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Polar bears rely upon sea ice to hunt, travel, and reproduce. Declining sea ice extent and duration has led polar bears to be designated as “threatened” (ESA). Population monitoring is vital to polar bear conservation; but recently, poor sea ice has made traditional aircraft-based methods less viable. These methods largely rely upon the capture and handling of polar bears, and have been criticized over animal welfare concerns. Monitoring polar bears via DNA sampling is a promising option. One common method utilizes biopsy darts delivered from a helicopter to collect DNA, a method that faces similar ice associated challenges to those described above. However, epidermal cells shed from the foot pads of a polar bear into its paw-prints in snow are a source of “environmental DNA” (e-DNA) that can be collected non-invasively on the sea ice or on land for potential use in population monitoring. Mitochondrial DNA (mt-DNA) is used to assess whether polar bear DNA is present within a snow sample, and nuclear DNA (n-DNA) can identify individuals and their sex. The goal of this investigation was to assess the viability of using e-DNA collected from paw-prints in the snow to identify individual polar bears and their sex. Snow was sampled from 13 polar bear trails (10 paw-prints per trail) on the sea ice in the Chukchi and Beaufort seas along the North Slope of Alaska. Species verification was based on a mt-DNA PCR fragment analysis test. Identification of individuals was accomplished by amplifying a multiplex of seven n-DNA microsatellite loci, and sex was determined by the amelogenin gene sex ID marker. Six of the 13 bear trails sampled (46%) yielded consensus genotypes for five unique males and one female. To our knowledge, this is the first time that polar bears have been individually identified by genotype and sex using e-DNA collected from snow. This method is non-invasive, could be integrated into genetic mark-recapture sampling designs, and addresses some of the current challenges arising from poor sea ice conditions. It also can involve, engage, and empower Indigenous communities in the Arctic, which are greatly affected by polar bear management decisions.

Current and past climatic changes can shift plant climatic niches, which may cause spatial overlap or separation between related taxa. The former often leads to hybridization and introgression, which may generate novel variation and influence the adaptive capacity of plants. An additional mechanism facilitating adaptations to novel environments and an important evolutionary driver in plants is polyploidy as the result of whole genome duplication. Artemisia tridentata (big sagebrush) is a landscape-dominating foundational shrub in the western United States which occupies distinct ecological niches, exhibiting diploid and tetraploid cytotypes. Tetraploids have a large impact on the species’ landscape dominance as they occupy a preponderance of the arid spectrum of A. tridentata range. Three distinct subspecies are recognized, which co-occur in ecotones – the transition zone between two or more distinct ecological niches – allowing for hybridization and introgression. Here we assess the genomic distinctiveness and extent of hybridization among subspecies at different ploidies under both contemporary and predicted future climates. We sampled five transects throughout the western United States where a subspecies overlap was predicted using subspecies-specific climate niche models. Along each transect, we sampled multiple plots representing the parental and the potential hybrid habitats. We performed reduced representation sequencing and processed the data using a ploidy-informed genotyping approach. Population genomic analyses revealed distinct diploid subspecies and at least two distinct tetraploid gene pools, indicating independent origins of the tetraploid populations. We detected low levels of hybridization (2.5%) between the diploid subspecies, while we found evidence for increased admixture between ploidy levels (18%), indicating hybridization has an important role in the formation of tetraploids. Our analyses highlight the importance of subspecies co-occurrence within these ecotones to maintain gene exchange and potential formation of tetraploid populations. Genomic confirmations of subspecies in the ecotones support the subspecies overlap predicted by the contemporary climate niche models. However, future mid-century projections of subspecies niches predict a substantial loss in range and subspecies overlap. Thus, reductions in hybridization potential could affect new recruitment of genetically variable tetraploids that are vital to this species’ ecological role. Our results underscore the importance of ecotone conservation and restoration.

Urbanization constitutes one of the most aggressive drivers of habitat and biodiversity loss worldwide. However, studies focused on determining the response of local biodiversity to urbanization are still scarce, especially in tropical ecosystems. Urban ecosystems are characterized by low biological productivity which in turn leads to a reduction in biodiversity. However, the responses to urbanization should be species dependent. For instance, changes in the availability of resources can favor certain species with specific characteristics. We assessed the effects of the urbanization process on a bird community in a city located in the Tropical Andes of southern Ecuador, a region widely recognized for its diversity and endemism of birds. We selected three independent localities in each of the four levels of the urbanization gradient in the study area (forest, forest-pasture, pasture, and urban). In each locality, we sampled the bird community by visual and auditory surveys along 1 km transects between 2016 and 2017. We recorded a total of 1,257 individuals belonging to 74 bird species. We evaluated if the responses of richness and abundance of birds are dependent on trophic guild and foraging strata. We found a significant decrease in bird species richness and abundance from forest to urban sites. However, the response of birds was dependent on the trophic guild and foraging strata. Granivorous birds showed a positive response associated with the urbanization gradient while insectivorous birds showed a negative response. Insectivorous birds were more abundant in forest sites and decreased in abundance across the urbanization gradient. We found that the proportion of birds using different foraging strata drastically changed along urban gradient. Forest sites exhibited a bird community using a variety of habitats, but the bird community became simpler toward the most urbanized sites. Our findings showed different effects of urbanization on bird communities. The ugly: urbanization leads to a dramatic reduction in the diversity of birds, which is consistent in cities with different characteristics and ecological contexts. On the other hand, the responses of bird guilds to urbanization are species dependent. Some guilds are positively impacted by urbanization and show increases in species richness and abundance while other guilds are negatively impacted.

The persistence of small populations is influenced by genetic structure and functional connectivity. We used two network-based approaches to understand the persistence of the northern Idaho ground squirrel (Urocitellus brunneus) and the southern Idaho ground squirrel (U. endemicus), two congeners of conservation concern. These graph theoretic approaches are conventionally applied to social or transportation networks, but here are used to study population persistence and connectivity. Population graph analyses revealed that local extinction rapidly reduced connectivity for the southern species, while connectivity for the northern species could be maintained following local extinction. Results from gravity models complemented those of population graph analyses, and indicated that potential vegetation productivity and topography drove connectivity in the northern species. For the southern species, development (roads) and small-scale topography reduced connectivity, while greater potential vegetation productivity increased connectivity. Taken together, the results of the two network-based methods (population graph analyses and gravity models) suggest the need for increased conservation action for the southern species, and that management efforts have been effective at maintaining habitat quality throughout the current range of the northern species. To prevent further declines, we encourage the continuation of management efforts for the northern species, whereas conservation of the southern species requires active management and additional measures to curtail habitat fragmentation. Our combination of population graph analyses and gravity models can inform conservation strategies of other species exhibiting patchy distributions.