Ch 26+ Flashcards
Many organisms use the same environments and ____ are often limited.
resources
Ecology
the study of interactions of organisms with one another and their environment
Community
all species that occur in a given area
______ have characteristics that populations and species do not have.
communities
What are some characteristics of communities?
- energy flow, nutrient cycling, species turnover
- can be vague and quite difficult to quantify
Assemblage
group of (potentially) interacting organisms in a community
Guilds
set of species that use resources in a similar manner; deals with how they use resources
A kingsnake, red-tail hawk, and the red-fox can be considered a _____ based on what they eat.
guild
Species richness
the number of species in a given agea
How is species richness determined?
intensive and long-term sampling
Major determinants for species richness and abundance
- latitude and elevation
- environmental factors
- time
____ and ____ are major determinants in biodiversity
latitude and elevation
Latitudinal species gradient
-species richness increases from the poles to the tropics
Habitats with greater ___ and ____ complexity tend to have more species.
spatial and structural
Intermediate disturbance hypothesis
The basic idea is that some disturbance in an ecosystem continually disrupts interspecific competition. If you leave an ecosystem alone, things become specified.
How are assemblages determined?
by interactions at different levels
Assemblages determined by individual organisms:
competition, predation, parasitism
Assemblages determined by population processes
- density-dependent
- reciprocal negative density dependence
Reciprocal negative density dependence
one population keeps the other one down
Density-dependent processes
the size you have determines what you experience. ex. sickness
3 main results of competition
- resource partitioning
- habitat/geographic displacement of species
- morphological differentiation of sympatric species
Resource partitioning
differential use of resources by species in an assemblage
Competitive exclusion principle
no two species can occupy the same niche indefinitely
Competition is stronger between
ecologically more similar species
In the case of anoles, when can the small A. wattsi successfully compete with the larger A. gingivinus?
when parasite reduces competitive ability of A. gingivinus (the big anole)
Example of Morphological differentiation of sympatric species
character displacement
Types of character displacement
- convergent
- divergent
Character displacement= convergent
Frog example
- different release calls when isolated
- similar release calls when sympatric
Character displacement= divergent
frog example
- similar advertisement calls when isolated
- different advertisement calls when sympatric
_______ and _________ can effectively result in resource partitioning.
phenotypic plasticity; character displacement
Phenotypic plasticity and character displacement can effectively result in _________.
resource partitioning
When both Spea tadpole species occurs, the S. multiplicata becomes less carnivorous and S. bombifrons becomes more carnivorous. What does this show?
character displacement
Predation
one organism killing and eating another
parasitism
one organism feeds on another in a way that is non-lethal (at least in short term)
Predation and parasitism depends on:
density of prey and hosts
Predation and parasitism can interact with ______
competition; ex. predator can reduce density of prey to the point where competition among prey individuals is reduced
Predation and parasitism can affect ____ _____
resource partitioning; ex. presence of predators can reduce activity of prey
Phylogenetic relationships and evolutionary history affect _____.
ecology; hard to determine evolutionary cause of lineage diversity
Phylogenetic inertia
the limitations on the future evolutionary pathways that have been imposed by previous adaptations. “You are what you are because of the genes your ancestors gave you”
Ecomorphs
species of different phyletic origin with similar morphological adaptations to similar niches; ex. anoles on different islands
___ ____ is an example of a new analytical tool becoming important to ecology.
niche modeling
niche modeling
- uses distribution and environmental data to generate models of environmental features that should be associated with a species niche
- identifies possible distributions associated with predicted changes in climate, diet, habitat alteration, etc.
What are some of the major factors affecting communities and assemblages?
- latitude and elevation
- temperature and humidity
- competition
- predation and parasitism
- physiological tolerances
- phylogenetic history
The importance of the major factors affecting communities and assemblages depends on
the kinds of organisms involved, nature of the environment, and interactions
Biogeography
study of past and present distributions of organisms
_____ history strongly affected the evolution and distribution of organisms
earth
Equilibrium Theory of Island Biogeography
- # of species on an island reflects balance of colonization and extinction
- rates of colonization and extinction depend largely on island size and distance from mainland
- so island size and distance affect # of species present
The theory of island biogeography combines what two common patterns in nature?
