Biodiversity and biogeography of the islands of the Kuril Archipelago

14 Pages·2005·0.21 MB·English

JournalofBiogeography,30,1297–1310
Biodiversity and biogeography of the islands
of the Kuril Archipelago
Theodore W.Pietsch1*, VictorV. Bogatov2,KunioAmaoka3,Yuri N.Zhuravlev2,
Vyacheslav Y. Barkalov2,SarahGage4, HidekiTakahashi5,ArkadyS.Lelej2,Sergey Y.
Storozhenko2,Norobu Minakawa6,Daniel J.Bennett1, TrevorR. Anderson1,Masahiro
Oˆhara5,LarisaA. Prozorova2,Yasuhiro Kuwahara7, SergeyK. Kholin2,MamoruYabe3,
Duane E.Stevenson8andErin L.MacDonald1 1Schoolof Aquatic andFishery Sciences,
UniversityofWashington,Seattle,WA,USA,2InstituteofBiologyandSoilSciences,Russian
Academyof Sciences, FarEast Branch, Vladivostok, Russia, 3Laboratory of Marine
Biodiversity, Graduate Schoolof FisheriesSciences, HokkaidoUniversity, Hakodate,
Hokkaido,Japan, 4Department ofBotany,University of Washington, Seattle, WA,USA,
5HokkaidoUniversity Museum, HokkaidoUniversity, Sapporo,Japan, 6Department of
Microbiology,SagaMedicalSchool,Saga,Japan,7HokkaidoAbashiriFisheriesExperimental
Station,Abashiri,Japanand8ResourceAssessmentandConservationEngineeringDivision,
AlaskaFisheries Science Center,National MarineFisheries Service, Seattle, WA,USA
Abstract
Aim Basedonsevenconsecutiveseasonsofbioticsurveyandinventoryoftheterrestrial
and freshwater plants and animals of the 30 major islands of the Kuril Archipelago, a
description of the biodiversity and an analysis of the biogeography of this previously
little known part of the world are provided.
Location TheKurilArchipelago,anaturallaboratoryforinvestigationsintotheorigin,
subsequent evolution, and long-term maintenance of insular populations, forms the
eastern boundary of the Okhotsk Sea, extending 1200 km between Hokkaido, Japan,
andtheKamchatkaPeninsulaofRussia.Achainofmorethan56islands,thesystemis
only slightly smaller than the Hawaiian Islands, covering an area of 15,600 km2 and
providing 2409 km of coastline.
Methods Collections of whole specimens of plants and animals, as well as tissue sam-
ples for future molecular studies, were made by teams of scientists from Russia, Japan,
and the USA, averaging 34 people for each of the seven annual summer expeditions
(1994–2000). Floral and faunal similarities between islands were evaluated by using
Sorensen’s coefficient of similarity. The similarity matrix resulting from pair-wise cal-
culations was then subjected to UPGMA cluster analysis.
Results Despitetherelativelysmallgeographicalareaofallislandscombined,theKuril
Islandbiotaischaracterizedbyunusuallyhightaxonomicdiversity,yetendemismisvery
low. An example of a non-relict biota, it originated from two primary sources: a
southernsource,theAsianmainlandbywayofSakhalinandHokkaido,andanorthern
source by way of Kamchatka. The contribution of the southern source biota to the
species diversity of the Kurils was considerably greater than the northern one.
Main conclusion The Bussol Strait, lying between Urup and Simushir in the central
Kurils, is the most significant biogeographical boundary within the Archipelago. Of
lesserimportancearetwotransitionalzones,theDeVriesStraitor(cid:1)MiyabeLine(cid:2),which
passes between Iturup and Urup in the southern Kurils, and the fourth Kuril Strait,
between Onekotan and Paramushir in the northern Kurils.
*Correspondence:TheodoreW.Pietsch,SchoolofAquaticandFisherySciences,CollegeofOceanandFisherySciences,UniversityofWashington,
Box355020-5020,Seattle,WA,USA.E-mail:[email protected]
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1298 T.W.Pietschetal.
Keywords
Biodiversity, biogeography, vascular plants, mollusks, insects, fishes, mammals,
Hokkaido, Sakhalin, Kamchatka, Kuril Islands, Russian Far East.
Kuril Ridge includes the Shiretoko Peninsula of eastern
INTRODUCTION
Hokkaido,alloftheremainingKurilIslands,fromKunashir
The Kuril Archipelago is a chain of more than 56 islands, north to Shumshu, and the southern tip of the Kamchatka
onlyslightlysmallerthantheHawaiianIslands,coveringan Peninsula.
