Population Ecology (Ch 46) Flashcards
What is the Biological Hierarchy?
Population; Species: Community; Ecosystem
Define Ecology.
The study of the relationships of organisms to one another and to the environment.
What did Thomas Malthus proposed in 1790?
The remarkable recent growth of the American population was a consequence of ample food supply and the active encouragement of marriages
Define Population.
It consists of all the individuals of a given species that live and reproduce in a particular place.
Define Species.
A group of individuals that can exchange genetic material through interbreeding to produce fertile offspring.
Define Community.
A set of all populations found in a given place.
Define Ecosystem.
A community of organisms and the physical environment it occupies.
What are some characteristics of a population?
- Density and dispersion
- Factors affecting the growth and decline of populations.
What is a Population Density?
A population’s size divided by its range.
What is a Population Size?
It is simply the number of individuals of all ages alive at a particular time in a particular place.
What is Demography?
The study of size, structure, and distribution of populations over time, including changes in response to birth, aging, migration, and death.
What do we call a patchy distribution of populations?
Clumped population
Some populations may go extinct; _____ may restore them
Migration
Immigrate is to ___; _____ is to death
Born; Emigrate
What are the different patches of habitat?
Control patch; small, isolated patches; small patches connected by corridor.
The density of an organism is dependent on a number of factors, such as:
Food availability, nesting sites, and predators.
How do we estimate population densities?
Quadrat and Transect
What is a Quadrat?
Usually several areas that are counted
What is a Transect?
A line across a habitat or part of a habitat.
What is the Mark-Recapture Method?
It is commonly used to estimate an animal’s population size. A portion of the population is captured, marked, and released. Later, another portion is captured and the number of marked individuals within the sample is counted.
Define Clumped Dispersal.
Individuals are clustered together.
Define Uniform Dispersal.
Individuals are evenly spaced.
Define cohort.
A group defined as the individuals born at a given time.
Define Random Dispersal.
Individuals are randomly spaced.
What are characteristics of r-strategists?
Species producing large numbers of offspring but provide few resources. They are Type III on the survivorship curve. i.e. Mouse, plants, trees
What are characteristics of k-strategists?
Species producing few young but invest considerable resources. They are Type I on the susrvivorship curve. i.e. Humans, elephants, whales
Name some factors that regulates population.
Predation Food availability Nesting area/Habitats Disease Pollution Natural Disasters
What do the variables in the exponential growth equation represent? (G=rN)
G - Growth rate
r - per capita rate of increase
N - # of individuals @ the start of time
Give examples of density-dependent factors.
Famine. These are factors where the effects on the size or growth of a population vary with the density of population itself.
Give examples of density-independent factors.
These are weather based factors that strike populations without regard for the size of the population. Harsh. Really.
What is an Island Biogeography theory and its 2 factors?
The theory states that the number of species that can occupy a habitat island depends on 2 factors:
1) The size of the island
2) The distance of the island from a source of colonists.
