Ecology

review notes and labs

ecology

the study of relationships among living organisms and their interactions with other organisms and with their environment

what are the levels of organization from least to greatest

organism, population, community, ecosystem, biome, biosphere

organism

a single living thing; depends on and adapts to the abiotic and biotic factors of the environment to survive

biotic factors

living factors in the environment

abiotic factors

nonliving factors in the environment

habitat

where the organism lives

niche

role/position an organism has in its environment

population

group of organisms of the same species sharing the same space at the same time; they rely on the same resources and are influenced by the same environmental factors

community

groups of different types of species interacting with each other and sharing the same space

ecosystem

biological community including the abiotic factors

biome

large group of ecosystems that share the same climate and similar type of communities

biosphere

part of Earth that supports life; most complex level affected by human interaction

population dynamics

the study of changes in population size and factors that regulate populations over time

how do populations increase in size

immigration (entering), birth

how do populations decrease in size

emigration (leaving), death

population density

describes number of organisms per unit area

equation for population density

Dp = N/A

if the population density is not a whole number, what do you do?

round down

population dispersion

how organisms are spaced within their area

what are the 3 types of population dispersion?

uniform, clumped, random

uniform

equally spaced

clumped

grouped in patches, most common

random

unpredictable, rare

limiting factors

any abiotic or biotic factors that restricts the numbers of reproduction, or distribution of organisms

density-independent factors

factors that do not depend on the number of members in a population

density-dependent factors

factors that do depend on the number of members in a population

population growth rate

how fast a given population grows

how to calculate population growth rate

# births - # deaths = change in population

exponential growth

population increases rapidly under ideal conditions (no limiting factors, competition, perfect habitat, etc.)

how to calculate exponential growth?

G=rN

how to find r when not given?

r = (birth-death)/N

what kind of curve does an exponential growth show when graphed?

J curve

carrying capacity

maximum number of individual in a species the environment can support; not fixed

logistic growth

takes limiting factors into account; population growth eventually slows and stops as the population density increases

what does logistic growth result in?

decrease in birth rate, increase in death rate, or both

what is the formula for logistic growth?

G = rN [(K-N)/K]

what kind of curve does logistic growth form?

S curve

which type of population growth is more realistic?

logistic growth