Populations - Community Evolution Flashcards
What may allow predator coexistence?
Niche differentiation, evolutionary forces driving competition avoidance.
Competition varies with…
Taxon, habitat and trophic level
How does interspecific competition influence community structure>
Niche differentation by comeptito
Character displacement
How does niche differentiation express mostly?
Resource use, within a single habitat or microhabitats
Niche Complementarity
Is where coexisting speceis use different forms of a resource
Guild
A group of species exploiting the same resource, or exploit different resources in related ways
Example of a guild…
Tropical borneo trees with different light tolerances differentiating along soil gradients based on nutrition.
Unified Neutral Theory
Explains diversity and relative abundance of species in ecological communities
Theoretical situation of unified neutral theory…
A local communtiy of interest within a metacommunity, providing a mix of well-sourced immigratns, containing fixed number of individuals(one dies-one born)
Unified Theory population migration…
Depends on relative spatial distributions not on individuals characterisitscs..
Unified Theory metacommunity migration…
Driven by random death and birth except immigration in the form of speciation in this case
Importance of unified neutral theory despite unrealism?
Allow outlook of a world of which this were the case allowing interpretations of deviations of particular characteritis.
Species Abundance Distribution
Describes the full distribution of commonness and rarity in ecological systems.
Hutchinsons rule
This is the ratio of size differences between simialr species when they are living together as compared to when they are isolated
Theory of Limiting Similarity
States that coexistence between species is more limited by competitive exclusion when species share niche properties.
Example of hutchinsons rule…
Different species may consume different size prey, thus niche differentiation manifesting as morphological differences.
Null Models
Are a random object that match on specific object in some of its features
Evidence for interspecific competition…
Distribution patterns - (memebrs mutually exclusive but distributions so any one islands supports only one of the species
Null model for interspecific competition….
Comapre patterns of species co-occurences at a locations with what would be expected if each species were distributed at random with excess of negative associations.
Intransitive Competition
Where there is no single best competitor
Intransitive Competition
Just because species A outcompetes B and B outcompetes C, does not mean A outcompetes C
Example of outcompetition in Intransitive?
Allelechemicals.
Importance of Intransitive Competition in structure…
Allowing co-existence as not one species can out compete all others
Geometries of predation interacitons…
A diamond shape module where preadtor preys on two prey species, also sharing a common resource.
Exampel of predator diamond module?
Omnivores preying on more than one of the lower trophic levels, maybe linked by predator-prey interactions.
Most common effect of predation on structure?
Removal of prey
Example of predation effect on structure…
Parasitism of endemic bird fauna on Hawaiian islands, attributed partly to bird pathogens
Predator-Mediated Coexistence
The increase of species diversity of by a predator in comeptitve communties.
Janzen-Connell Hypothesis
An explanation for the maintenance of tree species biodiversity in tropical rainforest.
Distance Reponsive Predator
These lower seed/seedling survival or growth near adults of their main host.
What is JC hypothesis a function of?
Host-specific predation(herbivory, pathogens) making areas near parent trees inhospitable for survival of seedlings.
What drives JC hypothesis?
Higher prey densities promoting higher predation.
When might parasite mediated coexistence occur?
Infection of multiple species where the superior competitior is differentially affected, allowing coexistence.
Example of parasite-mediated coexistence?
Red Squirrels and Grey infection by parapox viruse
What does predation effects on community depend on?
Strenghts o the links
Stress-Gradient Hypothesis
Says that psoitve interactiosn are more commonly distsributed in harsher communities due to that being the most likely way to survive.
Reasoning behind stress-gradient hypothesis…
Unproductive low resource envrionemtns more facilitation.
A caveat in stress-gradient hypothesis…
Nurse species providing shade will out-compete for water levels