area of 15,600km2 and providing 2409km of coastline AlloftheKurilsarevolcanicinorigin,ranginginagefrom
(Fig.1).Stretching1200kmbetweenHokkaido,Japan,and UpperCretaceoustoLatePleistocene.About160volcanoes
the Kamchatka Peninsula of Russia (from 43(cid:2) to 51(cid:2)N can be counted today,40 of themcurrently active.The lar-
latitude), the Kurils divide the Sea of Okhotsk from the gest are Alaid (maximum elevation 2339m) on Atlasova
PacificOceanandformthenorthernextensionofaninsular IslandatthenorthernendofthechainandTyatya(1819m)
arcthatoriginatesintheRyukyuandMarianaarchipelagos onKunashirIslandatthesouthernend.Availablehabitatis
to the south and continues as the Aleutian Islands to the highly variable ranging from sea-level sand, rocky-beach,
northandeast.Itiscomposedoftwomainridges:theLesser and grassland to high-mountain stream/conifer forest; from
Kuril Ridge and the Greater Kuril Ridge. The Lesser Kuril deep, slow-moving lowland rivers to fast-flowing gravelly
Ridge includes the Nemuro Peninsula of eastern Hokkaido, streams; and from sphagnum bogs to high mountain lakes.
the Habomai Island group, and Shikotan, and continues to Each island has a unique geological and biological history.
the northeast as the submarine Vityaz Ridge. The Greater Substantial opportunities for in situ diversification are pro-
vided by great distances between the islands and mainland
sourcebiotas,andbysignificantbarrierstoplantandanimal
dispersal,suchasdeepchannelsbetweenislands,associated
with strongocean currents.
The island chain is bounded on each side by very deep
water. On the Pacific side, the 8000-m isobath is situated
c.145kmsoutheastofSimushirIsland,whileonthewestin
the Sea of Okhotsk the isobath of 3500m lies c. 130 km
northwestofSimushir.Incontrast,depthsbetweenadjacent
islands are relatively shallow, most not exceeding 100 m.
TheonlyexceptionistheBussolStrait,lyingnearthecentre
oftheArchipelagobetweenUrupandSimushir,whichhasa
maximumdepthof 2659m.
Although the general outlines of the flora and fauna of
the Kurils can be summarized, more detailed information
has been non-existent or unpublished; what little is avail-
able is confined to the Russian and, to a lesser extent, the
Japanese scientific literature. Prior to the work described
here, little systematic collecting had ever been carried out,
and since the close of World War II, only a few Russian
biologists had done any work of significance in this region.
With the exception of a few Russian collections (e.g. those
ofthevariousinstitutesoftheRussianAcademyofSciences
at Vladivostok, Magadan, St Petersburg, Moscow, Novo-
sibirsk and Yuzhno-Sakhalinsk), museum samples of plants
and animals originating from the Kurils have been una-
vailable and frozen tissues completely non-existent. The
biota is a mix of Japanese, Kamchatkan, and endemic
species, but the biodiversity of the islands, relative to each
otherandtothemainland,hasremainedunknown.Limited
coastal regions of several of the larger, more strategically
Figure1 TheseaofOkhotskregionintheLateWu¨rm,c.18,000–
positioned islands have been heavily impacted since the
15,000yrBP(afterBezverkhniyetal.,2002).1,recentcoastline;
2,theLateWu¨rmcoastline;3,searegions[(a)shallow, close of World War II by the construction of Russian
(b)deepwater];4,pathwaysofbioticimmigrationfromsouthern military installations, but otherwise the islands remain
andnorthernsourceareas. undisturbed (although most likely perturbated extensively
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KurilArchipelagobiodiversityandbiogeography 1299
in the recent past by indigenous peoples, i.e. maritime a total of 164 students and professionals (97 Russians,
hunters and gatherers; Fitzhugh etal., 2002). Only six 50 Americans, and 17 Japanese) helped to collect some
islands are currently inhabited. 500,000 specimens that are now archived in various insti-
Despitethelackofcomprehensivework,limitedgreatlyin tutionsofallthreenations.Taxaofmajoremphasisincluded
the recent past by political, climatic, and logistical difficul- vascular plants, aquatic and terrestrial insects, spiders and
ties,afewbiogeographicalstudiesofthefloraandfaunaof harvestmen, freshwater and terrestrial mollusks, freshwater
some of the Kuril Islands have been conducted by Japanese fishes,amphibians,andreptiles,butsignificantcollectionsof
and Russian investigators. The results of some of this work lichens, mosses, liverworts, fungi, diatoms, platyhelminths,
provide evidence for a number of significant faunal and oligochaetes,amphipods,pseudoscorpions,mites,decapods,
floral boundaries within the Archipelago that divide the water fleas, centipedes, millipedes, and marine fishes were
chain into a number of biotic regions. For example, also made. A research vessel provided by the Russian
Tatewaki(1947,1957)presentedevidenceforafloralbreak AcademyofSciences,FarEastBranch(the68.5-mProfessor
between Iturup and Urup. He named this boundary the Bogorov in 1994, 1995, and 1997; the 75.5m Academic
(cid:1)Miyabe Line(cid:2) after the famous Japanese botanist Kingo Oparin in 1996, 1998, and 1999; and the 100-m Okean in
Miyabe(1860–1951)whowasoneoftheveryfirstscientists 2000), served asa means of transportation to and from the
to study Kuril Island plants. Tatewaki’s conclusion was islands,assleepingquarters,thesourceofallmeals,andasa
quickly accepted and is now almost universally recognized floating research laboratory while at sea and when on-site.
