Lecture Exam #4 ch. 53 Flashcards
types of ecology (6) (OPCELG)
1) organismal
2) population
3) community
4) ecostystem
5) landscape
6) global
the scientific study of the interactions between organisms and the environment
ecology
what do the interaction in ecology determine?
the distribution of organisms and their abundance
what does modern ecology include?
observation and experimentation
what does population ecology in turtle tracks explore how biotic and abiotic factors have influence on? (4) (DDSA)
1) density
2) distribution
3) size
4) age structure
what is an example of the influence of biotic and abiotic population ecology in turtle tracks?
the number of the loggerhead turtle hatchnlings that survive in their first journey to the ocean is affected by both biotic and abiotic factors
what does biological processes influence? (3) (PDD)
1) population density
2) dispersion
3) demographics
a group of individuals of a single species living in the same general area
population
what are populations described by?
their boundaries and size
what levels do ecologists work at?
levels ranging from individual organisms to the planet
the number of individuals per unit area or volume
density
the pattern of spacing among individuals within the boundaries of a population
dispersion
in most cases can you count all individuals in a population?
no it’s impractical or impossible
what can sampling techniques be used to estimate?
the densities and total population sizes
what can population size be estimated by? (3) (EIM)
1) extrapolation from small samples
2) index of a population size (number of nests)
3) mark-recapture method
what is density the result of?
an interplay between the processes that add individuals to a population and those that remove individuals
the influx of new individuals from other areas (to an area)
immigration
the movement of individuals out of a population which decreases population. (leaves)
emmigration
patterns of dispersion (3) (CUR)
1) clumped
2) uniform
30 random
how do scientists determine the population siz using the mark-recapture method
they capture, tag and release a random sample of individuals (s) in a population
when using the mark-recapture method what are marked individuals given time to do?
mix back into the population
what do scientists do after they capture the first sample with the mark-recapture method?
they capture a second sample of individuals (n) and note how many of them are marked (x)
with the mark-recapture method what is population size estimated by?
N= sn/x
what do births and immigration do for a population?
add individuals
what do deaths and emmigration do for a population?
remove individuals
what influences the spacing of individuals in a population?
environmental and social factors
in a clumped dispersion what happens to individuals?
they aggregate in patches
what may a clumped dispersion be influenced by?
resource availability and behavior
the study of the vital statistics of a population and how they change over time
demography
what are particular interest of demographers?
death rates and birth rates
a dispersion where individuals are evenly distributed
uniform dispersion
what may a uniform dispersion be influenced by?
territoriality
the defesne of a bounded space against other individuals
territoriatly
an age-specific summary of the survival pattern of a population
life-table
what is a life-table best be made by following the fate of and what is that?
a cohort, a group of individuals of the same age
what is an example that the life table of the Belding’s ground squirrels reveal about this population?
it provides data on the proportions of males and females alive at each age
the position of each individual is independent of other individuals
random dispersion
when does random dispersion occur?
in the absence of strong attractions or repulsions
a graphic way of respresenting the data in a life table
survivorship curve
what does the survivialship curve for the Belding’s ground squirrels show?
a relatively constant death rate and that females live longer
for species with sexual reproduction what do demographers often concentrate on?
females in a population
what do ecologists use many appraches to estimate?
the number of breeding females
whatis an example of ecologists using appraches to estimate the number of breeding females?
DNA profiling was used to determine the number of female loggerhead turtles laying eggs in is a season
of the 3 types of survivorship curves what is type 1?
low death rates an middle life and an increase in death rates among older groups
of the 3 types of survivorship curves what is type 2?
a constant death rate over the organism’s lifespan
of the 3 types of survivorship curves what is type 3?
high death rates for the young and a lower death rate for survivors
of the 3 types of survivorship curves what are many species?
intermediate to these curves
what does the exponential model describe population growth in?
an idealized, unlimited environment
what type of situation is it useful to study population growth?
an idealized one
what do idealized situation help us understand?
the capcity of species to increase and the conditions that may facilitate this growth
of the 3 types of survivorship curves what are humans?
type 1
an age-specific summary of the resproductive rates in a population
reproductive table or fertility schedule
what does a reproductive table describe the reproductive patterns of ?
