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large group, one species in 1 time and 1 place (interbreed)
all populatin in a location, living together
community plus environment
interactions btwn organisms, and btwn organisms and envrionment
- abiotic - living factors and
- biotic - non living factors
role of organism in environment
on scale of earth - communities of a particular type
Characteristics of populations:
- 1)population size
- 2)arrangment of organisms
- 3)density of population
- birth rate - # of offspring per female per time
- death rate
- immigration and emigration
- -if population is small= this is bad, reduced genetic variabilty, chance of extinction
arrangment of organisms:
- uniformly spaced
- random spacing (least common)
- 1) exponential growth - cant go on forever
- 2) logistic growth - "sigmoid growth"
- k= carrying capacity of environment
- k/2 harvesting population "optimal harvest population"
- statistical analyze about population
- -statistics about pop- births, deaths, marriage etc...
- summary of statistics "life table"
- *see handout
- cohort- original group
- "proportion of individuals surviving" - common variable used.
- Type I: humans
- type II: birds
- type III: fish, insects
Birth data from survivors:
gather birth data, calulate pop. growth, overall from survivor data and birth data.
- time it will take a population to double.
- -How young, birth #rs, freq...
Human pop. growth:
- growing exponentially
- why so rapid:
- 1) increased earth's carrying capacity
- 2) Expanded into more habitats
- 3) removed limiting factors (reduced diseases)
- -cant go on forever (resources must double as well)
- -living together or less permanently, of 2 or more diff kinds of organisms (species)
- One species benefits and the other is neutral
- epiphytes and tree (tree is neutral)
- marine passengers (benefit)
- parasite benefits
- host - does not benefit
- endoparasites: tapeworm *inside
- ectoparasites: leech, ticks, mistletoe
- both species benefit
- nitrogen fixing bacteria and members of pea family
- seed dispersal-- some cases
- polinators and plants
- mycrorrhizae - root/fungus relationship
- huge affect on community (beavers)
- ants and plants - BOOK
- interaction between organism of same or diff. species for required by limited resources
- Intraspecific- between
- interspecific - within
functional role of organism in community
no other competitive species present
niche w/ competitive species present
- "Gause's competitive exclusion principle"
- -only 1 species can occupy a particular niche @ a particular time. (The other goes extinct if they do try to do so)
- lab - paramecium - consitent w/ gaue's principle
- Nature: new england warblers' 5 species shown in pic
- -not sharing niche (each has their own)
- beak size dictates size of food
- can live in same envrionment if beak size is diff.