Habitat Expansion Research Articles

15~19세기 한반도 산림의 민간 개방과 숲의 변화

Essentially examined in this article are probable changes that would have been brought upon the forests, when the Joseon government newly designated forests as public lands and therefore allowed people to have access to most forests as well as resources inside them. In earlier times, all the forests were considered as private property of the king and therefore inaccessible. But the Joseon government (while excluding some areas as limited exceptions) opened forests to the public, and permitted them to freely take advantage of them. As a result, since the 15th century through the 19th, the primeval forest of the Korean peninsula, which had been kept intact till the end of the Goryeo dynasty, was severely reduced in its mass and depleted in its resources. Forests literally became mere ‘green lands.’BR Of course, there were other reasons which supposedly reduced the forests’ mass in the Joseon period. Large-scale constructions of palaces, offices and ships, production of salt (by boiling sea water), expansion in usages of a certain heating system(“Ondol”) in civilian residences, increase in iron refinery operations and even escalating usage of porcelain and earthenware (which required operation of kilns), all contributed to the increase in usage of wood and therefore would have been detrimental to forest preservation. But an overall analysis of the amount of wood that would have probably been used in each of the above-mentioned areas show that any one of them would not have been severe enough to compromise the forests’ ultimate regenerative power. They could have temporarily damaged the forests from time to time to be sure, but would not have brought them to a point beyond recovery.BR Examination of written records suggest that the most irrefutable cause for the forests’ ultimate reduction was a steady increase in reclamation projects aiming for the enlargement of usable agricultural lands, and the expansion of human habitats and villages. Forests were irrevocably damaged in regions where lands were newly upgraded and people started to gather in a concentrated fashion. Also, forests which were close to villages were placed under constant logging, and in many cases slowly turned into pine tree-based pure forests. These places were relatively more fertile that others, and therefore were developed more quickly (than other areas) as slash-and-burn lands, and large pine tree forests close to such lands were oftentimes sacrificed by open fire.

Overabundance of sika deer and immunocontraception

The impact of deer overabundance is a worldwide problem. Along with habitat expansion and population increase, damage by sika deer to the forest ecosystem and agriculture has become a serious issue in Japan. Deer also transmit a number of diseases and parasites to humans and livestock. The overabundance of deer is a result of their strong fecundity, and therefore the present situation should, in theory, be tackled by experts in reproductive biology.

Seasonal Habitat Patterns of Japanese Common Squid (Todarodes Pacificus) Inferred from Satellite-Based Species Distribution Models

The understanding of the spatio-temporal distributions of the species habitat in the marine environment is central to effectual resource management and conservation. Here, we examined the potential habitat distributions of Japanese common squid (Todarodes pacificus) in the Sea of Japan during a four-year period. The seasonal patterns of preferential habitat were inferred from species distribution models, built using squid occurrences detected from night-time visible images and remotely-sensed environmental factors. The predicted squid habitat (i.e., areas with high habitat suitability) revealed strong seasonal variability, characterized by a reduction of potential habitat, confined off of the southern part of the basin during the winter–spring period (December–May). Apparent expansion of preferential habitat occurred during summer–autumn months (June–November), concurrent with the formation of highly suitable habitat patches in certain regions of the Sea of Japan. These habitat distribution patterns were in response to changes in oceanographic conditions and synchronous with seasonal migration of squid. Moreover, the most important variables regulating the spatio-temporal patterns of suitable habitat were sea surface temperature, depth, sea surface height anomaly, and eddy kinetic energy. These variables could affect the habitat distributions through their impacts on growth and survival of squid, local nutrient transport, and the availability of favorable spawning and feeding grounds.

Pleistocene refugia and their effects on the phylogeography and genetic structure of the wolf spiderPardosa sierra(Araneae: Lycosidae) on the Baja California Peninsula

