Sexual Selection pt. 1 Flashcards
What are the different mating systems?
Polygyny
Monogamy
Promiscuity
Polyandry
Polygyny
males mate with more than one female; females mate with only one male
What do males do in polygyny systems?
-males contribute only sperm, females often provide majority of parental care
-males either defend territories which attract females looking for resources, or they defend groups of females directly
What mating system is this an example of?
Males guanacos that can defend rare wetlands can attract a heard of females that need the resource and will mate with territorial male.
Polygyny
Monogamy
males only mate with one female, females only mate with one male
What mating system is this an example of?
Male and female black swans pair for life. They raise and care for many broods of offspring together, forage together, and migrate together.
Monogamy
What are characteristics of monogamy?
-lifetime monogamy or just within a single breeding season
-high parental investment from males and females
-social monogamy
What is social monogamy?
both sexes mate with multiple partners, but males help raise the offspring of their social parter (which may or may not be their own)
Where do monogamous mating systems typically exist?
in environments where parental care from both parents is needed to successfully raise young
Promiscuity
males and females both mate with many individuals
Where is promiscuity common?
very common in aquatic species (and all outcrossing plants)
What mating system is this an example of?
For several days each mont, thousands of two-spot red snappers gather to spawn in the western Pacific Ocean and all breed.
Promiscuity
In promiscuity, what do males and females contribute?
males contribute only sperm
females may or may not provide any post-fertilization parental care
Polyandry
females mate with more than one male; males mate with only one female
What mating system is this an example of?
Male Jacana carrying chicks under his wings. Aka male is providing post-fertilization care.
Polyandry
Characteristics of polyandry:
-large, flashy, aggressive females fight for territories
Is polyandry common or uncommon?
relatively uncommon mating system
What is parental care like in polyandry
-if post-fertilization care is present, males provide the vast majority (or all) of it
-females still produce large eggs and invest more pre-fertilization energy
In which mating system would we expect the greatest variation in male reproductive success?
a. monogamy
b. polygyny
c. polyandry
d. promiscuity
b. polygyny
In natural selection, allele frequency changes over time due to differences in:
survival and reproductive success
In sexual selection, allele frequency changes over time due to differences in:
reproductive success
Sexual selection causes individuals to differ in their reproductive success due to _________.
Sexual selection causes individuals to differ in their reproductive success due to COMPETITION FOR MATES.
Individuals have different traits they use to compete for mates…song, dance, color, morphological structure, etc.
If these traits increase the likelihood an individual will mate…they are favored by _____.
sexual selection
T or F
ONLY males can have sexually selected traits.
FALSE
BOTH males and females can have sexually selected traits.
