Geoscience Reference
In-Depth Information
associated. with. large. populations. of. larvae. that. locally. defoliate. their. host. plants.
(Murphy.and.White.1984)..The.frequency.with.which.
E. editha
.recolonize.patches.
of.habitat.after.extirpation.events.has.decreased.because.of.the.establishment.of.non-
native.annual.plants.in.former.patches.of.habitat.after.ire.events.and.local.decreases.
in.abundance.of.
Plantago
..The.remaining.patches.of.habitat.are.increasingly.isolated.
and.often.are.fragmented..Given.these.conditions,.drought.increases.the.probability.
of.regional.as.well.as.local.extirpation.of.the.butterly.
A.second.set.of.
Plantago
-feeding.populations.of.
E. editha
.that.once.likely.was.
widespread.across.much.of.central.California.now.is.restricted.to.a.relatively.small.
number.of.patches.of.grasslands.on.serpentine-based.soils..These.soils.impede.colo-
nization. by. non-native. annual. grasses.. However,. because. serpentine-based. soil. is.
porous,.
Plantago
.senesces.relatively.early,.especially.on.south-facing.slopes..When.
temperature. increases. and. precipitation. decreases. even. modestly,. recolonization.
of.these.locations.following.extirpation.becomes.less.frequent.(Murphy.and.Weiss.
1989).
Females. from. a. population. of.
E. editha
. just. east. of. the. Sierra. Nevada. once.
oviposited. nearly. exclusively. on.
Collinsia parvilora
,. a. native. annual. plant. that.
grows.in.the.understory.beneath.sagebrush.(
Artemisia
.spp.).and.mixed.coniferous.
woodland..In.response.to.a.decrease.in.abundance.and.earlier.senescence.of.
C.
parvilora
.over.a.decade,.the.butterly.began.to.oviposit.almost.exclusively.on.non-
native.
Plantago lanceolata
.in.a.nearby.patch.of.grassland.(Thomas.et.al..1987)..
Recent.reduction.in.the.intensity.of.local.grazing.by.domestic.livestock.reduced.
the. abundance. of.
Plantago
. and. facilitated. colonization. by. other. grasses,. which
shaded. surviving.
Plantago
.. As. a. result,. habitat. quality. for.
E. editha
. decreased..
Abundance. of. the. butterlies. decreased. considerably,. and. no. individuals. have.
been.detected.for.several.years..It.appears.that.a.shift.by.ovipositing.females.to.
the. use. of. a. novel. species. of. host. plant. prevented. a. potential. weather-induced.
extirpation. event,. yet. another. change. in. habitat. quality. resulted. in. extirpation.
(Singer.et.al..2008).
AN IDEAL SCHEME FOR TRACKING THE EFFECTS
OF CLIMATE CHANGE ON BUTTERFLIES
Inference.on.the.responses. of.butterlies. to.climate. change. has.been. based.on.ret-
rospective.analysis.of.time-series.data.rather.than.studies.designed.explicitly.to.test.
competing. hypotheses. about. the. potential. effects. of. shifts. in. climate. versus. other.
environmental.stressors..Two.criteria.must.be.satisied.for.one.to.infer.that.changes.
in. climate. are. driving. changes. in. the. distribution. or. population. dynamics. of. but-
terlies..First,.data.on.the.butterlies.and.climatic.variables.must.be.available.across.
extensive.areas.and.many.years..Second,.one.must.understand.mechanistically.how.
climate.changes.can.affect.individuals.and.populations.
If.one.is.focused.on.potential.assemblage-level.signals.of.climate.change,.it.may.
be. most. valuable. to. examine. multiple. butterly. species. with. different. predicted.
responses.to.climate.change..This.criterion.was.largely.met.by.Forister.et.al..(2010),.
who. reported. annual. occurrence. data. from. multiple. sites. across. an. elevational.
