametes in different sexes

isogamy

production of gametes of the same size by all individuals

Disruptive selection against intermediate sized gametes

How did we end up with egg and spem?

numerical, zygotes

Small gametes have a ______ advantage, resulting in the most ________

highest

large gametes will result in zygotes with the ______ survival

Bateman’s hypothesis

female reproductive success is most strongly limited by the number and success of eggs that a female can produce, while a male’s reproductive success is limited by the number of mates a male has

Parental Investment theory (trivers)

the sex with greater investment in offspring should be choosier when it comes to mates, increasing competition in the less investing sex, driving sexual selection

Weapons

exaggerated morphological traits used in male-male competition

ornaments

exaggerated morphological traits used to attract females

operational sex ratio

the ratio of the number of sexually receptive males to sexually receptive females in a population

Mating success varied more in males than in females, especially so in species with female-biased parental care, which is why we see more sexual selection in males

Research: 66 different species

males with longer horns won more fights (intrasexual competition)

Research: Dung beetles

Larger males with longer tails were most successful in defending territory on a lek. Males that performed the most displays with the greatest number of ocelli obtained the most copulations (intersexual competition)

Research: Peacocks

males spent more time with and were quicker to dance with females that had greater ornamental displays (intersexual)

Research: pipefish

sex role reversed species

species where females compete for males that invest heavily in parental care

Both males and females preferred the orange color, which is associated with their food, females then preferred males with more orange (sensory bias hypothesis)

Research: guppies

sensory bias hypothesis

female mating preferences are a by-product of pre-existing biases in a female’s sensory system

direct material benefits

material resources obtained by a female mating with a particular male

indirect genetic benefits

genetic benefits females can obtain for their offspring by mating with males that have high genetic quality

Nuptial gift

physical resource such as a food item that a male provides to a female to enhance his mating success

larger nuptial gifts resulted in more eggs produced by the female (direct material benefit)

Research: Butterflies

females preferred and produced larger eggs with males that had better territories (direct material benefit)

Research: lizards

an evolutionary process in which a male trait coevolves with a female preference for it and it becomes increasingly exaggerated and will continue until too costly

Explain Fisher’s Runaway Process

well developed secondary sexual characteristics are costly to survival because they are a handicap, therefore females should prefer such males because they overcome the handicap

Explain Zahavi’s handicap principle

exaggerated secondary sexual characteristics must be costly to produce for them to be a reliable indicator of male genetic quality, the cost of the trait doesn’t need to be a handicap to survival

explain mate choice for good genes

indirect fitness

_______ ______ is the benefit of selecting a mate with better genetics to produce the offspring

females selected males based on costly vocalizations, and these males produced offspring with higher growth rates (good genes)

Research: Tree frogs

Hamilton-Zuk Hypothesis

parasites and pathogens play an important role in sexual selection when secondary traits are costly and condition-dependent

females preferred the males that produced the more costly high vocalizations, and these males had better immune systems

Research: crickets

females chose the same pheromone in both trials, the females who mated with preferred males had larger egg sacs with more and heavier eggs

research: spitting spiders

males that mate guarded more had fewer extra pair offspring

Research: warblers

mate guarding

a behavior in which the male remains close to his mate to prevent her from mating with rivals

extra pair young

offspring of a pair bonded that the female produced outside the pair bond by a third party mate

sperm competition

competition between sperm of different males to fertilize eggs

cryptic female choice

when female influences the fertilization success of sperm from one male over others

inbreeding depression

a reduction in fitness as a result of mating with close relatives

male, female pairs that copulate more frequently had fewer extra-pair offspring (sperm competition)

Research: Tree swallows

Females mated readily with siblings and non-siblings, but females stored more sperm from the nonsibling and more eggs were fertilized (Female cryptic choice)

Research: Orb spider

alternative reproductive tactics

The existence of multiple behavioral mating phenotypes in a population

bourgeois stretegy

competitive males defend the nest or territory, males are large, older, and in the best physiological condition

parasitic strategy, satellite, sneaker

less competitive males try to usurp mating from bourgeois males, examples are ______ and _____ males

satellite male

remains near a bourgeois male to intercept females that are attracted to the bourgeois male

Sneaker male

attempts to avoid detection so that he can quickly enter a bourgeois territory to fertilize eggs being deposited in a nest

conditional strategy

a strategy that an individual chooses based on its condition

evolutionary stable strategy

A strategy that, if adopted by individuals in a population, cannot be trumped by another strategy because it yields the highest fitness

in order to locate dominant males, satellite males were drawn to the same low frequency vocalizations as females (satellite male)

Research: green tree frogs

Parental males were larger and greater in number, and satellite males make up about 15% of the population, but the sneakers reproductive success is in proportion to their abundance, so the two strategies have equal reproductive fitness (ESS)

Research: pumpkin seed sunfish

mate choice copying

a situation in which one individual observes and copies the mating decisions of another individual

females preferred males after they saw them being chose by other females

Research: Guppies (copying)

Initially, females spent more time near the high quality male, but after observing a model female with a low quality male, females spent more time near the low-quality male

Research: Fruit flies

it is difficult for a female to determine which male is of higher quality if the males are similar or if she has little experience discriminating between males

When is mate copying benefical?

when a rival male was near a preferred female, a test male spent less time with the preferred female in subsequent stages, and mated more with a non-preferred mate

Research: mosquitofish

for couples interested in each other, attractiveness ratings by women increased after seeing the male interact with a mutually interested rival

Research: humans

mating systems

a description of the social associations and number of sexual partners an individual has during one breeding season

1 female and 1 male

monogamy

more than 1 female, 1 male

polygyny

1 female, more than 1 male

polyandry

more than 1 female, more than 1 male (mating occurs within social groups)

polygynandry

more than 1 female, more than 1 male (mating is not restricted to specific social associations)

promiscuity

pair bond

an exclusive social relationship between a male and a female that exists beyond the time of the courtship and mating

sexual conflict, resource amount and distribution vary in different environments

What are the two factors that influence the evolution of social mating systems?

sexual conflict

differential selection on males and females to maximize their fitness

female fitness is most often limited by access to resources, while male fitness is most often limited by the number of mates

what causes sexual conflict?

monogamy

If the female’s sexual partner provides high levels or resources to the young, __________ can be favored

polyandry

if multiple males all provide care to the female’s offspring, ______ will be favored

For males, selection will favor ______ when males that mate with multiple partners have higher fitness than those that mate with a single female

monogamy, biparental ccare

If sexual conflict does not exist because care from both parents is required to raise offspring successfully, selection will favor ______ and ___________

polygyny

selection favors _______ when biparental care is not required

female defense polygyny

a mating system in which a single male monopolizes and mates with two or more females

resource defense polygyny

a mating system in which a male mates with multiple females that are attracted to resources he defends

male dominance polygyny

a mating system in which a few males on a lek mate with many females

polyandry

________ can evolve when it is advantageous to both sexes that females be freed from providing parental care, making parental care male biased

polygynandry

_________ occurs in some social species, and particularly in mammals that defend a territory from other such groups (lions)

promiscuity

________ should evolve when the benefits of social living are low

Monogamy and high levels of care were predominant in poor-quality habitat, while polygyny, promiscuity, and reduced levels of male care were associated with medium and good quality habitats

Research: reed warblers