The phylogeographic structure of some species distributed across the Baja California Peninsula has been traditionally hypothesized as resulting from vicariant events thought to have occurred between 1–3 Mya. Climatic fluctuations during the Pleistocene have also been shown to influence the distribution patterns of species, and vicariant patterns may have been erased as a consequence of population contractions or expansions into or out of refugia generated during the last glacial maximum ca. 21,000 years ago. Thus, there is still some uncertainty regarding the relative role of vicariance in shaping the modern biota of Baja California. To understand the evolutionary history of the wolf spider Pardosa sierra Banks, 1898 on the peninsula, a phylogeny of this species and closely related taxa was generated using a fragment of the mitochondrial gene cytochrome c oxidase subunit I (CO1). Sequences of a fragment of the CO1 gene for 38 individuals from 14 sampling sites along the entire distribution range of P. sierra were used to infer phylogeographic patterns, and five nuclear microsatellite loci were also used to genotype 296 individuals from seven of these 14 locations. The current and past potential distributions from two Pleistocene periods were estimated using niche-based distribution modeling, and scenarios of colonization from detected refugia were simulated. We found that Californian populations of P. sierra diverged from peninsular populations 4 Mya, this divergence coinciding with the northern-gulf split. However, we did not detect genetic breaks in regions where the mid-peninsular and Isthmus of La Paz canals were presumably formed, either with mitochondrial DNA sequences or microsatellite loci. Two refugia were further detected at the geographic ends of the peninsula, these likely preceding subsequent habitat expansion.

Isolation of fungi from dead arthropods and identification of a new mosquito natural pathogen.

BackgroundInsects are well known vectors of human and animal pathogens and millions of people are killed by mosquito-borne diseases every year. The use of insecticides to target insect vectors has been hampered by the issues of toxicity to the environment and by the selection of resistant insects. Therefore, biocontrol strategies based on naturally occurring microbial pathogens emerged as a promising control alternative. The entomopathogenic fungus Beauveria bassiana is well characterized and have been approved by the United States Environmental Protection Agency as a pest biological control method. However, thousands of other fungi are unexploited and it is important to identify and use different fungi for biocontrol with possibly some vector specific strains. The aim of this study was to identify new fungal entomopathogens that may be used as potential mosquito biocontrol agents.MethodsCadavers of arthropods were collected from pesticide free areas and the fungi associated isolated, cultured and identified. Then the ability of each isolate to kill laboratory insects was assayed and compared to that of B. bassiana.ResultsIn total we have isolated and identified 42 fungal strains from 17 different arthropod cadavers. Twenty four fungal isolates were cultivated in the laboratory and were able to induce sporulation. When fungal spores were microinjected into Drosophila melanogaster, eight isolates proved to be highly pathogenic while the remaining strains showed moderate or no pathogenicity. Then a selection of isolates was tested against Aedes mosquitoes in a model mimicking natural infections. Only one fungus (Aspergillus nomius) was as pathogenic as B. bassiana and able to kill 100 % of the mosquitoes.ConclusionThe obtained results are encouraging and demonstrate the feasibility of this simple approach for the identification of new potential mosquito killers. Indeed, it is essential to anticipate and prepare biocontrol methods to fight the expansion of mosquitoes’ habitat predicted in certain geographical areas in association with the occurring climatic changes.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1763-3) contains supplementary material, which is available to authorized users.

Habitat compression and expansion of sea urchins in response to changing climate conditions on the California continental shelf and slope (1994–2013)

Echinoid sea urchins with distributions along the continental shelf and slope of the eastern Pacific often dominate the megafauna community. This occurs despite their exposure to naturally low dissolved oxygen (DO) waters (<60μmolkg−1) associated with the Oxygen Limited Zone and low-pH waters undersaturated with respect to calcium carbonate (ΩCaCO3<1). Here we present vertical depth distribution and density analyses of historical otter trawl data collected in the Southern California Bight (SCB) from 1994 to 2013 to address the question: Do changes in echinoid density and species’ depth distributions along the continental margin in the SCB reflect observed secular or interannual changes in climate? Deep-dwelling burrowing urchins (Brissopsis pacifica, Brisaster spp. and Spatangus californicus), which are adapted to low-DO, low-pH conditions appeared to have expanded their vertical distributions and populations upslope over the past decade (2003–2013), and densities of the deep pink urchin, Strongylocentrotus fragilis, increased significantly in the upper 500m of the SCB. Conversely, the shallower urchin, Lytechinus pictus, exhibited depth shoaling and density decreases within the upper 200m of the SCB from 1994 to 2013. Oxygen and pH in the SCB also vary inter-annually due to varying strengths of the El Niño Southern Oscillation (ENSO). Changes in depth distributions and densities were correlated with bi-monthly ENSO climate indices in the region. Our results suggest that both a secular trend in ocean deoxygenation and acidification and varying strength of ENSO may be linked to echinoid species distributions and densities, creating habitat compression in some and habitat expansion in others. Potential life-history mechanisms underlying depth and density changes observed over these time periods include migration, mortality, and recruitment. These types of analyses are needed for a broad suite of benthic species in order to identify and manage climate-sensitive species on the margin.