among Japanese botanists (e.g. see Takahashi, 2001). Simi- Large rubber inflatables, equipped with 40-horsepower
larly, Takhtajan (1978, 1986), in his well-known Floristic engines, were used to transport equipment and personnel
Regions of the World, drew the boundary between the between ship and shore. On some of the larger inhabited
EasternAsiaticandCircumborealregionsthroughtheKuril islands (Paramushir, Urup, Iturup, and Kunashir), Russian
Archipelago,betweentheislandsofIturupandUrup(i.e.the military vehicles were used to move between distant col-
De Vries Strait). Considering animal distributions on lecting sites. Specific collection sites, totaling c. 6700, were
the Kurils, Semenov Tian-Shanskij (1935) recognized the selected to maximize geographical and habitat diversity.
boundary between Palearchearctic and Eurosiberian subre- Totheextentpossible,collectionsweresortedandidentified
gions of the Palearctic Region at the southern end of the aboard ship, and field data entered into a computer data
Archipelago between Hokkaido and Kunashir (see also base.Followingeachexpedition,thedataweredownloaded
Kuwayama,1967;Kryvolutskaja,1973).Inagreementwith toanIKIPwebsite(availableviahttp://www.okhotskia.ws),
Berg (1949), Takhtajan (1978, 1986), based on an analysis maintained at the University of Washington, Seattle, to
of fresh-water ecosystems, drew the boundary between the provide easy access to project results and data bases. The
Palearctic Region and an Amur-Manchurian Transitional website provides a full-text search interface to access both
Region between Iturup and Urup. Finally, Starobogatov locality and taxonomic data bases. In addition, the locality
(1970) considered a transition zone between the Palearctic data base can be accessed via maps that show survey and
Region and a Chino-Indian Region to coincide with some inventory sites. This map-based browser allows the user to
indefinitespecificsiteinthecentralKurilIslands.Inthelight click on maps to select an island, then to click on major
oftheseseveralcompetinghypotheses,aprimarygoalofthis collection areas to get a list of all collection sites for that
paper is to clarify the major patterns of biodiversity and area,and finallyto view thefull localityrecord.
biogeographyof theKuril Archipelago. IndicatortaxausedforaquantitativeassessmentofKuril
The work described here is based on a long-term pro- biodiversityandpatternsofdistributionwereselectedonthe
gramme designed to survey and inventory the biota of the basisofthefollowingfivecriteria:(1)thosetaxawithawell-
islands of the Kuril Archipelago: the International Kuril known and stable taxonomy; (2) those having a number
Island Project (IKIP), focusing primarily on plants, aquatic of contained species sufficient for mathematical analysis;
and terrestrial insects, spiders, freshwater and terrestrial (3) those containing at least some species that are broadly
mollusks, freshwater fishes, amphibians, and reptiles. distributed geographically, over a breadth of habitat types,
Having now completed seven field seasons of collecting with limited dispersal capabilities; (4) those containing at
(1994–2000), on all 30 major islands, it is now possible to least some subtaxa sensitive to habitat change and repre-
provide some general distributional and zoogeographical sented by endemic species and subspecies within the study
information. Here is a report specifically on the vascular area;and(5)thosethatoccupythemajorityoftheterrestrial
plants, insects, freshwater and terrestrial mollusks, and and/or freshwater ecosystems available on the Archipelago.
freshwaterfishes. For example, such well-known taxa as birds and marine
mammalswerenotconsideredinthisstudybasedoncriteria
3 and 4. Lists of species of indicator taxa identified in pre-
MATERIALS AND METHODS
liminary analyses of Kuril Island distribution patterns are
Collections of whole specimens of plants and animals, as provided by Kholin (1993); Kerzhner & Marusik (1996);
well as tissue samples for future molecular studies, were Mutin&Barkalov(1997);Nilssonetal.(1997);Belokobyl-
made by teams of scientists from Japan, Russia, and the skij & Tobias (1998); Mutin & Barkalov (1999); Nilsson
USA, averaging 34 people for each of the seven annual et al. (1999); Barkalov (2000); Belokobylskij & Tobias
summerexpeditions(1994–2000).Forall7yearscombined, (2000); Kupianskaya et al. (2000); Lelej & Kupianskaya
(cid:1)2003BlackwellPublishingLtd,JournalofBiogeography,30,1297–1310
1300 T.W.Pietschetal.
(2000); Lelej (2001); Marusik & Crawford (2001); Pietsch Kuril Ridge emerged from the sea. After the subduction of
etal. (2001); Barkalov (2002); Kostenko (2002); Lafer theKula–PacificRidge,avolcanichiatusensued,andthereis
(2002);Lelejet al.(2002);Marusik(2002);Prozorovaetal. no evidence of subsequent volcanic activity in the Lesser
(2002); Prozorova (2002); Shedko (2002); Storozhenko Kuril Ridge. During the hiatus of the Late Eocene and
(2002)and Teslenko (2002). Oligocene, the Okhotsk Plate was subsiding, and there is
Floralandfaunalsimilaritiesbetweenislandswereevalu- evidence that the Lesser Kuril Ridge may have been sub-
ated,withoutregardtodifferencesinislandareaordegreeof mergedduringpartofthisperiod(Kimura&Tamaki,1985;
isolationfromsourcebiotasateitherendoftheislandchain, Pietsch etal.,2001).
