Geoscience Reference
In-Depth Information
ecosystems.(Lovejoy.and.Hannah.2005)..Predictions.of.future.range.shifts.have.relied.
on.a.variety.of.modeling.approaches,.some.of.which.are.more.accurate.than.others.
Relatively. few. studies. have. attempted. to. model. the. potential. future. impacts. of.
climate.change.on.amphibians.(e.g.,.Araújo.et.al..2006;.Thomas.et.al..2004;.Lawler.
et.al..2010)..The.studies.that.have.been.conducted.generally.make.use.of.bioclimatic.
models.to.predict.climate-driven.shifts.in.the.potential.ranges.of.species..Bioclimatic.
models.deine.the.current.distribution.of.a.species.as.a.function.of.current.climate.
and. then. project. future. potential. ranges. based. on. projected. future. climate. data.
(Pearson.and.Dawson.2003;.discussed.in.Lawler.et.al..2006,.2010)..These.models.
are.generally.good.for.projecting.potential.continental-scale.responses.of.species.to.
climate.change..However,.these.models,.in.general,.do.not.take.evolution.or.biotic.
interactions.into.account,.even.though.there.is.some.empirical.evidence.that.evolu-
tion.is.responsive.to.climate.variation.(Skelly.et.al..2007)..Although.climate.is.likely.
to.be.the.dominant.driver.of.species.distributions.at.broad.scales,.interactions.with.
competitors,.predators,.prey,.and.other.species.may.inluence.ranges.even.at.broad.
scales..The.ability.of.a.bioclimatic.model.to.capture.the.range.of.a.species.depends.
in.part.on.whether.the.climate.variables.used.in.the.model.act.as.adequate.surrogates.
for.these.biotic.interactions.and.whether.the.relationships.between.climate.and.the.
biotic.factors.are.conserved.in.a.changing.climate..Despite.these.limitations,.biocli-
matic.modeling.is.a.powerful.tool.that.provides.a.irst.approximation.of.how.species.
might.respond.to.climate.change.at.broad.scales.
Lawler. et. al.. (2010). used. a. set. of. bioclimatic. models. to. assess. the. relative. vul-
nerability. of. amphibians. to. climate. change. throughout. the. Western. Hemisphere..
The.bioclimatic.model.projections.provide.a.general.indication.of.where.changes.in.
amphibian.faunas.might.be.expected.to.occur.over.the.coming.century..Lawler.et.al..
(2010).supplemented.these.projections.with.two.other.analyses..First,.they.mapped.
the.distributions.of.1099.restricted-range.species.for.which.they.were.unable.to.build.
accurate. bioclimatic. models.. Many. of. these. species. likely. occupy. very. narrowly.
deined.niches.and.thus.may.be.more.vulnerable.to.changes.in.climate..Second,.they.
mapped.projected.climatic.changes.for.the.Western.Hemisphere..They.mapped.areas.
that.were.consistently.projected.to.get.both.warmer.and.drier..Such.climatic.changes.
have.the.potential.to.adversely.affect.amphibian.populations.and.thus.alter.distribu-
tions..By.combining.the.range-shift.projections,.restricted-range.species.distribution.
maps,.and.climate.projections,.Lawler.et.al..(2006).highlighted.areas.in.which.cli-
mate.change.may.have.large.impacts.on.amphibians.
Using. this. three-part. vulnerability. assessment,. Lawler. et. al.. (2010). con-
cluded. that. some. of. the. greatest. impacts. to. amphibian. populations. will. likely.
occur.in.Central.America..Several.areas.in.this.region.have.high.concentrations.
of. restricted-range. species. and. are. simultaneously. projected. to. get. hotter. and.
drier. and. to. experience. high. rates. of. species. turnover.. Other. portions. of. the.
hemisphere.were.projected.to.experience.either.one.or.two.of.these.factors..For.
example,. although. the. Caatinga. region. in. northeastern. Brazil. was. projected. to.
experience.relatively.little.species.turnover.and.harbors.relatively.few restricted-
range. species,. it. was. consistently. projected. to. experience. decreases. in. pre-
cipitation.. Although. the. analysis. of. Lawler. et. al. (2010). included. three. ways. in.
which.amphibians.might.be.vulnerable.to.climate.change,.there.are.several.other.
