Peripheral Habitats Research Articles

Fine-scale phylogeography of Tripneustes gratilla revealed a core-periphery pattern in the South China sea

The Core-Periphery Hypothesis (CPH) is a theoretical framework in phylogeography used to examine the spatial distribution of genetic diversity. The tropical Indian-Western Pacific (IWP), serving as a prominent marine biodiversity hotspot, constantly exports species and evolutionary novelties to peripheral habitats. Many species display genetic patterns consistent with CPH predictions from the IWP to periphery regions. However, the presence of CPH’s genetic signals in intermediate distribution zones remains underexplored. Here, we collected four sea urchin populations of Tripneustes gratilla in the South China Sea and analysed their population structure and evolutionary patterns using 13 morphological parameters, one mitochondrial 16S rRNA gene and nine polymorphic microsatellites. The results revealed substantial genetic homogeneity among the populations, implying a single origin from a glacial refugium. Nonetheless, morphological and microsatellite data distinctly differentiate the northernmost Fengjiawan population from the others, which could be attributed to increased environmental selection pressures such as temperature. Analysis of genetic diversity variation along latitudinal gradients and the relationship between geographic and genetic distances align with CPH expectations for both 16S and microsatellites, albeit to varying degrees of significance. This study enhances our understanding of tropical marine invertebrate evolution and supports the applicability of the CPH model at a fine-scale level.

Habitat connectivity for conserving cervids in a multifunctional landscape

Habitat fragmentation is a considerable threat to biodiversity worldwide. To minimize the effects of fragmentation, it is important to identify and conserve the existing habitat connections that facilitate dispersal and gene flow among populations. Connected populations are more resilient to the changing environment that affects local populations due to greater demographic stability and higher genetic diversity. Our study is the first attempt to identify the crucial habitats facilitating the dispersal of two key sympatric cervids - spotted deer Axis axis and sambar Rusa unicolor in central India. We use species distribution models followed by landscape pattern analyses and connectivity analyses to delineate the essential habitats. Thereafter, we estimated the relative contribution of habitats outside protected areas in maintaining the ecological network, using graph-based metrics. We then locate and predict the areas that have a high risk of human-influenced cervid mortality using a Bayesian regression model that accounts for spatial structure in the data. The results show that about 55% of the core habitats, integrated across both species, lie outside the protected areas and are important in maintaining the ecological network for these cervids. Some peripheral habitats have an increased risk of anthropogenic cervid mortality, which poses high demographic risk. There is an urgent need to regulate the nature and intensity of human activities in areas of human-wildlife coexistence to maintain habitat connectivity and ensure the survival of wildlife populations. Our results on cervids complement analyses on connectivity for large carnivores and thus enables one to account for important trophic interactions among wildlife species in land use planning.

The largest known cowrie and the iterative evolution of giant cypraeid gastropods

Based on the fossil record, we explore the macroevolutionary relationship between species richness and gigantism in cowries (Cypraeidae), the best-studied family of gastropods, with a global diversity distribution that parallels that of tropical corals, mangroves and seagrasses. We introduce Vicetia bizzottoi sp. nov. based on a Priabonian fossil found in northeastern Italy, the largest documented cowrie found so far and the youngest of a lineage of Eocene Gisortiinae species. The Gisortiinae stratigraphic record in western Europe indicates that species selection favoured large size and armouring of the shell. Palaeoecology and per-stage species richness suggest that gigantism occurred in peripheral habitats with respect to diversity hotspots, where smaller species were favoured. The Eocene–Oligocene boundary was marked by a turnover and the Chattian global warming favoured small-sized species of derived clades. Species selection leading to gigantism is further documented in Miocene lineages of Zoila and Umbilia, in the southern hemisphere, two extant genera distributed at the periphery of modern diversity hotspots, suggesting that the negative relationship between size and diversity is a recurring pattern in the evolutionary history of cowries. This palaeontological evidence is projected onto the existing hypotheses that explain analogous biogeographic patterns in various other taxa. Likewise, body size-species richness negative relationship was possibly driven in cowries by physiological, ecological and life history constraints.

Demographic and genetic characterization of harvested Corbicula fluminea populations.

