QUIZ ON BATEMAN TRIVERS MODEL Flashcards
How can you tell which individuals are male and female?
Males are more brightly colored to attract females
What is the difference between males and females, biologically speaking?
their sex cells: sperm and egg
fun fact about males and females
females have their sex cells in the womb
males have their sex cells during puberty but have them till they die
Why do you think males rather than females (typically) exhibit sexually selected traits, whereas females tend to choose among them?
Males often evolve traits and displays that advertise their ability to provide direct and indirect benefits, and females evolve preferences for these traits. They do it to optimize their fitness
sexual selection
a case of natural selection in which evolution is driven by mate choice of the opposite sex
What does it all start with?
The gametes
anisogamy
sexual reproduction involving dissimilar gametes
What type of selection is thought to be responsible for anisogamy?
Define this type of selection.
disruptive selection:
eggs are…
sperm are…
Eggs are larger and fewer.
Sperm are smaller and more abundant.
There are two ways to be an excellent gamete!
It’s the extremes idea where the disruptive selection makes it either really good at one thing or the other. It is either really big or small and fast
The difference in size of egg and sperm may result from…
disruptive selection.
original population:
there are few individuals that have very light fur
there are few individuals that have very dark fur
there are many individuals that have fur of an intermediate color.
disruptive selection:
occurs when both extreme traits are favored in an environment
At the moment of fertilization, who has made the greater investment?
females because they stick around and care for the child
skewed operational sex ratio
more males are willing to mate than females.
operational sex ratio
the sex ratio of breeders in the population
Draw a graph of the relationship between how much care an animal gives its offspring and the amount of time it has for sex.
Graph: tradeoff
y axis: time available for sex
x axis: amount of parental care given
how do males optimize fitness? What about females?
The Bateman-Trivers model predicts that males optimize fitness my mating with MANY females, and that females optimize fitness by choosing high quality mates.
Under what circumstances might there be an exception? When might females evolve traits specifically to attract males?
In the case that there are not many mates
