Geoscience Reference
In-Depth Information
to. climatic. change,. such. that. a. population. can. persist. in. a. newly. unsuitable. area,.
has.long.been.thought.to.be.a.slow.process..Therefore,.the.very.rapid.(in.terms.of.
geologic.time).changes.we.are.now.experiencing.will.be.unlikely.to.allow.for.novel.
adaptive.response.(Etterson.and.Shaw.2001;.Jump.and.Pẽuelas,.2005;.Parmesan,.
2006)..It.is.possible.that.strong.selection.may.favor.existing.genotypes.that.are.more.
plastic.or.tolerant.to.an.altered.climate,.but.asymmetric.gene.low.from.range.core.
to.range.edges.may.inhibit.the.rate.and.amount.of.local.adaptation..Because.many.
mammals,.especially.larger.ones,.have.relatively.long.generation.times.and.are.capa-
ble.of.signiicant.dispersal,.it.is.unlikely.that.adaptive.evolutionary.responses. will.
be.common.
If.adaptation.is.indeed.unlikely,.then.the.probability.of.dispersal.versus.extinc-
tion.is.dependent.on.a.set.of.factors:.the.dispersal.capability.and.habitat.specializa-
tions.of.the.mammal.in.question.(Warren.et.al..2001),.its.physiological.tolerance.for.
climatic.conditions.(Walther.et.al..2002;.Root.et.al..2003),.and.the.rate.and.magni-
tude.of.climate.change..Broadly.tolerant.and.highly.vagile.species.may.be.the.least.
likely. to. show. range. collapse. in. response. to. rapid. and. signiicant. climate. change,.
while.narrowly.tolerant.and.poorly.dispersing.species.are.likely.prone.to.rapid.local.
extinctions.and.potential.range.collapse.(Warren.et.al..2001;.Walther.et.al..2002)..In.
addition. to. the. obvious. impacts. of. species. tolerance. and. climatic. trends. on. mam-
malian.range.response,.a.fourth.main.factor.controlling.species.response.to.climate.
change.less.discussed.in.the.literature.is.topographic.habitat.heterogeneity,.a.topic.
to.which.we.turn.in.the.following..While.we.do.recognize.the.importance.of.land-
scape.changes.and.the.interacting.effects.of.landscape.change.and.climate.change.
in.relation.to.colonization-extinction.dynamics,.we.instead.focus.here.primarily.on.
climatic.changes..The.major.factors.affecting.mammal.response.to.climate.change.
are.summarized.in.Table.5.1.for.easy.reference.
T
he
i
mporTanCe
of
T
opographiC
h
eTerogeneiTy
Guralnick. (2006a,. 2006b). discussed. the. importance. of. topographic. heterogeneity.
as.a.factor.in.mammal.distributional.response.to.climatic.warming..He.argued.that.
animals.living.in.mountainous.regions.might.respond.to.warming.by.preferentially.
moving. along. elevational. gradients. as. opposed. to. latitudinal. gradients.. Climate.
can. quickly. change. along. steep. elevational. gradients,. thus. providing. mammals.
with. much. shorter. dispersal. distances. to. favorable. climatic. conditions. than. along.
TABLE 5.1
Factors That Affect Mammalian Response to Climatic Changes
Key Abiotic Factors
Key Biotic Factors
•. Magnitude.of.local.climatic.change
•. Thermal.physiology.of.species
•. Rate.of.local.climatic.change
•. Ability.to.behaviorally.thermoregulate
•. Habitat.availability.and.topographic.heterogeneity.
locally.and.across.the.range.of.the.species
•. Dispersal.capability.of.species
•. Habitat.specialization.of.species