species-area relationship
species-isolation relationships
Species-area relationship
as area increases, so does species richness (levels off eventually)
species-isolation relationships
the greater the distance form the mainland, the lower the number of species that arrive at a new location
Ecological biogeography
early studies of ecological determinants of distributions; emphasizes recent correlates of current distributions
Historical biogeography
integration of Earth history and phylogenetic relationships with ecological biogeography
Consideration of _____ critical for recognizing historical effects in addition to recent ecological effects
phylogenetics
niche conservatism
closely related species maintaining ecologically similar traits
niche evolution
divergence in ecological traits; “use something new”
Endemism
restriction of species to a particular area
Disjunct populations
occurrence in different areas with gaps in between
Vicariance
fragmentation of ancestral distribution by formation of geographic barriers
Dispersal
migration of organisms across pre-exisiting barriers
Area cladogram
phylogeny diagram of areas
Assumptions of vicariance
- biotas geographically static
- geological events create barriers
- biotas diverge after separation by barriers
Dispersal Theory
- lineages have a center of origin
- lineages disperse from center of origin across barriers
Dispersal is common within ______ . Dispersal to ___ infrequent, but known to occur.
land masses; islands
_____ are responsible for many dispersal events
humans
Correspondence between distributions and phylogenetic divergences indicate _______.
vicariances
Many kinds of barriers can result in vicariance:
continents, mountains, rivers, ecological transitions, etc.
Phylogeography
the study of the historical processes that may be responsible for the contemporary geographic distributions of individuals
Historical biogeography and phylogeography founded on principle that:
Earth and life evolved together
Conservation Biology
a synthetic discipline addressing the dynamics and problems of perturbed species, communities, and ecosystems.
Managing endangered species, addressing effects of human influence on populations, and habitat restoration are all aspects of:
conservation biology
Why has conservation biology not been very successful?
- governments view growth as positive (human population)
- unsustainable resource use (using it fast)
- global climate change
Major focus of conservation biology is the maintenance and preservation of _______.
biodiversity
Biodiversity
variety of living organisms at all levels of organization and the variety of habitats and ecosystems (and processes therein)
3 common measures of Biodiversity:
- ecosystem
- genetic
- species
Genetic diversity
the gene pool of a population
Alpha diversity
number of species in a community or habitat
Beta diversity
difference/change in species number along an environmental gradient
Gamma diversity
difference/change in species composition among similar habitats in different areas
Community/Ecosystem Diversity
number of species associations or communities throughout an entire naturally occurring or artificially defined gradient
Extinction
the permanent loss of a species (or gene, or lineage)
Background extinction rate
the number of species appearing is slightly higher than the number disappearing
Effects of habitat loss
- direct effect
- edge effect
Direct effect
species disappear from area (effects extend beyond the edges of lost habitat)
Edge effect
changes in community structures hat occur at the boundary of two ore more habitats
Effects of pollution are not always obvious. When does action occur?
action is rarely preventative, usually occurs with an impending crisis or in the midst of one.
Atrazine
- chemical contaminant
- compelling evidence of hormonal interruptions in amphibians
- EPA allows 3.0 ppb in drinking water
- effects studied in frogs by Tyrone Hayes
Environmental acidification (acid rain)
- arises from the combustion of fossil fuels and the release of Sulfur and Nitrogen Oxides into the air
- reacts with moisture to produce sulfuric acid and nitric acids and are returned to earth by snow or rainfall
Ecoestrogens
estrogen-mimicking chemicals produced by plants and fungi (defense compounds)
Fibropapillomatosis
-tissue-proliferation legions that interferes with organ function and reduces ability of turtles to escape enemies and find food
Overexploitation
Tragedy of the commons: when multiple individuals act in their own self-interest contrary to the common good, resources will be overexploited
Wildlife harvesting
legal or illegal capture of wildlife for human use
Sustainable use
allows the limited harvest of a population, providing that the portion of the population remaining is able to reduce and maintain itself
Fate of sustainable use programs depnds on:
how accurately biologists can assess reproductive potential and demography of each population in order to accurately track number captured
What has been an effective management tool for hunted populations when special interests do not override the recommendations of the biologists?
quotas
Exotic species
species that are non-native and introduced (intentionally or not)
Issues with exotic species
- can have very detrimental effects on native flora and fauna
- often accompany human habitat alteration, separating effects of each can be quite difficult
- bring their own diseases with them
- local populations have not evolved alongside these diseases