The freshwater clam Corbicula fluminea s.l. is an edible freshwater bivalve of economic value in Asia. The species has been particularly well studied in the invaded range. However, there is a lack of knowledge in its native range where it supports an increasing commercial harvest pressure. Among Asiatic countries, China accounts for 70% of known commercial harvest and aquaculture production. We aim to characterize here wild C. fluminea s.l populations exposed to commercial harvest pressure in Poyang Lake Basin. We found higher biomass, density and genetic diversity in lake populations compared to peripheral populations (i.e., lake tributaries). Given that lake habitats support more intense harvest pressure than peripheral habitats, we suggest that demographic and genetic differentiation among subpopulations may be influenced in some degree by different harvest pressure. In this regard, additional demographic and/or genetic changes related to increasing harvest pressure may place population at a higher risk of extirpation. Altogether, these results are especially relevant for maintaining populations at or above viable levels and must be considered in order to ensure the sustainability of the resource.

Environmental and behavioral controls on juvenile Chinook salmon migration pathways in the Columbia River estuary

Juvenile Chinook salmon population dynamics in the Columbia River estuary are influenced by physical processes, hatchery practices, and behavioral decision-making. To better understand how environmental forcing and swimming behavior influence estuarine migration and travel times, we developed an individual-based model (IBM) that uses 3-D outputs from a hydrodynamic model to simulate Lagrangian transport as well as swimming and bioenergetics sub-models to simulate active swimming and growth. Simulations were run in 2010 during the migration seasons for yearling and subyearling Chinook salmon. For both life history types, alternative behaviors were simulated, from random walks to behaviors that optimized efficient system migration for yearling Chinook salmon and growth for subyearling Chinook salmon. Simulation results compared well against observed data on travel times and common migration pathways; the simulated travel times for both yearling and subyearling Chinook salmon were within several hours of the observed travel times. In general, residence times and pathways were largely driven by river discharge and the phase of the tide. During periods of greater river discharge, simulated estuarine residence times were reduced and variability across individuals was minimal. The timing of estuarine exit was closely tied to the phase of the tide, with most simulated individuals exiting the system during the ebb phase. While travel times were largely driven by flow velocities, swimming behavior was likewise important. Simulated yearling Chinook salmon behaviors that optimized movement with surrounding flows resulted in reduced estuarine residence times when compared to passive and random walk behaviors. Similarly, simulated subyearling Chinook salmon behaviors that optimized growth directed individuals to shallow peripheral habitats, resulting in longer residence times and higher growth rates. Even if potentially important factors such as predator avoidance were not included, this IBM provides an informative tool to model migration pathways, growth, and residence times of juvenile salmon in an estuarine environment and could be used to inform management decisions by evaluating various scenarios.

The adaptive value of epigenetic mutation: Limited in large but high in small peripheral populations.

The fate of populations during range expansions, invasions and environmental changes is largely influenced by their ability to adapt to peripheral habitats. Recent models demonstrate that stable epigenetic modifications of gene expression that occur more frequently than genetic mutations can both help and hinder adaptation in panmictic populations. However, these models do not consider interactions between epimutations and evolutionary forces in peripheral populations. Here, we use mainland-island mathematical models and simulations to explore how the faster rate of epigenetic mutation compared to genetic mutations interacts with migration, selection and genetic drift to affect adaptation in peripheral populations. Our model focuses on cases where epigenetic marks are stably inherited. In a large peripheral population, where the effect of genetic drift is negligible, our analyses suggest that epimutations with random fitness impacts that occur at rates as high as 10-3 increase local adaptation when migration is strong enough to overwhelm divergent selection. When migration is weak relative to selection and epimutations with random fitness impacts decrease adaptation, we find epigenetic modifications must be highly adaptively biased to enhance adaptation. Finally, in small peripheral populations, where genetic drift is strong, epimutations contribute to adaptation under a wider range of evolutionary conditions. Overall, our results suggest that epimutations can change outcomes of adaptation in peripheral populations, which has implications for understanding conservation and range expansions and contractions, especially of small populations.

