Edge Populations Research Articles

Parmotrema tinctorum as an indicator of edge effect and air quality in forested areas bordered by intensive agriculture.

Pollutants inhibit thallus growth and development or alter the metabolism and associated anatomical and morphophysiological characteristics of lichens. Since agricultural matrices can act as sources of pollution by dispersing agrochemicals to vegetation fragments, this study tested the hypothesis that Parmotrema tinctorum can serve as the indicator of edge effect in such fragments. In other words, we assumed the impact of pollutant accumulation to be greater at the vegetation edges and explored the utility of this lichen as a bioindicator of pollutants dispersed from agricultural matrices. Differences in the anatomical layers of P. tinctorum thalli sampled from the edge and center of four vegetation fragments (CER, SSF, SSC, and ENP) were evaluated, and the effects of agricultural matrices on macro- and micronutrient levels, heavy metal levels, and photosynthetic pigment content were analyzed. Anatomical layers were thicker in P. tinctorum thalli from the edges of SSC and ENP, indicating the need for photobiont protection at these sites. Edge effect was observed on Al accumulation in the thallus, indicating dispersion of this metal from agricultural matrices and its greater impact in the edge populations. Edge effect was also evident on photosynthetic pigment content, macro- and micronutrient levels, and heavy metal concentration in the thallus, and the values reflected high ecological imbalance currently verified at the edge of ENP, an area of permanent protection. In areas within ENP, chlorophyll a/b ratio reflected stress factors acting on the thallus, indicating that even legally protected areas are not free from the impact of atmospheric pollutants. P. tinctorum may serve as an effective indicator of edge effects and may be used for biomonitoring pollutant dispersion from agricultural matrices.

Variations in growth and architecture in the range limit of Salix humboldtiana, the willow native to South America

The conditions faced by edge populations of a tree species may affect the architecture of individual trees. The latitudinally broad range of Salix humboldtiana Willd. encompasses tropical to cold-temperate climatic regions, with its southernmost population in central Patagonia. We expected S. humboldtiana trees from the southern-edge population to develop smaller shoots and a lower level of axis differentiation than trees of this species from a more northern population, and we expected edge trees to outperform non-edge trees when growing in a common garden at an intermediate latitude. For juvenile individuals of S. humboldtiana from edge and non-edge natural populations, the trunk diameter, height, branching angle, as well as the length, number of nodes, diameter, leaf area, and specific leaf area of the main branch and the trunk annual shoots were measured. The size and extension rates of shoots developed by trees of both origins in a common garden were also evaluated. In natural populations, the shoot leaf area and the specific leaf area were higher for the edge population than for the non-edge population. In a common garden, the shoot extension period and the length were higher for non-edge plants than for edge plants. The growth-period differences between populations in a common garden may support the hypothesis of stress adaptation in the southernmost S. humboldtiana trees.

Genetic diversity and structure of Musa balbisiana populations in Vietnam and its implications for the conservation of banana crop wild relatives.

Crop wild relatives (CWR) are an indispensable source of alleles to improve desired traits in related crops. While knowledge on the genetic diversity of CWR can facilitate breeding and conservation strategies, it has poorly been assessed. Cultivated bananas are a major part of the diet and income of hundreds of millions of people and can be considered as one of the most important fruits worldwide. Here, we assessed the genetic diversity and structure of Musa balbisiana, an important CWR of plantains, dessert and cooking bananas. Musa balbisiana has its origin in subtropical and tropical broadleaf forests of northern Indo-Burma. This includes a large part of northern Vietnam where until now, no populations have been sampled. We screened the genetic variation and structure present within and between 17 Vietnamese populations and six from China using 18 polymorphic SSR markers. Relatively high variation was found in populations from China and central Vietnam. Populations from northern Vietnam showed varying levels of genetic variation, with low variation in populations near the Red River. Low genetic variation was found in populations of southern Vietnam. Analyses of population structure revealed that populations of northern Vietnam formed a distinct genetic cluster from populations sampled in China. Together with populations of central Vietnam, populations from northern Vietnam could be subdivided into five clusters, likely caused by mountain ranges and connected river systems. We propose that populations sampled in central Vietnam and on the western side of the Hoang Lien Son mountain range in northern Vietnam belong to the native distribution area and should be prioritised for conservation. Southern range edge populations in central Vietnam had especially high genetic diversity, with a high number of unique alleles and might be connected with core populations in northern Laos and southwest China. Southern Vietnamese populations are considered imported and not native.

