reproductive strategies Flashcards
sexual reproduction
a reproduction mechanism in which progeny inherit DNA from two parents
gonads
the primary sexual organ in animals
sexual gametes are produced through meiosis, which results in
haploid cells contain a single full set of chromosomes
haploid gametes fuse together to produce a
diploid zygote
asexual reproduction
a reproduction mechanism in which progeny inherit DNA from a single parent
vegetative reproduction
a form of asexual reproduction in which an individual is produced from the nonsexual tissues of a parent
clones
individuals that descend asexually from the same parent and bear the same genotype
parthenogenesis
a form of asexual reproduction in which an embryo is produced without fertilization
-can produce clones (no meiosis)
-can produce genetically variable offspring (full or partial meiosis)
-recently discovered in boas and pythons
costs of sexual reproduction
-sexual organs require energy and resources
-mating behaviors require time and energy
hermaphroditism
when an individual possesses both male and female gametes
-counterbalances the cost of meiosis
offset to sexual reproduction
if the male helps the female take care of offspring, reducing female energy costs
purging mutations
sexually reproducing organisms can lose deleterious mutations during meiosis
-due to random assortment, many gametes will not contain mutations
red queen hypothesis
sexual reproduction allows hosts to evolve at a rate that counter the rapid evolution of parasites
-in spite of their higher reproductive rates, asexual clones cannot persist in the face of high rates of parasitism
simultaneous hermaphrodites
individuals that possess male and female reproductive functions at the same time
sequential hermaphrodites
individuals that possess male or female reproductive function and then switch to the other
perfect flowers
flowers that contain both male and female sexual organs
-2/3 of plants have perfect flowers
monoecious
plants that have separate make and female flowers on the same individual
dioecious
plants that contain either only male flowers or only female flowers on a single individual
for hermaphrodites, selfing occurs when
an individual’s male gametes fertilize its own female gametes
-poses a cost due to inbreeding depression
mixed mating
some species are able to switch between outcrossing and selfing
-can be in response to a lack of resources
environmental sex determination
a process in which sex is determined largely by the environment
-type of phenotypic plasticity, where the phenotype is sex
temperature dependent sex determination
occurs when the sex of an individual is determined by the temperature at which eggs develop
frequency dependent selection
when the rarer phenotype in a population is favored by natural selection
local mate competition
when competition for mates occurs in a very limited area, and only a few males are required to fertilize all the females
-can cause skewed sex ratios to occur
mating system
pattern of matings between males and females
-number of mates each individual has and the permanence of the relationship with those mates
promiscuity
males mate with multiple females and females mate with multiple males and do not crease social bonds
-common among animals and outcrossing plants
MALES BENEFIT
polygamy
a single individual of one sex forms long-term social bonds with more than one individual of the opposite sex
polygyny
a polygamous mating system in which a male mates with more than one female
-may evolve when males compete for females or when a male can defend territory and resources
polyandry
a polygamous mating system in which a female mates with more than one males
-may evolve when females reach for superior sperm or receive material benefit from each suitor (spermatophores)
monogamy
when a social bond between a male and female persists through the period that is required for them to rear offspring
-favored when males make important contributions in raising offspring
extra-pair copulation
when an individual that has a social bond with a mate also breeds with other individuals
mate guarding
a behavior in which one partner prevents the other partner from participating in extra-pair copulations
sexual selection
differential survival and reproduction due to sex-specific traits that are related to reproduction
-leads to a variety of differences between males and females
sexual dimorphism
the difference in the phenotype between males and females of the same species
primary sexual characteristics
traits related to fertilization
-gonads
secondary sexual characteristics
traits related to differences between the sexes in terms of body size, ornaments, color, and courtship
life history differences between sexes
body size differences between sexes are common in animals
contests between males
when males compete for females, selection will favor the evolution of weapons
-antlers or leg spurs
good genes hypothesis
the hypothesis that an individual chooses a mate that possesses a superior genotype
good health hypothesis
the hypothesis that an individual chooses the healthiest mates
-could be. based on genes or resources
parasite-mediated sexual selection
parasites reduce host fitness, parasites alter male showiness, parasite resistance is inherited, and females choose less parasitized males
runaway sexual selection
when 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
-extreme traits (peacock feathers) also burden males by requiring energy and resources, and attracting predators
the handicap principle
the greater the handicap an individual carries, the greater its ability must be to offset that trait
