Geoscience Reference
In-Depth Information
Franco.et.al..2006;.Merrill.et.al..2008).(Table 6.2)..In.other.studies,.models.for.popu-
lation.survival.versus.extinction.that.show.signiicant.effects.of.altitude.once.habitat.
effects.have.been.accounted.for.also.imply.an.inluence.of.climate.change.on.extinc-
tion.risk.(Beever.et.al..2003;.Epps.et.al..2004)..In.contrast,.for.three.high-latitude/-
elevation.butterly.species.studied.by.Franco.et.al..(2006),.extinctions.were.largely.
recorded.from.locations.where.suitable.host.plants.were.no.longer.present..A.study.
of.the.fen.plant.
Swertia perennis
in.northern.Switzerland.found.that.the.low.elevation.
limit.had.increased,.but.that.low-elevation.sites.were.now.managed.unsuitably.for.the.
species.(Lienert.et.al..2002)..In.these.two.cases,.climate.conditions.may.now.be.less.
suitable.for.species.at.low.elevations,.but.direct.effects.of.habitat.degradation.may.be.
the.major.driver.of.local.extinctions.
Uphill. range. expansions. can. also. be. identiied. by. sampling. suitable. habitats. or.
host.plants.for.species.above.their.recorded.elevation.range:.when.suitable.host.spe-
cies.or.habitats.were.also.present.beforehand,.climate.change.is.likely.to.have.pro-
moted.the.range.extension.(Battisti.et.al..2005,.2006;.Dahlhoff.et.al..2008).
MECHANISMS BEHIND UPHILL RANGE SHIFTS
Further.support.for.the.role.of.climate.change.in.driving.range.shifts.is.provided.by.
research.identifying.the.mechanisms.responsible.for.distribution.change.
Population. extinctions. at. low. elevations. in. the. butterly.
E. editha
have. been.
linked. to. drier. and. less. predictable. rainfall. conditions,. which. affect. rates. of. lar-
val.host-plant.senescence.and.larval.mortality.(McLaughlin.et.al..2002;.Parmesan.
2005)..Translocation.of.egg.batches.for.the.butterly.
Aporia crataegi
in.central.Spain.
showed.that.summer.egg-hatch.and.larval.survival.increased.with.elevation,.suggest-
ing.that.populations.may.no.longer.be.able.to.survive.at.elevations.below.900.m,.even.
though.host-plant.species.remain.(Merrill.et.al..2008)..Herptile.extinctions.in.Costa.
Rica.have.been.linked.to.increasingly.dry.conditions,.and.to.uphill.range.expansions.
of.the.fungus.
Batrachochytrium
.
dendrobatidis
,.which.causes.the.disease.chytridio-
mycosis.in.amphibians.(Pounds.et.al..1999,.2006)..Temperatures.at.high.elevations.
may. be. shifting. toward. the. growth. optimum. for.
B. dendrobatidis
. (Pounds. et. al..
2006;.but.see.Rohr.et.al..2008.for.a.challenge.to.this.hypothesis),.and.infections.have.
been.recorded.up.to.5348.m.in.anuran.populations.on.recently.deglaciated.terrain.
in.the.Andes.(Seimon.et.al..2007)..For.the.Brown.Trout.
Salmo trutta
,.a.quantitative.
physiological.model.for.the.effects.of.water.temperature.on.population.size.was.used.
to.show.that.the.thermal.habitat.range.for.the.species.shifted.uphill.by.130.m.because.
of.0.1-1.1°C.increases.in.water.temperature.between.1978-1987.and.1988-2002.in.
Switzerland.(Hari.et.al..2006)..The.proportion.of.
S. trutta
.infected.by.temperature-
dependent.proliferative.kidney.disease.also.decreased.with.elevation..For.this.spe-
cies,. all. populations. below. 600. m. were. declining. before. 1987,. yet. all. populations.
below.1000.m.have.declined.following.rapid.warming.since.1987.
Fecundity.and.recruitment.can.also.decline.at.low.elevations.because.of.increased.
temperatures,.as.shown.for.the.beech.
Fagus sylvatica
.at.its.low-elevation.limits.in.
northeast.Spain.(Pẽuelas.and.Boada.2003)..However,.temperature.increases.do.not.
always.lead.to.reductions.in.fecundity.at.low-latitude.or.-elevation.range.margins;.if.
there.is.a.bell-shaped.physiological.response.to.temperature,.the.response.to.warming.