Differential responses of trailing-edge populations of a foundation alga to thermal stress

ABSTRACT Populations within the same species range edge may experience contrasting local conditions and exhibit diverse levels of environmental tolerance. This heterogeneity within a range boundary has seldom been considered in studies forecasting the impact of anthropogenic habitat alteration and climate change on species distributions. Moreover, any ecological prediction under changing environmental conditions requires a good understanding of the combined responses of organisms to multiple stressors, in particular the effects on key life cycle stages of species. The intertidal seaweed Fucus serratus is a dominant species on northern Atlantic shores and whose southern limit is in the NW Iberian Peninsula. We examined how early developmental stages of southern-edge populations of this foundation alga responded to the combined effects of environmental stressors, including salinity and aerial and seawater temperature. Four populations from two different areas of the NW Iberian coast were considered: two populations from open shores on the northern coast and two populations from the western rias on the Atlantic coast. The study findings revealed inter-population variability in the response to heat stress, with greater survival of germlings from the northern populations than those from western rias. Environmental conditions are still more benign within western rias, under the influence of strong summer upwelling events. The results also suggest the key role of aerial thermal stress in determining the southern limit of distribution of the target species. The future of these heterogeneous edge populations from NW Iberian Peninsula depends on trends in climate change and the ability of populations to cope with these. Environmental changes may already be occurring at rates that exceed the plastic and adaptive potential of edge populations in N Spain, while the future of western rias as climate refugia for this and other foundation alga is also uncertain.

Evaluating Assisted Gene Flow in Marginal Populations of a High Mountain Species

Many species cannot either migrate or adapt at the rate of temperature increases due to climate warming. Therefore, they need active conservation strategies to avoid extinction. Facilitated adaptation actions, such assisted gene flow, aim at the increase of the evolutionary resilience of species affected by global change. In elevational gradients, marginal populations at the lower elevation edges are experiencing earlier snowmelt and higher temperatures, which force them to adapt to the new conditions by modifying their phenology. In this context, advancing the onset of flowering and seed germination times are crucial to ensure reproductive success and increase seedling survival prior to summer drought. Assisted gene flow may bring adaptive alleles and increase genetic diversity that can help throughout ontogeny. The main aim of this work is to assess the effects that different gene flow treatments could have on the desired trait changes in marginal populations. Accordingly, we established a common garden experiment in which we assayed four different gene flow treatments betweenSilene ciliataPourr. (Caryophyllaceae) populations located in similar and different elevation edges, belonging to the same and different mountains. As a control treatment, within-population crosses of low elevation edge populations were performed. The resulting seeds were sown and the germination and flowering onset dates of the resulting plants recorded, as well as the seedling survival. Gene flow between populations falling on the same mountain and same elevation and gene flow from high-elevation populations from a different mountain to low-elevation populations advanced seed germination time with respect to control crosses. No significant effects of gene flow on seedling survival were found. All the gene flow treatments delayed the onset of flowering with respect to control crosses and this effect was more pronounced in among-mountain gene flows. The results of this study highlight two important issues that should be thoroughly studied before attempting to apply assisted gene flow in practical conservation situations. Firstly, among-populations gene flow can trigger different responses in crucial traits throughout the ontogeny of plant species. Secondly, the population provenance of gene flow is determinant and plays a significant role on the effects of gene flow.