by using Sorensen’s coefficient of similarity: S ¼2a/ LateintheOligocene(c.30 MyrBP)theOkhotskTerrane
(2a þbþ c), where a is the number of species common to began to rotate clockwise and the backarc basin that now
bothislandsandbandcarethenumberofspeciesoccurring formsthesouthernSeaofOkhotskbegantoopentothewest
oneachoftheislands(seeLegendre&Legendre,1998).The of the Kuril Arc. During this period, volcanic activity
similarity matrix resulting from pair-wise calculations was resumed near the Kuril–Kamchatka Trench, but was con-
then subjected to single and complete linkage clustering as centrated in the location of what is now the Greater Kuril
well as unweighted arithmetic average clustering (UPGMA; Ridge.Consequently,theoldestrocksinthemainarcofthe
NTSYS program, version 1.70, Net Technology Systems, Kuril Islands are of Late Oligocene and Early Miocene age
Ecully, France). The results obtained by these approaches (Markhinin, 1968; Markov & Khotin, 1973). The backarc
being all very similar, we constructed dendrograms using basin was fully formed by Mid-Miocene. Although this
UPGMA. Cluster analysis was performed on the following periodmarksthebeginningoftheformationoftheprimary
groups: vascular plants (1194 species), terrestrial mollusks chain of the present-day Kuril Islands, sediment records
(45),freshwatermollusks(90),truebugs(230),divingbeetles indicate that they probably did not emerge above the sea
(36),andsyrphidflies(207).Theaccuracyofeachclusterwas surface until the Early Pliocene (Kimura & Tamaki, 1985).
estimatedbybootstrapanalysisusingthestatisticalprogram During the past 10Myr, the Greater Kuril Ridge has
CMS3 2.0 (developed by Y. Kuwahara of the Hokkaido experienced intense volcanic activity and crustal uplift
AbashiriFisheriesExperimentalStation,Abashiri,Japan).A (Markhinin, 1968; Yakushko & Nikonov, 1983; Gnibi-
dendrogramwasdeducedfrom10,000bootstrapsamples. denko,1985).Althoughmostoftheislandsalongthisridge
The general biotic similarity of the islands was analysed havenotbeenstudiedclosely,thereisgoodevidencethatthe
using principal coordinate analysis (Legendre & Legendre, southernKurilIslandsofKunashirandIturupemergedfrom
1998).Thismethodallowsobjects(inthiscasespeciesfound the sea during the Pliocene or Early Pleistocene and have
onislands)tobeplottedinaspaceofreduceddimensionality been abovesea leveleversince (Bulgakov, 1996).
thatpreservesasmuchaspossiblethedistancerelationships The coastline of the Sea of Okhotsk in the Early Pleisto-
between them. The principal coordinate analysis for 16 cene (1.8Myr BP) was very similar to the present configur-
selectedislandswasbasedondistributionsof2425speciesof ation, indicating that the subsequent evolution of the
the follow taxa: vascular plants (1194 species), terrestrial Okhotsk basin relates primarily to global climate changes
mollusks (45), freshwater mollusks (90), freshwater fishes (Bezverkhniyet al.,2002).DuringtheLatePleistocenethere
(28),terrestrialmammals(24),andthefollowinginsecttaxa: wereatleasttwomajorsea-levelregressionsassociatedwith
theorderHeteroptera(230species),thecoleopteranfamilies glacio-eustatic changes in this region (Briggs, 1974;
Carabidae (181) and Dytiscidae (36), the dipteran family Korotkii,1985).Sealevelfluctuationsvariedbetweenalow
Syrphidae(207),andthehymenopteranfamiliesBraconidae of)140mandahighofþ10mrelativetopresent-daylevel
(341), Formicidae (30), and the apid subfamily Bombinae (Morley et al., 1986; Keigwin & Gorbarenko, 1992;
(16). Bezverkhniyetal.,2002).Thepresentbioticfeaturesofthe
Kuril Island ecosystem were evidently laid down primarily
during the large-scale regression of the Late Wu¨rm (the
PALEOGEOGRAPHY OF THE KURIL
fourth of the four great glacial stages of the Pleistocene of
ARCHIPELAGO
Europe)andthe subsequentrise of sea level.
