Euphydryas editha taylori (Edwards) is a charismatic butterfly- black with orange and white speckles above, white and brick red with fine black lines below (Figure 1). It historically was found from southern Vancouver Island, British Columbia, Canada to the southern Willamette Valley, Oregon, in the United States. Euphydryas butterflies have been extensively investigated as model organisms for metapopulation studies, genetics, and conservation and population biology (Britten et al. 1995; Ehrlich 1992; Ehrlich and Hanski 2004; Ehrlich and Murphy 1987; McLaughlin et al. 2002a). Euphydryas editha bayensis is one of the most thoroughly studied non domesticated organisms on earth. It is probably the most well studied butterfly (Ehrlich and Hanski 2004; McLaughlin et al. 2002b; New 1997b). Euphydryas editha is a highly variable species with many subspecies though there are differences of opinion on exactly how many (i.e. Austin and Murphy 1998; Baughman and Murphy 1998; Guppy and Shepard 2001; Hodges et al. 1983; Scott 1986). As recently as 1983 there was still confusion as to the limits of the editha complex, with the now federally endangered E.e. quino (Quino checkerspot) being considered a member of the E. chalcedona complex (Hodges et al. 1983).
Native grasslands, the habitat of E.e. taylori, have declined in extent to about 3% of the area they occupied in 1850 throughout the Willamette Valley-Puget Trough-Georgia Basin ecoregion (Crawford and Hall 1997). This is primarily due to development for agriculture, urbanization, gravel mining, succession to forest, and non-native invasive species. Many species of prairie dependent vertebrate animals have declined dramatically and some are threatened with extinction or have already been extirpated from prairies (Leonard and Hallock 1997; Rogers et al. 1997; Rogers 2000; Ryan 1997). Plants of the prairie have declined as well with the golden paintbrush (Castilleja levisecta), an E.e. taylori host plant, federally listed as threatened under the Endangered Species Act. Several other plants are listed as sensitive under the Washington State Natural Heritage Program.
Work on insects, thus far mostly confined to butterflies, is beginning to show the same pattern of population decline and endangerment in prairie obligates. Butterflies in particular are declining. Four butterflies of the Puget Prairies are listed as “endangered” or “species of concern” by the state of Washington. Two butterfly species, including E.e. taylori, are Candidates for listing under the federal Endangered Species Act. This means there is likely to be enough evidence to warrant listing but the US Fish and Wildlife Service has yet to list the species. Thirteen butterflies that use grasslands in the ecoregion are listed as endangered, threatened, candidate, or extirpated (or equivalents) by national or state/provincial governments. Recently a petition from several conservation groups was submitted to the U.S. Fish and Wildlife Service for emergency listing of E.e. taylori and two other butterflies in the ecoregion (Vaughan and Black 2002a, 2002b). Butterflies are often considered to be both good indicator (Black et al. 2001; Pollard and Yates 1993; Samways 1994) and umbrella (Launer and Murphy 1994; New 1997a) taxa. The imperiled nature of these taxa is particularly troubling and indicates, along with the dramatic reduction in habitat, that the prairie system is in crisis.
Euphydryas editha taylori is small (wingspread 26-43mm), and its wings are spectacularly checkered with white and brick orange-red spots on a deep brown/black background (Figure 1). Like other members of its genus, it is quite variable in the proportion of the colors expressed on wings. The variation is striking, with specimens that are dorsally mostly black to specimens that are quite light with narrower black lines between the orange and white “cells.” However, all have distinct dark lines between colored patches. The underside of the wings is generally less variable than the upper side (Figure 2). Forewing shape is rounded on the outer margin, becoming more acute at or near the R5 vein. The apex of the wing is very rounded. Ground scales on the upper side of the forewing are deep chocolate brown to black on newly emerged individuals. The ventral side of the hind wing has the standard “editha line” that reliably separates editha from other Euphydryas (Guppy and Shepard 2001; Pyle 2002; Scott 1986) (Figure 2). The hind wing is nearly evenly rounded with the distance from the base of the wing to the outer margin only slightly differing between the radial sector and the second branch of the anterior cubitus, though in southern populations the distance from the base to the outer margin trends slightly longer in the vicinity of the radial sector. Antennae are ringed with alternating bands of black and orange on basal segments while the terminal club segments are banded in orange.
