Ch. 56
Biology 2003 with Brooker/seabloom at University of Minnesota - Twin Cities
About this deck
By: Cassandra Skoog
Created: 2011-04-19
Size: 22 flashcards
Views: 19
Created: 2011-04-19
Size: 22 flashcards
Views: 19
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Population
group of interbreeding individuals occupying same habitat at same time
Population Ecology
- Study of what factors affect population size and how these factors change over space and time
- uses tools of demography: birth rates, death rates, age distribution, population sizes
Population Density
- # of individuals in a given area
- affected by population growth
- knowledge about it can help us make decisions about managing species
Dispersion Patterns
- Clumped
- most common
- resources clustered in nature
- may be due to social behaviors
- Uniform
- may be due to competition
- or social behaviors
- seen in territorial animals
- Random
- rarest
- resources rarely randomly spaced
- may occur where resources common and abundant
Reproductive Strategies
- semelparity
- produce all offspring in single reproductive event
- indiviudals produce once and die
- iteroparity
- reproduce in successive years or breeding seasons
- seasonal iteroparity - distinct breeding seasons
- continuous iteroparity - can reproduce continually, any time of the year
age classes
- reproductive strategies has great effect on subsequent age classes of populations
- semelparous organisms with same aged young called cohorts
- iteroparous organisms have young of different ages
- population increasing in size has many young, one decreasing has few young
Life Tables
- data on number of individuals alive in particular age class
- males normally not included
survivorship curve
- plots number of surviving individuals at each age
- use log scale to make it easier to examine populations with greatly varying sizes
- 3 patterns:
- Type I: rate of juvenile loss low, most individuals die later in life
- Type II: Uniform death rate
- Type III: rate of juvenile loss high, survivor loss low
Age-specific fertility rate mx
- proportion of female offspring born to females of reproductive age
- e.g. 100 females produce 75 female offspring, is 0.75
age-specific survivor rate Ix
use survivorship data to find # of individuals alive at start of any age class
exponential growth
resources not limiting, prodigious growth
denisty-independent
e.g. reintroduction of population to habitat, human world population, growth of introduced exotic species
logistic growth
resources limiting, limits growth
density dependent
growth slows as approaches K
factors affecting population growth
births -> increase
deaths -> decrease
immigration -> increase
emigration -> decrease
factors operate at different temporal and spatial scales
Density Dependent Factors
- mortality factor whose presence varies with density of the population
- parasitism, predation (kill more prey when there is more prey) , competition
- positive slope when plotting mortality against population density
Density Independent Factors
mortality factor that is not associated with population density
e.g. physical occurences (natural disasters) floods, earthquakes
Life History Strategies
r selected species: higher per capita growth rate (r); but poor competitive ability
e.g. weeds
small size, rapid growth, short life span
k selected species: stable populations adapted to exist at around K; lower reproducitve rate, better competitors
e.g trees
large size, slow growth, long lifespan
Human Population
2006, growth rate 146 peeps (way more in developing countries)
fits exponential growth pattern
can exist in equilibrium:
high birth rate, high death rate (case before 1750)
low birth, low death rate (low birth rate associated with social changes for women)
demographic transistion
1: birth and death rates high (equilibrium)
2: death rate declines (rapid growth)
3: birth rate declines (growth decrease)
4: both low (equilibrium)
age structure
# of individuals in each age group
displayed as pyramid
helps make projections
Earth's carrying capacity
global fertility rate decline; at 2.59, needed 2.3 for no growth
developing nations pop increasing; developed nations population stabilization
current pop: 6 billion
stabilized pop projection: 10 billion (2150)
About this deck
By: Cassandra Skoog
Created: 2011-04-19
Size: 22 flashcards
Views: 19
Created: 2011-04-19
Size: 22 flashcards
Views: 19
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy
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