parental care
any behaviour on the part of the parent that appears likely to increase the survival and fitness of offspring
flow of influences on reproduction
gametic and parental investment
reproductive rates
operational sex ratio
sexual selection: who competes, who chooses?
parental effort
expenditure of parental resources (ex. time and energy) spent on parental care of 1+ offspring.
% of resources a parent can expend will vary with age, size and other biological factors.
parental investment
any action on the part of a parent that increases fitness of offspring at a cost to any component of the parent’s fitness
benefits of care
increased survival and reproduction (fitness) of offspring
treehoppers, what are the benefits of care?
hatching success depends on the amount of care received. When the eggs are abandoned, there are significantly fewer hatching nymphs.
what are the conditions for care to be beneficial?
parents must:
costs of care
decrease in survival, opportunities to feed, and future mating opportunities
st. peter’s fish, costs of care
males carry young in their mouths, and lose a significant amount of weight during this period. females also lose weight.
non caring males are able to gain weight.
when will care evolve?
benefits > costs
what are the forms of care? (4 forms)
a nuptial gift is an example of
pre fertilization investment
what do male widow spiders use for nuptial gifts?
they somersault into the mouths of females. (themselves)
egg production is an example of
pre fertilization investment
what does a larger egg volume usually indicate?
greater % survival
fecundity
the ability to produce an abundance of offspring
what is the trade off between egg size and fecundity
can either produce many, small eggs. or fewer, larger eggs.
how do tree frogs balance egg size and fecundity?
in permanent water bodies, their eggs are one size. In temporary water bodies, the eggs are variable in size.
care for eggs is an example of
investment between fertilization and hatching
incubation or internal gestation are examples of
investment between fertilization and birth
provisioning before birth is an example of
investment between fertilization and hatching
what does provisioning after birth look like in a few different animals + what does it mean?
young eat food collected by parents or feed on parental secretions
discus fish - mucus
mammals - milk
birds - regurgitated food
suppression of a daughter’s competitor is an example of
care for nutritionally independent young, and a form of social care. occurs in some social primates where daughters and mothers share a home range/group for life
how would each sex maximize their reproductive success with respect to parental care?
males: mate with many females, leave each one to care for the offspring
females: mate and then leave male to take care of offspring