Exam 2 Flashcards
11/4/24
Population
Group of individuals of the same species who live in the same area at the same time.
Population Ecology
The study of how and why a population changes over time.
Population Density
Number of individuals of a species per unit at a given time.
Population Dispersion
Spacing of a populations (Can be clumped, random, or uniform.
Niche
Organism’s place in the environment defined by physiological tolerances and resource requirments.
Two ways predator structure communities
Keystone predators
Trophic cascades
Time lags
Delays in the responses to births and deaths to an environmental change produce population cycles
Realized niche
Constrained by biological interactions among species
Three types of species interactions
Competitive, consumptive, mimicry
Competition
use of or defense of a resource by one individual that causes a reduction in that resource availability to another.
Competitive Exclusion
Two or more species with the same niche cannot coexist.
Intraspecific competition reduces resources in…
A density dependent manner; underlies the regulation of population size.
Interspecific population decreases…
The pop. of both species; may result in the ending of one species; upper hand goes to more efficient species.
Resource
Substance or factor that is consumed by an organism that supports population growth as it increases in availability.
Liebig’s law of minimum
Each pop. increases until the supply of a resource (limiting) becomes depleted, applies to resources that do not interact to determine population growth rate.
Interference Competition
Organism’s harm each other directly through physical force. Occurs when individuals defend resources in antagonistic behaviors.
Resource Competition
Occurs when individuals defend resources indirectly through mutual effects on the resource.
Allelopathy
Chemical competition, more often than not, plants do this.
Quantifying Competition in Plants vs. Animals
Plants = biomass; animals = numbers.
Plants = no escape from comp; Animals = can move away.
Range of Competitive Effects
Reduce growth + pop., reduce foraging, increase mortality (overgrowth comp), affect species diversity, drive resource partitioning (divergence in patterns of resource use).
Commensalism
An association between two species where only one is benefitted, other is unaffected.