Chapter 9 Flashcards
(112 cards)
1
Q
Haplodiploidy
A
sex-determination system where males develop from unfertilized eggs and females develop from fertilized eggs
2
Q
males develop from unfertilized eggs and are
A
haploid
3
Q
females develop from fertilized eggs and are
A
diploid
4
Q
sexual reproduction
A
a reproduction mechanism in which progeny inherit DNA from two parents
5
Q
a reproduction mechanism in which progeny inherit DNA from two parents
A
sexual reproduction
6
Q
gonads
A
primary sexual organs in animals
7
Q
how are sexual gametes produced
A
through meiosis
8
Q
what does meiosis result in
A
haploid cells containing a single full set of chromosomes
9
Q
what do haploid gametes fuse together to produce
A
diploid zygote
10
Q
asexual reproduction
A
reproduction mechanism in which progeny inherit DNA from a single parent
11
Q
reproduction mechanism in which progeny inherit DNA from a single parent
A
asexual reproduction
12
Q
a form of asexual reproduction in which an individual is produced from the nonsexual tissues of a parent
A
Vegetative reproduction
13
Q
Vegetative reproduction
A
a form of asexual reproduction in which an individual is produced from the nonsexual tissues of a parent
14
Q
clones
A
individuals that descend asexually from the same parent and bear the same genotype
15
Q
individuals that descend asexually from the same parent and bear the same genotype
A
clones
16
Q
binary fission
A
reproduction through duplication of genes followed by division of cell into two identical cells
17
Q
parthenogenesis
A
asexual reproduction in which an embryo is produced without fertilization
18
Q
asexual reproduction in which an embryo is produced without fertilization
A
parthenogenesis
19
Q
what results in clones
A
when germ cells develop directly to egg cells
20
Q
what results when germ cells undergo partial or complete meiosis
A
genetically variable offspring
21
Q
benefits of parthenogenesis
A
- reproduction during times of scarcity
2. genetic stability in constant environments
22
Q
disadvantages of parthenogenesis
A
limited genetic variation through recombination and mutations (low adaptability in unstable environments)
23
Q
costs of sexual reproduction
A
- sexual organs need energy and resources
2. mating behaviors need time and energy, increase risk of herbivory, predation, and parasitism
24
Q
cost of meiosis
A
the 50% reduction in the number of a parent’s genes passed on to the next generation via sexual reproduction versus asexual production; occurs because sexual genes are haploid
25
what is the cost of meiosis counterbalanced by
hermaphroditism
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hermaphroditism
an individual possesses both male and female gametes
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how can the costs of sexual reproduction be offset
if the male helps the female take care of offspring, reducing female energy costs
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benefits of sexual reproduction
1. purging mutations
2. coping with environmental variation
3. coping with parasites and pathogens
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purging mutations
sexually reproducing organisms can lose deleterious mutations during meiosis
- due to random assortment, many gametes will not contain mutations
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what will the fusion of two gametes with the same mutation result in
an offspring that is homozygous recessive for that mutation; likely that the offspring will not be viable
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what organisms have no means of purging mutations
asexual
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coping with environmental variation
offspring are likely to encounter different environmental conditions than their parents did
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what do offspring with genetic variation resulting from sexual reproduction have
an increased probability of possessing gene combinations that will help them adapt to different conditions
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coping with parasites and pathogens
pathogens have much shorter generation times and larger population sizes than the host species they infect
- this allows pathogens to evolve ways around host defenses and forces hosts to repidly evolve new defenses
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Red Queen Hypothesis
sexual selection allows hosts to evolve at a rate that counters the rapid evolution of parasites
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perfect flowers
flowers that contain both male and female flowers
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simultaneous hermaphrodites
individuals that possess male and female reproductive functions at the same time
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individuals that possess male and female reproductive functions at the same time
simultaneous hermaphrodites
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individuals that possess male or female reproductive function and then switch to the other
sequential hermaphrodites
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sequential hermaphrodites
individuals that possess male or female reproductive function and then switch to the other
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monoecious
plants that have separate male and female flowers on the same level
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plants that have separate male and female flowers on the same level
monoecioius
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plants that contain either only male flowers or only female flowers on a single individual
dioecious
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dioecious
plants that contain either only male flowers or only female flowers on a single individual
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polygamo-dioecious
having bisexual and male flowers on some plants and bisexual and female flowers on others
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having bisexual and male flowers on some plants and bisexual and female flowers on others
polygamo-dioecious
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natural selection should favor the strategy with the highest
fitness
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if a male can invest in female function while giving up only a small amount of male fitness (or vice versa), selection should favor
hermaphroditism
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when does self-fertilization (selfing) occur for hermaphrodites
when an individual's male gametes fertilize its own female gametes
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selfing poses a cost due to
inbreeding depression
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since self-fertilization poses a cost due to inbreeding depression, what should selection favor
individuals that can breed with other individuals (outcrossing) when possible
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how does sequential hermaphroditism avoid the problem of selfing
by separating sexual functions in time
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What do some species have that prevents organisms from being able to self
self-incompatibility genes
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some species can switch between
outcrossing and selfing
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What happens when mates are available
individuals outcross
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what happens when mates are unavailable
individuals self-fertilize
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what does self-fertilization produce
less viable offspring (better than nothing)
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what can mixed mating be in response to
a lack of resources in the environment
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in organisms with separate sexes, what is the typical sex ratio of male to female offspring
1:1
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what is sex determined by
