Chapter 9 Flashcards
population dynamics
major abiotic and biotic factors that tend to increase or decrease the population size and age and sex composition of a species.
density
number of individuals in a certain space.
age distribution
the proportion of individuals of each age in a population
clumping
when a species stay in tight packs.
uniform dispersion
all the species have an equal space between them.
random dispersion
when a species is distributed unevenly in an area.
immigration
migration of a species into a country or area to take up permeant residence
emigration
when a species leaves their native country and goes to live somewhere else.
prereproductive stage
organisms that are not mature enough to reproduce.
reproductive stage
organisms that are capable of reproduction
post reproductive stage
and organisms that are too old to reproduce.
biotic potential
maximum rate at which the population of a given species can increase when there are no limits on its rate.
intrinsic rate of increase
rate at which a population could grow if it had unlimited resources.
environmental resistance
all the limiting factors that act together to limit the growth of a population.
carrying capacity
maximum population of a particular species that a given habitat can support over a given period.
logistic growth
pattern in which exponential population growth occurs when the population is small, and the population growth decreases steadily with time as the population approaches the carrying capacity.
exponential growth
growth in which some quantity, such as population size or economic output, increases at a constant rate per unit of time (such as 2% per year). Ex: 2, 4, 8, 16, 32, 64 and so on; when the increase in quantity over time is plotted, this type of growth yields a curve shaped like a J.
sigmoid/S-shaped curve
leveling off of an exponential, J-shaped curve when a rapidly growing population exceeds the carrying capacity of its environment and ceases to grow.
overshoot
organisms use up their resource supplies and temporarily exceed the carrying capacity of the environment.
reproductive time lag
the period need for the birth rate to fall and the death rate to rise in response to resource overconsumption.
dieback/crash
sharp reduction in the population of a species when its numbers exceed the carrying capacity of its habitat.
density-independent population control
affects a population’s size regardless of its density. ex: flood
density-dependent population control
factors that limit population growth have a greater effect as a population’s density increase. ex: no food
stable fluctuation
a species whose population size is said to have a fairly stable population size.
irruptive fluctuation
their population growth may occasionally explode, to a high peak and then crash to a more stable lower level or in some cases a very level.
cyclic fluctuation
population size over a regular time period, populations rise and fall.
irregular fluctuation
some populations appear to have irregular behavior in their changes in population sir, with no recurring pattern.
asexual reproduction
reproduction in which a mother cell divides to produce two identical daughter cells that are clones of the mother cell. this type of reproduction is common in single-celled organisms.
r-selected species
species with a capacity for a high rate of population increase (r). have many, usually small offspring and give them little or no parental care or protection.
K-selected species
species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.
survivorship curve
graph showing the number of survivors in different age groups for a particular species.
late loss
a population that typically has high survivorship to a certain age , then high mortality.
early loss
a population survivorship is low early in life.
constant loss
a population shows fairly constant death rate at all ages.
founder effect
when a few individuals in a population colonize a new habitat that is geographically isolated from other members of the population.
demographic bottleneck
occurs when only a few individuals in a population survive a catastrophe such as a fire of hurricane.
genetic drift
involves random changes in the gene frequencies in a population that can lead to unequal reproductive success.
inbreeding
occurs when individuals in a small population mate with one one another.
metapopulations
mobile populations that are geographically separated from one another can exchange genes when some of their members get together occasionally and mate.
sexual reproduction
reproduction in organisms that produce offspring by combining sex cells or gametes (eggs or sperm) from both parents. this produces offspring that have combinations of traits from their parents.
