Chapter 13 - Population Community Ecology

BIO 1334

ecology

study of the interactions among organisms, between organisms, and their nonliving environment

what is Isle Royale

a habitat undisturbed by humans, protected park; long running predator/prey study'; tracks wolves and moose for many years

individual

a single organism of a particular species; a wolf

population

a group of individuals of the same species living and interacting in the same region

example of population

a pack of wolves whose individuals live and reproduce with another

community

interacting populations of different species

community example

wolves prey on moose, ticks infest moose, moose feed on trees

ecosystem

species interacting with other species and the environment

ecosystem example

moose eat trees, less vegetation alters the landscape for other species; hot summers reduce food for moose, affecting their winter survival

what is the order of ecology?

individual —> population —> community —> ecosystem

population ecology

population sizes fluctuate from year to yearsp

species distribution patterns

individuals are observed in different spatial patterns driven by the environment, food ability, competition, tates, predator avoidance

random distribution

may allow individuals to maximize their access to resources and spreading out means less completion for resources; no strong attraction or repulsion

clumped distribution

when resources are unevenly distributed across the landscape or when social behavior dictates grouping

random distribution example

schooling fish are clumped to avoid predators

uniform distribution

results from territorial behavior; strong repulsion; has allelopathy

allelopathy

plants produces a chemical that inhibits other plants

allelopathy example

creosote bush

growth rate

difference between the birth rates and death rates influenced by immigration and emigration

immigration

movement of individuals into a population

emigration

movement of individuals out of a population

what are the two types of population growth

exponential growth and logistical growth

exponential growth

unrestricted growth of a population increasing at a constant growth rate; resources are unlimited; no competition; can go to infinity; growth is slow at first because there are few individuals; happens when an area is newly colonized

logistical growth

starts off fast and then levels off; environmental factors will limit an organism’s ability to reproduce, such as competition for resources and access to habitat

what shape is exponential growth on a graph

exponential growth on a graph is J shaped

what shape is logistical growth

logistical growth is S shaped

carrying capacity

the maximum number of individuals that an environment can support given its space and resources; upper limit on the size of any population

boom and bust patterns

size of a population may fluctuate around the environment’s carrying capacity; disease or food shortage cause population to shrink; allows environment time to recover its food supply; population may begin to grow again

what are patterns of population growth?

anything that affects the size of one population in the ecosystem as well

how is prey and predator population growth connected?

population of predator and prey are fluctuating; they are interconnected and dependent on each other

predator-prey example on Isle Royale

the main diet of Isle Royale wolves is moose, the wolf population grows and diminishes in response to the availability of this resource. a larger moose population means that more tree material is eaten so tree growth slowsh

how is tree growth measured

tree growth is measured by the width of each tree ring- one ring represents the amount of growth in one year; the wider the ring, the more growth in that year

population density

number of organisms per given area; as the population density of a species increases, individuals of that species may face food shortages

what are the factors influencing population growth?

density dependent factors, density independent factors, abiotic factors, and biotic factors

density dependent factors

influence on population size depends on the crowding of individuals in population- predation

density dependent factors example

the more moose crowding in an area makes it easier to be preyed by wolves, wolves try to eat smaller amount of moose

density independent factors

can influence population size or growth regardless of numbers and crowding within a population - weather

density independent factors example

harsh weather makes it harder for moose to run away from wolves

biotic factors

living components of the environment; density dependent

abiotic factors

non-living components of the environment; density independent

what type of growth is bald eagles

bald eagles growth is exponential

what are other factors impacting the moose

disease (density dependent) - canine parovirus (cpV)~ many wolves died in 1980 except for 4 and moose population increased dramatically; climate change (density independent) - less eating in warm weather (weaker) and warm weather favors ticks