1. Population Ecology

2. Population – all the individuals of the same species in a specific area.
4 characteristics of populations:
Geographic distribution
Density
Growth rate
Age

3. 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?

4. STATE
population
Area
(Sq. miles)
Population
density 1 NJ
8,682,661
7,417
1,170.64 2 RI
1,050,788
1,045
1,005.54 3 MA
6,497,967
7,840
828.82 4 CT
3,501,252
4,845
722.65 5 MD
5,633,597
9,774
576.39 6 DE
873,092
1,954
446.82 7 NY
19,490,297
47,214
412.81

5. Population density can be random, uniform, or clumped.

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

7. 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

8. 1. What else might cause organisms to be clumped?
2. What else might cause organisms to be evenly distributed?
3. Which of these 3 types of distributions would be least likely to occur for a population of organisms in nature?
4. When might a population be both uniform and clumped?

9. 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

12. 2) Age Structure and survivorship Age structure can indicate the potential for future population growth. Which population has a greater potential to increase in the future?

14. Survivorship Curve:
If birth rates are constant, then age structure can be used to calculate survivorship.
(patterns in age-specific death rates) 
Some species produce many offspring, with most dying young (Type III).
While other species produce few offspring with most surviving to maturity (Type I).
This indicates that there is an evolutionary trade-off between energy invested to reproduction versus energy invested to survival. 

16. 3) Changes in population size over time
Population growth rate = birth rates - death rates
If birth rates are greater than death rates: The Population grows by more and more each time period.
This is simply because there are more individuals each month so that a certain % increase represents more individuals each month.  As a result, the size of a population can rapidly increase after a particular time of growth.

17. Fictional "Tribbles" from Star Trek: One of the more peculiar species encountered, the defining characteristic of the Tribbles is their extreme reproductive rate. Over half of a Tribbles metabolism is devoted to reproduction, allowing them to bear a litter of young every twelve hours. 
With an average litter of ten, a single Tribble can therefore create a population of 1,771,561 within three days,
and an amazing 304,481,639,541,400,000,000,000,000,000,000,000,000,
000,000,000,000,000,000,000,000 in thirty days!