Increasing climate sensitivity of beech and pine is not mediated by adaptation and soil characteristics along a precipitation gradient in northeastern Germany

Rising temperature and altered precipitation regimes will lead to severe droughts and concomitant extreme events in the future. Forest ecosystems have shown to be especially prone to climate change. In assessing climate change impacts, many studies focus on high altitude or ecological edge populations where a climate signal is supposedly most pronounced. While these studies represent only a fraction of the forest ecosystems throughout Europe, findings on climate sensitivity of lowland core populations remain comparatively underrepresented.By using tree-ring widths of a large region-wide network of European beech and Scots pine populations along a precipitation gradient in northeastern Germany, we identify main climatic drivers and spatio-temporal patterns in climate sensitivity. Further, we analyze the resistance of tree growth towards drought. Detailed data on soil characteristics was used to interpret climate-growth relationships.Beech was found to be most sensitive to summer drought during early summer at dry sites, whereas pine displayed highest sensitivity for winter temperature at wet sites. The resistance to extreme drought was lower for beech. By splitting the observation period (1964–2017) into an early and late period, we found non-stationary climate-growth relationships for both study species with beech showing an increase in drought sensitivity and pine in winter temperature sensitivity.Overall, beech populations seem to be especially endangered by prospective climate changes, whereas climate-growth relationships of pine seem more ambiguous with a possible trade-off between enhanced photosynthetic activity caused by early photosynthesis in late winter and reduced activity due to summer drought.

Evolution of cold tolerance and thermal plasticity in life history, behaviour and physiology during a poleward range expansion

Many species that are moving polewards encounter novel thermal regimes to which they have to adapt. Therefore, rapid evolution of thermal tolerance and of thermal plasticity in fitness-related traits in edge populations can be crucial for the success and speed of range expansions. We tested for adaptation in cold tolerance and in life history, behavioural and physiological traits and their thermal plasticity during a poleward range expansion. We reconstructed the thermal performance curves of life history (survival, growth and development rates), behaviour (food intake) and cold tolerance (chill coma recovery time) in the aquatic larval stage of the damselfly Ischnura elegans that is currently showing a poleward range expansion in northern Europe. We studied larvae from three edge and three core populations using a common-garden experiment. Consistent with the colder annual temperatures, larvae at the expansion front evolved an improved cold tolerance. The edge populations showed no overall (across temperatures) evolution of a faster life history that would improve their range-shifting ability. Moreover, consistent with damselfly edge populations from colder latitudes, edge populations evolved at the highest rearing temperature (28°C) a faster development rate, likely to better exploit the rare periods with higher temperatures. This was associated with a higher food intake and a lower metabolic rate. In conclusion, our results suggest that the edge populations rapidly evolved adaptive changes in trait means and thermal plasticity to the novel thermal conditions at the edge front. Our results highlight the importance of considering besides trait plasticity and the evolution of trait means, also the evolution of trait plasticity to improve forecasts of responses to climate change.

Looking for diversity in all the right places? Genetic diversity is highest in peripheral populations of the reef-building polychaete Sabellaria alveolata

Species distributions have been profoundly affected by past climate change, and are expected to change considerably in response to future environmental change. To better apprehend how future climate change is likely to affect genetic diversity in marine populations, it is essential to first evaluate the processes that have shaped the current distribution of genetic diversity in the sea. The honeycomb worm is a reef-building polychaete that hosts high biodiversity. Here we show that the genetic diversity in populations of S. alveolata is highest towards the edges of the current species range and lowest at its center. Pleistocene glacial cycles likely led to extirpations of S. alveolata from central populations in the Bay of Biscay, with coalescent-based estimates of post-glacial colonization dating to the beginning of the Holocene interglacial, from 10,000 to 14,000 years ago. Meanwhile, populations in the Irish Sea and English Channel likely persisted in glacial refugia since the Eemian interglacial, 120,000 years ago. Northern populations host at least two sets of divergent haplotypes, indicating that two refugia possibly existed in the north, with Ireland being a likely second refugium. Within biogeographic regions, populations were overall well-connected, but strong genetic differentiation suggests that little exchange occurs between regions. These two unexpected reservoirs of genetic diversity at the range edges deserve greater attention as warming temperatures threaten trailing edge populations, while greater climatic variability threatens leading edge populations.