The formation of the Kuril Archipelago (Fig. 1) apparently The lowest sea level of the Late Wu¨rm (c. 18,000–
began in the Late Cretaceous, c. 90 Myr BP, when the 15,000 yr BP) is estimated to have been )130 m (Chappell
OkhotskTerraneoftheKulaPlatecollidedwiththeSiberian &Shackleton,1986;Bezverkhniyetal.,2002).Duringthat
continent, thereby creating a subduction zone along the period,Sakhalin,Hokkaido,Habomai,Shikotan,Kunashir,
southeastern margin of the Okhotsk Terrane (Kimura & and probably Iturup were united into a single mountainous
Tamaki,1985).Thissubductionzoneinitiatedtheformation region that was connected as well to the mainland Sikhote-
of the Kuril Kamchatka Trench and the subsequent volcan- AlinMountainsthatpresentlystretchalongtheeastcoastof
ismthatcreatedtheAcademyofSciencesRise(nowlocated Primorski Krai (Fig. 1). At the same time, Paramushir and
in the central Sea of Okhotsk) and the Lesser Kuril Ridge. Shumshu in the north were connected to Kamchatka, and
VolcanicactivityandupliftintheregionoftheLesserKuril thesouthern Kuril islandsof Urup,Chirpoi, Brat Chirpoev,
Ridge intensified during the Paleocene and Eocene, as the and Broutona were probably united as a single island, as
Kula–PacificRidgewassubductedintotheKuril–Kamchatka were the central islands of Ekarma, Shiashkotan, Khar-
Trench. It was probably during this period that the Lesser imkotan, and Onekotan. Glaciers covered the northern and
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KurilArchipelagobiodiversityandbiogeography 1301
centralislandsduringtheglacialmaximaoftheLateWu¨rm, Sakhalin is nearly five times greater than that of the Kurils:
but probably did not extend any farther south than central excluding introduced forms, there are 1196 species, 462
Iturup(therearenotracesofglaciationonKunashirorinthe genera, and 122 families of vascular plants on Sakhalin
Lesser Kuril Islands; Kryvolutskaja, 1973). Throughout the compared with 1194 species, 550 genera, and 135 families
year, most of the surface of the Okhotsk Sea was covered ontheKurils.Thisdifferencestronglycontradictsthealmost
withice,whichblockedtheshallowstraitsbetweenmostof universally accepted ideas about island biogeography as
the islands. The deep Bussol Strait, however, even in the demonstratedbyMacArthur&Wilson(1967).(MacArthur
most extreme glacial epochs, was never covered by ice andWilsonhypothesizedthatthenumberofspeciesonone
because of strong current exchange between the Sea of largeislandshouldbelargerthanthatfoundontwoormore
Okhotsk and the Pacific Ocean (Bezverkhniy etal., 2002). smaller islandshavingthe samecombined area;butclearly,
All things considered, the Bussol Strait was and is an inthiscase,thenumbersarenearlythesamedespitethehuge
important limiting factor for the distribution of the Kuril discrepancyinarea.)ThefloraofKamchatkaincludesc.890
biota. species, while thatof Hokkaido contains c.1700species. It
AttheendoftheLateWu¨rm(c.15,000–13,000 yrBP)the should be pointed out that the species richness of the
climate became warmer as the post-glacial transgression southernKurilfloraismorethantwotimesgreaterthanthat
periodbegan.Climaticwarmingduringthistimewasrapid; of the northern Kurils and about three times greater than
for example, during a period of only 750 years (13,150– that of thecentral Kurils(Fig.2).
12,400yr BP) the average air temperature in East China The insect fauna of the Kuril Archipelago is also rich
increasedby7(cid:2)C(Yang&Xie,1983).Atc.12,500 yrBP, compared with outlying regions. Although Kuwayama
very rapid hydrological changes also occurred in the near- (1967) reported only 1917 species and Kryvolutskaja
bottomlayersoftheOkhotskSea(Khusid&Basov,1999). (1973),2884species,thecurrentestimatednumberofKuril
Probably the most intensive introduction of warm-adapted insects is c. 8000 in 441 families and 25 orders. Only five
elementsoftheKurilbiotatookplaceduringthistime,when insect orders, which are otherwise widely distributed in the
theclimate waswarmbutthe sea-level low. RussianFarEast(RFE)andinJapan,areabsentontheKuril
Subsequentwarmingandcontinuedsea-levelriseresulted Islands:Mantoptera,Isoptera,Grylloblattida,Phasmoptera,
inasequenceofisolationoftheislands.Between15,000and and Raphidioptera (Lelej etal., 2002; Storozhenko etal.,
14,000yr BP, Iturup was separated from Kunashir, Shiko- 2002).Ingeneral,thenumberoftheinsectspeciesfoundon
tan, and Habomai in the south, and from Chirpoi, Brat the Kurils comprises a full 25% of the total number of
Chirpoev, and Broutona in the north (Bezverkhniy etal., speciesknownfromtheRFE,despiteatotalareathatisonly
2002). Sakhalin was separated from Hokkaido c. 12,000– 0.5%ofthatoftheRFE(Table 1).Inanotherexample,the
11,000yr BP, Paramushir and Shumshu from Kamchatka number of species of carabid beetles (Carabidae and Cicin-
c.10,000 yrBP,KunashirfromHokkaido,7500yrBP,and delidae) on Hokkaido is 373 species, whereas Kunashir
Sakhalin from the Asiatic Mainland c. 7000yr BP. Full Island at the southern end of the Archipelago supports
isolation of the Kurils as we see them today was thus com- 140 species (37.5% of the fauna of Hokkaido), although
pletebymid-Holocene. the area encompassed by Kunashir is less than 2% of that
of Hokkaido (1490vs.78,500 km2;Lafer, 2002).
