Population Ecology Flashcards
What is the definition of ecology?
the study of how organisms interact with one another and their environment
Whats an environmental challenge?
Homeostasis
homeostasis responses can be short term or long term. Describe both
short term: a few minutes to an individual’s lifetime
long term: natural selection can operate to make a population better adapted to the environment (evolution)
Natural selection leads to evolutionary adaptions to environmental conditions. This is closely related to what?
species that are related that live in different environments and evolve differently.
ie: finches
What is a population?
groups of individuals of the same place
What are the three characteristics of population ecology?
- ) population range, area throughout which a population occurs
- ) pattern of spacing of individuals
- ) How population changes in size through time
Most species have limited geographic_____
range
name three ways ranges change over time
- ) environment changes
- ) dispersal to new areas
- ) humans have expanded and reduced ranges
What is a metapopulation?
a network of distinct (physically distant) interacting populations
Where do metpopulations occur?
occurs in areas in which suitable habitat is patchily distributed and is separated by intervening stretches of unsuitable habitat
What is population demography?
the quantitative study of populations
-how populations size changes through time (whole populations or birth/death rates of a specific age)
Population growth can be influenced by the population’s ______ ratio
sex
the number of births is directly related to the number of ________
females
What is Generation Time?
average interval between birth of an individual and birth of its offspring
populations with short generations can (increase/decrease) in size more quickly than populations with long generations
increase
True or False:
In general, larger organisms have longer generation times
true
What is useful in making predictions?
linear regression
have a p-value
What is Age Structure?
determined by the number of individuals in each different age group
What is Cohert?
group of individuals of the same age
What is Fecundity?
number of offspring produced in a standard time
True or False:
Age structure has little influence on a population’s growth rate
false
it has a critical influence
What is survivorship?
the percent of an original population that survives to a given age
know how to sketch a graph
Natural selection favors traits that maximize the number of surviving offspring left in the next generation. Two factors affect this quantity; what are they?
- ) how long an individual lives
2. ) how many young it produces each year
True or False:
the number of offspring produced is not as important as how many of those offspring themselves survive to reproduce
true
Large offspring have a (greater/lesser) chance of survival while producing many small offspring may result in (high/low) survival rates
greater; low
populations often remain the same size regardless of the number of offspring born. The equation used to calculate this would be….
r = (b-d) + (i-e)
r=rate of population increase b=birth rate d=death rate i=immigration e=emmigration
What is biotic potential?
What is the equation used to calculate this?
When there are no limits on population growth
dN/dt=riN
N=number of individuals in the population
dN/dt=the rate of change over time
ri=the intrinsic rate of increase for the population
the biotic potential of any population is _________ even when the rate of increase remains constant
exponential
all populations eventually………
reach some limit imposed by a shortage
What is Carrying Capacity?
What letter represents it?
The maximum number of individuals that the environment can support
K
What equation is used to calculate logistic growth? (applies to populations as they reach K
dN/dt = rN (K-N)/K
Density-dependent
factors that affect the population and depend on population size
Density-independent
other factors, such as natural disasters, affect populations regardless of size
Density Dependent:
What is negative feedback?
What is positive feedback?
negative: reduce population size
positive: Allee effect; growth rates increase with population size
Density independent effect rate of growth of a population is limited by something unrelated to the size of the population. What are some examples?
cold winters, droughts, storms, volcanic eruptions
Animals like the North American snowshoe hare have 10-year cycles where population numbers fall and jump over a ten year period. There are two factors that effect this. What are they?
- ) food availability
2. ) predators
K-Selected populations are adapted to thrive when…..
population is near its carrying capacity
r-Selected populations: selection favors…..
individuals with the highest reproductive rates
True or False:
most natural populations exist along a continuum of r and k selected traits
true
Changes since the _______ allowed humans to escape_____
1700s; escape logistic growth
human populations have grown exponentially
- birth rates have____
- death rates has______
dropped
fallen dramatically
True or False:
Earth’s rapidly growing human population constitutes as the smallest challenge to the future of the biosphere compared to other factors.
False
the human population constitutes perhaps the greatest challenge to the future of the biosphere
True or False:
world population growth rate is in decline
give figures to support answer
true
high of 2% in 1965-1970
1.2% in 2008
however still an increase of 78 million people a year
Name a reason why there may be a decline in population growth rate
- increased family planning efforts
- increased economic power and social status of woman
What is an Ecological Footprint?
amount of productive land required to support an individual
Look at graphs in the slide show; week 10