Effects of the Climate Change on Peripheral Populations of Hydrophytes: A Sensitivity Analysis for European Plant Species Based on Climate Preferences

Biogeographical theory suggests that widespread retractions of species’ rear edges are expected due to anthropogenic climate change, affecting in a particularly intense way those linked to fragile habitats, such as species’ rear edges closely dependent on specific water conditions. In this way, this paper studies the potential effects of anthropogenic climate change on distribution patterns of threatened rear edge populations of five European hydrophyte plants distributed in the Iberian Peninsula. We explored (i) whether these populations occur at the limit of the species’ climatic tolerance, (ii) we quantified their geographic patterns of vulnerability to climate change, and in addition, (iii) we identified in a spatially explicit way whether these threatened populations occur in vulnerable environments to climate change. To do this, we simulated the climatic niche of five hydrophyte species using an ecological modelling approach based on occurrences and a set of readily available climatic data. Our results show that the Iberian populations studied tended to occur in less suitable environments relative to each of the species’ optimal climates. This result suggests a plausible explanation for the current degree of stagnancy or regression experienced by these populations which showed high sensitivity and thus vulnerability to thermal extremes and high seasonality of wet and temperature. Climatic predictions for 2050 displayed that most of the examined populations will tend to occur in situations of environmental risk in the Iberian Peninsula. This result suggests that the actions aimed at the conservation of these populations should be prioritized in the geographic locations in which vulnerability is greatest.

Distribution Characteristics, Population Structure and Dynamics of the Endangered Plant, <i>Viola websteri</i> Hemsl.

Plant species exhibit current characteristics as a result of interactions with environmental conditions. The plants of Viola sp. have selected chasmogamous flowers with vigorous vegetative propagation or development of cleistogamous flowers as an adaptation strategy. Viola websteri is distributed on the Korean peninsula and the eastern part of Jilin Province, China. The center and edge of the distribution are expected to exhibit different population-dynamics. It is necessary to investigate the cause of its current limited distribution even though V. websteri has a mixed-mating strategy. Firstly, We examined the vegetation environment of habitats and evaluated its characteristics. Growth characteristics were examined through plant phenology. We then evaluated the population structure, characteristics of chasmogamous flowers, and productivity of cleistogamous flowers. Moreover, we compared population sizes between 2014 and 2018. Most habitats were located in deciduous broadleaf mixed forests adjacent to valleys. V. websteri produced chasmogamous flowers with self-incompatibility in April-May and cleistogamous flowers in June-September. The cleistogamous flower production is a strategy ensuring seed production under uncertain environmental fluctuations; these were approximately twice as numerous as chasmogamous flowers. The population structure was distinguished into stable and very unstable regions. There were sites where the population experienced a sharp decline in the 2018 compared to that of 2014. This large decline was found in the edge populations. The habitats had different microsites depending on the natural disturbances of drought and the matrix constituting the habitat, thus supporting various plants. Ensuring the production of seeds through cleistogamous flowers, it was determined that rapid seedling re-establishment and population replenishment were possible when the natural disturbance factor was removed. Environmental factors did not equally affect all populations or individuals. Therefore, it was expected that it would be able to persisted in a long time, despite the rapid decrease in the number of individuals in the population regionally. Local extinction and re-establishment are likely to repeat according to environmental change. We propose the additional population investigation based on this works are required. We also suggest a need to assess the long-term population dynamics and the genetic characteristics of chasmogamous flowers and cleistogamous flowers to establish and implement effective conservation strategies.

From glacial refugia to hydrological microrefugia: Factors and processes driving the persistence of the climate relict tree Zelkova sicula.

