Range collapse in the Diana fritillary,Speyeria diana(Nymphalidae)

Abstract

Global warming can affect the distributions, phenology and, ultimately, conservation status of species worldwide, but most published studies on its biological effects have focused on higher latitude species. We extended this work to the Diana fritillary, a butterfly which once ranged throughout the Southeastern United States but now is severely restricted in range. We searched for all scientific records of this species, from publications, catalogued and uncatalogued specimens in public and private collections in the United States and Europe, online databases, contemporary field surveys by scientists and amateurs, and our own field surveys. We analysed these records for shifts in latitude, longitude, elevation and phenology. We found that the Diana fritillary has disappeared entirely from the Atlantic coastal plain, where it was first described, and from interior lowland sites. It now persists in two disjunct parts of its former range, the Southern Appalachian Mountains and the Interior Highlands of Oklahoma and Arkansas, and is shifting to higher elevations at about 18 m per decade. In addition, females are being collected 4.3 days earlier per decade though males, which emerge first, have not shifted their phenology. All these patterns are weakly dependent on latitude. These shifts in distribution and phenology are consistent with the predicted effects of global warming, but we review other large scale changes to the region which also might contribute singly or jointly to these patterns. We also comment on the implications for the conservation of this species.

Changes in the Geographic Distribution of the Diana Fritillary (<em>Speyeria diana</em>: Nymphalidae) Under Forecasted Predictions of Climate Change

“…Both CCSM and MIROC climate models predicted severe habitat loss and fragmentation in the Southern Appalachian Mountains by 2050, with some range expansion predicted into higher latitudes in both eastern and western populations. High elevation habitat will be an important refuge for the species across the entire distribution, as the range of S. diana is already shifting to higher elevations at an estimated rate of 18m per decade [33]. Recent evidence further suggests that some S. diana populations may already be adapting to high elevations, as S. diana female forewings from high elevation populations were found to be narrower than low elevation populations, indicating that these females may be more mobile than those from low elevations with wider forewings [35].…”

“…We also collected 419 S. diana butterflies in our own field surveys. Our dataset represents essentially a complete dataset of all publicly available records for the species, and is as comprehensive as for any taxon in the region [33]. For this reason, our dataset should be especially informative in creating an accurate bioclimate envelope for the species, as collection bias is a major consideration with ecological niche modeling [43,44].…”

“…This species is of particular conservation interest because it has experienced a range collapse in recent decades resulting in an 800 km geographic and genetic disjunction between western populations in the Ouachita and Ozark Mountains and populations in the southern Appalachian Mountains, and has shifted to a higher elevation at an estimated rate of 18m per decade [33]. This range contraction is consistent with the predicted effects of a warming climate, and might represent the first such documented case in the southeastern US, though the region has experienced other environmental changes in recent decades as well [33]. Previous research using coalescent-based population divergence models dated the earliest splitting of the western population from the east at least 20,000 years ago, during the Last Glacial Maximum [34].…”

Observations of Resource Use by the Threatened Diana Fritillary Butterfly (Speyeria diana) in the Southern Appalachian Mountains, USA

“…The Diana fritillary, Speyeria diana (Cramer, 1777), is an endemic butterfly species in the southeastern USA that has experienced a severe range collapse over the past century [1]. Speyeria diana was once distributed more widely across the southeastern US than it is at the present, ranging from coastal Virginia across the Ohio River Valley to Arkansas and Missouri.…”

“…Speyeria diana was once distributed more widely across the southeastern US than it is at the present, ranging from coastal Virginia across the Ohio River Valley to Arkansas and Missouri. This species now persists in two geographically separated population groupings across the Interior Highlands of Arkansas and Oklahoma in the west, and throughout the Southern Appalachian Mountains in the east [1]. Due to its rapid decline over the past century, S. diana is considered to be a species of federal concern in North Carolina by the Fish and Wildlife Service and is included on the North Carolina Animal Watch List published by the North Carolina Natural Heritage Program [2].…”