3/29 community ecology Flashcards
Species diversity
and feeding relationships questions to ask
How many different species? verity is important
Who’s dominant?
Who’s dominant?
can be described as
most abundant
or highest biomass
(total weight)
Community Structure
Species diversity
Keystone species
Ecological Succession
Species diversity
greater diversity = greater stability
Greater biodiversity offers:
more food
resources
more habitats
more resilience
in face of environmental change
variation gene pools
what ever decreses the gene pool won’t have a big affect if there is a variety of them
2 ways to compose species diversity
species richness
relative abundance
species richness
number of diff species in a community
relative abundance
how many are there of each organism in each species related to the other species
The impact of reduced biodiversity
when diversity decreases its harder for plants to comeback from devestation
biodiversity can change
ot
understand food webs
and how to read them
roles-
can be at more than 1 lvl
grouping
specise with similar trophic relationship
isolating
interacts very little with the rest on a food web
limits
on food chain length becuase energy runs out
Dominant Species
Species with a large impact
most abundant or have the highest biomass
Control over other species
exploiting resources
outcompetes most in community
avoiding predators
no predators exist in the community
Invasive species
can become dominant
biomass
weight
abundance
large in numbers
Species with a large impact:
Keystone species
A species that has a large effect on its environment relative to its abundance
A consumer organism (herbivore or carnivore)
Low biomass in numbers
they baiscally hold up the community
Ecosystem engineers
AKA foundation species
redo landscape
cause physical changes in the environment that affect community structure
Characterizing Disturbance
this can be a good or bad thing
event that changes a community, removes organisms from it, and alters resource availability
old idea of disturbance
Communities are in a state of equilibrium
Climax community – superorganism
recent idea for disturbance
nonequilibrium model
Communities constantly changed by disturbance
Intermediate disturbance hypothesis:
moderate levels of disturbance can foster greater diversity than either high or low levels of disturbance
high disturbance will be bad for
slow-growing species
low disturbance will be bad because
dominant species vs. less competitive species
understand graph on slied 41
new zeland stream
Human Disturbance
they are the biggest disturbance and causes bad affects Reduces species diversity
Fire adapted species
adaptations to survive and reproduce in areas than experience frequent fires
Latitude
richness declines along equatorial-polar gradient
Tropics to Polar
species richness declines
why does richness decline
Evolutionary History
Climate – primary cause
Evolutionary History
Greater age = greater species richness
Growing season never stops in the tropics and stops in polar area
Restarts polar area restarts in warmer times
Climate – primary cause for diverstiy
sun/solar energy
Water / Evapotranspiration (evaporation of water from soil plus transpiration of water from plants)
intensity of sun dwindles
Species-area curve
quantifies the idea that, all other factors being equal, a larger geographic area has more species
Island Equilibrium Model
Species richness depends on:
- island size, distance from the mainland, immigration, and extinction
Equilibrium model of island biogeography:
- species richness levels off at a dynamic equilibrium point
Larger area=large number of species
there is a sweet spot fro
area vs birth and immigration
islands are a little
diffrent
Pathogens
alter community structure locally and globally
Pathogens are
Zoonotic Diseases
starts in animals
Zoonotic pathogens - animals to humans
vector
Many emerging human diseases
Identify hosts and vectors to prevent disease
vector
transfer of pathogen
