Low-elevation Habitats Research Articles

Phylogenetic position of Electrostrymon picoloro, a new high elevation hairstreak from western Colombia (Lepidoptera: Lycaenidae: Eumaeini).

The phylogenetic position of a new high-elevation butterfly species, which we describe as Electrostrymon picoloro Prieto & Robbins, new species, is assessed. The ventral wing pattern and genitalic structures of this species are unique among Electrostrymon. This species is also unique among Electrostrymon in that it occurs, so far as is known, only in habitats above 2800 m elevation. A phylogenetic analysis places this species in Electrostrymon as the sister of a multi-species clade. The ancestors of E. picoloro appear to have colonized its high elevation habitat relatively early in the phylogenetic history of Electrostrymon, but the species then did not recolonize lower elevation habitats nor did it diversify into other extant species.

Long-term shifts in the phenology of rare and endemic Rocky Mountain plants.

• Mountainous regions support high plant productivity, diversity, and endemism, yet are highly vulnerable to climate change. Historical records and model predictions show increasing temperatures across high elevation regions including the Southern Rocky Mountains, which can have a strong influence on the performance and distribution of montane plant species. Rare plant species can be particularly vulnerable to climate change because of their limited abundance and distribution.• We tracked the phenology of rare and endemic species, which are identified as imperiled, across three different habitat types with herbarium records to determine if flowering time has changed over the last century, and if phenological change was related to shifts in climate.• We found that the flowering date of rare species has accelerated 3.1 d every decade (42 d total) since the late 1800s, with plants in sagebrush interbasins showing the strongest accelerations in phenology. High winter temperatures were associated with the acceleration of phenology in low elevation sagebrush and barren river habitats, whereas high spring temperatures explained accelerated phenology in the high elevation alpine habitat. In contrast, high spring temperatures delayed the phenology of plant species in the two low-elevation habitats and precipitation had mixed effects depending on the season.• These results provide evidence for large shifts in the phenology of rare Rocky Mountain plants related to climate, which can have strong effects on plant fitness, the abundance of associated wildlife, and the future of plant conservation in mountainous regions.

Predicting Effects of Climate Change on Habitat Suitability of Red Spruce (Picea rubens Sarg.) in the Southern Appalachian Mountains of the USA: Understanding Complex Systems Mechanisms through Modeling

Alpine, subalpine and boreal tree species, of low genetic diversity and adapted to low optimal temperatures, are vulnerable to the warming effects of global climate change. The accurate prediction of these species’ distributions in response to climate change is critical for effective planning and management. The goal of this research is to predict climate change effects on the distribution of red spruce (Picea rubens Sarg.) in the Great Smoky Mountains National Park (GSMNP), eastern USA. Climate change is, however, conflated with other environmental factors, making its assessment a complex systems problem in which indirect effects are significant in causality. Predictions were made by linking a tree growth simulation model, red spruce growth model (ARIM.SIM), to a GIS spatial model, red spruce habitat model (ARIM.HAB). ARIM.SIM quantifies direct and indirect interactions between red spruce and its growth factors, revealing the latter to be dominant. ARIM.HAB spatially distributes the ARIM.SIM simulations under the assumption that greater growth reflects higher probabilities of presence. ARIM.HAB predicts the future habitat suitability of red spruce based on growth predictions of ARIM.SIM under climate change and three air pollution scenarios: 10% increase, no change and 10% decrease. Results show that suitable habitats shrink most when air pollution increases. Higher temperatures cause losses of most low-elevation habitats. Increased precipitation and air pollution produce acid rain, which causes loss of both low- and high-elevation habitats. The general prediction is that climate change will cause contraction of red spruce habitats at both lower and higher elevations in GSMNP, and the effects will be exacerbated by increased air pollution. These predictions provide valuable information for understanding potential impacts of global climate change on the spatiotemporal distribution of red spruce habitats in GSMNP.

Revision and phylogeny of narrow-mouthed treefrogs (Cophyla) from northern Madagascar: integration of molecular, osteological, and bioacoustic data reveals three new species.

