Jessica R. Young

A NEW SPECIES OF SAGE-GROUSE (PHASIANIDAE: CENTROCERCUS) FROM SOUTHWESTERN COLORADO

Abstract The Gunnison Sage-Grouse (Centrocercus minimus) is described as a new species from southwestern Colorado and contrasted with the Sage-Grouse (Centrocercus urophasianus) from northern Colorado and western North America. Gunnison Sage-Grouse differ from all other described sage-grouse (C. u. urophasianus, C. u. phaios) in morphological measurements, plumage, courtship display, and genetics. The species currently is limited to 8 isolated populations in southwestern Colorado and adjacent San Juan County, Utah. Total estimated spring breeding population is fewer than 5000 individuals with the largest population (<3000) in the Gunnison Basin (Gunnison and Saguache counties), Colorado.

Genetic and ecological data provide incongruent interpretations of population structure and dispersal in naturally subdivided populations of white‐tailed ptarmigan (Lagopus leucura)

The dispersal of individuals among populations affects the demographic and adaptive trajectories of animal populations and is fundamental to understanding population dynamics. White‐tailed ptarmigan (Lagopus leucura) are a high elevation grouse species that live year‐round in patchily distributed alpine areas in western North America. We investigated the patterns of dispersal and identified barriers to gene flow for a threatened subspecies (L. l. saxatilis) endemic to Vancouver Island, Canada. Connectivity among seven sites was examined using nine microsatellite loci (n = 133 individuals, HO = 0.62, mean number of alleles = 10) and direct movement observations using radio‐telemetry (n = 118 individuals). Average movement distances of individuals measured by radio‐telemetry were 0.63–3.23 km and considerably less than the shortest distance between sampling sites (18 km). Furthermore, despite extensive radio‐telemetry data, movement was never observed between any of the seven sampling sites. In contrast, genetic results (structure, tess) showed connectivity among most of the seven sampling sites and suggested that genetic variation is best explained by two clusters of individuals which separated the South sampling site from all other areas of Vancouver Island. Analysis of molecular data also showed a generally consistent pattern of isolation by distance (Mantel test r = 0.11, P < 0.01) with large areas of unsuitable low elevation habitat possibly acting as barriers to gene flow. Despite the naturally subdivided distribution of populations, white‐tailed ptarmigan do not fit well into any common definition of a metapopulation. We conclude the incongruities between the genetic and radio‐telemetry data are best explained by episodic dispersal patterns. In this study, we demonstrated the importance of combining genetic and ecological data in understanding patterns of dispersal and population structure.

The historic and current distribution of the Vancouver Island White-tailed Ptarmigan (Lagopus leucurus saxatilis)

Abstract Lagopus leucurus saxatilis, a subspecies of White-tailed Ptarmigan endemic to Vancouver Island, is listed as vulnerable by the British Columbia Conservation Data Centre, but little is known about its population status or trends. The only previous journal paper concerning this subspecies was published in 1939. Data on distribution, gathered using historical records and public survey (166 records) in combination with our field studies, indicated that this ptarmigan subspecies currently inhabits most, if not all, available habitat on Vancouver Island, and the range has not contracted over the past 25 yr.

A COMPARATIVE BEHAVIORAL STUDY OF THREE GREATER SAGE-GROUSE POPULATIONS

Abstract We compared male strut behavior of the genetically distinct Lyon, Nevada/Mono, California Greater Sage-Grouse (Centrocercus urophasianus) population with that of two proximal populations: Nye, Nevada, and Lassen, California. We measured strut rates and nine acoustic components of the strut display in all three populations. Male strut rates did not differ among populations. Acoustic components of the Lyon/Mono and Lassen populations were similar, whereas the Nye population was distinct. The genetically distinct Lyon/ Mono population was more similar behaviorally to the Nye population than the genetically similar Nye and Lassen populations were to each other. Overall, the Lyon/Mono population did not exhibit detectable differences in male strut behavior. Reproductive isolation through sexual selection does not appear to have occurred in the Lyon/Mono population.

THE HISTORICAL DISTRIBUTION OF GUNNISON SAGE-GROUSE IN COLORADO

Abstract The historical distribution of Gunnison Sage-Grouse (Centrocercus minimus) in Colorado is described based on published literature, observations, museum specimens, and the known distribution of sagebrush (Artemisia spp.). Historically, Gunnison Sage-Grouse were widely but patchily distributed in up to 22 counties in south-central and southwestern Colorado. The historical distribution of this species was south of the Colorado-Eagle river drainages primarily west of the Continental Divide. Potential contact areas with Greater Sage-Grouse (C. urophasianus) were along the Colorado-Eagle river system in Mesa, Garfield, and Eagle counties, west of the Continental Divide. Gunnison Sage-Grouse historically occupied habitats that were naturally highly fragmented by forested mountains and plateaus/mesas, intermountain basins without robust species of sagebrush, and river systems. This species adapted to use areas with more deciduous shrubs (i.e., Quercus spp., Amelanchier spp., Prunus spp.) in conjunction with sagebrush. Most areas historically occupied were small, linear, and patchily distributed within the overall landscape matrix. The exception was the large intermountain basin in Gunnison, Hinsdale, and Saguache counties. The documented distribution east of the Continental Divide within the large expanse of the San Luis Valley (Alamosa, Conejos, Costilla, and Rio Grande counties) was minimal and mostly on the eastern, northern, and southern fringes. Many formerly occupied habitat patches were vacant by the mid 1940s with extirpations continuing to the late 1990s. Counties from which populations were recently extirpated include Archuleta and Pitkin (1960s), and Eagle, Garfield, Montezuma, and Ouray (1990s).

Characterizing range-wide divergence in an alpine-endemic bird: a comparison of genetic and genomic approaches

The delineation of intraspecific units that are evolutionarily and demographically distinct is an important step in the development of species-specific management plans. Neutral genetic variation has served as the primary data source for delineating “evolutionarily significant units,” but with recent advances in genomic technology, we now have an unprecedented ability to utilize information about neutral and adaptive variation across the entire genome. Here, we use traditional genetic markers (microsatellites) and a newer reduced-representation genomic approach (single nucleotide polymorphisms) to delineate distinct groups of white-tailed ptarmigan (Lagopus leucura), an alpine-obligate species that is distributed in naturally fragmented habitats from Alaska to New Mexico. Five subspecies of white-tailed ptarmigan are currently recognized but their distinctiveness has not been verified with molecular data. Based on analyses of 436 samples at 12 microsatellite loci and 95 samples at 14,866 single nucleotide polymorphism loci, we provide strong support for treating two subspecies as distinct intraspecific units—L. l. altipetens, found in Colorado and neighboring states; and L. l. saxatilis, found on British Columbia’s Vancouver Island—but our findings reveal more moderate patterns of divergence within the remainder of the species’ range. Results based on genetic and genomic datasets generally agreed with one another, indicating that in many cases microsatellite loci may be sufficient for describing major patterns of genetic structure across species’ ranges. This work will inform future conservation and management decisions for the white-tailed ptarmigan, a species that may be vulnerable to future changes in climate.