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ERTH 1006 (1)
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Department
Earth Sciences
Course
ERTH 1006
Professor
John Buschek
Semester
Fall

Description
f-4a POPULATION ECOLOGY Things to consider regarding population: 1) Size (over time tells us whether growth is happening or not) 2) Density a. Terrestrial = # of ppl/ unit area b. Aquatic/Marine = # of ppl/unit volume 3) Distribution / Dispersion (4 types) a. Random – people inhabit places regardless of others (rare due to competition) b. Uniform – spaced evenly among the environment (territorial behavior) c. Clumped – Population dense and clump-like (most common, due to nutrient supply) d. Scale size – real time size (can be seen via satellite) 4) Sex Ratios a. Worldwide M=102-108 births/100F b. Canada 51.2%M, 48.8%F c. One interesting place = Pangasiwaang, ON. i. 1984-1992 = Canadian ratio ii. 1993-2003 = 41.2%M 58.8%F iii. 1999-2003 = 34.6%M 65.4%F What causes change? 1) Growth a. Births b. Immigration 2) Decrease a. Deaths b. Emigration Crude Birth Rate = #births/1000 ppl/yr Crude Death Rate = #deaths/1000 ppl/yr >> CBR + I – CDR – E = Growth Rate -> % Exponential growth (the function looks like a J) Logistic growth (the function looks like an S) Carrying Capacity = # individuals a habitat can sustain Kaibob Plateau (near Grand Canyon) >lots of predators (wolves, coyotes, cougars >upset farmers, began to kill off predators > led to an increase of deer > deer caused overgrazing and pushed them past the carrying capacity >began to die off, back to equilibrium Which factors provide environmental resistance? - Density dependent o Predation o Starvation o disease - Density independent o Climates  Temperature  Typhoon o earthquakes o asteroids HUMAN POPULATION 8000 BC  population = 5M 1 AD  200M 1650 AD  500M (1650yrs) 1850 AD  1B (200yrs) 1945 AD  2.3B (95yrs) 1980 AD  4.4B (35yrs) 2013 AD  7.2B (33yrs) I = P x A x T (x5) EX. From 1650-1850 our population doubled. Doubling time = 70/ growth rate (%) The growth rate from 1650-1850 = 70/200 or .35 EX2. From 1945-1980 the growth rate is 70/35 or 2%. Educations effect on population A. Stopping the growth a. People staying in school and not having kids b. Focus on career, not child bearing B. Speeding the growth a. Educates us to live healthier and cleaner b. October 19 2013 ISCI 1001T Parasitism: 2 types a) endoparasite (lives in you) b) ectoparasite (lives on you) - macroparasite – ticks, worms, plants - microparasite – bacterium/fungus macro example – mistletoe > hemiparasite > does photosynthesis (makes its own food, but needs nutrient + water, which it gets from another plant) social parasite (a separate class) – don’t tend to eat or derive nutrition, but need host to complete their life cycle. A social parasite if they change the behavior of the host. Ie. coockoo bird > lays eggs in other birds nest > lets other bird nurse and hatch eggs > then move in and take over the birds once hatched Ie2. Toxoplasma gandii >single celled, will infect any animal (people, cats, dogs) > rarely find symptoms if healthy > weak immune system poses symptoms > can only sexually reproduce in the intestines of CATS > gets into mice – making mice aggressive to cats > get spread through the food chain > also spread through cat feces – infant exposure maybe be linked to schizophrenia later in life (ie don’t deal with cats directly when pregnant) Herbivory (a predator parasite) – eat plants Mutualism – an interaction that helps both species involved ( + , + )  Pollination; animal getting food & plant which is reproducing  Mychorrhizae; fungus/plants (roots) o Fungus excretes digestive juice and then absorbs the nutrients o Mutual because fungus receives sugar from the plant root, while the mushroom breaks things down in the soil and enriches plant food  probiotics; help humans digest, while feeding off your digestive tract  ** human cells (eukary
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