We provide a revision of microhylid treefrogs of the genus Cophyla, the type genus of the subfamily Cophylinae. A phylogeny inferred from DNA sequences of multiple mitochondrial and nuclear genes, with representatives of all cophyline genera except Madecassophryne and including representatives of the two most divergent intrageneric lineages within Cophyla, placed Cophyla as sister group of Platypelis and confirmed both genera as reciprocally monophyletic. We describe three new Cophyla species based on osteological, morphological and bioacoustic characters as well as genetic differentiation in one nuclear and several mitochondrial markers. As in the vast majority of cophylines, all species of Cophyla emit long, stereotyped repetitions of a single tonal note, and we here consider one of these notes as a call; call duration thus equals note duration and the intervals between calls are named inter-call intervals. Cophyla maharipeo sp. nov. collected in Joffreville and Forêt d'Ambre Special Reserve (adult SVL 22-27 mm) is characterized by having long calls (1166-1346 ms) with long inter-call intervals (2154-3881 ms). Cophyla noromalalae sp. nov. collected in Montagne d'Ambre National Park (adult SVL 22-29 mm) is characterized by having short calls (662-821 ms) and short inter-call intervals (874-1882 ms). Cophyla puellarum sp. nov., also from Montagne d'Ambre National Park, is larger than the other two species (adult SVL 27.3-33.6 mm) and characterized by the shortest calls (326-390 ms) and long inter-call intervals (1961-3996 ms). Osteological analyses based on micro-CT scans and cleared and stained specimens confirms that the shape of the posterior vomer (centrally divided vs. undivided) may be a useful character to diagnose most species as belonging to either Platypelis and Cophyla, and suggest the absence of clavicles (present in Platypelis) is a derived character of most Cophyla. However, clavicles were present in C. puellarum, the only known Cophyla occurring at relatively high elevations (1250-1300 m a.s.l.) while otherwise in northern Madagascar, forests at higher elevations up to 2700 m a.s.l. are occupied by Platypelis species. Cophyla maharipeo was found at relatively low elevations (630-720 m a.s.l.), similar to the three previously known congeners (C. berara, C. occultans, C. phyllodactyla). Cophyla noromalalae occurs at intermediate elevations (900-1050 m a.s.l.). The molecular phylogeny inferred herein suggests that the ancestor of a clade containing all Cophyla species except C. puellarum evolved a modified shoulder girdle structure without ossified clavicles, and adapted to low-elevation habitats.

Resource Selection by an Endangered Ungulate: A Test of Predator-Induced Range Abandonment

We investigated influences of risk of predation by mountain lions (Puma concolor), topographic metrics at multiple scales, and vegetation, land, and snow cover on resource selection by Sierra Nevada bighorn sheep (Ovis canadensis sierrae), an endangered taxon, during winters 2002–2007, in the Sierra Nevada, California, USA. We hypothesized that those mountain ungulates would trade off rewards accrued from using critical low-elevation habitat in winter for the safety of areas with reduced risk of predation. Sierra Nevada bighorn sheep did not trade off benefits of forage for reduced risk of predation but selected areas of high solar radiation, a correlate of vegetation productivity, where risk of predation by mountain lions was greatest, while mitigating indirect risk of predation by selecting for steep, rugged terrain. Bighorn sheep selected more strongly for areas where mountain lions were active, than for low-elevation habitat in winter, likely because mountain lions were most active in those areas of bighorn sheep winter ranges overlapping ranges of mule deer (Odocoileus hemionus), where both ungulates accrued forage benefits. We demonstrated reduced benefit of migration to low elevation during drought years, providing an alternative explanation to the predator-induced abandonment hypothesis for the disuse of low-elevation winter range observed during drought years.

Four new non-spiny Solanum (Solanaceae) species from South America.