With only two tiny populations, the climate relict Zelkova sicula (Sicily, Italy) is one of the rarest trees in the world. It also represents the most marginal member of genus Zelkova that was widespread in the broadleaved forests thriving in warm–temperate climates throughout Eurasia until the Last Glacial Age. Occurring at the westernmost range of the genus under typical Mediterranean climate, the micro‐topographic settings have always appeared crucial for the survival of this relict. However, the factors and processes actually involved in its persistence in the current refugia, as well as the response of similar relict trees in arid environments, are poorly understood worldwide. In the aim to elucidate these aspects, in the two sites hosting Z. sicula analyses of topographical attributes were combined with investigations on soil moisture dynamics. Additionally, plants’ growth and spatial distribution patterns were analyzed to detect fine‐scale differences between populations and assess the possible ecological amplitude of the species. Results revealed that convergent topographies are basic determinants of microrefugia in arid environments. Within the investigated sites, underground moisture never decreases below 25%, buffering seasonal rainfall fluctuations. Therefore, hydrological microrefugia play a key role in decoupling from regional climate, supporting the target species in coping with an unsuitable climatic envelope. Additionally, the inter‐population variability of biometric attributes showed that individual growth is site‐dependent and the species retains a relative ecological plasticity, whereas the strongly clumped spatial patterns confirmed the common clonal growth. On one hand, deeply incised landforms have acted as effective hydrologic microrefugia, on the other clonality coupled with triploidy supposedly improved the resistance of Z. sicula to harsh environments, though entailing inability to reproduce sexually. Most likely, sterility and environmental/physical barriers that have existed for millennia have prevented this relict from leaving the last suitable microrefugia, resulting in the two current rear edge populations.

Shifts from pulled to pushed range expansions caused by reduction of landscape connectivity

Range expansions are key processes shaping the distribution of species; their ecological and evolutionary dynamics have become especially relevant today, as human influence reshapes ecosystems worldwide. Many attempts to explain and predict range expansions assume, explicitly or implicitly, so‐called ‘pulled' expansion dynamics, in which the low‐density edge populations provide most of the ‘fuel' for the species advance. Some expansions, however, exhibit very different dynamics, with high‐density populations behind the front ‘pushing' the expansion forward. These two types of expansions are predicted to have different effects on e.g. genetic diversity and habitat quality sensitivity. However, empirical studies are lacking due to the challenge of generating reliably pushed versus pulled expansions in the laboratory, or discriminating them in the field. We here propose that manipulating the degree of connectivity among populations may prove a more generalizable way to create pushed expansions. We demonstrate this with individual‐based simulations as well as replicated experimental range expansions (using the parasitoid wasp Trichogramma brassicae as model). By analyzing expansion velocities and neutral genetic diversity, we showed that reducing connectivity led to pushed dynamics. Low connectivity alone, i.e. without density‐dependent dispersal, can only lead to ‘weakly pushed' expansions, where invasion speed conforms to pushed expectations, but the decline in genetic diversity does not. In empirical expansions however, low connectivity may in some cases also lead to adjustments to the dispersal‐density function, recreating ‘classical' pushed expansions. In the current context of habitat loss and fragmentation, we need to better account for this relationship between connectivity and expansion regimes to successfully predict the ecological and evolutionary consequences of range expansions.

Genomic vulnerability of a dominant seaweed points to future-proofing pathways for Australia's underwater forests.

