Social Influences on Reproduction Flashcards
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
Fertility
ability to produce young
Fecundity
ability to produce many young
When assessing potential mates, a female will look for what?
- get the best genetics for her offspring
- best resources for raising offspring
- avoid exposing herself to disease during the mating process
- 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?
- introduction of male results in increased gonadotropins which results in increased estrogen secretion
- increased estrogen induces LH surge and the females ovulate
- wave of follicle growth occurring increases systemic estrogen levels
- 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?
- pheromone in male urine causes an increase in dopamine release from the hypothalamus resulting in suppression of prolactin and the CL regresses
- 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