Four new species of “non-spiny” Solanum from South America are described. Solanum longifilamentum Särkinen & P.Gonzáles, sp. nov. (Morelloid clade) is widespread from Ecuador to Bolivia and is most similar to Solanum macrotonum Dunal from Central and northern South America. Solanum antisuyo Särkinen & S.Knapp, sp. nov. (Morelloid clade) is found on the eastern Andean slopes in Ecuador, Peru and Bolivia and is most similar to the widespread lower elevation species Solanum polytrichostylum Bitter. Solanum arenicola Särkinen & P.Gonzáles, sp. nov. (Morelloid clade) is found in low elevation habitats on the eastern Andean slopes and in Amazonia of Peru and Bolivia and is most similar to the higher elevation species Solanum aloysiifolium Dunal of Bolivia and Argentina. Solanum mariae Särkinen & S.Knapp, sp. nov. (Potato clade) is endemic to Cajamarca Department in Peru, and is most similar to the widespread Solanum caripense Dunal. Complete descriptions, distributions and preliminary conservation assessments of all new species are given.

Divergence of vocal culture among isolated alpine habitats is inconsistent among three Oscine species

Divergence in song culture has been well documented among isolated bird populations. Montane populations separated by unsuitable lower-elevation habitats thus appear to be excellent candidates for cultural divergence, and existing data support this conjecture. To explore the generality of this phenomenon, we investigated song sharing patterns in songbird species breeding in isolated alpine life zones in the Rocky Mountains of Colorado. We recorded songs of American Pipits (Anthus rubescens alticola), Wilson’s Warblers (Cardellina pusilla pileolata), and White-crowned Sparrows (Zonotrichia leucophrys leucophrys) across 19 sites among 6 mountain ranges. We used spectrographic cross-correlation to calculate song similarity coefficients between individuals within and among populations. White-crowned Sparrows exhibited significantly elevated song sharing within isolated mountain ranges, but Wilson’s Warbler and the American Pipit did not. Cluster analyses showed that White-crowned Sparrow songs diverged among alpine fragments but were generally similar among sites within contiguous alpine habitat within mountain ranges. There was no such clustering within American Pipit or Wilson’s Warbler populations. Song similarity declined with distance between sites within contiguous alpine habitat in White-crowned Sparrows but not in American Pipits or Wilson’s Warblers. Our results provide convincing evidence for the existence of geographically structured vocal culture in White-crowned Sparrow populations in Colorado, and this geographic pattern may be explained by clinal variation rather than by a mosaic pattern of divergence among isolated alpine fragments.

Recent evolutionary history of Lost World endemics: Population genetics, species delimitation, and phylogeography of sky-island treefrogs

The tepuis of South America are massive flattop mountains with cliffs up to 1000m and summits up to 3100m. Tepuis hold enormous endemicity levels, but little is known about the origins of the endemic flora and fauna. Recently diverged lineages offer the possibility of understanding the origins of summit endemicity by examining population dynamics and dispersal. We examine species delimitation, clade relationships, and demographic patterns of three recently diverged lineages of Tepuihyla, an endemic treefrog clade. These three lineages represent two currently recognized species, T. edelcae and T. rodriguezi. Given the low divergences in both nuclear and mitochondrial genes among lineages, we find unexpectedly high numbers of unique nuclear haplotypes and moderate levels of lineage sorting. We also find support from multiple analyses for a cryptic, undescribed summit species within T. edelcae. We suggest that the genetic and distribution patterns of the four most recently diverged Tepuihyla lineages support a concurrent speciation event during the Pliocene, and suggest a biogeographic hypothesis in which a widespread climatic change made mid- and low-elevation habitat unsuitable for the common ancestor within the timeframe of their divergence.

Cold tolerance performance of westslope cutthroat trout (Oncorhynchus clarkii lewisi) and rainbow trout (Oncorhynchus mykiss) and its potential role in influencing interspecific hybridization

Hybridization between rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)) and westslope cutthroat trout (Oncorhynchus clarkii lewisi (Girard, 1856)) occurs commonly when rainbow trout are introduced into the range of westslope cutthroat trout. Typically, hybridization is most common in warmer, lower elevation habitats, but much less common in colder, higher elevation habitats. We assessed the tolerance to cold water temperature (i.e., critical thermal minimum, CTMin) in juvenile rainbow trout and westslope cutthroat trout to test the hypothesis that westslope cutthroat trout better tolerate low water temperature, which may explain the lower prevalence of rainbow trout and interspecific hybrids in higher elevation, cold-water habitats (i.e., the “elevation refuge hypothesis”). All fish had significantly lower CTMin values (i.e., were better able to tolerate low temperatures) when they were acclimated to 15 °C (mean CTMin = 1.37 °C) versus 18 °C (mean CTMin = 1.91 °C; p < 0.001). Westslope cutthroat trout tended to have lower CTMin than rainbow trout from two populations, second–generation (F2) hybrids between two rainbow trout populations, and backcrossed rainbow trout at 15 °C (cross type × acclimation temperature interaction; p = 0.018). Differential adaptation to cold water temperatures may play a role in influencing the spatial distribution of hybridization between sympatric species of trout.