a population
what is the equation for per capita rate of increase?
change in population size= births + immigrants entering pop- deaths - emmigrants leaving pop
what does a population’s growth rate (per capita increase) equal if immigration and emigration is ignored?
birth rates minus death rate
occurs when the birth rate equals the death rate (r=0)
zero population growth (ZPG)
a population increase under idealized conditions
exponential population growth
under an exponential population growth what happens to the rate of increase ?
it’s at the maximum, denoted as rmax
what can births and deaths be expressed as?
the average numbers of birth and deaths per individual during the specified time interval
what does exponential population growth result in?
a J-shaped curve
with exponential population growth what is the rate of increase?
constant but the population accumulates new individuals per unit time when its is large than when it is small
what does the j-shaped curve of exponential growth characterize?
some rebounding populations
what is an example of a rebounding population?
the elephant population in Kruger National Park, South Africa grew exponentially after hunting was banned
the per capita rate of increase declines as carrying capacity is reached
logistic population growth model
what does the logitstic model start with and what does it add?
exponential model and adds an expression that reduces per capita rate of increase as N approaches K
what does the logistic model of population growth produce?
a sigmoid (s-shaped) curve
what’s added to the population most rapidly at an intermediate population size in the logistic model?
new individuals
what happens to the population rate with the logistic model?
growth rate increases as N approaches K
when N is small compared to K (K-N) what happens?
K is close to 1 and per capita rate of increase approaches the maximum
when N is larged compared to K (K-N) what happens?
K is close to 0 and the per capita rate of increase is small
when N equals K what happens?
the population stops growing
what does the logistic model describe?
how a population grows more slowly as it nears its carrying capacity
what can’t be sustatined for long in any pop?
exponential growth
what limits growth by incorporating a carrying capacity?
a more realistic population model
(K) the maximum population size the environment can support
carrying capacity
what does carrying capacity vary with?
the abundances of limiting resources
what type of curve does the growth of laboratory populations of paramecia fit?
an S-shaped curve
in a logistic model and real population what type of environment are these organism grown in and what do they lack?
a constant environment lacking predators and competitors
what does the logistic model fit?
few real populations but is useful for estimating possible growth
what can conservation biologists use the logistic model for?
to estimate the critical size below which population may become extinct
3 main variables of life history (3) (AHH)
1) the age at which reproduction begins
2) how often the organism reproduces
3) how many offspring are produced per reproductive episode
what do some populations overshoot before settling down to a relatively stable denstiy
K
when species exhibit a big-bang reproductions, reproduce once and die
semelparity
when species exhibit repeated reproduction, produce offspring repeatedly
iteroparity
what does highly variable or unpredictable environments likely favor?
semelparity
what might dependable environments favor?
iteroparity
what do some populations do and what does it make it difficult to define?
fluctuate and make it difficult to define K
when individuals have a more difficult time surviving or reproducing if the population size is too small that some population shown
an allee effect
what are life history traits a product of?
natural selection
comprises the traits that affect the schedule of reproduction and survival in an organism
life history
what are life history traits an evolutionary oucome reflected in? (3) (DPB)
1) the development
2) physiology
3) behavior in an organism
what type of resources do organisms have and what does it lead to?
finite resources, may lead to trade-offs between survival and reproduction
what is an example of a trade-off?
a trade-off between survival and parental care in European Kestrels
what are the concepts of K-selection and r-selection?
oversimplications but stimulated alternative hypothesis or life history evolution
what do other types of plants produce?
a moderate number of large seeds that provide a large store of energy that will help seedlings become established
what are many factors that regulate population growth?
density dependent
2 general questions about regulation of population growth
1) what environmental factors stop a population from growing indefinitly
2) why do some populations show radical fluctuations in size over time but others remain stable?
what do some plants produce a large number of?
small seeds
what does plants producing a large number of small seeds ensure?
that at lease some of them will grow and eventually reproduce
selects life history traits that are sensitive to population density. density-dependent selection
K-selection
selects for lifehistory traits that maximize reproduction. density-independent selection
R-selection
when birthrate and death rate do not change with population density
density-independent populations
when birthrates fall and death rate rise with population density
density-dependent populations
in crowded populations what happens to increasing population density?