Males are smaller than females overall with a wingspread averaging 3.8cm. The male abdomen is significantly more slender and less conspicuously ringed with orange banding than the female abdomen. The harpe is distinctive in E. editha (Figure 3). Female wingspread averages 4.1cm, slightly larger than males. The abdomen is proportionately longer and wider than the male with obvious wide orange banding near the posterior end.
First instar larvae are tan with small dark spines along the dorsal and lateral surfaces. Third instar larvae are brown with branched spines (Figure 4). The larvae gradually become darker with each instar change so that by the fourth and later instars the larvae have black to dark brown skin splotched with pearlescent lighter spots and a row of orange tubercles topped with complex black spines along the dorsal surface. The spines on the larvae become gradually more branched and take on a complex “Christmas tree” appearance by later instars (Figure 5). Larvae feed in groups within a loose silken web during the first through third instars. During the third instar larvae will often leave the web and by diapause in the fourth instar all larvae have begun a mostly solitary existence. Development from egg to diapause as a fourth instar larva takes place in 4-6 weeks (Table 1) Solitary larvae often bask either on host plants or nearby vegetation.
Pupae have irregular splotches of muted color similar to those found on the underside of the adult wing, white, reddish yellow and black all with gray overtones. They have been found suspended from low growing vegetation within a few centimeters of the ground during pupation (D. Ross personal communication).
The phenotype of E.e. taylori is, on average, darker than any other E. editha subspecies with a higher proportion of dark ground color scalation and it has a distinctively rounded forewing apex and outer margin. Some of the distinctions are subtle and there is some overlap with other subspecies. Taken as a whole it can be reliably distinguished from other subspecies though the most reliable characteristic is the location the butterfly was found (Figure 7).
The type locality is Beacon Hill in Victoria, British Columbia. Currently this is an urban park and there is little or no vegetation capable of supporting the butterfly. There appear to be no surviving populations in British Columbia but the few populations directly across the Straight of Juan de Fuca near Port Angles are phenotypically very similar to the extirpated type populations (Pelham personal communication). Specimens captured in Helliwell Provincial Park about 30km from Victoria are pictured in Figure 6. The lectotype is in the Carnegie Museum in Pittsburgh, Pennsylvania.
All sorted specimens in the Oregon State Arthropod Collection and my personal collection were examined. The Oregon State Arthropod Collection is the most complete collection of Northwestern U.S. Lepidoptera and it contains E.e. taylori from all U.S. counties from which the butterfly has been collected. It also contains the Nymphalidae portions of the J.S. Shepard collection, which contains many Canadian specimens of the butterfly. Additional specimens reside at the American Museum of Natural History, Canadian National Collection, Natural History Museum of Los Angeles County, Royal Ontario Museum, Royal British Columbia museum in Victoria, British Columbia, Burke Museum of Natural History and Culture, and several private collections. Data collected from these specimens was used for distribution records. Most specimens at the museums above have been entered into databases- either Hinchliff’s atlases (1996), Guppy and Shepard (2001), or the Washington Department of Fish and Wildlife’s database. Additionally, those collections have been examined by specialists. Additional unsorted and papered material at the M.T. James Entomological Collection at Washington State University is known to contain some lowland E. editha that are likely taylori from collections donated by Calkins and Frechin (Shepard personal communication). The M.T. James specimens have the potential for the most distribution surprises but they are at present the least accessible specimens and the only ones not yet in a database. Additional efforts in curation there, especially in the Nymphalidae, are slowly being accomplished by John Shepard working part time as a volunteer curator.
Euphydryas is derived from the Greek euphys (a goodly shape) and dryas (a dryad or wood nymph). It has been assumed that the specific epithet editha came from a woman named Edith (Guppy and Shepard 2001) though this is not clear in the original description (Boisduval 1852). Subspecies taylori is named after the Reverend George W. Taylor, an early British Columbia lepidopterist (Guppy and Shepard 2001). There have been two widely used common names. Taylor’s checkerspot is obviously based on the subspecific designation and probably the most “proper” common name since it was first applied in print by Holland (1898). It has also been referred to as the Whulge checkerspot (Pyle 1989), Whulge is the Salish word for what later became known as Puget Sound.