Consequences of a large-scale fragmentation experiment for Neotropical bats: disentangling the relative importance of local and landscape-scale effects

Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect species in human-modified landscapes, is of great importance for informing conservation and management. We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient. We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics. Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats. Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat.

Distribution and ecology ofColpomenia peregrina(Phaeophyceae) within the Northwest Atlantic

The saccate Asiatic brown seaweed Colpomenia peregrina was first recorded within the NW Atlantic in 1960 at Atkins Point, Nova Scotia. By 2014 it was recorded from 57 sites ranging from the Grand Barachois Lagoon, Newfoundland to South Wellfleet, MA. We first found extensive populations in New England at Fort Foster, Kittery, Maine where we subsequently conducted floristic and ecological studies of the alga. Colpomenia peregrina is superficially similar to another saccate brown alga, Leathesia marina, although they have differences in morphology, anatomy, and reproduction. The species is a common epiphyte on at least 33 seaweeds within the NW Atlantic, with Corallina officinalis being its most common host. It also grows on the seagrass Zostera marina and on at least two common invertebrates, Mytilus edulis and Semibalanus balanoides. Colpomenia peregrina is an annual somewhat like Petalonia fascia, with some specimens bearing plurilocular gametangia year-round. Based upon collection of samples from 57 sites, its convoluted hollow thalli had mean diameters and heights of less than 7.5 cm and damp dried weights of less than 10.0 g. Subtidal transects studies within the shallow subtidal zone at the Isles of Shoals, NH/ME, showed a wide range of densities (15–2721 m−2) and mean diameters of 0.47–1.72 cm. The demography of 663 drift, 442 attached, and 903 epiphytic thalli were documented from Fort Foster, ME during 31 monthly visits. Drift thalli had their largest diameter and height in winter (6.9×4.7 cm), whereas those from low intertidal ledge quadrats were largest in summer (3.4×2.5 cm), and random mid-intertidal pool samples were largest in the fall (2.9×1.6 cm). The mean number of epiphytic thalli on apical parts of three fucoid algae within a mid-intertidal pool ranged from 0.09 cm−1 on Ascophyllum nodosum, to 0.23 cm−1 on Fucus vesiculosus, and 0.43 cm−1 on F. distichus subsp. evanescens. The alga's southward expansion and colonization of low intertidal and shallow subtidal habitats in the NW Atlantic indicate that it is already competing for space and resources with native vegetation as well as causing removal of attached hosts.

Spatio-temporal changes of a mangrove–saltmarsh ecotone in the northeastern coast of Florida, USA

General circulation models predict warming trends and changes in temperature and precipitation patterns that have the potential to alter the structure and function of coastal habitats. The purpose of this study was to quantify the expansion and contraction of mangroves and saltmarsh habitats and assess the impact of climate on these landscape changes. The study was conducted in a mangrove/saltmarsh ecotone in Flagler County, FL, near the northern range limit of mangroves along the Atlantic coast of North America. We used time series of historical aerial photography and high-resolution multispectral satellite imagery from 1942 to 2013 to quantify changes in the extent of mangrove and saltmarsh vegetation and compared these changes to climate variables of temperature and precipitation, temperature–seasonality, as well as historical sea-level data. Results showed increases in mangrove extent of 89% between 1942 and 1952, and a continuous increase from 1995 to 2013. Largest decrease in saltmarsh extent occurred between 1942 and 1952 (-136%) and between 2008 and 2013 (-81%). We found significant effects of precipitation, temperature, seasonality, and time on mangrove and saltmarsh areal extent. The statistical effect of sea-level was rather small, but we speculate that it might have ecological impacts on these two coastal ecosystems. Results also showed a cyclical dynamism as well as a reversal in habitat dominance, which may be the result of complex interactions between plant habitats and several environmental drivers of change such as species interactions, and hydrological changes induced by sea-level rise, in addition to temperature and precipitation effects. Our results on mangrove/saltmarsh expansion and contraction may contribute to the improvement of management and conservation strategies for coastal ecosystems being impacted by climate change.

Investigating past range dynamics for a weed of cultivation, Silene vulgaris.