Alternative functional strategies and altered carbon pathways facilitate broad depth ranges in coral‐obligate reef fishes

Abstract Spatial refuges in peripheral habitats will become increasingly important for species persistence as climate change and other disturbances progressively impact habitat quality and assemblage compositions. However, the capacity for persistence will be determined in part by species‐specific abilities to absorb costs related to altered or decreased quantities and quality of resources at range peripheries. We compared variations in dietary strategies and energy acquisition trade‐offs along depth gradients in two obligate corallivores that differ in level of diet specialization. We also assessed depth‐related changes in energy pathways and energy content of their mixotrophic prey. We found no changes in feeding effort or total resource availability (total coral cover) towards deep range margins, but availability of the preferred resource (Acropora coral) decreased. While both species selectively targeted Acropora, the more specialized species (Chaetodon baronessa) exhibited limited feeding plasticity along the depth gradient. The degree of selectivity towards the preferred coral increased rather than decreased with depth, being 40 times greater than expected, given availability, at their range periphery. In contrast, the generalist's diet (Chaetodon octofasciatus) varied greatly in response to changes in resource availability with depth. Unexpectedly, the energy content of Acropora did not decline with depth, likely due to increased coral heterotrophy in deeper water, indicated by shifts in their molecular isotope geochemistry. This shift was accompanied by a 20% increase in plankton‐sourced carbon in the muscle tissue of deep‐resident fish, despite no observations of direct feeding on plankton food sources. Our results indicate that deep ranges in coral‐obligate reef fishes are supported by multiple mechanisms of trophic versatility in both the fish and corals. This nutritional plasticity likely serves a compensatory role in the resilience and eventual adaptation of organisms at their range peripheries. For species vulnerable to increasing anthropogenic impacts at range cores, variable and multi‐trophic functional responses can act to buffer against costs and increase the refuge potential of range peripheries. Specialist consumers may also be supported indirectly at range margins via trophic plasticity within their preferred prey. A free Plain Language Summary can be found within the Supporting Information of this article.

Patterns of Resource Use and Isotopic Niche Overlap Among Guanaco (Lama guanicoe), Pampas Deer (Ozotoceros bezoarticus) and Marsh Deer (Blastocerus dichotomus) in the Pampas. Ecological, Paleoenvironmental and Archaeological Implications

ABSTRACT In this paper, we analyze the isotopic niche and resource use of the guanaco (Lama guanicoe), pampas deer (Ozotoceros bezoarticus) and marsh deer (Blastocerus dichotomus) on the temperate plain of the northern Pampa region in the southeast of South America. The measured stable isotope compositions in bone tissue are δ13C, δ15N and δ18O. All the analyzed samples were recovered from different archaeological sites from the late Holocene. According to the results, the guanaco was strictly confined to the Pampa plain environment, developing a broad niche based on C3 plants and a variable contribution of C4 grasses within a grazing trend. The pampas deer preferentially used the Pampa plain, but also the prairies on the borders of the wetland, showing eurioic characteristics and a narrower niche based on C3 plants. In turn, the marsh deer was strictly confined to wetland environments, developing a C3 diet–base, within a narrow isotopic niche and stenoic characteristics. The three mammals showed a wide range of intraspecific variability, which was a key factor in their adaptability to spatial and temporal changes in the vegetation coverage. In fact, the temporal trends of their isotopic values were concurrent with the major climatic variations of the Holocene. Differences in the correlations between the values of both carbon sources in both deer species compared with the guanaco suggest a distinct chemical composition of their diet and/or differences in the allocation of nutrients. The isotopic values of nitrogen and spacing of the carbon sources in guanaco (pseudoruminant) and both deer species (ruminants) show no significant differences between them, thus establishing the values for local large herbivores. Significant correlations between δ13C and δ15N were found in the guanaco and marsh deer. The regional and extra–regional variability in the guanaco's δ13Ccollagen and δ15N probably reflect the clinal variations in the vegetation coverage and the amount of rainfall. The collagen isotope values in the guanaco throughout the entire Holocene show that the humid Pampa would have shifted between being a more recurrent mesic and temperate plain with minor phases of dry–mesic conditions like during the Little Ice Age, and a humid and warm one at the peaks of the Holocene Thermal Maximum and the Medieval Climatic Anomaly. The guanaco and the pampas deer adapted to all the climatic changes that happened on the humid Pampa until the biological invasions of large European mammals changed the herbivores’ guild composition of this vast plain, pushing them into peripheral habitats due to competition. The within–species variability in isotopic signals through time and space make it necessary to carry out adequate sampling before reconstructing the diets of local past populations.

