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Flashcards in Social Influences on Reproduction Deck (28):

What is the best way to ensure that your genetics are passed on to the next generation?

breed with the best available mate


Sexual selection

competition for mating opportunities, which involves selection both within the members of a sex and between the sexes


What is the parental investment of females?

-gestation, lactation, and offspring care
-produce relatively few gametes and require relatively few matings to ensure these are fertilized


What is the parental investment of males?

-produce lots of gametes but have little or no involvement in gestation, lactation, and offspring rearing
-capable of fertilizing more than a single female's eggs


What is female reproductive success limited by?

access to resources to develop eggs and raise offspring


What is male reproductive success limited by?

access to female eggs


What is the difference between the limiting sex and the competing sex?

limiting sex = females b/c while engaged in gestation she is not available form sting

competing sex = males b/c they must compete for limited opportunities to mate



ability to produce young



ability to produce many young


When assessing potential mates, a female will look for what?

1. get the best genetics for her offspring
2. best resources for raising offspring
3. avoid exposing herself to disease during the mating process
4. paternal assistance with offspring care


How are males chosen by females?

-males advertise for mates
-advertisements can be long or short-range and most are visual or auditory


Why must advertisements be costly to produce or maintain?

keeps the signal honest (i.e. it is representing a fit animal who is ready to mate)


What is intersexual selection?

-secondary sex characteristics that are designed to attract mates
-they advertise general fitness of the male, his quality, and freedom from diseases


What is intrasexual selection?

visual signals between males in establishing a dominance hierarchy for mating purposes


What are pheromones?

substances secreted by one individual that give specific physiologic reactions in other individuals of the same species


Pheromones are detected by what?

main olfactory system (MOS)

(sometimes vomeronasal organ)


How are pheromones used in mate choice?

they are a mechanism for avoidance of interbreeding


How are auditory cues used for mating?

-reinforce olfactory cues when females are sending out a notice of their willingness to mate
-quality of a male's song to make mate selection
-establish dominance (ex: roaring contests)


The Whitten Effect

introduction of a novel male into a group of females that have suppressed cycles


How does the Whitten Effect work?

1. introduction of male results in increased gonadotropins which results in increased estrogen secretion
2. increased estrogen induces LH surge and the females ovulate
3. wave of follicle growth occurring increases systemic estrogen levels
4. reduced progesterone and increased estrogen results in premature onset of luteolytic mechanisms and CL is destroyed so new ovulation can occur


The Bruce Effect

exposure of an early pregnant female to a different male results in failure of her pregnancy and she returns to estrus


What are the two explanations for the Bruce Effect?

1. pheromone in male urine causes an increase in dopamine release from the hypothalamus resulting in suppression of prolactin and the CL regresses
2. testes of male mice secrete estrogen in the urine and it is absorbed in the females via the vomeronasal organ, making the uterus non-receptive


The Lee-Boot Effect

females housed in crowded groups have extended estrous cycles by entering a period of pseudopregnancy/extended diestrus


The Coolidge Effect

males mated to exhaustion or refusal with one female will recover libido when exposed to another female


Explain illegitimate receivers

many signals used by animals as part of intrasexual and intersexual competition are used by their predators and parasites as a means of locating prey or hosts



by having their territory near that of the dominant male, they can intercept females that have been attracted to his resources as they pass through



subordinate males mate females that are attracted from neighboring groups because they may think they are mating the dominant male


Sneaky rutters

immature or weaker males wait at the edge of a harem for the dominant male to be occupied, then they run into breed and run away again