LIFE HISTORIES Flashcards
species lifetime pattern of
growth, development and reproduction.
life history
Birds would increase fitness by increasing clutch size,
unless reduced survival of offspring in large broods
offset this advantage
David Lack
Given time and
resources are limited, how can the
organisms best use them to achieve its
maximum possible fitness?
Allocation of resources
Age of first reproduction
maturity
number of
episodes of reproduction
parity
number of offspring
produced per reproductive episode
fecundity
age to live
longevity
short-lived, e.g.,
dandelion, with rapid population growth
rate, small body size, early maturity, larger
number of offspring, minimal parental care
(animals). Inhabit unstable conditions,
disturbed areas.
r-selected organism
competitive species,
long-lived, e.g., oak tree with long life,
production of few, large seeds that can
grow readily in shaded environments, but
lack of mean of wide dispersal, poor
colonizers of new or empty habitats.
K-selected organism
high annual survival rate (94%), start at 10
yrs.
albatross
50% survival rate, start at 1 yr.
Natural selection favors the age of maturity that results in the
greatest number of offspring over the lifetime of the individual.
small songbirds
fish, reptiles, amphibians
Different investments on growth and reproduction
indeterminate growth
cold-blooded animals
ectothermic
warm-blooded animals
endothermic
One reproductive effort with all resources, then die
semelparity
