Great Basin Naturalist Volume 47 Number 2 Article 2 4-30-1987 Zoogeography of Great Basin butterflies: patterns of distribution and differentiation George T. Austin Nevada State Museum and Historical Society, Las Vegas Dennis D. Murphy Stanford University Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Austin, George T. and Murphy, Dennis D. (1987) "Zoogeography of Great Basin butterflies: patterns of distribution and differentiation," Great Basin Naturalist: Vol. 47 : No. 2 , Article 2. Available at: https://scholarsarchive.byu.edu/gbn/vol47/iss2/2 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. ZOOGEOGRAPHY OF GREAT BASIN BUTTERFLIES: PATTERNS OF DISTRIBUTION AND DIFFERENTIATION George T. Austin and Dennis D. Murphy" Abstract. —The butterflies of the Great Basin exhibit general patterns of distriljution and speciation similar to those found for other taxa, particularly birds. Two major centers of infraspecific differentiation and coinciding distribution limits of taxa are identified, each with three subregions. Great Basin butterflies are characterized by pallidity and substantial endemism below the species level. The Great Basin of western North America Materials and Methods is a huge area, nearly 520,000 square kilome- Distribution maps for butterfly taxa and ters, of largely internal drainage between the other distinct phenotypes occurring within Rocky Mountains to the east and the Sierra and on the margins of the Great Basin were Nevada to the west. It includes Utah west of constructed from a variety of sources. Nevada the Wasatch Plateau, extreme southwestern data are drawn primarily from the collections Idaho and southeastern Oregon, California and field notes at the Nevada State Museum, east of the Sierra Nevada, and nearly all of Carson City, the senior author's personal col- Nevada (Fig. 1). Elevations range from lection, and collections made by the Center l,000-m lowlands dominated by sagebrush for Conservation Biology at Stanford Univer- {Artemisia) and saltbush {Atriplex) to numer- sity. Eastern California data were obtained ous, mostly north-south oriented mountain from the notes and collections of a number of ranges which may exceed 3,000 m. These private collectors. Southern Oregon records mountain ranges, most of which are forested are from Dornfeld (1980), and Rocky Moun- only at the higher elevations, constitute is- tain and eastern Great Basin records are from lands of boreal habitat. Lowland wet areas are Ferris and Brown (1981). Some Sierra Nevada similarly islandlike. The area is largely unin- data were obtained from Shapiro et al. (1979) habited by and is relatively undis- humans and the collections of the Nevada State Mu- livestock has turbed except for grazing which seum. Numerous other literature sources had substantial impact on the composition of were consulted. the vegetation, especially at lower elevations The maps thus prepared were examined to (e.g., 1982, 1983). Rogers Thomas determine patterns of distribution within the Studies of the distribution and biogeogra- Great Basin and adjacent areas. Attention was phy of Great Basin biota have dealt largely paid to the absence or presence of species with vertebrates (e.g., Behle 1963, 1978, within the Great Basin and the extent of their Brown 1971, 1978, Grayson 1982, 1983, John- apparent distributions and differentiation in son 1975, 1978, Smith 1978) and plants (e.g., the Great Basin. Billings 1978, Harper et al. 1978). Here we present information on the distribution of Taxa and Distribution Great Basin butterflies, paying particular at- tention to the distributional limits of species, The 155 butterfly species occurring in the subspecies, and well-differentiated segre- Great Basin include some 240 subspecies and gates, and to centers of infraspecific differenti- well-differentiated segregates. More than half ation. Additionally, we discuss the role of "is- the species are geographically polytypic in land" effects in shaping local species richness. this and adjacent regions, including the Rocky Nevada State Museum and Historical Society, 700 Twin Lakes Drive, Las Vegas, Nevada 89107. Department of Biological Sciences, Stanford University, Stanford, California 9430.5. 186 April 1987 Austin, Murphv: Great Basin Butterflies 187 OREGON IDAHO [ NEVADA f WARNER Jarbidge Mountains I SUBREGION Independence Mountains JARBIDGE SUBREGION •KEast Humboldt Mountains ^ i CENTRAL IF Ruby Mountains SUBREGION Virginia ^[/ ^ Range , Pine Nut 3|l Mountains jl A Snake Range Wassuk ?V,^ Range . TOIYABE \ SUBREGION INYOV^ SNAKE ^^ SUBREGION SUBREGION White Mountains • ..