Core-periphery dynamics in the Kern River watershed

This study generates a comprehensive database of archaeological resources to evaluate Late Prehistoric (c 1500-150 cal BP) settlement and land use behaviours in the Kern River watershed of the far southern Sierra Nevada, California. These behaviours are evaluated using a habitat suitability model that relates the spatial distribution of critical subsistence resources present within the study area to suitability. Determining the habitat distribution operating in the Kern River watershed during the Late Prehistoric period is difficult using the model developed here. Settlement and land use behaviours trend towards a free distribution when evaluating all archaeological data associated with the Late Prehistoric period, but the results trend towards a despotic distribution when only incorporating lower elevation sites typically associated with more intensive residential activities. While it is difficult to identify these patterns using the model developed here, it is possible to identify several preferred areas within the study area. Preferred areas in the Kern River watershed are generally located in ecotonal habitats which contain less access to staple resources than peripheral habitats reflecting traditional Californian or Great Basin ecosystems. A settlement and land use strategy focused on ecotonal habitats at the core of the territory promotes territorial maintenance in several ways including creating a physical and social buffer against potential competitors, maintaining access to two staple resource bases and promoting long-term territorial stability among numerous ethnolinguistic populations. These results have implications for our understanding of the range of territorial behaviours practised by foraging groups, particularly low population density groups like the Tubatulabal.

Small mammals in cornfields and associated peripheral habitats in central Nebraska

In the Great Plains, many native grasslands have been converted to agricultural fields during the last two centuries. Peripheral habitats along edges of crop fields generally consist of linear habitats along roads, with many of these habitats used by native fauna. Our study examined capture rates and species composition of small mammals in cornfields, herbaceous roadside ditches, and wooded shelterbelts in central Nebraska. We captured nine species of small mammals. The Prairie Vole (Microtus ochrogaster) and Western Harvest Mouse (Reithrodontomys megalotis) were captured almost exclusively in roadside ditches, the White-footed Deermouse (Peromyscus leucopus) was captured most often in wooded shelterbelts, and the North American Deermouse (Peromyscus maniculatus) was common to abundant in all three habitats. Capture rates of small mammals were greatest in roadside ditches and least in cornfields. Herbaceous roadside ditches contained the greatest species richness with seven species, whereas shelterbelts and cornfields each had five species. Species composition of rodents differed in shelterbelts comprised solely of eastern red-cedars (Juniperus virginiana) compared to those with a mixture deciduous and coniferous trees. Our study demonstrated that roadside ditches associated with agricultural fields serve as habitats for many prairie species whereas wooded shelterbelts along agricultural fields support both woodland and prairie species in central Nebraska. Cornfields mainly were inhabited by North American Deermice but did not support many other species of small mammals. Although agricultural practices have reduced the quantity of grasslands for prairie species across the region, habitats associated with periphery of fields appear to serve as alternative habitats for small mammals throughout the Great Plains.

Lizards of the lost arcs: mid-Cenozoic diversification, persistence and ecological marginalization in the West Pacific.

Regions with complex geological histories often have diverse and highly endemic biotas, yet inferring the ecological and historical processes shaping this relationship remains challenging. Here, in the context of the taxon cycle model of insular community assembly, we investigate patterns of lineage diversity and habitat usage in a newly characterized vertebrate radiation centred upon the world's most geologically complex insular region: island arcs spanning from the Philippines to Fiji. On island arcs taxa are ecologically widespread, and provide evidence to support one key prediction of the taxon cycle, specifically that interior habitats (lowland rainforests, montane habitats) are home to a greater number of older or relictual lineages than are peripheral habitats (coastal and open forests). On continental fringes, however, the clade shows a disjunct distribution away from lowland rainforest, occurring in coastal, open or montane habitats. These results are consistent with a role for biotic interactions in shaping disjunct distributions (a central tenant of the taxon cycle), but we find this pattern most strongly on continental fringes not islands. Our results also suggest that peripheral habitats on islands, and especially island arcs, may be important for persistence and diversification, not just dispersal and colonization. Finally, new phylogenetic evidence for subaerial island archipelagos (with an associated biota) east of present-day Wallace's Line since the Oligocene has important implications for understanding long-term biotic interchange and assembly across Asia and Australia.

Evolutionary divergence in life history traits among populations of the Lake Malawi cichlid fish Astatotilapia calliptera.