Euphydryas editha taylori is known to use Castilleja hispida, C. levisecta, and Plantago spp. as host plants (Guppy and Shepard 2001; Pyle 2002). Recent work has shown extensive feeding on Orthocarpus pusillus, Collinsia parviflora, C. grandiflora, and Plectritis congesta (unpublished data). Other populations of E. editha are known to use various Scrophulariaceae and a few Valerianaceae as hosts and some populations require more than one host for development- one or more prediapause and one or more postdiapause (Cushman et al. 1994; Hellmann 2002; Rausher 1982; Singer 2004; Singer et al. 1988; Singer et al. 1993; White 1974; White and Singer 1974). The distribution of C. hispida in prairies is highly patchy with many existing prairies containing few plants. The non-native Plantago lanceolata is widespread but E.e. taylori may not be able to use it as a sole food source in all years and no extant population in Washington has been known to use it as a host. The other potential hosts are either absent or nearly absent from lowland prairie sites. Euphydryas editha bayensis is less able to persist in areas with only Plantago erecta hostplants than it is in areas with Castilleja (Hellmann 2002). In many E. editha populations, larvae usually starve before diapause (Kuussaari et al. 2004; White 1974) this appears to be the case for E.e. taylori as well (unpublished observations).
Nectar plants used by the E.e. taylori include Camassia quamash, Lomatium triternatum (Hays, Potter, Thompson, and Dunn, unpublished data), L. utriculatum (Guppy and Shepard 2001), Balsamorhiza deltoidea (Hardwick personal communication, Potter personal communication), Plectritis congesta, Marah oraganum (personal observation), Fragaria virginiana, Callicortis spp. and Malus spp. (Ross 2003). Like most butterflies, they are able to adapt to different nectar sources to some extent but they in most cases they use native plant sources that are particularly abundant at a site. Extant populations are found in areas with a high proportion of native grass cover. In areas heavily invaded by non-native vegetation, E.e. bayensis is less successful (Weiss 1999) and this is probably the case for the E.e. taylori as well. Anecdotal accounts suggest that E.e. taylori usually avoids any vegetation over about 0.75m in height (personal observation) and most other western Washington prairie specialist butterflies avoid dense, tall non-native grasses (Hays, Potter, Thompson, and Dunn, unpublished data). Certainly all extant populations are found in areas with a high percentage of native grassland plant cover. Restricted nectar sources can severely limit egg production though this may be of slightly less importance in E. editha than some other species (Boggs 1997).
There is clear evidence that other populations of E. editha act as metapopulations and exhibit tremendous variability in abundance and local distribution (Baughman 1999; Baughman et al. 1988; Ehrlich 1961; Harrison et al. 1988; McLaughlin et al. 2002a; Singer and Ehrlich 1979). The fragmentation of prairies combined with the low vagility of E.e. taylori indicates the isolated populations of the Puget sound can no longer act as metapopulations (Char and Boersma 1995). This isolation increases the chance that the populations will become permanently extinct by because natural recolonization is unlikely.
Distribution and conservation
The historical distribution of E.e. taylori was the Puget trough from southern Vancouver Island to the Willamette valley in Oregon. About 60 historic populations are documented from this region (Vaughan and Black 2002b) but large scale conversion of prairies to agriculture was well underway before any populations were documented so this is likely a significant undercount. As of 2003 there was only one known population left in Oregon though it was known to be abundant in some colonies in fairly recent times (Dornfeld 1980). In spring of 2004 extensive searches by the Xerces Society and volunteers turned up two new colonies also in balds on the edge of the Willamette Valley. It has apparently been extirpated from British Columbia (Miskelly and Guppy personal communications). Remaining populations in Washington have declined significantly. As recently as 1996, several populations in the South Puget Sound numbered in the thousands. In 2000 only a few populations were found and even in the largest of these, few checkerspots were found (Fleckenstein and Potter 1999; Remsberg 2000). They crashed dramatically leaving researchers few butterflies to study (Hays, Potter, Thompson, and Dunn, unpublished data) and recent monitoring has not detected a rebound (Potter personal communication; Lombardi personal communication). A few populations persist but their locations are not reported here for conservation reasons. There are no clear answers as to why the E.e. taylori populations here have crashed though obviously habitat loss played the major part in earlier declines.