A new species of small-eared shrew (Mammalia, Eulipotyphla,Cryptotis) from the Lacandona rain forest, Mexico

The diversity and distribution of mammals in the American tropics remain incompletely known. We describe a new species of small-eared shrew (Soricidae, Cryptotis) from the Lacandona rain forest, Chiapas, southern Mexico. The new species is distinguished from other species of Cryptotis on the basis of a unique combination of pelage coloration, size, dental, cranial, postcranial, and external characters, and genetic distances. It appears most closely related to species in the Cryptotis nigrescens species group, which occurs from southern Mexico to montane regions of Colombia. This discovery is particularly remarkable because the new species is from a lowelevation habitat (approximately 90 m), whereas most shrews in the region are restricted to higher elevations, typically . 1,000 m. The only known locality for the new shrew is in one of the last areas in southern Mexico where relatively undisturbed tropical vegetation is still found. The type locality is protected by the Mexican

A review ofRinodina(Physciaceae) in Great Smoky Mountains National Park highlights the growing significance of this “island of biodiversity” in eastern North America

A review of the crustose lichen genus Rinodina in Great Smoky Mountains National Park is presented. Seventeen species are reported from the study area, of which three represent new reports (R. bullata, R. excrescens, and R. oxydata) and one is described as new to science (R. brodoana). Based on current collections, the new species is restricted to old growth hardwoods and occurs at middle to low elevations. Also based on collections information, two species (R. brodoana and R. chrysomelaena) are proposed to have IUCN Red List ranks of critically endangered. We discuss the increasing significance of middle to low elevation habitats in this biodiversity hotspot. All 17 species reported from the study are illustrated, their biogeographic patterns and ecologies are discussed, and maps showing revised North American distributions, are provided. A key to the 21 species of Rinodina known to occur in the southern Appalachian Mountains is also provided.

Notes on Mangrove Snake Boiga dendrophila multicincta (Boulenger, 1896) in Iwahig River, Puerto Princesa City

The genus Boiga is composed of about 20-30 species (Rodda et al. 1999) and widespread throughout low elevation and coastal habitats of the Philippines and other Asian countries. A sub-species, Boiga dendrophila divergens had been reported from the northeastern Luzon including the Babuyan Islands (see Brown et al. 2013). A Palawan endemic sub-species Boiga dendrophila multicincta is locally called ‘binturan’ (Leviton 1970). The species is commonly encountered in a semi-disturbed river in Iwahig, Puerto Princesa City, Palawan, Philippines. The one shown in the photo (~2m long) was spotted resting on branches of the mangrove tree Scyphiphora hydrophyllacea along the bank of Iwahig River, Puerto Princesa City (Figure 1). Two of the nine transect lines (intended for molluscs) had one mangrove snake at the start; several individuals were subsequently noted resting on branches of mangrove trees along the river banks, suggesting an unusually high population density. The same species is abundant in a semi-disturbed mangrove forest in Sitio Bunuangin, Port Barton, San Vicente (MPG Soniega, pers. comm.) and in a pristine mangrove forest in Puerto Princesa Underground River – one of the New Seven Wonders of Nature. The snake is feared for its tendency to chase intruders (people) once hurt. At night, it feeds on a variety of small vertebrates including birds, frogs, snakes and fishes (Minton & Dunson 1978; Savidge 1988). Boiga spp. are both important in the pharmaceutical industry (e.g. Lumsden et al. 2005; Mackessy et al. 2006) and pet trade (Shepherd et al. 2004; Mendizabal 2011). The mangrove snake is one of the many reptilian fauna in Palawan – the so-called “Philippines’ Last Frontier”. However, mangrove snake and other reptiles are illegally traded from Palawan. In 2011, 25 snakes, including 15 mangrove snakes, 9 vipers and a spitting cobra were seized by officials of the Palawan Conservation for Sustainable Development (PCSD) in El Nido, Palawan (Mendizabal 2011). While record of confiscation is limited, the magnitude of trade could be far higher than this. In addition, the seemingly unabated widespread habitat degradation in Palawan (Ramirez 2012; Tesorio 2013) could also threaten the existence of these species. Population survey and trade along with education and information campaign, and habitat protection and restoration could help conserve the populations of these mangrove snakes.

