54 terms

Chapter 6 APES: Population & Community Ecology

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Population
a group of organisms of the same species populating a given area
Community
(ecology) a group of interdependent organisms inhabiting the same region and interacting with each other
Population Ecology
The study of populations in relation to the environment, including environmental influences on population density and distribution, age structure, and variations in population size.
Ecosystem
all of the biotic and abiotic components in a particular location
Population Size
The number of individual organisms present at a given time.
Population Density
number of individuals of a particular species per unit area or volume
Population Distribution
description of locations on the earths surface where populations live
Population Sex Ratio
ratio of males to females
Population Age Structure
examines the number of individuals of a species in a certain age group
Density-Independent Factors
Limiting factor that affects all populations in similiar ways, regardless of population size.
Limiting Resource
a particular natural resource that, when limited, determines the carrying capacity of an ecosystem for a particular species
Carrying Capacity
number of organisms in a population that an environment can maintain
Density-Dependent Factors
limiting factors (such as competition, predation, parasitism, and disease) that are affected by the number of individuals in a given area
Exponential Growth Model
growth model that estimates a population's future size after a period of time based on the intrinsic growth rate and the number of reproducing individuals currently in the population
J-shaped curve
Produced by the exponential growth model. Occurs when populations are not limited by resources.
Growth Rate
an expression of the increase in the size of an organism or population over a given period of time.
Intrinsic Growth Rate
Under ideal conditions, with unlimited resources available, every population has a particular maximum potential for growth.
Logistic Growth Model
a description of idealized population growth that is slowed by limiting factors as the population size increases. only accounts for density dependent factors, not density independent (such a natural disasters) because they are unpredictable thus the model cannot account for them
S-Shaped Curve
Leveling off of an exponential, J-shaped curve when a rapidly growing population exceeds the carrying capacity of its environment and ceases to grow.
Overshoot
The extent to which a population exceeds the carrying capacity of its environment
Die-Off
a rapid decline in population size when carrying capacity is exceeded and resources are limited
K-Selected Species
Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.
R-Selected Species
A species that has a high intrinsic growth rate, which often leads to population overshoots and die offs.
Survivorship Curves
curves depicting when in an organisms life it species is likely to decline
Corridors
A strip of natural habitat that connects two adjacent nature preserves to allow migration of organisms from one place to another
Metapopulation
A collection of populations that have regular or intermittent gene flow between geographically separate units
Community Ecology
The study of how interactions between species affect community structure and organization
Competition
the struggle between organisms to survive in a habitat with limited resources
Competitive Exclusion Principle
ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time
Resource Partitioning
in a biological community various populations sharing environmental resources through specialization thereby reducing direct competition
Temporal RP= diff times of year/day
Spatial RP = diff habitats
Morphological RP = the evolution of differences in body size or shape, i.e. Darwin's finches
Predation
the act of preying by a predator who kills and eats the prey
True Predators
organisms who a. kill their prey and b. consume most of what they kill
Herbivores
an organism that eats only plants.
Parasites
an organism that lives in or on another organism, deriving nourishment at the expense of its host, usually without killing it
Pathogens
an organism that produces disease in a host organism disease being alteration of one or more metabolic functions in response to the presence of the organism
Parasitoids
Organisms that lay eggs inside other organisms. When eggs hatch, parasitoid larvae slowly consume host from the inside out, eventually leading to the host's death. ex-wasps and flies
Mutualism
the relation between two different species of organisms that are interdependent
Commensalism
the relation between two different kinds of organisms when one receives benefits from the other without damaging it
Symbiotic relationship
The relationship of 2 species that live in close association with each other
Keystone Species
a species whose impact on its community or ecosystem are much larger and more influential than would be expected from mere abundance
Predator-Mediated Competition
Competition in which a predator is instrumental in reducing the abundance of a superior competitor, allowing inferior competitors to persist.
Ecosystem Engineers
an organism that causes changes in the physical environment sufficient to influence the structure of landscapes, ecosystems, or communities.
Ecological Succession
The predictable replacement of one group of species by another group of species ver time.
Primary Succession
an ecological succession that begins in a an area where no biotic community previously existed
Secondary Succession
succession on a site where an existing community has been disrupted
Pioneer Species
first species to populate an area during primary succession
Aquatic Succession
Water ecosystem changes to terrestrial one. Lake, lake fills in, becomes meadow, meadow becomes forest.
Theory Of Island Biogeography
A theory that demonstrates the dual importance of habitat size and distance in determining species richness.
Biosphere
All of Earth's ecosystems
Scientist who study the biosphere...
are interested in movement of air, water, and heat around the globe
Ecosystem Ecologists study...
the flows of energy and matter (ie cycling of nutrients through a system)
Population Ecologists study...
the factors that regulate population and abundance distribution
Community Ecologists study...
species interactions
Note
Older communities have more opportunities for speciation