During the early stages of adaptive radiation, populations diverge in life history traits such as egg size and growth rates, in addition to eco‐morphological and behavioral characteristics. However, there are few studies of life history divergence within ongoing adaptive radiations. Here, we studied Astatotilapia calliptera, a maternal mouthbrooding cichlid fish within the Lake Malawi haplochromine radiation. This species occupies a rich diversity of habitats, including the main body of Lake Malawi, as well as peripheral rivers and shallow lakes. We used common garden experiments to test for life history divergence among populations, focussing on clutch size, duration of incubation, egg mass, offspring size, and growth rates. In a first experiment, we found significant differences among populations in average clutch size and egg mass, and larger clutches were associated with smaller eggs. In a second experiment, we found significant differences among populations in brood size, duration of incubation, juvenile length when released, and growth rates. Larger broods were associated with smaller juveniles when released and shorter incubation times. Although juvenile growth rates differed between populations, these were not strongly related to initial size on release. Overall, differences in life history characters among populations were not predicted by major habitat classifications (Lake Malawi or peripheral habitats) or population genetic divergence (microsatellite‐based F ST). We suggest that the observed patterns are consistent with local selective forces driving the observed patterns of trait divergence. The results provide strong evidence of evolutionary divergence and covariance of life history traits among populations within a radiating cichlid species, highlighting opportunities for further work to identify the processes driving the observed divergence.

Woodland features determining home range size of roe deer

Use of ecotones by ungulates may be mediated by their movements between main feeding areas and woodland, where they locate their shelter. The roe deer Capreolus capreolus has been termed as a woodland species, although we suggest that it did not evolve as a forest ungulate, but depending on forest glades. Roe deer feed on a wide range of vegetal species, although their diet is mainly dominated by woody plants. Our study was carried out in a fragmented area covered with small forest patches of Mediterranean “macchia” scrubwood, interspersed in an agricultural matrix. Aim of our study has been to test how ranging movements of roe deer are influenced by landscape heterogeneity and to evaluate which features of woodland affect home range size. Radio-locations of 22 female and 12 male adult roe deer, monitored for three years, were used to assess home range size. A linear mixed model was fitted to investigate variation in home range size according to eleven spatial parameters estimated to describe home range size and composition. Throughout the year, no significant difference was found between home range sizes of males (median: 16.70ha, Q1–Q3: 13.20–31.60ha) and females (median: 23.52ha, Q1–Q3: 13.30–44.00ha: lme: F=0.9; P=0.35). Habitat density, edge density, percentage of woodland within home range and woodland structure determined home range size. Home ranges with few habitat types and a small amount of wood were large, while roe deer occupied small home ranges when habitat density was high and when a high proportion of wood was concentrated in a single large patch. Woodland covered a mean±SE of 36.2±17.9% in each home range. In conclusion, roe deer seem to be particularly well adapted to live in human transformed, peripheral habitats, e.g. farmlands, as long as a minimum quantity of woodland is included within their HR.

Diet and behavior of extralimital Western burrowing owls (Athene cunicularia hypogea) in tallgrass prairie

Abstract Species geographic limits can be shaped by unfavorable conditions beyond range edges, and observations from peripheral habitats provide opportunities to assess individuals' capacity to tolerate environmental change. I monitored an extralimital breeding pair of Western burrowing owls (Athene cunicularia hypogea) in an eastern Kansas tallgrass prairie in 2013 using still and video photography. I quantified (1) the relative importance of different prey types in their diet, and (2) the timing and prevalence of a novel sunbathing behavior and discuss its possible adaptive significance. Owls in tallgrass prairie consumed more arthropods than vertebrates, with the latter contributing the most biomass in their diet. However, arthropods contributed more biomass than reported in studies that used indirect prey remains analyses. Owls sunbathed during midday when conditions were hot and dry, but never during cool periods or following rain events. I suggest owls in tallgrass prairie may sunbathe to shed ectop...

Habitat availability and depth‐driven population demographics regulate reproductive output of a coral reef fish

