•A _______________ is a group of individuals from the same species that live in the same area at the same time.
•___________________ is the study of how and why the number of individuals in a population changes over time.
The mathematical and analytical tools used in population ecology help biologists predict - what?
changes in population size and design management strategies to save threatened species
___________ is the study of factors such as these that determine the size and structure of populations through time
To make predictions about the future of a population, biologists need to know - what?
- how many individuals of each age are alive,
- how likely individuals of different ages are to survive to the following year
- how many offspring are produced by females of different ages.
•A _____________ summarizes the probability that an individual will survive and reproduce in any given time interval over the course of its lifetime.
_______________ is a key component of a life table and is defined as the proportion of offspring produced that survive, on average, to a particular age.
•These individuals represent a __________ —a group of the same age that can be followed through time.
•The _______________ is a plot of the logarithm of the number of survivors versus age.
What does a type I curve look like?
survivorship throughout life is high, and most individuals approach the maximum life span of the species; humans show this type of survivorship curve
What does a type II survivorship curve look like?
- most individuals experience relatively constant survivorship over their lifetimes; songbirds have this curve.
Type III survivorship curve - describe
result from high death rates early in life, with high survivorship after maturity; many plants have type III curves.
Fecundity is also a key part of a life table; it is defined as the number of female offspring produced by each female in the population
define age specific fecundity
•Age-specific fecundity is the average number of female offspring produced by a female in a given age class—a group of individuals of a specific age.
How do you calculate net reproductive rate?
growth rate of the population over a generation
= ave # of female offspring produced over life @ ea age class
= survivorship * age specific fecundity
if the R0 > 1 what does that mean?
population is growing
if R0 < 1 - what does that mean
if R0 = 0
what does that mean
define fitness trade off
•Fitness trade-offs occur because every individual has a restricted amount of time and energy at its disposal―its resources are limited.
What is the difference b/t net reproductive rate R0 and per capita growth rate r
R0 is that the growth rate of a population per generation equals the average number of female offspring that each female produces over the course of her lifetime
•The per-capita rate of increase (r) is the difference between the birthrate and death rate per individual.
r = b − d
define exponential pop growth
•Exponential population growth occurs when r does not change over time. It does not depend on the number of individuals in the population—it is density independent.
under which circumstances is exponential pop growth typically seen?
1.A few individuals found a new population in a new habitat.
2. A population has been devastated by a storm or some other type of catastrophe and then begins to recover, starting with a few surviving individuals.
define carrying capacity
•Carrying capacity, K, is the maximum number of individuals in a population that can be supported in a particular habitat over a sustained period of time. K can change depending on conditions.
what are the limits on carrying capacity?
- soil quality
- resting or nesting sites.
- Carrying capacity can change from year to year, depending on conditions.
define logistic growth equation
•The logistic growth equation describes logistic population growth—a change in growth rate that occurs as a function of population size.
- density dependant
If individuals from a species occupy many small patches of habitat so that they form many independent populations, they represent metapopulations―a population of populations
survivorship * fecundity
density independent factors that affect birth and death rates
typical of exponential pop growth - ussually abiotic
they change birthrates and death rates irrespective of population size.
Positive: new habitat
overcoming big storm where pop has been wiped out
density dependant population growth factors
•When population density—the number of individuals per unit area—gets very high, the population’s per-capita birthrate should decrease and the per-capita death rate increase, causing r to decline.
describe two examples of density dependent factors that influence pop growth in natural populations
altered by changes in the abiotic enviro
food and deer pop
density of forest and nutrients and sun abailable
- coral reef fish - bridled goby - lower density = highter survivorship
- sparrows - high density = lower eggs laid
define particular habitat's carrying capcity