Taxonomic revision of the olingos (Bassaricyon), with description of a new species, the Olinguito.

We present the first comprehensive taxonomic revision and review the biology of the olingos, the endemic Neotropical procyonid genus Bassaricyon, based on most specimens available in museums, and with data derived from anatomy, morphometrics, mitochondrial and nuclear DNA, field observations, and geographic range modeling. Species of Bassaricyon are primarily forest-living, arboreal, nocturnal, frugivorous, and solitary, and have one young at a time. We demonstrate that four olingo species can be recognized, including a Central American species (Bassaricyon gabbii), lowland species with eastern, cis-Andean (Bassaricyon alleni) and western, trans-Andean (Bassaricyon medius) distributions, and a species endemic to cloud forests in the Andes. The oldest evolutionary divergence in the genus is between this last species, endemic to the Andes of Colombia and Ecuador, and all other species, which occur in lower elevation habitats. Surprisingly, this Andean endemic species, which we call the Olinguito, has never been previously described; it represents a new species in the order Carnivora and is the smallest living member of the family Procyonidae. We report on the biology of this new species based on information from museum specimens, niche modeling, and fieldwork in western Ecuador, and describe four Olinguito subspecies based on morphological distinctions across different regions of the Northern Andes.

Complex evolutionary history of the pallid dotted-blue butterfly (Lycaenidae:Euphilotes pallescens) in the Great Basin of western North America

Aim The aim of this study was to investigate patterns of genetic isolation associated with populations in discrete habitat patches in a North American cold desert through analysis of the pallid dotted-blue butterfly, Euphilotes pallescens. This small butterfly is largely restricted to low-elevation habitats across the Great Basin. The apparent geographical isolation and reported morphological variation among E. pallescens populations makes this species an ideal candidate with which to investigate patterns of genetic isolation and diversification in this arid region. Location Great Basin, western North America. Methods We used sequence data from nuclear and mitochondrial genes to investigate genetic diversity among E. pallescens populations, and among E. pallescens and a number of closely related Euphilotes species, using Bayesian phylogenetic analyses, as well as population genetic analyses. In conjunction with genetic variation, morphological variation was examined in the context of geographical and subspecific differentiation. Results Our genetic and morphological analyses suggest a moderate amount of isolation among populations, consistent with the hypothesis of restricted gene flow among isolated dune habitats, and possibly associated with isolation in distinct Pleistocene refugia. The patterns of diversification within E. pallescens and among closely related species are complicated by discordance among phylogenetic reconstructions based on nuclear and mitochondrial genes. Discordance among gene genealogies suggests a complex evolutionary history, perhaps involving alternating periods of reticulation and divergence in isolation. Main conclusions Although E. pallescens may be a vagile species, we find that persistence on isolated dunes in the Great Basin is associated with appreciable genetic and morphological differentiation among populations. However, genetic, morphological and taxonomic axes of variation are only partially in agreement. More generally, the discordance we find among genetic regions is consistent with the ascendant paradigm in phylogenetic reconstruction: gene genealogies often do not perfectly match species trees. Thus we present Euphilotes as a model for future biogeographical and phylogenetic reconstructions employing larger data sets of independent sequence markers.

