Genetic data reveal a cryptic species of New World flying squirrel: Glaucomys oregonensis

Abstract

The genus Glaucomys (New World flying squirrels) is currently considered to be comprised of 2 species, the northern flying squirrel (G. sabrinus) and the southern flying squirrel (G. volans). We synthesize new information from mitochondrial DNA (mtDNA) control region sequences and microsatellite data to demonstrate that the genus consists of 3, rather than 2 species, and that Glaucomys sabrinus, as currently recognized, is actually composed of 2 separate, apparently non-hybridizing species. Control region mtDNA data from 185 individuals across North America revealed 2 distinct clades embedded within G. sabrinus: a widespread "Continental" lineage and a more geographically restricted "Pacific Coastal" lineage. The geographic distributions of these 2 lineages are largely mutually exclusive, with sympatry observed at only 3 sites in the Pacific Northwest. Analysis of 8 microsatellite loci showed no evidence of hybridization between the 2 lineages of G. sabrinus in the region of sympatry. This lack of gene flow is noteworthy given that populations of the Continental lineage of G. sabrinus have been shown to hybridize with G. volans in southeastern Canada. Finally, phylogenetic analyses and estimates of divergence times show that G. volans and Continental G. sabrinus are actually sister taxa that diverged from one another more recently than either did from Pacific Coastal G. sabrinus. We propose that these observations provide strong evidence for a third, previously unrecognized species of North American flying squirrel, whose geographic range extends along the Pacific Coast from southern British Columbia to southern California. Glaucomys oregonensis (Bachman, 1839), whose type locality is in Oregon, is the senior available name for this taxon. We propose that this newly recognized species be given the common name "Humboldt's flying squirrel."

Oldest skeleton of a fossil flying squirrel casts new light on the phylogeny of the group

“…These forests provided a suitable habitat for flying squirrels and would have contributed to their initial radiation and dispersal into different continents. Our phylogenetic analyses show that some extant genera, such as Petaurista , Pteromys and Glaucomys , diverged approximately at that time (Figure 7 and Figure 7—figure supplement 1), thus agreeing with previous molecular results (Arbogast et al, 2017; Mercer and Roth, 2003). …”

“…It is not surprising that this last record of a large-sized flying squirrel in North America comes from Florida, an area that is still characterized by a humid subtropical climate with abundant densely forested areas. The extant American flying squirrel genus Glaucomys , which today inhabits temperate deciduous forests and boreal coniferous forests, is recorded for the first time already in the Pleistocene (Ruez, 2001) although it would have diverged significantly earlier according to molecular results (Figure 7 and Figure 7—figure supplement 1; Arbogast et al, 2017; Mercer and Roth, 2003). …”

Conservation genetics of the threatened plant species Physaria filiformis (Missouri bladderpod) reveals strong genetic structure and a possible cryptic species

“…Genetic data can also be used to help resolve species boundaries, such as determining whether a rare species is genetically unique and worthy of protection or whether it is instead a subpopulation of a more widespread species [ 33 , 34 ]. Genetic data may also unexpectedly reveal that some populations are genetically unique and may be cryptic species [ 35 , 36 ], in which case both the new species and the existing one may be in need of conservation. All of this information is important to ensure that diversity is being effectively conserved.…”

Peer Review #3 of "Effects of trapping effort and trap placement on estimating abundance of Humboldt’s flying squirrels (v0.1)"

“…Abundance of small mammals has been of research interest in the Pacific Northwest USA (hereafter, PNW) because small mammals comprise a large proportion of the prey base for many avian and mammalian predators, including mustelids and owls. Two species of flying squirrels, the recently describe Humboldt's flying squirrel (Glaucomys oregonensis; Arbogast et al 2017) and the northern flying squirrel (G. sabrinus), have been of interest because they serve as prey for the federally threatened northern spotted owl (Strix occidentalis caurina; Forsman, Meslow & Wight, 1984;Forsman et al, 2004;USFWS 1990). Flying squirrels also contribute to the maintenance of ecosystem health through the dispersal of hypogeous fungi, berries, and seeds (Maser, Trappe & Nussbaum, 1978;Bowers & Dooley Jr., 1993;Carey et al, 1999).…”