Flashcards in Ch. 19 Deck (34):
equal distances between every organisms-try to stay as far as possible ex. birds nesting
major factors to human population growth
better control of disease, better hygiene/ sanitation, stable food supply
problems associated with small populations
inbreeding, vulnerable to extinction
three types of population dispersion
uniform, clumped, random
where food supply is- snakes
probability that members of a population will survive
survivorship curves type l+ex.
very likely to survive younger but less likely when older ex. humans,large mammals,eagles
survivorship curves type ll+ ex.
chance of dying/living doesn't change during lifetime ex. birds, squirrels
survivorship curves type lll+ex.
very likely to die when young and less likely to die when older ex.salmon, insects
limiting factors+ ex.
any factor that restrains the growth of a population ex. space, food, clean water
carrying capacity (k)
number of individuals the environment can support over a long period of time
density-independent factors+ ex.
reduce the population by the same proportion regardless of populations size ex. weather, floods, fires
density-dependent factors+ ex.
include resources limitations and are triggered by increasing population density ex.shortages of food or nesting sites
lynx and hare study
Elton thought their cycles were related- more hare= more lynx, less hare= less lynx
lynx and hare/ moose and wolves on island royale
small populations are in much more danger than large populations
problems with inbreeding
in small pop., can lead to decreased genetic variability which means less likely to adapt
calculate pop. density
# of individuals/ unit of area
distribution of individuals among different ages- developed countries have older pop./ developing countries have younger pop.
growth rate depends on:
births, deaths, immigration, emigration
individuals gathered together- food supply is clumped/flocks or herds
calculate GR per capita
birth rate-death rate= growth rate
growth rate/pop.= growth rate per capita
the population increases rapidly after several generations = exponential growth- "j" shaped
-doesn't work with limiting factors
like exponential models but takes limiting factors into account
10,000-12,000 years ago, stabilized-increased food supply
industrial development causes economic and social changes that affect population growth rates
how are modern humans like hunter gathers?
GR of the world now?
typical wolf mass (lbs.)
% of wolf accuracy
Cons to the agricultural revolution
more people= disease spreads easier
4 most consumed crops
current world population