Aswithvascularplants,thenumberofinsectspeciesofthe
RESULTS AND DISCUSSION KurilArchipelagoisalmostthesameasthatofSakhalin,but
larger than that of Kamchatka and smaller than that of
Biodiversityof theKuril Archipelago
Hokkaido (Table 1). The insect diversity of the large con-
The Kuril Archipelago supports an unusually high taxo- tinental regions in the temperate zone of the Northern
nomic diversity, despite its relatively small total area Hemisphere generally depends on latitude rather than area
(Zhuravlev, 2001; Zhuravlev & Sazonova, 2002). This can (Storozhenko etal., 2002). For example, the total number
beillustratedbycomparingtheKurilswithSakhalinIsland. of insect species found in the RFE (with a total area of
TheareaencompassedbySakhalinis76,400km2whilethe 3,016,000 km2)isalmostequal(c.30,000species)tothatof
Kurilstotalonlyc.15,600 km2.SakhalinandtheKurilsare Canada (total area 9,976,000km2); moreover the percent-
nearlyequalinlength,extendingoveradistanceof948and ages of the insect faunas contained by large orders such as
1200km, respectively, at almost the same range of longi- theLepidoptera(16%)andDiptera(24–25%)arethesame.
tude. The overall vegetation types, the general landscape, Thesouthernmostboundariesofthesevastregionshavethe
and the average elevation above sea level are also similar. same latitude (42(cid:2)N), resulting in similar climates and
Only the largest volcanos of the Kurils, Alaid on Atlasova vegetation belts, which in turn strongly influence the distri-
(maximum elevation 2339m) and Tyatya on Kunashir butionsand diversityof organisms.
(1819m),arehigherthanMountLopatina,thehighestpoint Our data on the insect faunas of the Kurils and Sakhalin
on Sakhalin (1609 m). The climate of Sakhalin and the (Table 1) show that the number of species in these temper-
Kurils is predominantly oceanic temperate, with relatively ate-zoneislandsystems,whichstretchoverlongnorth–south
abundantprecipitationandalowannualmeantemperature. distances (much like large mainland regions), correlates
TheflorasofSakhalinandtheKurilscontainvirtuallythe primarily with latitude (especially southern borders) rather
samenumberofvascularplantspecies,althoughtheareaof than with area. Moreover, such regularity of species
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1302 T.W.Pietschetal.
Sakhalin, Hokkaido, and Kamchatka (Table2). However,
the number of freshwater fishes known to inhabit the
Archipelago (28 species) is about half that of Sakhalin (64)
andHokkaido(64),andslightlylessthanthatofKamchatka
(33).
Endemicspecies
The proportion of endemic species found in island ecosys-
tems is determined by the duration and degree of island
isolation, keeping in mind that taxa containing slowly
movingorganismsmoreoftendisplayendemismthanhighly
mobile ones. The Kuril Archipelago has a very lownumber
of endemic species. For example, there are 25 endemic spe-
cies of vascular plants, which account for only 2% of the
1367speciesfoundontheKurils(Barkalov,2000).Ofsome
300 species of birds either inhabiting or migrating through
the Kurils, there is only one known endemic subspecies,
Cepphus columba snowi (Zhuravlev & Sazonova, 2002).
There are no endemic species or subspecies of fishes on the
Kurils (Pietsch etal., 2001). As for mammals, there is only
oneendemicspecies(Sorexleucogaster;seeKostenko,2002)
although the percentage of endemic mammal species in
nearbyJapanis40%(Millien-Parra&Jaeger,1999).While
no endemic mammal species are found on Hokkaido (61%
of the mammal fauna is continental in origin while the
remaining 39% appears to have originated from Honshu),
there are numerous examples distributed in the southern
parts of Japan. Of c. 425 species of spiders found on the
Kurils, there are no known species restricted to the archi-
pelago (Marusik & Crawford, 2001; Marusik, 2002).
Neverthless, there are endemic species of insects and fresh-
water mollusks, but even these numbers are low. For
example,of27speciesofOrthopteraknownfromtheKuril
Islands, only two species (Podisma tyatiensis and Podism-
opsis konakovi) and four subspecies (Diestrammena japa-
nicakurilensis,Podismasapporensiskurilensis,Chorthippus
fallax saltator, and Ch. fallax kurilensis) are found only
there (Storozhenko, 2002). There are six known endemic
species of freshwater mollusks: Lymnaea zarenkovi, Cin-
cinna chishimana, C. iturupensis, Kunashiria sinanodonto-
ides, Beringiana compressa, and Lacustrina etorohuensis
Figure2 TheKurilArchipelagoshowing(inparentheses)the (Prozorovaet al.,2002),whichaccountforonly6.7%ofthe
numberofspeciesofvascularplantsoneachisland.
