Chapter 6-7
Chapter 6: Primate Mating Systems
A. The language of Adaptive Explanations
Biologists often use the term “Strategy” to describe the behavior of animals.
However, “strategy” refers to a set of behaviors occurring in a specific functional context (such as mating, parenting, or foraging).
This led to greater reproductive success in ancestral populations have been favored by natural selection and represent adaptations.
Costs and Benefits of some Strategies
(+) If they increase the genetic fitness of individuals
(-) If they reduce the genetic fitness of individuals
B. The Evolution of Reproductive Strategies
Primates provide much more resources to their young (males in some species).
In species without parental care, females produce large, nutrient rich gametes. Males produce small gametes and supply only genes.
Many males do not care for their offspring
They can have more offspring if they have sex with more females
When caring for young, it does not increase their fitness
These males are either the “investing” or “non-investing” type of father
Primate females have to commit in their offspring
In primates, and other mammals, selection tends to favor low male investment because females lactate and males don’t.
C. Reproductive Strategies of Females
Primates have considerably longer pregnancies than smaller animals
This is because brain tissue develops extremely slowly.
Females reproductive success depends on the ability to acquire resources
They must achieve a minimum nutrition level in order to ovulate and conceive.
Limited amount of resources in habitat which can allow them to: grow faster, mature early, and give birth at shorter intervals
Sources of variation in female reproductive performance
Primiparous= primates who give birth for the first time
Very young and very old females do not have a high reproductive rate as middle aged females.
Younger females may lack experience in handling newborn infants and may not provide proper care
A. The language of Adaptive Explanations
Biologists often use the term “Strategy” to describe the behavior of animals.
However, “strategy” refers to a set of behaviors occurring in a specific functional context (such as mating, parenting, or foraging).
This led to greater reproductive success in ancestral populations have been favored by natural selection and represent adaptations.
Costs and Benefits of some Strategies
(+) If they increase the genetic fitness of individuals
(-) If they reduce the genetic fitness of individuals
B. The Evolution of Reproductive Strategies
Primates provide much more resources to their young (males in some species).
In species without parental care, females produce large, nutrient rich gametes. Males produce small gametes and supply only genes.
Many males do not care for their offspring
They can have more offspring if they have sex with more females
When caring for young, it does not increase their fitness
These males are either the “investing” or “non-investing” type of father
Primate females have to commit in their offspring
In primates, and other mammals, selection tends to favor low male investment because females lactate and males don’t.
C. Reproductive Strategies of Females
Primates have considerably longer pregnancies than smaller animals
This is because brain tissue develops extremely slowly.
Females reproductive success depends on the ability to acquire resources
They must achieve a minimum nutrition level in order to ovulate and conceive.
Limited amount of resources in habitat which can allow them to: grow faster, mature early, and give birth at shorter intervals
Sources of variation in female reproductive performance
Primiparous= primates who give birth for the first time
Very young and very old females do not have a high reproductive rate as middle aged females.
Younger females may lack experience in handling newborn infants and may not provide proper care