Global warming may have complex effects on E.e. taylori populations. Parmesan (1996) indicated that global warming was causing a net northward shift in the distribution of E. editha. This seems manifestly untrue for E.e. taylori, which has vanished from the northern end of its range, though evidence from other butterfly species supports this general pattern (Warren et al. 2001). There is evidence that increases in climate variability can negatively affect E. editha (McLaughlin et al. 2002a) and that this is particularly true in homogenous habitats (McLaughlin et al. 2002b). Local populations of a species may be less fit throughout the range of a species in some cases rather than showing a positive response to warming at the northern limits, and a negative response at the southern limits (Hellmann 2004).
Euphydryas editha taylori is listed as a species of concern by the State of Washington and is likely to be listed soon as a State Endangered Species, which provides some protection on lands owned by the State. The butterfly has been red listed in British Columbia. It is a candidate species under the federal Endangered Species Act in the United States (Vaughan and Black 2002b).
A number of research and conservation efforts targeting E.e. taylori habitat are planned or ongoing. Efforts by the Washington Department of Fish and Wildlife and Ft. Lewis are underway to survey historical locations in Washington. So far, all of these efforts, with the exception of the small populations on balds in Clallam County, Washington mentioned earlier, have failed to find taylori populations (Potter personal communication). Habitat enhancement and Scot’s broom (Cytisus scoparius) control have been a focus for several years on historic E.e. taylori sites including Fort Lewis prairies, Glacial Heritage Preserve, Rocky Prairie Natural Area Preserve, and Scatter Creek Wildlife Area. That work has been accomplished by The Nature Conservancy, Fort Lewis, and the Washington Departments of Fish and Wildlife and Natural Resources.
Organizations within British Columbia have been actively working to find ways to bring back their former E.e. taylori populations. James Miskelly at the University of British Columbia is working to identify key habitat parameters and potential restoration sites in British Columbia. There have been efforts to find extant populations in British Columbia. Planning for recovery in British Columbia as well as ongoing planning efforts at specific sites (i.e. Helliwell Park) is ongoing. Draft recovery plans call for the reestablishment of three robust metapopulations within the area formerly occupied by the butterfly (Guppy et al. 2003).
In Oregon, several individuals and organizations are involved with research on the E.e. taylori population near Corvallis. Dave McCorkle and Dana Ross at Oregon State University and Mace Vaughn and Scott Black of the Xerces Society have been doing population and natural history work with the butterflies at that site and working to protect habitat (Ross 2003).
Euphydryas editha has one of the most complex taxonomic histories of any butterfly in North America. Therefore, it is not surprising that many of the named subspecies are disputed. There are over 30 currently valid (non-synonymous) subspecies (Emmel 1998; Hodges et al. 1983) with twenty one in California alone (Murphy et al. 2004). Edwards originally named E.e. taylori in 1888. Subsequently Gunder named both victoriae and barnesi which are considered synonyms (Hodges et al. 1983). The case for subspecific rank in taylori is fairly strong--that is to say, it likely designates real and properly delimited (monophyletic) nearly discrete variation within Euphydryas editha--and primarily rests on three attributes: phenotype, ecology, and distribution.
Clarity in the taxonomy of E.e. taylori is particularly important in light of previous difficulties in the designation and limits of federally listed Endangered Species (O'Brien and Mayr 1991). At the genus and species level E. editha appears to be fairly stable with the most recent revision clarifying relationships within the genus (Higgins 1978) but failing to gather wide support for splitting the genus (Murphy et al. 2004).
The ecology and flight period of E. e. taylori is different from other subspecies. Euphydryas editha taylori is found in low elevation cool wet winter, summer drought conditions distinct from conditions present for any other subspecies of E. editha. Without genetic evidence, its relationship to other E. editha subspecies is unclear. Euphydryas editha bayensis is found in remnant coastal meadows in the San Francisco Bay area and it experiences some of the cool wet winter weather though of a much shorter duration. Euphydryas editha baroni is found in Mendocino County in coastal northern California and it has been speculated that coastal forms north of Mendocino share a phenotypic affinity with taylori to the north (Murphy 1982). It is plausible that taylori diverged from a common ancestor of bayensis or baroni in coastal northern California during the Hypsothermal period when extensive grasslands may have connected the historically extensive central California grassland areas with the Willamette Valley. It is also plausible that the lowland E. e. taylori diverged from a common alpine ancestor with beani, colonia, or another alpine subspecies though phenotypically E. e. taylori is closer to the coastal subspecies. It possibly originated from some southern Oregon ancestor and colonized northward after the end of the Vashon glaciation about 12,000ybp. This would account for its warmer lowland habitat and its life history adaptations to the Mediterranean climate of its range.