AbstractGlobal habitat decline may displace organisms from optimal environments, increasing reliance on ecosystems with lower habitat suitability and availability. For coral reef fishes, potentially marginal mesophotic coral ecosystems (~30–150 m) may be buffered from anthropogenic stressors; however, variation in habitat quality across depths can alter population demographics, reproductive output, and subpopulation size, potentially restricting the ability for peripheral habitats to support declining populations through larval supply. This study incorporated population density, benthic habitat, and depth‐stratified population demographics to assess bicolor damselfish (Stegastes partitus) subpopulation reproductive output from a broad geographic region encompassing the known depth distribution of the species, including coral reefs in the Florida Keys (0–35 m depths) and mesophotic reefs (~60–90 m) at Pulley Ridge (PR) on the west Florida Shelf. Results indicated that densities of bicolor damselfish peaked in mid‐shelf (10–20 m) and deep‐shelf (20–30 m) habitats, and subpopulation sizes and reproductive output peaked at mid‐depths (10–20 m) in the Florida Keys and declined as depth increased. Subpopulation egg production was affected by differences in demographics across depths, including fish size, sex ratios, and a lower probability and frequency of spawning in deeper habitats. Despite low population densities on mesophotic reefs, the expansive reef area at PR resulted in an estimated subpopulation size that comprised ~14% of the population in the study region, and ~9% of the total reproductive output, indicating that peripheral mesophotic reefs may be sources of larvae that can subsidize declining populations. Larval dispersal and population connectivity models used to inform ecosystem management should incorporate spatially explicit demographics across depth distributions and habitat availability that have substantial effects on egg production and larval supply.

The landscape of anthropogenic mortality: how African lions respond to spatial variation in risk

Summary Demography and conservation status of many wild organisms are increasingly shaped by interactions with humans. This is particularly the case for large, wide‐ranging carnivores. Using 206 mortality records (1999–2012) of lions in Hwange National Park, Zimbabwe, we calculated mortality rates for each source of anthropogenic mortality, modelled risk of anthropogenic mortality across the landscape accounting for time lions spent in different parts of the landscape, and assessed whether subsets of the population were more at risk. Anthropogenic activities caused 88% of male and 67% of female mortalities; male mortality being dominated by trophy hunting while the sources for female mortality were more varied (bycatch snaring, retaliatory killing, hunting). Landscapes of anthropogenic mortality risk revealed that communal subsistence farming areas, characterized by high risk (due to retaliatory killing) but avoided by lions, are population sinks. Trophy hunting areas and areas within protected areas bordering communal farmland, where bushmeat snaring is prevalent, form ‘ecological traps’ (or ‘attractive sinks’). Lions avoided risky areas, suggesting they may make behavioural decisions based on perceptions of risk. Experienced adults used risky areas less and incorporated lower proportions of them in their home ranges than young individuals, suggesting that the latter may either be naïve or forced into peripheral habitats. Synthesis and applications. This paper contributes to an understanding of how large carnivore populations are affected by anthropogenic mortality across the conservation landscape. This is critical to designing focussed, appropriate and cost‐effective conservation management strategies. Agricultural areas are intuitively identified by conservationists as being risky for carnivores due to retaliatory killing, with threats largely mitigated against by improving livestock protection. However, parts of protected areas may also form less easily identified ‘attractive sinks’ for carnivores. In particular, trophy hunting areas adjacent to national parks need careful management to avoid damaging effects of overhunting. Law enforcement is needed to reduce the effects of bushmeat poaching on predators and other wildlife in protected areas. To be most effective, resource‐limited antipoaching activities should prioritize wildlife‐rich areas close to human settlement as these tend to be hot spots for bushmeat poaching.

Demographic and reproductive plasticity across the depth distribution of a coral reef fish.

As humans expand into natural environments, populations of wild organisms may become relegated to marginal habitats at the boundaries of their distributions. In the ocean, mesophotic coral ecosystems (30–150 m) at the depth limit of photosynthetic reefs are hypothesized to act as refuges that are buffered from anthropogenic and natural disturbances, yet the viability and persistence of subpopulations in these peripheral habitats remains poorly understood. To assess the potential for mesophotic reefs to support robust coral reef fish populations, we compared population density and structure, growth, size, and reproductive output of the bicolor damselfish (Stegastes partitus) from shallow (<10 m), deep shelf (20–30 m), and mesophotic reefs (60–70 m) across the Florida Platform. Population densities decreased and size and age distributions shifted toward older and larger individuals in deeper habitats. Otolith-derived ages indicated that S. partitus found on mesophotic reefs reach larger asymptotic sizes and have longer lifespans than fish in shallower habitats. Based on measurements of oocyte area and batch fecundity, mesophotic fish also have higher reproductive investment. These demographic patterns indicate that mesophotic fish populations composed of large, fecund individuals produce high condition larvae and rely on longevity of individuals for population persistence and viability.

Peripheral genetic structure of Helicoverpa zea indicates asymmetrical panmixia.

