48 terms

APES Friedland Chapter 6

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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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