Chapter 8/9 Flashcards
population
all the individuals of a species that live in the same geographic area and are able to interact and interbreed.
population dynamics
the changes over time of population size and composition.
minimum viable population
the smallest number of individuals that would still allow a population to be able to persist or grow, ensuring long-term survival.
environmental impact statement
an evaluation of the positive and negative impacts of a proposed environmental action, including alternative actions that could be pursued.
population density
the number of individuals per unit area.
population distribution
the location and spacing of individuals within their range.
clumped distribution
individuals are found in groups or patches within the habitat.
random distribution
individuals are spread out over the environmental irregularly with no discernible pattern.
uniform distribution
individuals are evenly, perhaps due to territorial behavior or mechanisms for suppressing the growth of nearby individuals.
population growth rate
the change in population size over time (births minus deaths over a specific time period)
birth rate
the number of births per 1,000 individuals per year.
death rate
the number of deaths per 1,000 individuals per year.
biotic potential (r)
the maximum rate at which the population can grow due to births if each member of the population survives and reproduces.
exponential growth
population size becomes progressively larger each breeding cycle; produces a J curve when plotted over time.
logistic growth
the kind of growth in which population size increases rapidly at first but then slows down as the population becomes larger; produces an S curve when plotted over time.
carrying capacity (K)
the population size that a particular environment can support indefinitely without long-term damage to the environment.
density dependent
factors, such as predation or disease, whose impact on the population increases as population size goes up.
density independent
factors, such as storm or avalanche, whose impact on the population is not related to population size.
reproductive strategies
how quickly a population can potentially increase, reflecting the biology of the species (life span, fecundity, maturity rate, etc.)
r-related species
species that have high biotic potential and that share other characteristics such as short lifespan, early maturity, and high fecundity.
k-selected species
species that have a low biotic potential and that share characteristics such as long lifespan, late maturity, and low fecundity; generally show logistic population growth.
boom-and-bust cycles
fluctuations in population size that produce a very large population followed by a crash that lowers the population size drastically, followed again by an increase to a large size and subsequent crash.
extrirpation
local extinction of a species.
community ecology
the study of all the populations (plants, animals, and other species) living and interacting in an area.
indicator species
the species that are particularly vulnerable to ecosystem perturbations, and that, when we monitor them, can give us advance warning of a problem.
ecosystems
all of the organisms in a given area plus the physical environment in which they interact.
food chain
a simple, linear path starting with a plant (or other photosynthetic organism) that identifies what each organism in the path eats.
food web
a linkage of all the food chains together that shows the many connection in the community.
producer
a photosynthetic organism that captures a solar energy directly and uses it to produce its own food (sugar).
consumer
an organism that eats other organisms to gain energy and nutrients; includes animals, fungi, most bacteria.
trophic levels
feeding levels in a food chain.
detritivores
consumers (including worms, insects, crabs, etc.) who eat dead organic material.
decomposers
organisms such as bacteria and fungi that break down organic matter all the way down to constituent atoms or molecules in a form that plants can take back up.
gross primary productivity
a measure of the total amount of energy captured via photosynthesis and transferred to organic molecules to organic molecules in an ecosystem.
net primary productivity (NPP)
a measure of the amount of energy captured via photosynthesis and actually stored in the photosynthetic organism.
niche
the role a species plays in its community, including things like how it gets energy and nutrients, what habitat requirements it has, and which other species and parts of the ecosystem it interacts with.
habitat
the physical environment in which individuals of a particular species can be found.
resilience
the ability of an ecosystem to recover when it is damaged or perturbed.
species diversity
the variety of species in an area; includes measure of species richness and evenness.
species richness
the total number of different species in a community
species evenness
the relative abundance of each species in a community
ecotones
regions of distinctly different physical areas that serve as boundaries between different communities.
edge effects
the different physical makeup of the ecotone which creates different conditions that either attract or repel certain species (for instance, it is drier, warmer, and more open at the edge of a forest and field than it is further in the forest).
edge species
species that prefer to live close to the edges of two different habitats. (ecotone areas)
core species
species that prefer core areas of a habitat – areas deep within the habitat, away from the edge
keystone species
a species that impacts its community more than its mere abundance would predict
competition
species interaction in which individuals are vying for limited resources
intraspecific competition
competition between members of the same species
interspecific competition
competition between individuals of different species
resource partitioning
when different species use different parts of aspects of a resource, rather than competing directly for exactly the same resource.
symbiosis
a close biological or ecological relationship between the two species
mutualism
a symbiotic relationship between individuals of two species in which both parties benefit.
commensalism
a symbiotic relationship between individuals of two species in which one benefits from the presence of the other but the other is unaffected.
parasitism
a symbiotic relationship between individuals of two species in which one benefits and the other is negatively affected (a form of predation)
restoration ecology
the science that deals with the repair of damaged or disturbed ecosystems.
ecological succession
progressive replacement of plant (and then animal) species in a community over time due to the changing conditions that the plants themselves create (more soil, shade, etc.)
primary succession
ecological succession that occurs in an area where no ecosystem existed before (for example, on bare rock with no soil)
pioneer species
plant species that move into an area during early stages of succession; these are often r species and may be annuals, species that live one year, leave behind seeds, and then die.
secondary succession
ecological succession that occurs in an ecosystem that has been disturbed; occurs more quickly than primary succession because soil is present.
climax species
species that move into an area at later stages of ecological succession.
climax community
the end stage of ecological succession in which the conditions created by the climax species are suitable for the plants that created them so they can persist as long as their environment remains unchanged.