Globally, critical habitats are in decline, threatening ecological, economic and social values and prompting calls for 'future proofing' efforts that enhance resilience to climate change. Such efforts rely on predicting how neutral and adaptive genomic patterns across a species' distribution will change under future climate scenarios, but data is scant for most species of conservation concern. Here, we use seascape genomics to characterise genetic diversity, structure and gene-environmental associations in a dominant forest-forming seaweed, Phyllospora comosa, along its entire latitudinal (12° latitude), and thermal (~14°C) range. Phyllospora showed high connectivity throughout its central range, with evidence of genetic structure and potential selection associated with sea surface temperatures (SSTs) at its rear and leading edges. Rear and leading-edge populations harboured only half the genetic diversity of central populations. By modelling genetic turnover as a function of SST, we assessed the genomic vulnerability across Phyllospora's distributional range under climate change scenarios. Despite low diversity, range-edge populations were predicted to harbour beneficial adaptations to marginal conditions and overall adaptability of the species may be compromised by their loss. Assisted gene flow from range edge populations may be required to enhance adaptation and increase resilience of central and leading-edge populations under warming oceans. Understanding genomic vulnerability can inform proactive restoration and future-proofing strategies for underwater forests and ensure their persistence in changing oceans.

Range expansion, habitat use, and choosiness in a butterfly under climate change: Marginality and tolerance of oviposition site selection.

Poleward range shifts under climate change involve the colonization of new sites and hence the foundation of new populations at the expanding edge. We studied oviposition site selection in a butterfly under range expansion (Lycaena dispar), a key process for the establishment of new populations. We described and compared the microhabitats used by the species for egg laying with those available across the study sites both in edge and in core populations. We carried out an ecological niche factor analysis (ENFA) to estimate (1) the variety of microhabitats used by the butterfly for egg laying (tolerance) and (2) the extent to which these selected microhabitats deviated from those available (marginality). Microhabitat availability was similar in edge and core populations. Ambient temperature recorded at the site level above the vegetation was on average lower at core populations. In contrast with what is often assumed, edge populations did not have narrower microhabitat use compared to core populations. Females in edge populations even showed a higher degree of generalism: They laid eggs under a wider range of microhabitats. We suggest that this pattern could be related to an overrepresentation of fast deciding personalities in edge populations. We also showed that the thermal time window for active female behavior was reduced in edge populations, which could significantly decrease the time budget for oviposition and decrease the threshold of acceptance during microhabitat selection for oviposition in recently established populations.

Agricultural land use disrupts biodiversity mediation of virus infections in wild plant populations.

Summary Human alteration of natural habitats may change the processes governing species interactions in wild communities. Wild populations are increasingly impacted by agricultural intensification, yet it is unknown whether this alters biodiversity mediation of disease dynamics.We investigated the association between plant diversity (species richness, diversity) and infection risk (virus richness, prevalence) in populations of Plantago lanceolata in natural landscapes as well as those occurring at the edges of cultivated fields. Altogether, 27 P. lanceolata populations were surveyed for population characteristics and sampled for PCR detection of five recently characterized viruses.We find that plant species richness and diversity correlated negatively with virus infection prevalence. Virus species richness declined with increasing plant diversity and richness in natural populations while in agricultural edge populations species richness was moderately higher, and not associated with plant richness. This difference was not explained by changes in host richness between these two habitats, suggesting potential pathogen spill‐over and increased transmission of viruses across the agro‐ecological interface. Host population connectivity significantly decreased virus infection prevalence.We conclude that human use of landscapes may change the ecological laws by which natural communities are formed with far reaching implications for ecosystem functioning and disease.

Current distribution, microhabitat requirements and vulnerability of the Keeled Plump Bush-cricket (Isophya costata) at the north-western periphery of its range

