Species PoolsSpecies Pools

Bio 255 SeminarBio 255 Seminar

Species PoolsSpecies Pools

What is a species pool?What is a species pool?

Species PoolsSpecies Pools

What is a species pool?What is a species pool? Is there a species pool Is there a species pool

hypothesis?hypothesis?

Species PoolsSpecies Pools

What is a species pool?What is a species pool? Is there a species pool Is there a species pool

hypothesis?hypothesis? Can regional species pools be Can regional species pools be

defined?defined?

What is a pool of species?What is a pool of species?

““PoolPool can be deathtrap for our can be deathtrap for our native native speciesspecies””

““These organisms are the These organisms are the ‘obligate’ vernal ‘obligate’ vernal pool speciespool species, so , so called because they must use a called because they must use a vernal pool for various parts of vernal pool for various parts of their life cycle. ...their life cycle. ... ‘ ‘

The species pool defined.The species pool defined.

““the set of species that are the set of species that are potentiallypotentially capable of coexistingcapable of coexisting in a in a particular community” (particular community” (M. Zobel 1997 M. Zobel 1997 TREETREE))

““the the limitedlimited set of species capable of set of species capable of growing under growing under certain habitat certain habitat conditionsconditions within a within a territoryterritory” (” (Partel et al. Partel et al.

1996 1996 OikosOikos))

Working definitionsWorking definitions

From M. Zobel 1997

Regional Pool: the set of species occurring in a certain region that is capable of coexisting in the target community

A region is a reasonably large area of the Earth’s surface, with a more or less uniform physiography and climate, from which species are expected to reach the target community, and for which there exists a proper list of its flora.

A target community is a plant community bound to a certain set of environmental conditions that provide appropriate ecological niches for the occurring species

Working definitionsWorking definitions

From M. Zobel 1997

Local Pool: the set of species occurring in the landscape around a target community that is capable of coexisting in that community. These species are able to migrate to the community relatively rapidly (~within a few years)

Actual pool: the set of species present in a target community

Zobel’s pool filtersZobel’s pool filters

From M. Zobel 1997

Origins of the Species Pool HypothesisOrigins of the Species Pool Hypothesis

r/K r/K 19671967

C-S-R C-S-R 19741974

Habitat Templet Habitat Templet 19831983

Grime’s triangle and the Grime’s triangle and the Southwood-Greenslade Habitat TempletSouthwood-Greenslade Habitat Templet

Species Pool HypothesisSpecies Pool Hypothesis Taylor, Aarssen & Loehle Taylor, Aarssen & Loehle 19901990

• ““On the relationship between r/K selection and On the relationship between r/K selection and environmental carrying capacity: a new habitat environmental carrying capacity: a new habitat templet for plant life history strategies”templet for plant life history strategies”(Oikos (Oikos 58:239-250)58:239-250)

Taylor et al.’s Taylor et al.’s “species pool “species pool hypothesis”hypothesis”

Is the species pool hypothesis testable?Is the species pool hypothesis testable?

Partel et al. Partel et al. (1996)(1996) devised null devised null hypotheses based upon the fact that hypotheses based upon the fact that inevitably regional diversity must inevitably regional diversity must increase with local diversityincrease with local diversity• HoHo11–any size of the actual species pool –any size of the actual species pool

is equally probable in the interval is equally probable in the interval between zero and the regional species between zero and the regional species poolpool

• HoHo22-any value of species richness per -any value of species richness per unit area is equally probable in the unit area is equally probable in the interval between zero and the size of interval between zero and the size of the actual species poolthe actual species pool

Defining a regional pool of speciesDefining a regional pool of species

Regional flora listsRegional flora lists

Ellenberg indicator values Ellenberg indicator values (Pärtel 1996; Dupre (Pärtel 1996; Dupre 2002; Ewald 2003)2002; Ewald 2003)

Empirical assessment of viability or Empirical assessment of viability or occurrence occurrence (Gough et al. 1994; Weiher & Keddy 1995; (Gough et al. 1994; Weiher & Keddy 1995; Peet et al. 2003)Peet et al. 2003)

Microcosms Microcosms (Fox et al. 2000)(Fox et al. 2000)

PPäärtel rtel (Ecology 2002)(Ecology 2002)

Related soil pRelated soil pHH to plant species to plant species richness to infer species pool effectrichness to infer species pool effect

If the local species pool was biased If the local species pool was biased toward the ptoward the pHH of the dominant soil of the dominant soil type during recent evolutionary type during recent evolutionary history, then the regional species pool history, then the regional species pool was likely affecting local richness.was likely affecting local richness.

PPäärtel rtel (Ecology 2002)(Ecology 2002)

Results from meta-analysis:Results from meta-analysis:• 38/47 high p38/47 high pHH evolutionary centers evolutionary centers

showed a positive relationshipshowed a positive relationship• 21/34 low pH evoultionary center 21/34 low pH evoultionary center

exhibited a negative relationshipexhibited a negative relationship Although only 45 of these 81 relationships Although only 45 of these 81 relationships

were significant. (It was not specified with were significant. (It was not specified with respect to which of the above were respect to which of the above were significant; just that 35 were positive and 10 significant; just that 35 were positive and 10 were negative)were negative)

Hillebrand &Blenckner Hillebrand &Blenckner (Oikos 2002)(Oikos 2002)

Can local vs. regional richness plots be Can local vs. regional richness plots be used to interpret ecological vs. regional used to interpret ecological vs. regional processes?processes?• Suggest that body size and its relation to Suggest that body size and its relation to

dispersal limitation may bias some studies dispersal limitation may bias some studies toward a linear (unsaturated) relationship.toward a linear (unsaturated) relationship.

• Argue that spatial autocorrelation is too strong Argue that spatial autocorrelation is too strong to ignore when local areas are large or makeup to ignore when local areas are large or makeup a large proportion of the defined region.a large proportion of the defined region.

Hillebrand &Blenckner Hillebrand &Blenckner (Oikos 2002)(Oikos 2002)

Results from meta-analysis:Results from meta-analysis:• Body size does not seems to drive linear Body size does not seems to drive linear

relationships between local and regional relationships between local and regional diversity as proposeddiversity as proposed

• Local sampling size seems to bias local Local sampling size seems to bias local vs. regional plots as suspectedvs. regional plots as suspected

• Local vs. regional plots are a poor way of Local vs. regional plots are a poor way of getting at local ecological processes and getting at local ecological processes and their common application lacks a good their common application lacks a good method for differentiating between local method for differentiating between local and regional effectsand regional effects

Discussion…Discussion…