Life Histories Flashcards
R vs K selected Key differences
Number of offspring Offspring survival Parental care Reproductive age Reproductive bouts Habitat stability Competitiveness Population regulation Population fluctuation
What are life history traits
An individuals life time allocation of time and energy
Into survival e.g. growth, repair, defence
Or reproduction
Life span and reproduction
Animals that reproduce later often live longer
E.g. Luckinbill selected drosophila lines for reproducing early and found they died earlier
Also found inbreeding depression increases with age
The rate of living theory
Duration of life depends on the exhaustion of fixed quantity of vital substance
The rate this is exhausted would be determined by metabolic rate
The mutation accumulation hypothesis
If the symptoms of a deleterious mutation didnt display until later in life then it is likely the mutation was already passed onto next gen.
natural selection cant remove = slow accumulation
Precocious breeding
E.g. Tasmanian devils
- begin breeding earlier
- they are under selection pressure from emerging tumour disease
- sexual maturity slower in longer living birds = early breeders tend to die young
David Lacks (1947) hypothesis
“Bird will have clutch sizes that give offspring best survival chance”
- calculated optimum = 5
- actual size was larger than calculated
Has been supporting and opposing statements
- has been found mothers have fewer chicks than they could adequately feed
The Williams principle
Looked at types of parental care There are 4 stages: - no care - male care e.g. teleost fish - biparental care - female care
Single reproduction event =
Semelparity (animals)
Monocarpy (plants)
Multiple reproductive events
Iteroparity (animals)
Polycarpy (plants)
Factors that can influence number of reproductions
Length of survival
Survival chances of offspring
Does senescence affect offspring survival