Since the last glacial maximum (LGM), many plant and animal taxa have expanded their ranges by migration from glacial refugia. Weeds of cultivation may have followed this trend or spread globally following the expansion of agriculture or ruderal habitats associated with human‐mediated disturbance. We tested whether the range expansion of the weed Silene vulgaris across Europe fit the classical model of postglacial expansion from southern refugia, or followed known routes of the expansion of human agricultural practices. We used species distribution modeling to predict spatial patterns of postglacial expansion and contrasted these with the patterns of human agricultural expansion. A population genetic analysis using microsatellite loci was then used to test which scenario was better supported by spatial patterns of genetic diversity and structure. Genetic diversity was highest in southern Europe and declined with increasing latitude. Locations of ancestral demes from genetic cluster analysis were consistent with areas of predicted refugia. Species distribution models showed the most suitable habitat in the LGM on the southern coasts of Europe. These results support the typical postglacial northward colonization from southern refugia while refuting the east‐to‐west agricultural spread as the main mode of expansion for S. vulgaris. We know that S. vulgaris has recently colonized many regions (including North America and other continents) through human‐mediated dispersal, but there is no evidence for a direct link between the Neolithic expansion of agriculture and current patterns of genetic diversity of S. vulgaris in Europe. Therefore, the history of range expansion of S. vulgaris likely began with postglacial expansion after the LGM, followed by more recent global dispersal by humans.

PM022 The Economic Burden of Heart Diseases in Ecuador

Dengue fever, a vector-borne disease, represents a priority public health problem in Ecuador. Previous studies indicated that the ecology of the transmitter vector (Aedes aegypti) is influenced by environmental parameters and human behavior; however, the effects of those variables on mosquito population dynamics depend on local environmental features. In this study, we identified the most important factors influencing the risk of dengue virus infection in Ecuador. The maximum entropy algorithm (MaxEnt) was used to determine the areas with a high probability of the presence of Aedes aegypti under current and future (2050) climatic conditions, using the location of reported dengue cases and potential environmental factors. The model performance was quantified based on an accuracy assessment. Additionally, we used meteorological data from the study period in a partial least square regression (PLS-R) to predict the number of total dengue cases (TDC) and then estimated the future number of cases using the equation obtained with the PLS-R. Population density, elevation, and mean temperatures of the warmest and wettest quarters were found to be the most important variables influencing the mosquito’s geographical distribution. Maximum temperature and minimum temperature were the climatic factors with the best projecting capacity in predicting the TDC in the Ecuadorian coast region. The results show a greater mosquito presence probability in populated areas, with a considerable expansion of suitable habitat across the central and southern provinces by 2050. The temporal analysis revealed that the regional dengue outbreak season goes from March to June, and the future estimation predicted that the next large outbreak would occur in 2018. These results present a good intel for solutions of reduction of dengue cases in the country. This further will allow the responsible authorities to pinpoint proper vector control measurements by province.

A science-based approach to guide Amur leopard recovery in China

The future of the critically endangered Amur leopard (Panthera pardus orientalis) is at a crucial point, and effective conservation strategies implemented within its primary historical range in Northeast China may determine the fate of this species. However, when a conservation plan was first developed for the species, scarce information on the leopards' status existed. To illustrate regional conservation challenges, we focused on the Hunchun Nature Reserve and the surrounding area along the China-Russia border, a potential stronghold for Amur leopard conservation. We conducted large-scale data analysis with a field camera-trapping network to present the first population estimates for this species using a spatially explicit capture–recapture approach. We then used a zero-inflated regression model to analyze the relationship of leopards with major prey species and anthropogenic disturbances. Our results indicate that leopards are returning to China, but most of them are part of a “border population” or are transient; their numbers are far too few to establish a healthy population. The spatial counts of leopards were noticeably high in areas with high prey richness and areas far from settlements and roads. Areas with few prey species and high human and cattle use exhibited a greater probability of “excess absences” of leopards. Mitigating human disturbances by progressively minimizing cattle and human impacts on the forest should be pursued along with habitat expansion for large ungulates, whose presence is essential for leopard occupancy. This study provides crucial information to support Chinese government recovery efforts and for refining conservation practices in human-dominated landscapes to ensure the long-term survival of this species.

The Effects of Sub-Regional Climate Velocity on the Distribution and Spatial Extent of Marine Species Assemblages.