it intensifies competition for resources and results in a lower birth rate
what can population density influence?
the health and survival of organisms
what can happen regarding diseases in dense populations?
pathogens can spread more rapidly
what are density-dependent birth and death rates an example of?
negative feedback that regulates population growth
what factors are density-dependent birth and death rates affected by? (6) (CTDPTI)
1) competition for resources
2) territoriality
3) disease
4) predation
5) toxic wastes
6) instrinsic factors
as prey population builds up, predators may be preferentially on that species
predation
in some populations whhat does instrincic (physoiological) factors appear to regulate?
population size
in many vertebrates and some invertebrates what may competition for territory limit?
density
a study that focuses on the complex interactions between biotic and abiotic factors that cause variation in population size
population dynamics
what can accumulation of toxic wastes contribute to?
density-dependent regulation of population size
what have long-term population studies challenged?
the hypothesis that populations of large mammals are relatively stable over time
what can affect population size over time?
both weather and predator population
what is an example of both weather and predator population affecting population size over time?
the moose population on the Isle Royale collapsed during a harsh winter, and when wolf numbers peaked
what do some populations under go?
regular boom-and-bust cycles
what do lynx populations follow?
the 10 year boom-and-bust cycle of hare populations
what has been proposed to explain the hares’s 10 year interval?
two main hypotheses
What was the first hypothesis about the hare’s 10 year interval?
The hare’s population cycle follow a cyocle of winter food supply
if the first hypothesis was correct what does that mean?
that the cycles should stop if the food supply is increased
in the first hypothesis what was provided experimentally to a hare population and what happened?
additional food, the whole population increased in size but continued to cycle
does the first hyptothesis support the other one?
no
what is the second hypothesis about the hare’s 10 year interval?
the hare’s population cycle is driven by pressure from other predators
in a study conducted by field ecologists what happened to the hares?
95% of the hares were killed by predators including lynx, coyotes, hawks and owls
does the second hypothesis support the other one?
yes
what is a major factor influencing predator prey population dynamics?
availability of prey
when prey becomes scarce what happens?
predator species begin to prey on one another, accelerating collapse of predator populations
what does an individual’s ability to move between populations depend on?
a number of factors, including its genetic makeup
what is an example of genetic makeup being the cause of an individuals ability to move between populations?
Glanville frillary butterflies that are heterozygous at the Pgi gene fly further at low temperatures than homozygous individuals
2 configurations that exists to maintain population stability in a human population
1) zero population growth= high birthrate-high death rate
2) zero population growth= low birthrate- low death rate
the move from the firt state to the second state
demographic transition
what is happening to human populations?
it’s no longer growing exponentially but is still increasing rapidly
what is true of populations?
no population can grow indefinitely and humans are no exception
what is the global population?
more than 7 billion people
though the global population is still growing, what was happening in the 1960s?
it began to slow
what is the demographic transition associated with?
an increase in the quality of health care and improved access to education, especially for women
where is most of the current global population growth concentrated in?
developing countries
what is true of human population?
it increased relatively slowly until about 1650 and then began to grow exponentially
what is an important demographic factor in present and future growth trends?
a country’s age structure
the relative number of individuals at each age
age structure
how many humans can the biosphere support a according to population ecologists?
they predict a global population of 8.1-10.6 billion people in 2050
what can age structure diagrams predict
a population’s growth trends
what can age structure illuminate?
social conditions and help us plan for the future
what is the estimated carrying capacity of Earth for humans?
it’s uncertain
what have scientists based estimates on about carrying capacity for Earth for humans? (3) (LAF)
1) logistic growth models
2 ) area of habitable land
3) food availability
what can ecological footprints be calculated by?
using energy use
what does average per capita energy use differ greatly between?
developed and developing nations
what varies greatly among developed and developing countrites but does not capture the wide range of human condition?
infant mortality and life expectancy at birth
summarizes the aggregate land and water area needed to sustain the people of a nation
ecological footprint concept
what is the ecological footprint concept one measure of?
how close we are to the carrying capacity of Earth
what doe countries vary greatly in the ecological footprint concept?
footprint size and available ecological capacity
what could our capacity potentially be limited by? (4) (FSNB)
1) food
2) space
3) non-renewable resources
4) buildup of wastes