90 species known to inhabit the Archipelago. In summary,
the vast majority of Kuril Island species have distributions
diversityissupportedbyourdataonvascularplantsaswell, that extend well beyond the Archipelago, and those few
andisprobablycharacteristicofalltaxaofthetwoparallel forms that are endemic are closely related to species distri-
islandsystems,theKurilsandSakhalin.Obviously,thereare butedinnearby Japan,Sakhalin,andthe Asianmainland.
otherfactorsthatcontributetothenearlyequalnumbersof
speciesonbothSakhalinandtheKurils.Thebiodiversityof
Patterns ofdistribution
both island systems is influenced by paleogeographical fac-
tors,bythemoreintensivewarm-watercurrents(Kuroshio) Most botanists recognize the (cid:1)Miyabe Line(cid:2) coinciding with
near the southern Kurils, as well as by the presence of theDeVriesStraitbetweentheislandsofIturupandUrupas
numerous refugia for warm-adapted species near active asignificantbiogeographicalboundaryforplants(Tatewaki,
volcanoes (hot springs, etc.) in the Kurils, which are com- 1933, 1947, 1957; Vorobev, 1963; Takhtajan, 1986).
pletelyabsent on Sakhalin. However, based on a detailed analysis of the northernmost
Similarly,the numbers of terrestrial andfreshwater moll- limitsofKurilplanttaxa,Barkalov(2000,2002)recognized
usks found on the Kurils are similar to those found on a distinct but more northern transition zone through the
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KurilArchipelagobiodiversityandbiogeography 1303
Table1 Numbersofspeciesofselected
Order Sakhalin Hokkaido KurilIslands Kamchatka RFE Japan
insectordersfoundinvariousregionsofthe
FarEast
Hymenoptera 2210 1785 2280 1070 9000 4297
Diptera 1970 1872 2020 950 8000 5215
Coleoptera 1480 2302 1410 560 5500 9125
Lepidoptera 1230 2375 1260 600 5000 5132
Otherorders 910 1544 1030 520 4000 5068
Totals 7800 9878 8000 3700 31,500 28,837
Data for Russian localities are numbers of estimated species, following Storozhenko etal.
(2002); those for Japanese localities are actual numbers of recorded species, following
Hirashima(1989,1990)andNakatani(1999).ValuesgivenforJapanandtheRussianFarEast
(RFE)aretotalsforthoseregions.
the importance of the Bussol Strait, with a similarity index
Table2 Numbersofspeciesofterrestrialandfreshwatermollusks
foundinselectedregionsoftheFarEast very close to zero(Figs 4&5).
Most insect species are restricted in distribution to the
Habitat Sakhalin Hokkaido KurilIslands Kamchatka southern Kurils (Lelej etal., 2002); for example, the spider
wasps (Hymenoptera: Pompilidae) extend only as far north
Terrestrial 40 72 45 23
as Urup (Fig.6). In contrast, true bugs (Heteroptera) and
Freshwater 75 80 90 73
braconid wasps (Hymenoptera: Braconidae) are found
Totals 115 152 135 96 throughout the Archipelago but c. 95% of the species are
southern; by far most are found on Kunashir Island (Figs 7
BussolStraitbetweenUrupandSimushir.Hedesignatedthis & 8). Hover-flies (Diptera: Syrphidae), diving beetles
zone as the boundary between the Circumboreal and East (Coleoptera: Dytiscidae), ground beetles (Coleoptera: Car-
Asiatic regions. Similarly, a UPGMA cluster analysis of abidae), ants (Hymenoptera: Formicidae), and bumble bees
vascular-plant similarities among the islands shows two (Hymenoptera: Apidae) are more evenly distributed
major assemblages that divide the chain into northern and throughout the Archipelago (Figs9–11). Cluster analyses
southern parts, the gap between again coinciding with the of faunal similarities among the Kurils for the most well-
BussolStrait(indexofsimilarity0.33;seeFig.3).Thissame studied of these insect taxa (Heteroptera, Dytiscidae, Syr-
analysisshowsthe(cid:1)MiyabeLine(cid:2)toformasignificantfloral phidae; Figs 8, 10 and 11) all produce two major clusters:
boundary, but with a much higher index of similarity Kunashir, Iturup, Shikotan, and Habomai forming a stable
(c.0.65). Cluster analyses of terrestrial (45 species) and cluster in the south; and the central and northern Kurils
freshwater(90species)molluskdistributionsshowthesame forming the branches of a northern cluster. The insect
thing,thelattergroupespeciallysupportingtheargumentfor fauna of Urup more often clusters with that of the
Figure3 Similarityof1994speciesof
vascularplantsamong16islandsoftheKuril
Archipelago.Bootstrapprobabilities
(expressedinpercentage)areindicatedatthe
nodeofeachcluster.
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1304 T.W.Pietschetal.
Figure4 Similarityof45speciesofterrest-
rialmollusksamong17islandsoftheKuril
Archipelago.Bootstrapprobabilities
(expressedinpercentage)areindicatedatthe
nodeofeachcluster.
