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Population Biology.

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Presentation on theme: "Population Biology."— Presentation transcript:

1 Population Biology

2 Density and Distribution
How Study Populations? Geographic Range Density and Distribution Growth rate Age structure

3 Geographic Range The area inhabited by a population
Can vary greatly depending on the species  (bacteria on a rotting pumpkin vs. cod in the western Atlantic ocean from Greenland to North Carolina

4 Density and Distribution
Population density refers to the number of individuals per unit area Distribution refers to how individuals in a population are spaced out across the range of the population:  random, uniform or clumps. Random Uniform Clumped

5 Growth Rate Age Structure
Determines whether the size of the population increases, decreases, or stays the same.  can be positive, negative or zero Age Structure The number of males and females of each age a population contains Important because most animals do not reproduce until a certain age

6 Factors that effect population growth
1. Birth Rate and Death Rate In a given period of time: Birth rate > death rate  population increases Birth rate = death rate  population stays the same Birth rate < death rate  population decreases 2. Emigration and Immigration Immigration – movement of individuals into an area occupied by an existing populations Emigration – movement of individuals out of an area

7 Exponential vs. Logistic Growth Would you take the money?
Exponential Growth Under ideal conditions with UNLIMITED resources, a population can and will grow exponentially. Exponential growth is when a population increases exponentially Xn (often doubling)

8 Logistic Growth Resources are NOT unlimited so a population can not grow exponentially forever Logistic growth occurs when a populations’ growth slows and then stops, following a period of exponential growth Carrying Capacity The maximum number of individuals of a particular species in a particular environment can support (without degrading it for future generations)

9 * Population will hover around the CC

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