Geoscience Reference
In-Depth Information
as.the.elevation.within.which.climate.was.appropriate.for.pinyon-juniper.woodland.
and.therefore.was.appropriate.for.montane.butterlies.(taxa.believed.to.complete.their.
entire.life.cycle.in.mountain.ranges.and.not.found.in.nearby.valleys)..More.recent.data,.
derived.from.remote.sensing.and.ield.measurements,.demonstrates.that.the.elevational.
boundaries.of.pinyon-juniper.woodland.are.highly.variable.both.within.and.among.
mountain.ranges.(Bradley.and.Fleishman.2008;.Fleishman.and.Dobkin.2009).
Assumptions.similar.to.those.for.the.Great.Basin.(Murphy.and.Weiss.1992;.Boggs.
and.Murphy.1997).have.been.made.elsewhere..As.mean.annual.temperature.in.cen-
tral.Spain.rose.by.1.3°C.over.30.years,.the.mean.lower.elevational.limit.of.16.species.
of.butterlies.increased.by.212.m.(Wilson.et.al..2005)..Wilson.et.al..(2005).estimated.
that.the.mean.geographic.range.of.the.species.decreased.by.approximately.33%.as.
a.result..But.many.montane.species.inhabit.lower.elevations,.and.each.species.is.not.
distributed. uniformly. across. higher. elevations. (Fleishman. et. al.. 1998).. Vegetation.
and.thermal.zones.are.patchy,.relecting.topographic.variation.in.microclimate.and.
land-use.history,.and.are.highly.unlikely.to.simply.move.upward.across.entire.moun-
tain. ranges.. Not. only. erroneous. assumptions. about. vegetation,. but. empirical. data.
on.the.elevational.ranges.of.individual.species.of.butterlies.(Fleishman.et.al..1998).
suggest. the. inference. that. 20-50%. of. the. species. in. a. given. mountain. range. were.
likely.to.be.extirpated.(Murphy.and.Weiss.1992;.Boggs.and.Murphy.1997).likely.is.
too.high.
Regional. extirpations. of. butterlies. for. which. robust. data. exist. often. have. been.
driven.by.disruptions.to.metapopulation.dynamics..The.distributions.of.most.species.
are. patchy,. relecting. disjunct. distributions. of. abiotic. and. biotic. attributes. of. their.
habitat. as. well. as. barriers. to. dispersal. and. stochastic. factors.. Accordingly,. simple.
latitudinal. or. elevational. shifts. in. range. are. unlikely..
E. editha
. is. cited. widely. as.
evidence.of.range.shifts.in.response.to.climate.change..Parmesan.(1996).resurveyed.
151. sites. in. western. North. America. from. which. the. species. previously. had. been.
recorded.. Sites. where. necessary. resources. for. the. species. (e.g.,. larval. host. plants).
no.longer.existed.were.excluded.from.analysis..Consistent.with.expectations.of.cli-
mate-driven. shifts. in. the. distribution. of. the. species,. the. incidence. of. extirpations.
fell. as. both. latitude. and. elevation. increased.. Disappearances. of. populations. were.
more.frequent.at.lower.latitudes.and.elevations..But.the.analysis.did.not.account.for.
geographically. correlated. life-history. variation,. or. loss. or. conversion. of. habitats..
Low-elevation.populations.of.
E. editha
.generally.feed.on.annual.plants,.the.avail-
ability.of.which.is.relatively.unpredictable,.whereas.populations.at.higher.elevations.
feed.on.perennials..The.low-elevation.populations.inhabit.areas.that.are.more.likely.
to.have.been.invaded.by.non-native.annual.grasses.or.urbanized,.both.of.which.may.
or.may.not.be.driven.by.climate.change..A.number.of.the.lowest.latitude.sites.were.
in.northern.Mexico,.where.land.use.was.especially.intense.
Changes.in.climate.across.extensive.areas.vary.in.their.effects.on.different.popu-
lations.of.the.same.species..In.the.southern.part.of.its.distributional.range,.
E. editha
.
is.believed.to.have.been.historically.abundant.and.widely.distributed..These.popula-
tions.oviposit.on.a.native.annual.
Plantago
that.varies.in.abundance.as.a.function.of.
precipitation..A.series.of.drought.years.that.both.decrease.abundance.and.accelerate.
senescence.of.
Plantago
.increases.the.probability.of.local.extirpation.of.the.butter-
ly.. A. series. of. years. with. relatively. high. precipitation,. by. contrast,. typically. are.
