Chapter 4

A group of individuals of the same species living in the same area of interbreeding and sharing genetic information

Worldwide disease outbreak 1918 Spanish flu 50 million died 1999 West Nile virus 2003 SARS 2004 bird flu

All individuals that are capable of interbreeding Made up of populations

The general study of population changes

Abundance Birth rates Death rates Growth rates Age structure

P2= p1 + (B-D) + (I-E) P1= population at t1 p2= population at t2 B = # of births. D = # of deaths I = of immigrants E= # of emigrants

b= B/ N d = D/ N g= b-d

TD= 70/k (not g) k= exponential rate b = birth rate B= # of births N = total population d = death rate D = # of deaths g = growth rate TD= doubling time

The proportion of the population in each age class Affects current and future birth rates, death rates, and growth rates Has an impact on the environment Has implication for current and future social and economic status

Exponential growth and doubling time Zero population growth, birth rate = death rate

S shaped curve that is generated by the logistic growth equation A small population grows rapidly The growth rage slows down The population eventually reaches a constant size

The population size at which births equal deaths and there is no net change in population

Average number of years an individual in a species can expect to live

Appears rapidly in the population Affects a comparatively large percentage of it Declines then almost disappears only to reappear later

Is always present in a population Typically occurs in a relatively small but relatively constant presentation of the population

T = P x I T= total impact P= population size I= average environmental impact per person Modern technology tends to increase I, but could be used to reduce it