lecture 9 Flashcards
what is life history theory?
questions regarding the nature and evolution of life history traits
what are life history traits?
biological traits that influence the schedule of survival or reproduction
(size at birth, age at sexual maturity, rate and pattern of growth, length of life)
what is the principle of allocation?
if an organisms can aqcuire a limited amount of resources/ energy for which two different processes compete, than an increase in resources to one must result in an equal decrease of resources to another
what is optimization?
natural selection favours those individuals with greatest firness
what is the currency for life history traits?
- intrisnic rate of increase of a genotype
- reproductive value
what is intrinsic rate of increase (r)?
how fast the number of individuals of that genotype increases over time
what is reproductive value (Ro)?
the number of descendants that a female of a given age is expected to have over the rest of its life
what are the two major types of trade offs?
- allocation of reproductive effort (size vs number)
- production effort (growth vs reproduction)
what is allocation of reproductive effort
the trade off between number of offspring and fitness of offspring (survival)
what does the trade off between number of offspring and fitness of offspring include?
- as the number of offspring increase, the amount of parental energy or care given to each offspring must decrease
- larger or better provisioned offspirng often have a higher probability of survival
what are the two scenarios when an organism is reproducing?
- few large offspring
- many small offspring
what is the trade off between number and size?
young in large broods are smaller, smaller young are less likely to survive
what are the current costs of reproduction?
reproduction uses energy and other reserves
what are the future costs of reproduction?
- may reduce future fecundity
- may reduce probability of parental survival
what is the trade off between growth vs reproduction?
if you allocate resources to reproduce you will have less resources available for grwoth which may potentially decrease future reproduction
what do the benefits of maturing earlier and at a smaller size include?
- a highe probability of survival to maturity because a shorter duration of the risky developmental juvenile period
- shorter generation time which allows parents to produce offspring that are born earlier and that start to reproduce sooner
what do the benefits of maturing later and at a larger size include?
- larger size at maturity = increased fecundity
- lower adult mortality due to larger size
- higher quality offspring (increased investement per offspring) which increases the probability of survival
what happens if mortality increases in all age classes?
reproductive effort increases early in life and age/size at maturity decreases
what happens if mortality increases after a particular age?
reproductive efforts increases before and decreases after that age