Euphydryas editha taylori currently appears to be reproductively isolated from other E. editha subspecies. Within the lowlands below 500m in elevation all E. editha collected to date have been assigned to subspecies taylori based on morphology. The only known location where any other subspecies come into near contact with taylori is in lowland grassy balds just west of the Elwha River near Port Angeles, WA. These colonies are approximately 5 miles from locations that are likely occupied by what is currently called E.e. "colonia" (this is possibly an as yet undescribed subspecies according to Pelham [personal communication]). This short spatial distance is misleading. The elevation difference between the alpine E.e. "colonia" and the lowland taylori is substantial. The highest colony of taylori is near 300m and the lowest potential habitat for the alpine subspecies is over 1500m. Lowland taylori are adults between May 1 and June 10 while the higher elevation "colonia" populations are adults from early July through early August. When the lowland populations are flying, the higher elevation sites are snow covered and too cold for flight. When the higher elevation populations are flying, the lowlands are desiccating due to summer drought and lowland host plants are senescing. Even if a gravid female butterfly managed to travel the distance there would be no host plants for larvae to eat. It is unlikely that there would be gene flow between the high elevation and low elevation populations of E. editha in this area because of this temporal ecological barrier. Euphydryas editha is known to be a poor disperser (Ehrlich 1961; Gilbert and Singer 1973; Harrison 1989; Weiss and Murphy 1988; Weiss et al. 1987). Significant difficulties in population movement between colonies with substantially less ecological separation have been shown by Baughman (1999).
Additional searches for suitable habitat in the area where high and low elevation E. editha populations are spatially close should be undertaken to determine whether or not there is potential for 'stepping stone' movement and interbreeding between the alpine and lowland populations similar to the reserve design network proposed by Schultz (1998) for another patchily distributed colonial butterfly. It is uncertain how long the barriers to movement between higher elevation and low elevation subspecies have existed. Certainly the lowland populations were more extensive because of larger areas of habitat when the lowland prairies in the Puget Trough and Willamette Valley were regularly burned (Crawford and Hall 1997; Potter et al. 1999; Tveten and Fonda 1999; White 1980) and this is likely to be true of the historic Sequim rain shadow prairies as well (D. Peter, personal communication). Whether or not these grasslands came close enough for E. editha to move between alpine and lowland populations is unknown. The distinctive phenotypes indicate that gene flow was probably not extensive over a long period of time. Because the origins of taylori are unknown, how it came to have its present day distribution is uncertain.
There is a case to be made that a higher taxonomic ranking as a species cannot be absolutely ruled out if the biological species concept is used. Euphydryas editha taylori is apparently part of a complex of coastal E. editha subspecies and it is considered perhaps the most well supported subspecies of E. editha (Shepard 2000). Some have speculated that the coastal E. editha subspecies should be considered for splitting from alpine and interior E. editha. There do not appear to be areas where there is currently gene flow between the two groups and they have phenotypic characteristics that separate them throughout the range. Allozyme data do not support separation along this coastal phenotypic divide though taylori was not included in the allozyme work (Baughman et al. 1990). There are no areas where taylori is known to be sympatric with any other E. editha subspecies, thus meeting the criteria of current genetic isolation. The duration of this isolation is unknown and it is unknown whether or not taylori can interbreed with other subspecies in the laboratory.
There do not appear to be any apomorphies that would clearly indicate that taylori is separate in a Hennigian or phylogenetic species concept. Euphydryas editha taylori exhibits heritable plasticity in its host preferences and has a variable phenology just like other E. editha. The fact that some populations of E.e. taylori use host plants no other subspecies uses could be related to local availability and local adaptation. There is no genetic evidence available to judge whether or not there are any significant genetic differences with other subspecies.
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(This document was completed as part of an Individual Learning Contract for the MES Program at The Evergreen State College, with faculty advisor John T. Longino.)