Geoscience Reference
In-Depth Information
Colwell. et. al.. (2008). used. the. elevational. ranges. of. 1902. plant. and. insect. species.
over.a.30-.to.2900-m.gradient.in.Costa.Rica.to.show.that.mountaintop.extinctions.
were. unlikely. over. 0-5°C. warming. (equivalent. to. 0-. to. 1000-m. upslope. shifts. in.
isotherms)..However,.for.2-3°C.warming.(400-.to.600-m.isotherm.shifts),.50-80%.
of.epiphytes,.Rubiaceae,.and.ants.and.10-20%.of.moths.would.need.to.shift.their.
distributions. upslope. to. elevations. not. overlapping. with. their. current. range.. Such.
range-shift.gaps.may.be.particularly.likely.in.the.Tropics,.where.lower.variation.in.
ambient.temperature.than.at.temperate.latitudes.may.select.for.narrower.thermal.tol-
erance,.and.hence.narrower.elevational.ranges.(Janzen.1967;.Ghalambor.et.al..2006)..
Lowland.biotic.attrition.was.also.predicted.to.affect.30-80%.of.taxa.analyzed,.given.
a.500-m.isotherm.shift..As.a.result,.Colwell.et.al..(2008).predict.that.“tropical.low-
land.biotas.may.face.a.level.of.net.lowland.biotic.attrition.without.parallel.at.higher.
latitudes. (where. range. shifts. may. be. compensated. for. by. species. from. lower. lati-
tudes).”.Although.there.is.an.opportunity.at.temperate.latitudes.(which.does.not.exist.
in. the. tropical. lowlands). for. warm-adapted. species. to. colonize. communities. from.
which.cool-adapted.species.are.lost,.the.existing.evidence.for.butterly.communities.
in.central.Spain.suggests.that.the.barriers.to.colonization.caused.by.lack.of.habitat.
availability.may.either.delay.or.prevent.this.replacement.from.occurring.(Wilson.et.
al..2007)..Hence,.lowland.biotic.attrition.may.be.a.consequence.of.climate.change.
at.a.wide.range.of.latitudes..Natural.habitats.need.to.be.protected.across.elevational.
ranges.to.allow.species.to.shift.their.distributions.uphill.as.the.climate.warms,.but.
protection.of.surrounding.lowland.habitats.may.be.critical.to.prevent.species.rich-
ness.declines.in.mountain.foothills.(Chen.et.al..2009).
It. is. by. no. means. certain. that. species. will. uniformly. maintain. their. thermal.
associations. as. the. climate. warms,. which. is. one. assumption. underlying. climate.
envelope.models.of.future.ranges..However,.if.species'.elevational.ranges.in.dif-
ferent.parts.of.their.geographic.distributions.show.similar.thermal.associations,.
this.could.support.the.validity.of.climate.envelope.predictions.by.implying.lim-
ited. local. thermal. adaptation.. Thermal. associations. of. butterlies. in. the. Sierra.
de. Guadarrama. (central. Spain). signiicantly. predicted. the. elevational. ranges. of.
the. same. species. elsewhere. in. central. and. northern. Spain,. but. were. much. more.
reliable. for. abundant. species. with. clearly. deined. elevational. ranges. than. for.
more. localized. or. less. abundant. species,. for. which. local. differences. in. habitat.
or.interacting.species.are.likely.to.play.a.key.role.(D..Andrés,.D..Gutiérrez,.and.
R..J..Wilson,.unpublished.data)..Comparisons.of.this.kind.among.the.elevational.
ranges.of.species.in.different.regions.could.help.to.identify.ecological.characteris-
tics.of.species.affecting.the.reliability.of.climate.envelope.approaches.to.modeling.
future.distributions.
Species.are.likely.to.show.individualistic.responses.to.climate.warming,.depend-
ing.on.the.roles.of.climate,.habitat,.and.interacting.species.in.limiting.their.distribu-
tions..Recent.documented.shifts.in.elevational.ranges.vary.widely.among.species.in.
the.same.communities.(e.g.,.Wilson.et.al..2005.[Table 3];.Le.Roux.and.McGeoch.
2008;.Moritz.et.al..2008;.Raxworthy.et.al..2008;.Bergamini.et.al..2009)..Given.the.
strong. evidence. that. species. are. generally. shifting. upslope,. the. challenge. now. is.
to. understand. the. heterogeneity. of. species. responses. and. the. implications. of. the.
changes. in. community. composition. that. follow.. Evidence. of. the. mechanisms. that.
