1. Symbiosis Concepts in Ecology

2. 1.___________________ - one organism lives with or on another (oftentimes for the sake of gaining shelter) – neither harming or benefitting the host. 2.___________________ - the relationship in which both species benefit. 3.___________________ - a symbiotic relationship with one species benefitting greatly and the other harmed. Symbiosis – interactions between organisms.

3. Population dynamics Concepts in Ecology

4. In 1798, Thomas Malthus, an economist, wrote “Principles of Populations” (an essay).

5. Essentially stated: “The human population has the potential to increase faster than the food supply.

6. In the 1840’s Charles Darwin expanded this idea: The potential for a population to outgrow its resources exists in all populations.

7. Categories of Population Growth: A. Exponential Growth – if a population is left to its own means and has unlimited food supply the rate of growth of ____________________

8. Time # of indiv. # of births exceed # of deaths 1.Reproduction occurs at maximum rate 2.All offspring survive to reproduce 3.Death occurs only at old age. The closer a population gets to these, the higher the rate of growth.

9. The value “ r ” can be positive, meaning the population is increasing in size; or negative, meaning the population is decreasing in size; or zero, where the population ’ s size is unchanging, a condition known as zero population growth. A further refinement of the formula recognizes that different species have inherent differences in their intrinsic rate of increase (often thought of as the potential for reproduction), even under ideal conditions. Obviously, a bacterium can reproduce more rapidly and have a higher intrinsic rate of growth than a human. The maximal growth rate for a species is its biotic potential, or r max, thus changing the equation to: dN dT =r max N (4) Logistic Growth Figure 1: When resources are unlimited, populations exhibit exponential growth, resulting in a J-shaped curve. When resources are limited, populations exhibit logistic growth. In logistic growth, population expansion decreases as resources become scarce, and it levels off when the carrying capacity of the environment is reached, resulting in an S-shaped curve.

10. WHAT KEEPS A POPULATION FROM GROWING EXPONENTIALLY?

11. Population pyramid. The pyramids show the age distribution, by sex, for typical European and African nations. The pyramids have the same total area, so the wide base of the African pyramid reflects the high birth-rate, and its fast-tapering shape indicates the low expectation of life.

12. Bangladesh population to hit 17.240m by 2021

13. To determine growth rate of a population (or the change in pop. size over time) MUST CONSIDER: 1.Birth rate 2.Death rate 3.Immigration (# of indiv. entering the population). 4.Emigration (# of indiv. leaving the population). Populations __________ in size if the number of births ____________ the number of deaths. Formula: Rate of increase = birth rate (b) – death rate (d) population size (N)

14. Solve: a population of Canada geese (Branta canadensis) has 1000 individuals b=30/yr. d=10/year What is the rate of increase?

15. According to Hans Rosling from TED TALK, the world population is expected to reach 9 billion by 2050. The US population is currently over 320 million. Explain in detail ( not list), 3 ways this global increase in population will affect your life in the United States? (and yes, your life will be affected). Critical Writing Human Population