Chapter 9: reproductive strategies Flashcards
sexual reproduction
reproduction mechanism in which progeny inherit DNA from 2 parents
- gametes (haploid germ cells) produce through meiosis
- 2 gametes combine = mixing of chromosomes –> fertilization –> diploid zygote
Asexual reproduction
reproductive mechanism in which progeny inherit DNA from 1 parent through vegetative reproduction or parthenogenesis
Vegetative reproduction
when an individual is produced from the nonsexual tissues of the parent
- Ex: plants growing new shoots
Clones
individual produced through asexual reproduction has same genotype as parent
Binary fission
reproduction though duplication of genes followed by division of cell into 2 identical cells; splitting in half
- ex: starfish
Haploid Parthenogenesis (“virgin birth”)
form of asexual reproduction in which an embryo is produced w/o fertilization
- Diploid egg, doesn’t need sperm
- Produce clones or w/ variation
- can ONLY produce females
Cost of sexual reproduction
energy and resources/cost for sexual organs
- Reduces fitness, increases risk of predation and parasitism
Cost of meiosis
~50% reduction in # of parent’s genes passed onto next generation via sexual reproduction versus asexual reproduction
cost of meiosis can be counterbalanced by ___ in hermaphrodites
can contributed twice as many copies of genes to offspring
cost of meiosis can be counterbalanced by ___
a male helping a female take care of offspring
Purging mutations
in sexual reproduction, deleterious mutations may not be transmitted to gametes
- Gametes produced do not form zygote w/ mutation
Red queen hypothesis
hypothesis that sexual selection allows hosts to evolve at rate that can counter the rapid evolution of parasites
benefits of sexual reproduction
purging mutations, genetic variation, environmental variation, evolving to be able to withstand new parasites and pathogens
Perfect flowers
flowers w/ male and female parts
Simultaneous hermaphrodites
individuals w/ male and female reprodictve funtions at the same time (self-fertilization)
Sequential hermaphrodites
individuals w/ either male or female reproductive function and then switch to other (out-crossing)
Monoecious
plants w/ separate male and female flowers on same individual
Dioecious
plants w/ either only male flowers or only female flowers on 1 individual
Genetic sex determination
sex-specific chromosomes determine sex
Genetic sex determination in mammals
XX = female
XY = male
Genetic sex determination in birds
ZW = female
ZZ = male
- allows for male and females to be produced through parthenogenesis
Environmental sex determination
process in which sex is determined by environment
Temperature-dependent sex determination
sex determined by temperature at which eggs develop
- sex determination = phenotypic plasticity
temperature-dependent sex determination in turtles
- lower temps = males
- higher temps = females
___ determine ratio of male/females produced
- females determine who receives X or Y
- selective abortion
Local mate competition
competition for mates occurs in very limited area; only a few males are required to fertilize all the females
Mating system
of mates each individual has and the permanence of the relationship w/ those mate
4 mating systems
promiscuity, polyandry, polygyny, monogamy
Promiscuity
mating system in which males mates w/ multiple females and females mate w/ multiple males; do not create lasting social bond
Polygamy
mating system in which 1 individual of 1 sex forms long-term social bonds w/ 2+ individuals of opposite sex
Polygyny
mating system in which male mates w/ more 2+ females
Polyandry
mating system in which female mates w/ 2+ males
Monogamy
mating system w/ social bond b/w 1 male and 1 female persists through bearing offspring
Extra-pair copulations
individual that has social bond w/ mate but also breeds w/ others
Mate guarding
behavior in which 1 partner prevents other partner from participating in extra-pair copulations
Sexual selection
natural selection for sex-specific traits related to reproduction
Sexual dimorphism
difference in phenotype b/w males and females of same species
Primary sexual characteristics
traits related to fertilization
Secondary sexual characteristics
traits related to differences b/w the sexes in terms of body size, ornaments, color, and courtship
2 types of female preference
material benefits and nonmaterial benefits
Material benefits
physical items males can provide females
- Ex: site for raising offspring, high-quality territory, and abundant food
Nonmaterial benefits
female preference for specific appearance on males based on the good genes and good healthy hypotheses
Good healthy hypothesis
individual chooses healthiest mates
Good genes hypothesis
individual chooses a mate that possesses superior genotype
Runaway sexual selection
selection for preference of sexual trait and selection for that trait continue to reinforce each other
Handicap principle
greater the handicap an individual carries, greater its ability to offset that handicap
Budding
little buds that pop off the mom plant when ig enough
Vegetative
reproduce through bulbs or tubers
Fragmentation
parents breaks into pieces and pieces develop as offspring (Starfish)
benefits to sexual reproduction
- gene variation (more combinations of genes = more variation = less susceptible to disease = more likely to survive
protogyny
changing sex female –> male
