Chapter 6 vocab

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Terms in this set (...)

intrinsic growth rate (r)
has particular maximum potential for growth labeled (r)
overshoot
when a population becomes larger than spring carrying capacity
community
incorporates all populations pf organisms within a given are
-boundries maybe defined by state or federal agencies responsible for managing it
-scientists who study this are interested in how species interact with one another
-exist within ecosystems
growth rate
number of offspring an individual can produce in given time period, minus deaths of individual or its offspring during the same period
die-off
-result of overshoot
-population crash
population
-composed of all individuals that belong to the same species & live in a given area at a particular time
-evolution occurs
-scientists who study this are interested in factors that cause number of individuals to increase or decrease
logistic growth model
-describes population whose growth is initially exponential but slows as population approaches carrying capacity of environment (K)
-s-shaped
age structure
description of how many individuals fit into particular age categories
-knowing this helps ecologists predict how rapidly populations can grow
limiting resource
-resource that a population cannot live without & which occurs in quantities lower than a population would require to increase in size
-if this decreases, so does population size that depends on it
water, nitrogen, phosphorous
s-shaped curve
logistic growth model
Gause Paramecium experiments
sex ratio
ration of males to females
-usually close to 50:50
-helps scientists estimate number of offspring a population will produce in the next generation
fig wasps=20 females:1 male
population ecology
study of factors that cause populations to increase or decrease
-knowing these factors that affect population size helps implement measures to improve survival & reproduction
carrying capacity (K)
limit to how many individuals an environment can sustain
j-shaped curve
exponential growth model
-populations not limited by resources, growth is rapid, as more births occur with each step in time
k-selected species
large organisms that reach reproductive maturity relatively late
-produce few large offspring
-provide parental care
-pose challenge because populations grow slowly
-endangered species cannot respond quickly to efforts to save it from extinction
-because carrying capacity is denoted as k
population density
number of individuals per unit area (or volume)
-helps scientists estimate whether species is rare or abundant
coyote=1 per square km:12 per square km
-useful measure for wildlife managers whi must set hunting or fishing limits on species
offer more hunting/fishing permits for high zones & fewer for low zones
population size
total number of individuals within a defined area at a given time
*california condor-combination of poaching, poisoning, flying into power lines=reduced
but by captive breeding, increased
density-independent factors
have same effect on an individual's probability of survival & amount of reproduction at any population size
-bird populations are regulated by these
tornado, hurricane, flood, fire, volcano
density-dependent factors
influence individual's probability of survival & reproduction in a manner that depends on size of the population
amount of food available-food scarcity affect large populations over smaller ones
r-selected species
exhibit rapid population growth that is followed by overshoots & die-offs
-small organisms that reach reproductive maturity relatively early
-produce many small offspring
-reproduce frequently
-provide little/no parental care
-because intrinsic growth rate is denoted by r
house mice, roaches, small fish, insects, weedy plants
population distribution
description of how individuals are distributed with respect to one another
random, uniform, clumped
clumped population distribution
large group, feeding opportunities & protection from predators
school fish, flocking birds, herding mammals
uniform population distribution
evenly spaced
-plants produce toxins to prevent other plants of same species from growing close
nesting birds
random population distribution
-no pattern
trees
survivorship curves
distinct patterns of survival over time
type I, II, III
type III survivorship curve
low survival early in life & rarely reach adulthood
r-selected species
type II survivorship curve
relatively constant decline
coral, squirrels
type I survivorship curve
as they approach old age, start to die in large numbers
k-selected species
exponential growth model
-(N v t) = (N v 0) e ^ rt
-e is base of natural logs, t is time
-future size of population (N v t) depends on current size of population (N v 0), intrinsic growth rate of population (r) & amount of time (t) over which population grows
-j-shaped
corridors
strips of natural habitat that connect separated populations
-provide connectedness among populations
metapopulation
groups of spatially distinct populations that are connected by occasional movements of individuals between them
-provide a species with some protection against threats such as diseases
community ecology
-study of how interactions between species affect community structure & organization
competition
struggle of individuals to obtain a limiting resource
competitive exclusion principle
principle stating that two species competing for the same limiting resource cannot coexist
resource partitioning
situation in which two species divide a resource, based on differences in their behavior or morphology
predation
interaction in which one organism kills & eats another
parasites
live in or on organism they consume, known as host
-rarely cause death to host, since they consume only small fraction of host
*tapeworms, protists that live in bloodstream & cause malaria
pathogens
parasites that cause disease in host
*viruses, bacteria, fungi, protists, helminths
parasitoids
-organism that lay eggs inside other organisms
-when eggs hatch, larvae consume host from inside out, which leads to death
*wasps, flies
mutualism
-an interaction between species that increases the chances of survival or reproduction for both species
-assist other species on order to benefit itself
commensalism
relationship between species in which one species benefits & the other species is neither helped nor harmed
*bird use tree as perch, fish use coral as place to hide from predators
symbiotic
relationship of two species that live in close association with each other
keystone species
species that are far more important in their community than their relative abundance might suggest
-exists in low numbers
*predators, source of food
ecological succession
replacement of one group of species by another group of species over time
-decades to centuries
-in terrestrial community, can be primary or secondary
primary succession
ecological succession occurring on surfaces that are initially devoid of soil
*parking lot, newly exposed rock from glacier retreat, newly cooled lava
secondary succession
succession of plant life that occurs in areas that have been disturbed but have not lost their soil
-follows event like fire, hurricane
-occur on abandoned agriculture field
*New England farms
pioneer species
species that can colonize new areas rapidly & grow well in full sunshine
*aspen & cherry trees
theory of island biogeography
-demonstrates importance of both habitat size & distance in determining species richness

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