Many studies illustrate variable patterns in individual species distribution shifts in response to changing temperature. However, an assemblage, a group of species that shares a common environmental niche, will likely exhibit similar responses to climate changes, and these community-level responses may have significant implications for ecosystem function. Therefore, we examine the relationship between observed shifts of species in assemblages and regional climate velocity (i.e., the rate and direction of change of temperature isotherms). The assemblages are defined in two sub-regions of the U.S. Northeast Shelf that have heterogeneous oceanography and bathymetry using four decades of bottom trawl survey data and we explore temporal changes in distribution, spatial range extent, thermal habitat area, and biomass, within assemblages. These sub-regional analyses allow the dissection of the relative roles of regional climate velocity and local physiography in shaping observed distribution shifts. We find that assemblages of species associated with shallower, warmer waters tend to shift west-southwest and to shallower waters over time, possibly towards cooler temperatures in the semi-enclosed Gulf of Maine, while species assemblages associated with relatively cooler and deeper waters shift deeper, but with little latitudinal change. Conversely, species assemblages associated with warmer and shallower water on the broad, shallow continental shelf from the Mid-Atlantic Bight to Georges Bank shift strongly northeast along latitudinal gradients with little change in depth. Shifts in depth among the southern species associated with deeper and cooler waters are more variable, although predominantly shifts are toward deeper waters. In addition, spatial expansion and contraction of species assemblages in each region corresponds to the area of suitable thermal habitat, but is inversely related to assemblage biomass. This suggests that assemblage distribution shifts in conjunction with expansion or contraction of thermal habitat acts to compress or stretch marine species assemblages, which may respectively amplify or dilute species interactions to an extent that is rarely considered. Overall, regional differences in climate change effects on the movement and extent of species assemblages hold important implications for management, mitigation, and adaptation on the U.S. Northeast Shelf.

Changes in habitat availability for outmigrating juvenile salmon (Oncorhynchus spp.) following estuary restoration

The restoration of the Nisqually River Delta (Washington, U.S.A.) represents one of the largest efforts toward reestablishing the ecosystem function and resilience of modified habitat in the Puget Sound, particularly for anadromous salmonid species. The opportunity for outmigrating salmon to access and benefit from the expansion of available tidal habitat can be quantified by several physical attributes, which are related to the ecological and physiological responses of juvenile salmon. We monitored a variety of physical parameters to measure changes in opportunity potential from historic, pre‐restoration, and post‐restoration habitat conditions at several sites across the delta. These parameters included channel morphology, water quality, tidal elevation, and landscape connectivity. We conducted fish catch surveys across the delta to determine if salmon was utilizing restored estuary habitat. Overall major channel area increased 42% and major channel length increased 131% from pre‐ to post‐restoration conditions. Furthermore, the results of our tidal inundation model indicated that major channels were accessible up to 75% of the time, as opposed to 30% pre‐restoration. Outmigrating salmon utilized this newly accessible habitat as quickly as 1 year post‐restoration. The presence of salmon in restored tidal channels confirmed rapid post‐restoration increases in opportunity potential on the delta despite habitat quality differences between restored and reference sites.

瀬戸内海における海を越えたイノシシの生息拡大プロセス

Habitat expansion of wild boar (Sus scrafa) cross the waters in Island See is studied based on interview research conducted in all residential islands in Matsuyama City, Ehime Pref., Japan. Wild boar has immigrated around 1999 from the direction of Kashima Island, Hiroshima Pref. in the north. In A group islands where far from original habitat, sporadic damage phase exists for 6-8 years. After damage increase phase of 3-4 years, grate damage phase starts from 2009. In B group islands where near from original habitat, sporadic damage phase relatively short. In other islands far from original habitat and with very small area, wild boar has immigrated but not colonized. Gogo Island is now in sporadic damage phase, but predicted to go into damage increase phase in the near future. It is effective solution of wildlife-human conflict to make opportunity for local people getting information and learning opportunity about wild boar, as well as to monitor wild boar habitat expansion on the edge of original habitat, resulting in effective control of wild boar habitat.