Figure5 Similarityof90speciesoffresh-
watermollusksamong14islandsoftheKuril
Archipelago.Bootstrapprobabilities
(expressedinpercentage)areindicatedatthe
nodeofeachcluster.
southern Kurils (Figs8, 10), but for some groups (e.g.
Biogeography
Syrphidae), Urup clusters with the northern assemblage
(Fig.11). In some cases (e.g. Heteroptera), Simushir clus- ThepatternsofdistributiondisplayedbyKurilIslandplants
ters with the southern assemblage (Fig. 8). Admittedly, the andanimalscorrelatewellwiththegeologicalhistoryofthe
faunas of Urup and Simushir appear to be somewhat Archipelago. Despite the relatively ancient origin of the
intermediate (and not studied as well as that of Kunashir), GreaterKurilRidge(LateOligocene,c.25–30MyrBP)and
but certainly the bulk of the evidence obtained from Kuril still older Lesser Kuril Ridge, the recent biota of the Kurils
insects agrees well with that for vascular plants and has probably been forming since Early Pleistocene (around
mollusks, supporting the Bussol Strait as the single most 1Myr BP). During that glaciation there were land connec-
important biogeographical boundary in the Archipelago. tions between the islands and with the mainland. The
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KurilArchipelagobiodiversityandbiogeography 1305
Figure6 Numbersofspeciesofwaspsof
thefamilyPompilidae(Hymenoptera)on
islandsoftheKurilArchipelago.
Figure7 Numbersofspeciesofwaspsof
thefamilyBraconidae(Hymenoptera)on
islandsoftheKurilArchipelago.
Figure8 Similarityof230speciesoftrue
bugs(Heteroptera)among13islandsofthe
KurilArchipelago.Bootstrapprobabilities
(expressedinpercentage)areindicatedatthe
nodeofeachcluster.
alternation of glacial and interglacial epochs resulted in a some of the islands were covered by the sea, or at least
broadrange ofsea-levelfluctuationsfromalowof)140 m dividedintoseveralsmallislands,nodoubtresultinginlocal
to a high of þ10m. During sea-level regression, mainland extinction of manyspecies.
speciesspreadtotheKurils.Duringsubsequenttransgression
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1306 T.W.Pietschetal.
Figure9 Numbersofspeciesofbumble
bees(Hymenoptera,Apidae,Bombinae)on
islandsoftheKurilArchipelago.
Figure10 Similarityof36speciesofdiving
beetles(Dytiscidae,Coleoptera)among13
islandsoftheKurilArchipelago.Bootstrap
probabilities(expressedinpercentage)are
indicatedatthenodeofeachcluster.
Themostimportanttimefortheformationofthepresent colonizedfromtwoadjacentsourcebiotas:asouthernsource,
Kuril biota was the period from Late Wu¨rm to Holocene, theAsianmainlandbywayofSakhalinandHokkaido,anda
when Sakhalin, Hokkaido, Habomai, Shikotan, Kunashir, northernsourcebywayofKamchatka.Thecontributionof
andprobablyIturupwereunitedintoasinglelandmassthat thesouthernsourcebiotatothepresent-dayspeciesdiversity
was connected as well with the mainland Sikhote–Alin of the Kuril Archipelago was considerably greater than the
Mountains. During this time many warm-adapted species northernsource.
probablyspreadfromsouthernsourceareastothesouthern A principal coordinate analysis of biotic similarity of the
Kurils. The northern extent of distribution of most of these Kurils,basedontheknowndistributionsof2425speciesof
EastAsian(Manchurian–Japanese)speciesofplants,insects, terrestrialandfreshwaterplantsandanimals,againindicates
non-marinemollusks,andterrestrialvertebratesontheKurils the importance of the Bussol Strait (Fig.12). These results
has been limited by the deep Bussol Strait (Barkalov, 2002; agreeremarkablywellwiththepatternofdistributionofthe
Bogatov,2002;Kostenko,2002;Lelejetal.,2002;Prozorova, littoral zone biota of the Archipelago as described by
2002;Prozorovaet al.,2002;Teslenko,2002).Atthesame Sukhanov(1982).
time,manycool-adaptedspecieshavespreadfromSakhalinto BesidestheBussolStraittherearetwoadditional,butless
HokkaidoandthesouthernKurils.Similarly,duringtheLate obvious, biogeographical boundaries: the De Vries Strait in
Wu¨rmtothemid-Holocene,ParamushirandShumshuwere the south and the so-called fourth Kuril Strait in the north
connected to Kamchatka allowing boreal and arctic-alpine (Fig. 12).Thesetwostraitsdividethechainintocontinental
species to spread southward from northern sources areas, and oceanic islands (see Fig.1). The De Vries Strait
includinghigh-mountainregions.ThustheArchipelagowas effectivelylimitsthenorthwarddispersaloffreshwaterfishes
(cid:1)2003BlackwellPublishingLtd,JournalofBiogeography,30,1297–1310