Seasonal climatic shifts create peripheral habitats that alternate between habitable and uninhabitable for migratory species. Such dynamic peripheral habitats are potential sites where migratory species could evolve high genetic diversity resulting from convergence of immigrants from multiple regionally distant areas. Migrant populations of Helicoverpa zea (Boddie) captured during two different seasons were assessed for genetic structure using microsatellite markers and for host plant type using stable carbon isotope analysis. Individuals (N = 568) were genotyped and divided into 13 putative populations based on collection site and time. Fixation indices (F‐statistics), analysis of molecular variance (AMOVA), and discriminant analysis of principal components (DAPC) were used to examine within and among population genetic variation. Mean number of alleles per locus was 10.25 (± 3.2 SD), and allelic richness ranged from 2.38 to 5.13 (± 3.2 SD). The observed and expected heterozygosity ranged from 0.07 to 0.48 and 0.08 to 0.62, respectively. Low FST (0.01 to 0.02) and high FIS (0.08 to 0.33) values suggest captured migrants originated from breeding populations with different allele frequencies. We postulate that high genetic diversity within migrant populations and low genetic differentiation among migrant populations of H. zea are the result of asymmetrical immigration due to the high dispersal and reproductive behavior of H. zea, which may hinder the adaptation and establishment of H. zea to peripheral habitat. These findings highlight the importance of assessing peripheral population structure in relation to ecological and evolutionary dynamics of this and other highly reproductive and dispersive species.

Species Composition and Abundance of Ixodid Ticks (Acari: Ixodidae) in the City of Petrozavodsk, Republic of Karelia, Russia

The aim was to study the species composition, abundances and distribution of ixodid ticks in the City of Petrozavodsk. Samples were collected in May–September, 2006–2014 using two methods simultaneously: by flagging from vegetation and by collection from dogs. In addition, 47 tick specimens were provided by veterinary clinics based in Petrozavodsk. Records from the entire study period include three tick species: Dermacentor marginatu s, Ixodes persulcatus and Ixodes ricinus . A substantial share in the samples belonged to Ixodes persulcatus – 344 specimens. I. ricinus (5 females) was identified only in the material coming from veterinary clinics. The only female D. marginatus was obtained from a dog from a route through the central part of the city. Samples collected by flagging contained only I. persulcatus , its relative abundance along the control transect (Botanical Garden, suburbs) ranging within 0.9–22 specimens per flag-km. I. persulcatus abundance within city limits was low (<1 tick per flag-km), all ticks collected by flagging being singular findings from peripheral areas adjoining natural habitats. The number of ticks recovered from dogs was much higher than the number of specimens collected by standard techniques, and the ticks were collected from relatively isolated, centrally located parks.

Does hybridization with a widespread congener threaten the long-term persistence of the Eastern Alpine rare local endemic Knautia carinthiaca?

Interspecific hybridization, especially when regularly followed by backcrossing (i.e., introgressive hybridization), conveys a substantial risk for many endangered organisms. This is particularly true for narrow endemics occurring within distributional ranges of widespread congeners. An excellent example is provided by the plant genus Knautia (Caprifoliaceae): Locally endemic K.carinthiaca is reported from two isolated populations in southern Austria situated within an area predominantly occupied by widespread K.arvensis. While K.carinthiaca usually inhabits low-competition communities on rocky outcrops, K.arvensis occurs mainly in dry to mesic managed grasslands, yet both species can coexist in marginal environments and were suspected to hybridize. Flow cytometry revealed that diploid K.carinthiaca only occurs at its locus classicus, whereas the second locality is inhabited by the morphologically similar but tetraploid K.norica. In the, therefore, single population of K.carinthiaca, flow cytometry and AFLP fingerprinting showed signs of introgressive hybridization with diploid K.arvensis. Hybridization patterns were also reflected in intermediate habitat preferences and morphology of the hybrids. Environmental barriers to gene flow seem to prevent genetic erosion of K.carinthiaca individuals from the core ecological niches, restricting most introgressed individuals to peripheral habitats. Efficient conservation of K.carinthiaca will require strict protection of its habitat and ban on forest clear cuts in a buffer zone to prevent invasion of K.arvensis. We demonstrate the large potential of multidisciplinary approaches combining molecular, cytometric, and ecological tools for a reliable inventory and threat assessment of rare species.