Habitat expansion of the Harris mud crab Rhithropanopeus harrisii (Gould, 1841) in the northern Baltic Sea: potential consequences for the eelgrass food web

Habitat expansion of the Harris mud crab Rhithropanopeus harrisii (Gould, 1841) in the northern Baltic Sea: potential consequences for the eelgrass food web

The Origin and Development of the Central European Man-made Landscape, Habitat and Species Diversity as Affected by Climate and its Changes – a Review

The Origin and Development of the Central European Man-made Landscape, Habitat and Species Diversity as Affected by Climate and its Changes – a Review

A review of the Leon springs pupfish (Cyprinodon bovinus) long‐term conservation strategy and response to habitat restoration

Abstract Choosing an optimal strategy to sustain imperilled wild populations is challenging, and many methods may be implemented before reaching an effective strategy. A review of previous conservation efforts used to maintain an endangered desert pupfish (Cyprinidon bovinus) are presented here. Conservation strategies for C. bovinus have included removal of fish hybridizing with a non‐native species, reintroduction of captive‐bred C. bovinus into their historic range, and habitat restoration and expansion. In general, these methods have successfully increased the C. bovinus population over a 15‐year period, with habitat expansion appearing to be the most critical intervention method. Habitat restorations that increased the available breeding habitat for C. bovinus and the total number of breeding males were also associated with a downward trend in individual male reproductive behaviour. Since habitat expansion resulted in unexpected consequences for reproductive ecology, it emphasizes the importance not only of monitoring species abundance but also of evaluating individual reproductive behaviour when implementing conservation strategies. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Gene Flow of a Forest-Dependent Bird across a Fragmented Landscape.

Habitat loss and fragmentation can affect the persistence of populations by reducing connectivity and restricting the ability of individuals to disperse across landscapes. Dispersal corridors promote population connectivity and therefore play important roles in maintaining gene flow in natural populations inhabiting fragmented landscapes. In the prairies, forests are restricted to riparian areas along river systems which act as important dispersal corridors for forest dependent species across large expanses of unsuitable grassland habitat. However, natural and anthropogenic barriers within riparian systems have fragmented these forested habitats. In this study, we used microsatellite markers to assess the fine-scale genetic structure of a forest-dependent species, the black-capped chickadee (Poecile atricapillus), along 10 different river systems in Southern Alberta. Using a landscape genetic approach, landscape features (e.g., land cover) were found to have a significant effect on patterns of genetic differentiation. Populations are genetically structured as a result of natural breaks in continuous habitat at small spatial scales, but the artificial barriers we tested do not appear to restrict gene flow. Dispersal between rivers is impeded by grasslands, evident from isolation of nearby populations (~ 50 km apart), but also within river systems by large treeless canyons (>100 km). Significant population genetic differentiation within some rivers corresponded with zones of different cottonwood (riparian poplar) tree species and their hybrids. This study illustrates the importance of considering the impacts of habitat fragmentation at small spatial scales as well as other ecological processes to gain a better understanding of how organisms respond to their environmental connectivity. Here, even in a common and widespread songbird with high dispersal potential, small breaks in continuous habitats strongly influenced the spatial patterns of genetic variation.

Novel wildlife in the Arctic: the influence of changing riparian ecosystems and shrub habitat expansion on snowshoe hares.

Warming during the 20th century has changed the arctic landscape, including aspects of the hydrology, vegetation, permafrost, and glaciers, but effects on wildlife have been difficult to detect. The primary aim of this study is to examine the physical and biological processes contributing to the expanded riparian habitat and range of snowshoe hares (Lepus americanus) in northern Alaska. We explore linkages between components of the riparian ecosystem in Arctic Alaska since the 1960s, including seasonality of stream flow, air temperature, floodplain shrub habitat, and snowshoe hare distributions. Our analyses show that the peak discharge during spring snowmelt has occurred on average 3.4 days per decade earlier over the last 30 years and has contributed to a longer growing season in floodplain ecosystems. We use empirical correlations between cumulative summer warmth and riparian shrub height to reconstruct annual changes in shrub height from the 1960s to the present. The effects of longer and warmer growing seasons are estimated to have stimulated a 78% increase in the height of riparian shrubs. Earlier spring discharge and the estimated increase in riparian shrub height are consistent with observed riparian shrub expansion in the region. Our browsing measurements show that snowshoe hares require a mean riparian shrub height of at least 1.24-1.36 m, a threshold which our hindcasting indicates was met between 1964 and 1989. This generally coincides with observational evidence we present suggesting that snowshoe hares became established in 1977 or 1978. Warming and expanded shrub habitat is the most plausible reason for recent snowshoe hare establishment in Arctic Alaska. The establishment of snowshoe hares and other shrub herbivores in the Arctic in response to increasing shrub habitat is a contrasting terrestrial counterpart to the decline in marine mammals reliant on decreasing sea ice.