ADAPTATION OF DIPLOID AND TETRAPLOIDCHAMERION ANGUSTIFOLIUMTO ELEVATION BUT NOT LOCAL ENVIRONMENT

Polyploid organisms often have different geographic ranges than their diploid relatives. However, it is unclear whether this divergence is maintained by adaptation or results from historical differences in colonization. Here, we conducted a reciprocal transplant experiment with diploid and autotetraploid Chamerion angustifolium to test for adaptation at the ploidy and population level. In the Rocky Mountains, pure diploid populations occur at high elevations and pure autotetraploid populations occur at low elevations with mixed ploidy populations between. We planted 3134 seedlings in 2004 and 3890 juveniles (bolting) in 2005 among nine plots, three in each of the diploid, mixed ploidy, and tetraploid zones, and monitored survival until 2008. For both seedlings and juvenile plants, elevation significantly influenced survival. The juvenile plants also showed a significant ploidy by elevation interaction, indicating that diploids and tetraploids survived best at their native elevations. In contrast, we found no evidence of local adaptation to plot within elevation. This suggests that the current distribution of diploids and tetraploids across elevations is the result of adaptation and that genome duplication may have facilitated the invasion of lower elevation habitats by limiting the movement of maladapted alleles from diploid populations at higher elevations.

Seasonal habitat selection of the red deer (Cervus elaphus alxaicus) in the Helan Mountains, China

We studied the seasonal habitat selection of the red deer, Cervus elaphus alxaicus Bobrinskii & Flerov, 1935, in the Helan Mountains, China, from December 2007 to December 2008. Habitat selection varied widely by season. Seasonal movements between high and low elevations were attributed to changes in forage availability, alpine topography, the arid climate of the Helan Mountains, and potential competition with blue sheep, Pseudois nayaur (Hodgson, 1833). The use of vegetation types varied seasonally according to food availability and ambient temperature. Red deer used montane coniferous forest and alpine shrub and meadow zones distributed above 2,000 m and 3,000 m in summer, alpine shrub and meadows above 3,000 m in autumn, being restricted to lower elevation habitats in spring and winter. The winter habitat of C. elaphus alxaicus was dominated by Ulmus glaucescens Franch. and Juglans regia Linnaeus, deciduous trees, and differed from the habitats selected by other subspecies of red deer. Cervus elaphus alxaicus preferred habitats with abundant vegetation coverage to open habitats in winter, but the reverse pattern was observed in summer and autumn. Red deer preferred gentle slopes (<10°) but the use of slope gradient categories varied seasonally. Red deer avoidance of human disturbance in the Helan Mountains varied significantly by season. Information on red deer habitat selection can help understand the factors affecting seasonal movements and also support decision making in the management and conservation of red deer and their habitats.

Natural protected areas of San Luis Potosí, Mexico: ecological representativeness, risks, and conservation implications across scales

Assessments of the conservation status of natural resources have been conducted at large (i.e., global, continental, and countrywide) extents. Studies at finer scales, however, can yield increased detail needed to identify conservation strategies for smaller scales which can contribute to goals at the larger extents. Our study was conducted at the scale of a single state, San Luis Potosí, in Central Mexico. Although the state harbors great biological diversity, large areas covered by natural vegetation communities have been and continue to be destroyed by land use changes, cattle grazing, and mine-generated pollution. Our purposes were to quantify the proportion of distribution within natural protected areas (NPAs) of land cover classes, soil types, ecoregions, and altitudinal steps. In addition, within individual NPAs, we aimed at assessing risks. We conducted our analysis at the 1:1, 1:250,000, and 1:1,000,000 scales depending on layer availability. Our results show that actions within the state could contribute to federal and global conservation goals by protecting sites of globally imperiled ecosystems (cloud forests and natural grasslands). At a finer scale, we identified that piedmont scrubland, medium and low tropical moist forests, wetlands, and low elevation habitats are rare and/or constitute conservation omissions within the state. Similarly, ecoregions with mesquite, semi-deciduous, and moist tropical thorn forest, wetlands, and low elevations (<1200 m.a.s.l.) are conservation omissions or gaps. Finally, at the smallest scale, risks within some protected areas (PAs) include the presence of agriculture, cattle grazing, and mine tailings from mines dedicated to extraction of Au, Ag, Cu, Pb, and Zn. Therefore, management within these PAs should minimize such risks through identification of the most important conservation zones within the PAs, and implementation of local legislation prohibiting such activities at the immediacies of conservation zones. Approaches like ours within similar administrative units will help identify ecosystems that are vulnerable and not well protected. However, to prioritize conservation action it is also important to consider surrogates such as species from different groups and ecosystems, as well as rarity and complementarity of such surrogates.

