Populations Flashcards
(13 cards)
Population parameters
Density dispersion and reproductive strategy
Population
A group of individuals of the same species that: live in a localized area, utilize a common pool of resources.
Dispersion patterns
Clumped: aggregated around a few resources; uniform: homogenous, usually results from competition for example trees fighting for light; random: most common type of dispersion pattern
Two types of reproductive strategy
Semelparity, breed once and die. Iteoparity, multiple breedings in lifetime, can be seasonal or continuous.
Demography
The study of the factors that influence population size and structure over time
Components influencing population size
The birthrate and death rate as well as the immigration rate and the emigration rate
Factors needed to predict population growth
The number of organisms alive now, the number of organisms likely to survive, the number of offspring produced, immigration and emigration rates, time from birth to first reproduction
Survivorship
Proportion of surviving organisms to a particular age class. Individuals born in the same period are known as a cohort.
Fecundity
The number of offspring produced. This measure is usually limited to the number of female offspring produced by female parents. The reason only females are used has to do with the fundamental asymmetry of sex.
Age-specific fecundity
A measure of the average number of females produced by a female in a certain age class.
Survivorship fecundity
Is generally a balance between one and the other. Selection favors the optimum allocation of each one. Survivorship and fecundity are inversely proportional to one another.
R selected species
R refers to intrinsic growth rate. R selected species have very rapid boom and bust birthing periods. There’s generally good dispersal short lifespan and these organisms are highly fecund
K selected species
K selected species have a carrying capacity generally slow growth and a long life