••' ^-1 \ ARIZONA MOJAVE SUBREGION Spring Range ^ \ / Fig. 1. The Great Basin showing subregions and locations mentioned in the text. Mountains and Sierra Nevada. No species are stricted to the Great Basin. A number of addi- endemic to the Great Basin, consistent with tional groups of populations within the region previous findings for birds (Behle 1963). show some measurable diflerentiation. The About 50 subspecies and other well-differen- distributions of these taxa and segregates by tiated infraspecific segregates (distinct groups geographic affinities are summarized in Table 1. of phenotypically similar, but unnamed, pop- Nearly 90% of all Great Basin butterfly spe- ulations) of butterflies, however, are re- cies are also found in the Rockv Mountains. 188 Great Basin Naturalist Vol. 47, No. 2 Table 1. AflFinities of the Great Basin butterfly fauna. Taxa include subspecies and distinct unnamed segre- gates. Species April 1987 Austin. Murphy: Great Basin Butterflies 189 Table 3. Distribution of Great Basin endemic butter- Table 3 continued. flies by region.' Speyeria zerene gtindeh Eastern Region Limenitis archipptis lahontani Jarbidge Cercyonis sthenele ))atilus Ochlodcs sijlvatwides bonneviUa Neominois ridingsii stretchii *Lycaeua eclitha nevadensis Here and in subsequent tables, seg. (segregate) is used to denote distinct *Euphilotes ritti mattonii sets of phenotypically similar populations which are as yet unnamed. *Speycha atlantis urcyi *Narrowl\ distributed ta.\on *Spcycria atlantis clko Speijcria mormonia ai-tonis Phyciodes campestris seg. est extant populations apparently are now Etiphydryas colon nevadensis well to the north. Papilio indra, in addition, Snake exists as a relatively isolated endemic subspe- Polites sabtileti seg. cies in the general area, Plebejus Satyritun sacpium seg. same and *Incisalia au^ttsttts (?) seg. lupini occurs as widely scattered populations *Euphilotcs hattoides seg. across central Nevada. Several of these same Toiyabe species also extend into montane areas south Polites sabtileti seg. of the Sierra Nevada cordillera (Emmel and Papilio indra nevadejisis Emmel 1973), indicating an ability to survive *Speyeria e^leis toiyabe in more xeric conditions than those at their *Cercyonis oetus pallesccns distribution centers. Widespread Euphydryas editha lehmani Etiphydryas editha koreti Centers of Differentution Western Region A number ol Great Basin species are com- Inyo paratively unvarying in phenotype over a Thorybes mexicana blanca broad area from the Rocky Mountains or east- *Hesperia miriamae seg. *Polites sabtileti seg. ward, west to the Sierra Nevada or beyond. Ltjcaena rtibidtis seg. Others exhibit considerable regional differen- Euphilotes mojave langstoni tiation and may include one or more pheno- *Plebejiis icarioides seg. types restricted to the Great Basin. The large *Plebejtis saepiohis seg. Coenonympha ochraceae mono number of phenotypic endemics suggests that *Cercyonis pegala tvheeleri the Great Basin is at least a moderately active Neominois ridingsii seg. area of infraspecific differentiation. Examina- Central tion of the distributions of subspecies and seg- *Pseiidocopaeodes eitntis seg. regates of polytypic species in the Great Basin *Polites sabtileti genoa and adjacent butterfly faunas shows rather *Etiphilotes rita seg. Speyeria zerene malcolmi well defined distribution patterns suggesting Speyeria callippe nevadensis "centers of differentiation. ' Similar to Behle s Etiphydryas editha monoensis (1963) findings for birds, these centers are *Cercyonis pegala seg. bounded by areas where numerous range lim- Warner its coincide, further suggesting that the Great Polites sabtileti seg. Basin consists of definable biogeographical *PoUtes sabtileti seg. units (Fig. 1, Table 3). These regions gener- *Pieris napi seg. Lycaena rtibidiis rtibidtis ally coincide with distril)utional limits or more Cercyonis pegala stephensi widespread butterfly taxa and are strikingly Widespread similar to distributional centers found for Hesperia tineas macstvaini birds (Behle 1963, 1978). Widespread in Gre.at Basin Eastern Region Colias alexandra edicardsii Lycaena arota virginiensis The Great Basin may be viewed as two Mitotira siva chalcosiva distinct centers of butterfly distribution and Euphilotes battoides baiieri differentiation (Fig. 1). The first is the Eastern Etiphilotes rita pallesccns Glaticopstjche piasiis ncvada Region bounded by the Wasatch Front in the Speyeria nokomis apacheana east, to and including the Reese River Valley — 190 Great Basin Naturalist Vol. 47, No. 2 and from the northern Hmits of the Mojave Subregion (southwestern