Variation in Habitat Characteristics of American Pikas along an Elevation Gradient at Their Northern Range Margin

Temperature is an important environmental variable in shaping the distribution of species. The American pika (Ochotona princeps) has been identified as a climate-change-sensitive species as documented by the extirpation of a number of populations at the southern end of the species' range. Limited tolerance to warm temperatures has previously been reported, yet recent evidence suggests that pikas are able to live outside of cool habitats with the discovery of warmer, low-elevation pika populations, such as those found in the Bella Coola Valley in British Columbia. Here we characterize the temperatures experienced by pikas living along an elevation gradient at the northern end of their distribution. Additionally, we recorded temperatures both above and below the talus at one of our sites and the relationship between pika activity and temperature. Temperatures differed along the elevation gradient by up to 6 °C from low- to high-elevation sites. Below-talus temperatures were lower than above-talus temperatures at noon and during the afternoon, and were warmer than above temperatures in the morning and night, suggesting that talus has insulative properties that guard against extreme temperatures. Lastly, a negative relationship was observed between temperature and pika activity. We show that although at the northern end of pika distribution, ambient temperatures 1.5 m above the talus surface often exceeded the threshold for acute heat stress. Our results also suggest that behavioral thermoregulation or other adaptations may enable pikas to inhabit low-elevation habitat that was previously thought as inhospitable to pikas.

Evaluating apparent competition in limiting the recovery of an endangered ungulate

Predation can disproportionately affect endangered prey populations when generalist predators are numerically linked to more abundant primary prey. Apparent competition, the term for this phenomenon, has been increasingly implicated in the declines of endangered prey populations. We examined the potential for apparent competition to limit the recovery of Sierra Nevada bighorn sheep (Ovis canadensis sierrae), an endangered subspecies under the US Endangered Species Act. Using a combination of location, demographic, and habitat data, we assessed whether cougar (Puma concolor) predation on endangered bighorn sheep was a consequence of their winter range overlap with abundant mule deer (Odocoileus hemionus). Consistent with the apparent competition hypothesis, bighorn sheep populations with higher spatial overlap with deer exhibited higher rates of cougar predation which had additive effects on adult survival. Bighorn sheep killed by cougars were primarily located within deer winter ranges, even though those areas constituted only a portion of the bighorn sheep winter ranges. We suspect that variation in sympatry between bighorn sheep and deer populations was largely driven by differences in habitat selection among bighorn sheep herds. Indeed, bighorn sheep herds that experienced the highest rates of predation and the greatest spatial overlap with deer also exhibited the strongest selection for low elevation habitat. Although predator-mediated apparent competition may limit some populations of bighorn sheep, it is not the primary factor limiting all populations, suggesting that the dynamics of different herds are highly idiosyncratic. Management plans for endangered species should consider the spatial distributions of key competitors and predators to reduce the potential for apparent competition to hijack conservation success.

Species Differentiation on a Dynamic Landscape: Shifts in Metapopulation Genetic Structure Using the Chronology of the Hawaiian Archipelago.

Species formation during adaptive radiation often occurs in the context of a changing environment. The establishment and arrangement of populations, in space and time, sets up ecological and genetic processes that dictate the rate and pattern of differentiation. Here, we focus on how a dynamic habitat can affect genetic structure, and ultimately, differentiation among populations. We make use of the chronology and geographical history provided by the Hawaiian archipelago to examine the initial stages of population establishment and genetic divergence. We use data from a set of 6 spider lineages that differ in habitat affinities, some preferring low elevation habitats with a longer history of connection, others being more specialized for high elevation and/or wet forest, some with more general habitat affinities. We show that habitat preferences associated with lineages are important in ecological and genetic structuring. Lineages that have more restricted habitat preferences are subject to repeated episodes of isolation and fragmentation as a result of lava flows and vegetation succession. The initial dynamic set up by the landscape translates over time into discrete lineages. Further work is needed to understand how genetic changes interact with a changing set of ecological interactions amongst a shifting mosaic of landscapes to achieve species formation.