Populations

Pop. Characteristics Geographic Distribution – the areas inhabited by populations (where?) Density - # of individuals per unit area Ex. 1000 people per sq. mile Growth Rate – depends on # of births # of deaths # of individuals entering or leaving a pop.

I vs. E IMMIGRATION – movement INTO a population EMIGRATION – movement OUT OF a population (Exited)

Growth Exponential – when individuals of a pop. reproduce at a constant rate. Occurs under IDEAL conditions J-curve plot Logistic – growth slows or stops following exponential growth

Carrying Capacity… The Maximum amount of individuals of a population that an environment can support. Generally means birthrate = deathrate

“Starving Child and a Missionary” Famous Photos

Limiting Factor (LF)  Limits the size of a population  causes decrease in numbers. Density DEPENDENT (LF) – factor that limits larger populations Ex. Competition, Predation, Parasitism, disease Density INDEPENDENT (LF) – affects all populations regardless of size Ex. Natural disasters, clear-cutting forests, etc.

Picture taken by Kevin Carter, March 1993 in Southern Sudan Picture taken by Kevin Carter, March 1993 in Southern Sudan. Carter chased vulture off. Journalists were told not to touch famine victims to help prevent disease transmission. Carter won a Pultizer Prize for this photo but haunted by guilt of not picking up the child and not knowing her fate, he committed suicide just 3 months later. http://iconicphotos.wordpress.com/2009/08/12/vulture-stalking-a-child/

DISEASE as a Limiting Factor …can disrupt an ecosystem’s balance Humans: AIDS, INFLUENZA, Tuberculosis OTHERS -Dutch Elm Disease (fungal-but spread by beetles) (Of the estimated 77 million elms in North America in 1930, over 75% had been lost by 1989) -PFIESTERIA – The genus of heterotrophic dinoflagellates which can lead to algal blooms and fish kills. (ex. Chesapeake Bay and off NC coast in 1980s and early 1990s)

Fish kill due to Pfiesteria in New Bern, NC (Neuse river) -OCTOBER 2013

Good adaptations can lead to higher population numbers… CLICK -Costa Rican caterpillar

Human Population… Is increasing with time. Really boomed in last 300 years Demography – study of human populations Demographic Transition – a dramatic change in birth rates…is complete when birth rate decreases to meet the death rate In US and Japan growth has slowed as both have already completed their demographic transition Worldwide population still grows exponentially.

World Population Population counter and past date-specific data