Biological Communities & Species Interaction. Who Lives Where and Why? nCnCritical Factors and...
-
Upload
stuart-ethelbert-haynes -
Category
Documents
-
view
215 -
download
0
Transcript of Biological Communities & Species Interaction. Who Lives Where and Why? nCnCritical Factors and...
Who Lives Where and Why?
Critical Factors and Tolerance Limits1. nutrients, temperature, water supply, living
space and other physical factors
2. tolerance limits - minimum and maximum levels (range) for each of the critical factors
3. factors are unique for each species, and often complex interaction between several factors
Saguaro cacti are extremelySensitive to temperature
Desert pupfish, lives in desert, Can survive at high temp up to42 C and in high salt.But eggs and juvenile fish live between 20-36C and are killed by high salt
Environmental Indicators
Jimson Weed a.k.a Loco Weed, or Devil’s Weed
Grows where selenium and uranium are high
Datura stramonium
Lichen and Frogs are Pollution Indicators
Natural Selection, Adaptation, Evolution1. physiological modifications - traits of species
that allow them to “adapt” to environment
2. evolution by natural selection -over time, traits that are beneficial “survive” while those that are less beneficial do not
3. factors influencing evolution - change in environment; predation; competition; luck
The Ecological Niche1. habitat -place and environmental conditions in
which an organism lives
2. ecological niche - functional description of role of species within a community
how it obtains food relationships with other species role it plays in biotic and abiotic aspects of area
Predation1. predator -an organism that feeds directly on
another living organism predator - prey relationships play vital a central role
in evolution of many species competitive exclusion principle - two species whose
niche overlap too much will compete for resources
Keystone Species1. keystone species - species or group of species
whose impact on community is greatest not always the highest on the food chain
i.e. Wolves limit the grazing of herbivores
i.e. Sea star limits population of clams etc.
Parasite: A type of symbiosis in which organism that completes part of its life cycle on a host organism. The host is harmed and the predator is not.
Pathogen: Disease causing organisms that are not free living.
Competition1. intraspecific competition - competition for
resources among members of same species territoriality
2. interspecific competion - competition for resources among members of different species
What two ways do grasses compete?Why is intraspecific competiton more intense?
Symbiosis - intimate interaction of species (often with one relying on another)
1. commensalism- one organism benefits, other is neither helped nor harmed
i.e. Bird in a tree
2. mutualism -both organisms benefit from a mutual relationship with each other
i.e. mycorrhizae and lichen
3. parasites- one organism benefits one is harmed
i.e. Sporozoan that causes malaria
Mimicry and Camouflage
1. Batesian mimicry- a related species evolves over time to appear similar to a dangerous species
Butterflies
Left is unpalatable
Right is palatable
Community Properties
Productivity - rate of biomass production Abundance and Diversity
1. abundance - actual total number of individual organisms in a community
2. diversity - number of actual species or niches present in a particular ecosystem
Complexity and Connectedness1. complexity - number of species at each trophic
level and number of trophic levels
2. connectedness - the relatedness of organisms within the entire trophic system
Resilience and Stability– constancy - lack of much change over time– inertia - change occurs, much resistance– renewal - ability to repair after severe damage
Community Structure– spatial distribution of organisms– relation of organisms to their surroundings
nesting birds schools of fish clusters of trees
Factors influencing distribution
Dispersal methods a) availability of water in the desert Behavior Biotic factors (predation parasitism, competition,
disease) b) competition for nesting space in a penguin
colony. c) clustered (optimum protection bird and fish) Abiotic factors (availability of nutrients, water,
light or presence of chemicals)
Community in Transition
Ecological Succession - gradual change of ecosystem over time1. primary succesion - community develops on
site with little/no biotic forms
2. secondary succession - new species begin to replace “original” species on the site
3. climax community - community that finally develops and resists any further change
4. equlibrium community - undergoes periodic disruptions and renewal
forests, grasslands
5. fire-climax community - often depends upon fire for part of it normal life cycle
the chaparral
Introduced Species - new species brought into a community1. natural -species moves into a community
without human intervention2. human introductions - new species brought
into community by humans eucalyptus trees Rabbits in Australia Mongoose in Jamaica and Hawaii