Ch 26 Community Ecology

Diversity

Diversity and Scale

Diversity and Latitude

Predator-Prey Interactions

One Predator, One Prey

Predator Selection Among Multiple Prey

Competition Between Species

Apparent Competition

Beneficial Interactions Between Species

Metapopulations in Patchy Environments

Interconnectedness of Species: Food Chains and Food Webs

larger communities more diverse than small

species-area relationship

relationship between area and species richness

S=cA^z

Level of Scale

Local

Region

Biome

Biogeographical region

measuring diversity

alpha

number of species or growth forms that occur at local site

beta

compares differences between smaller sites in large region

gamma

number of species within a region

species abundance distribution

plot of the number of species in a region into abundant classes

different plants depending on environment on earth

As+latitude+and+altitude+increase,+temperature+and+organism+diversity+decreases

far north

lower diversity than closer to the equator

equator

benign environment

higher latitude has more severe conditions

scale

could change in temperatures were the same long enough

functional response

predator's feeding rate and handling time

prey-dependent

predator's functional response depends on prey density

Lotka-Volterra model

dN/dt=rN-aNP

rate of change with time of prey population

dP/dt=faNP-qP

rate of change of predator number

zero growth isocline

line indicating population stability

criticized for being to simplistic

paradox of enrichment

loss of a population from a habitat as a result of that habitat being altered to benefit the population

maximum sustained yield

amount of organisms population that can be harvested without population decreasing

fixed effort harvesting

technique that limits damage to a species by automatically decreasing harvests

fixed quota harvesting

limits damage to a species by setting limits on amount that can be harvested

optimal foraging theory

examine the interactions between these factors in an attempt to understand why herbivores eat the plants they do while ignoring the others

optimal diet model

makes four predictions

exploitation competition

occurs when organism actually consume a shared resource making it less available for organism

interference competition

one organism restricts another organism's access to resources even though the first might not using it.

resource

any substance or factor that can lead to increased growth rate as its availability is increased and that is consumed by an organism

apparent

predator may prey on several species

mutualism

two organisms interact with that both organisms benefit

facilitation

one organism helps another without receiving any benefit

first organism facilitates

nurse plants

presence of some plants creates conditions that allow other plants to become established

spiny desert shrubs

primary succession

organism becomes established on newly created substrates

metapopulation

population that consists of several local populations interconnected by migration and gene flow between patches

makes four assumptions

  1. a region of the environment is composed of many discrete patches in which the species can live
  1. some patches are occupied by the species whereas other suitable patches are not
  1. empty patches will become colonized by migration from occupied patches
  1. populations within individuals patches have a probability of going extinct within that patch

source habitat

high quality patch

sink habitat

low quality

fugitive species

species that survives by colonizing new patches, flourishing temporarily, then colonizing more patches and dies out in old one

assisted dispersal

animals are capture in one area and released into another

food chain

direct line of consumption

food web

various organisms eat or decompose others, and these in turn are consumed

keystone species

web

species that dramatically effects the structure of its community

portion size

number of individuals

energy flow web

difficult to make for real communities

energy