Population Ecology

Population – all the individuals of the same species in a specific area.

4 characteristics of populations:• Geographic distribution• Density• Growth rate• Age

1. Geographic distribution – where the population is located, its range

2. Population Density - number of organisms per square unit volume

Which state is the most densely populated?

STATE population Area(Sq. miles)

Populationdensity

1 NJ 8,682,661 7,417 1,170.642 RI 1,050,788 1,045 1,005.543 MA 6,497,967 7,840 828.824 CT 3,501,252 4,845 722.655 MD 5,633,597 9,774 576.396 DE 873,092 1,954 446.827 NY 19,490,297 47,214 412.81

Population density can be random, uniform, or clumped.

A. Random - some areas with many individuals, some with few.

ex: seeds dispersed by wind

B. Uniform (Even) - all areas with the same number and the same distance between organisms.

ex: trees in an orchard

C. Clumped – groups of many individuals, with large spaces between the groups

Clumped distribution could result from individuals using a common resource ex: buffalo around water holes

1. What else might cause organisms to be clumped?

2. What else might cause organisms to be evenly distributed?

4. When might a population be both uniform and clumped?

3. Which of these 3 types of distributions would be least likely to occur for a population of organisms in nature?

Population Sampling:1. Random sampling – estimating a population by sampling a small area and scaling up.

ex: if there are 5 in one square foot, there would be 50 in 10 square feet.

2. Mark and recapture – animals are caught, tagged and released. They are periodically recaptured, and a formula is used to estimate the population:

Number caught x number tagged number caught with tag