Exam 2- Population Ecology

metapopulation

a population of populations, connected by migration

Population size (N)

number of population members in a habitat at the same time

Methods for determining N

– Count all individuals in the population

– Sub-sample and extrapolate

– Mark-recapture

Quadrat

square made of various materials used to determine population size and density in slow moving or stationary organisms

Transect

a path along which one counts and records occurrences of the objects of study

Mark-recapture

technique used to determine population size in mobile organisms where scientists catch some individuals and mark them and then return later, catch some individuals, tally number marked and unmarked

Population density

number of population members divided by the area or volume being measured

Population dispersion

how individuals are distributed relative to one another

Uniform

relatively equal spacing among individuals

Random

individual has equal probability of occurring anywhere in area

Clumped

individuals are closer than expected by chance

Demography

statistical study of changes in populations over time

– Birth and immigration rates (+)

– Death and emigration rates (-)

Life table

table showing the life expectancy (and/or other stats) of a population member based on its age

cohort

group of the same age that can be followed through time

Survivorship curve

graph of the number of surviving population members versus the relative age of the member

life history

inherited pattern of resource allocation under the influence of natural selection and other evolutionary forces

energy budget

allocation of energy resources for body maintenance, reproduction, and parental care

Fecundity

potential reproductive capacity of an individual, usually measured in females

Parental care

investment by parents in the production, survival, and reproduction of offspring

Semelparity

life history strategy characterized by a single reproductive event followed by death

Iteroparity

life history strategy characterized by multiple reproductive events during the lifetime of a species

r-selection life history

Type III survivorship curve

High fecundity

Low parental care

Fast maturity

Small body size

Low disease/predator resistance

Low survivorship/lifespan

K-selection life history

Low fecundity

High parental care

Slow maturity

Large body size

High disease/predator resistance

High survivorship/lifespan

Type I survivorship

Exponential growth

accelerating growth pattern seen in populations under conditions where resources are not limiting

Biotic potential (rmax)

maximal potential growth rate of a species

Logistic growth

leveling off of exponential growth due to limiting resources

Carrying capacity (K)

number of individuals of a species that can be supported by the limited resources of a habitat

Density-dependent regulation

regulation of population that is influenced by population density, such as crowding effects; usually involves biotic factors

Density-independent regulation

regulation of populations by factors that operate independent of population density, such as forest fires and volcanic eruptions; usually involves abiotic factors

Population cycles

Somewhat regular rise and fall in population size

Age structure

proportion of population members at specific age ranges

Ilkka Hanski

studied metapopulation dynamics; found overall balance between sub-population extinctions and re-colonizations