bio exam 3

organismal ecology

considers how organism structure, physiology, and behavior meet environmental challenges

population ecology

considers factors affecting population size and change over time

community ecology

a group of populations of different species in an area; interactions between species affect community structure and organization

ecosystem ecology

community of organisms in an area and the physical factors w/ which they interact. emphasizes energy flow and chemical cycling between organisms and environment

landscape ecology

a mosaic of connected ecosystems. factors controlling exchanges of energy, materials, and organisms across multiple ecosystems

global ecology

biosphere is the global ecosystem-the sum of all ecosystems and landscapes on the planet

characteristics of populations are

shaped by the interactions between individuals and their environment

climate

long-term prevailing weather conditions in an area: temp, precipitation, sunlight, wind

high temps in the tropics

evaporate water from the surface and cause warm, wet air to rise

as rising air expands and cools

it releases water as heavy precipitation over the tropics

high altitude air masses, when dry

flow toward the poles

dry air descends around 30-degree latitudes and

absorbs moisture from the land and creates arid conditions, then flows towards the equator and poles

at 60 degree laittiudes

the pattern of precipitation is repeated w/ drying near the poles

climate varies

seasonally and is affected by things such as bodies of water and mountain ranges

seasonal changes in wind patterns can

alter ocean currents

upwelling

cold, nutrient-rich water from the ocean floor moves to the surface, stimulating phytoplankton growth and productivity

ocean currents influence coastal climates by

heating or cooling air as it moves over land

large bodies of water are

resistant to temp fluctuation and can moderate the climate of nearby land

land heats up during the day, causing

overlying air to rise and pull cooler air from the water across the land

at night, air rises over warmer water and

pulls cool air away from the land

forests absorb more and reflect less

solar radiation than grasslands or deserts

solar radiation in forests increases

rates of photosynthesis and transpiration relative to other types of vegetation

evaporative water loss

cools surface temp and increases precipitation rate in forested regions

climograph

plots annual average temp and precipitation in a region

disutrbance

event that changes a community by removing organisms and altering resource availability

example of disturbance

fires kill woody plants and can prevent savanna from transitioning into woodland

abitoic factors

pg 16

biotic factors

pg 16

density

number of individuals of a species per unit area or volume

how do we measure population density

count all individuals in area, estimate using sampling techniques

mark recapture method of estimating population density

set traps within defined area, tag all captured individuals and release, reset traps after time has passed, both tagged and untagged individuals are captured, estimate # individuals in population (N)

dispersion pattern

the way individuals are spaced within their area, depends on resource distribution

clumped pattern dispersion

aggregate in patches, results from unequal distribution of resources or mating habits

uniform dispersion

is when individuals are evenly spaced

random dispersion

position of each individual is independent of the others

demography

studies vital statistics that affect population size; series of events from births, deaths, and migration rate of a population over time

snap shot intervals can

determine how a pop’s density changes over time

cohort

group of individuals born at the same time and tracked over their lifetime

A survivorship curve

physiological survivorship curve; most individuals survive to old age

B survivorhsip curve

ecological survivorship curve; individuals face a constant risk of mortality at all ages

C survivorship curve

maturational survivorship curve; most individuals die young

reprroductive table

age specific summary of the reproductive rates in a population

reproductive table for sexual species

table tallies the number of female offspring produced by each age group

life history

traits that affect an organism’s schedule of reproduction and survival

life histories are a result of

natural selection and often parallel environmental factors

big bang reproduction

large #’s of offspring are produced in each reproduction, after which the individual often dies

big bang reproduction also known as

semel parity

iteroparity

some organisms produce only a few eggs during repeated reproductive episodes

what factors contribute to the evolution of semel parity and iteroparity

limited resources mandate tradeoffs between investments in reproduction and survival

life histories represent

an evolutionary resolution of several conflicting demands

population growth rxpression

ΔN/Δt = B - D

ΔN

change in population size

Δt

time interval

B

number of births

D

number of deaths

exponential growth

model of population describes an idealized population in an unlimited environment

populations growing exponentially exhibit

J shaped growth curve

r

birth minus death

logistic model of population growth incorporates the concept of

carrying capacity and the effect of population density on the rate of increase

logistic growth

pop growth that is regulated by population limiting factors; s shaped graph

equation to calculate population growth under the influence of population limiting factors

deltaN/deltaT=r[(K-N)/K]N

k (carrying capacity) is not

constant. it varies for each species from season to season and year to year

an organism’s life history comprises the traits that

affect its schedule of reproduction and survival

in k selection

organisms live and reproduce around k, are sensitive to population density, and maximize reproductive success in uncrowded environments

in r selection

organisms exhibit high rates of reproduction and occur in variable environments in which population densities fluctuate well below k

density dependent factors are a kind of

negative feedback

density dependent factors definition

factors whos effects depend on population density (have no effect when N is small; greatest effect when N is above carrying capacity)

resource limitation in crowded populations can

stop population growth by reducing reproduction

examples of density dependent factors

limited resources, predation and parasitism, disease

intraspecific competition for food can also cause

density dependent behavior of populations

metapopulation

group of local populations linked by immigration and emigration

density independent factors example

severe weather, natural disasters, human activity

interspecific interactions

relationships between the species of a community which are positive and negative

examples of interspecific interactions

competition, predation, parasitism, mutualism, commensalism, amensalism

examples of positive interactions

mutualism and commensalism

interaction where one species gains and the other loses

exploitation

commensalism

individuals of one species benefit, while individuals of the other are not affected

2 possible outcomes of interspecific competition

one species is eliminated (competitive exclusion principle), they coexist (niche- set of physical and biological conditions required to survive, grow, and reproduce)

ecological niche

sum total of an organism’s use of abiotic/biotic resources in the environment

competitive exclusion principle can be restated to say

two species cannot coexist in a community if their niches are identical

similar species can coexist if

one ore more significant differences in their niche arise through time called resource partitioning

exploitation competition may lead to

coexistence

resource partitioning exploiting the same resource but in a different way

enables similar species to coexist in a community

fundamental niche

defined by physiological capabilities

realized niche

defined by interactions with other species

resource partitioning can lead to the formation of

guilds and character displacement

character displacement

can evolve when 2 competing species have geographically overlapping/sympatric populations

morphological and physiological defenses against predators

behavioral defenses

crypsis

camouflage/cryptic coloration/deceptive markings

aposematic coloraiton

indicated by warning colors, sometimes associated with other defenses like release of toxins

batesian mimicry

harmless species mimics a harmful one

Müllerian mimicry

2 or more unpalatable species resemble each other

plant defenses against herbivores

chemical compounds that are toxic, thorns, and spines

endoparasites

live inside the host

ectoparasites

live on the surface of the host

grooming behavior may have evolved in response to

ectoparasites

parasitoid

special type of parasitism where the parasite eventually kills the host

pathogens

disease causing organisms that can be considered predators

mutualism

both species benefit from their interaction

examples of mutualism

mycorrhiza and plant roots, animal pollinators