inheritance of sex-specific chromosomes
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XX
females
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XY
males
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what will the sex that possesses two different chromosomes produce
approximately equal number of gametes with each chromosome
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in some, what is sex determined by
the presence or absence of a sex-specific chromosome
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In bees, ants, and wasps, what is sex determined by
whether or not eggs are fertilized
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Environmental sex determination
a process in which sex is determined mostly by the environment
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a process in which sex is determined mostly by the environment
environmental sex determination
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type of phenotypic plasticity, where phenotype is sex
environmental sex determination
69
frequency dependent selection
when the rarer sex in a population is favored by natural selection
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when the rarer sex in a population is favored by natural selection
frequency dependent selection
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in a population with an uneven sex ratio, what will the rarer sex do
compete with fewer individuals for breeding
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what is the consequence of the rarer sex competing with fewer individuals for breeding
the rarer sex will experience higher fitness
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what will mothers that produce the rarer sex experience and why
increased fitness because her offspring will produce more offspring (selection should favor a mother that produces the rarer sex
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what happens as selection causes the rare sex to become common
the sex ratio of the population will eventually become even
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when may skewed sex ratios occur
with local mate competition
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local mate competition
competiton for mates occurs in a very limited area, and only a few males are required to fertilize all of the females
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mating system
the number of mates each individual has and the relationship with those mates
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the number of mates each individual has and the relationship with those mates
mating system
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what does a female's reproductive success depend on
how many eggs she can produce and mate quality
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what does a male's success depend on
the number of females he can fertilize
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promiscuity
males mate with multiple females and females mate with multiple males and do not create lasting social bonds; common among animals and outcrossing plants
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males mate with multiple females and females mate with multiple males and do not create lasting social bonds; common among animals and outcrossing plants
promiscuity
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what does rampant promiscuity fend off
disease, bad genes, and extinction
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the more different males and females look in a species...
the more polygamous they're likely to be
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polygamy
a single individual of one sex forms long-term social bonds with more than one individual of the opposite sex
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a single individual of one sex forms long-term social bonds with more than one individual of the opposite sex
polygamy
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polygyny
a polygamous mating system in which a male mates with more than one female
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a polygamous mating system in which a male mates with more than one female
polygyny
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when may polygyny evolve
when males compete for females, or when a male can defend territory and resources
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polyandry
a polygamous mating system in which a female mates with more than one male
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a polygamous mating system in which a female mates with more than one male
polyandry
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when may polyandry evolve
when females search for superior sperm or receive material benefits from each suitor
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where can polygyny typically be found
a group with one male and multiple females (humans, gorillas, elk)
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who usually provides the majority of parental care in polygynous systems
females
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polygyny threshold model
demonstrates the link between female reproductive success and territory quality or the quality of a breeding situation
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an explanation for why polygynous systems persist
polygyny threshold model
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what does the polygyny threshold model also show
the effects of female reproductive success when multiple females in the same territory mate with one male
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monogamy
when a social bond between a male and female persists through the period that is required for them to rear offspring
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when is monogamy favored
when males make important contributions in raising offspring
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extra-pair copulation
when an individual that has a social bond with a mate also breeds with other individuals
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why do females use extra-pair copulation strategy
to obtain superior genotypes an dproduce offspring with better genetics
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mate guarding
one partner prevents the other partner from participating in extra-pair copulations
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sexual selection
natural selection for sex-specific traits that are related to reproduction; leads to a variety of differences between males and females
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sexual dimorphism
the difference in the phenotype between males and females of the same species (body size, courtship behavior)
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primary sexual characteristics
traits related to fertilization
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secondary sexual characteristics
traits related to differences between the sexes in terms of body size, ornaments, color, and courtship
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what do female preference for male traits relate to
features that improve her fitness, such as material benefits (e.g., high-quality territory)
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good genes hypothesis
an individual chooses a mate that possesses a superior genotype
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good health hypothesis
an individual chooses the healthiest mates
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runaway sexual selection
selection for preference of a sexual trait and selection for that trait continue to reinforce each other; continues until males run out of genetic variation
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extreme traits
burden males by requiring energy and resources, and attracting predators
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the handicap principle
the greater the handicap an individual carries, the greater its ability must be to offset that trait