Edge populations are of conservation importance because they typically suffer an elevated risk of extinction, possess low genetic variation and can be genetically distinct from core populations. Peripheral populations are generally characterized as being less abundant and more vulnerable to habitat change. In this study, we investigated the current distribution and microhabitat requirements of the Keeled Plump Bush-cricket (Isophya costata), a threatened species, at the north-western periphery of its range (Austrian-Slovak trans-border area, Central Europe). To clarify the current distribution pattern in relation to microhabitat requirements, we employed a comprehensive combination of microhabitat assessment and microrelief topography in a flood-plain area, which was supplemented by photo documentation created using a drone. We found that the distribution of the bush-cricket follows isolated occurrences with low densities. Regarding microhabitat requirements, we discovered a link between the distribution pattern of the bush-cricket and micro-elevations connected to dicotyledonous broadleaf plants. We assume that the novel information on species ecology found in this study could be a first step in obtaining sufficient data for further systematic monitoring. To set these findings for species conservation, it is necessary to mitigate the most serious threats, which are represented by early mowing and habitat degradation. Therefore, further detailed analysis of major threats and determination of the genetic structure of the species will be crucial to ensure appropriate conservation measures for the threatened peripheral bush-cricket metapopulation. This research provides the novel information about microhabitat requirements of the threatened bush-cricket at the north-western edge of its range. Current distribution data together with detailed knowledge of the microhabitat requirements provide important ecological information, which could have significant implications for the further systematic monitoring and species conservation.

Southeastern Rear Edge Populations of Quercus suber L. Showed Two Alternative Strategies to Cope with Water Stress

Climate change models predict an increase in aridity, especially in the regions under Mediterranean-type climates such as the Mediterranean Basin. However, there is a lack of ecophysiological studies supporting the selection of the more drought-adapted ecotypes for reforestation programs. In this study, we analyzed the anatomical and functional adaptations of 18-month-old seedlings to drought on 16 Quercus suber L. populations from the southeastern rear edge of the species distribution in northern Tunisia growing in a common garden, in order to identify the most appropriate material to use in reforestations. The results evidenced that populations from more xeric habitats displayed the highest leaf dry mass per area (LMA) and lowest leaf area (LA) values, together with the largest increase in the bulk modulus of elasticity (Δε) in response to drought (i.e., elastic adjustment). On the other hand, some populations with intermediate values of aridity, LMA and LA displayed the sharpest increase in proline concentration (ΔPro), with a concomitant increase in osmotic potential at full turgor (Δπo) (i.e., osmotic adjustment). Therefore, two different strategies seem to drive the within-species variation of the studied Q. suber populations in response to water scarcity: (i) a water saver strategy for improving water stress tolerance through the maximization of the elastic adjustment; and (ii) a water spender strategy for maintaining water absorption and photosynthetic activity under moderate water stress through the maximization of the osmotic adjustment. We concluded that the higher elastic adjustment, together with reduced LA and increased LMA, implied a better performance under drought stress in the populations of Q. suber from more xeric habitats, which can be considered the most drought-adapted ecotypes and, consequently, the most appropriate for reforestation programs under an eventual increase in aridity.

Performance of a warm-water limpet species towards its poleward range edge compared to a colder-water congener

The demography and individual performance of species at their range edges provide important insight into how climate warming is impacting species distributions. The boreal limpet Patella vulgata and the Lusitanian limpet P. depressa have overlapping geographic ranges and local distributions in Britain. We measured individual performance at the 2 leading edges of P. depressa distribution (North Wales and South/South-east England) and in non-range edge populations in South-west England. Individuals of P. depressa towards both leading edges were expected to have reduced growth rates and higher mortality rates when compared with non-range edge populations. Conversely, P. vulgata was expected to have equivalent performance across regions, coinciding with the centre of its range. Tagged individuals did not show between-species differences in growth and mortality over a 12 mo period. Nonetheless, individual growth rates and population mortality rates of both Patella species were higher towards the range edge of P. depressa in South/South-east England, when compared with populations at its poleward edge and those in South-west England. Further analysis showed that growth and mortality rates were higher in denser populations for both P. depressa and P. vulgata, with equivalent site-specific performance patterns for both species in all regions. Thus, performance patterns of P. depressa reflected local factors in the same way as P. vulgata, overriding patterns of declining performance expected towards species borders. Comparisons between key congeneric species and their unexpected patterns of performance across their ranges provide insights into processes setting species boundaries and thereby their responses to climate change.

Analysis of landscape structure, habitat selection and urbanisation in edge populations of Scops Owls Otus scops in Central Europe×

Abstract The habitat selection of Scops Owl Otus scops has not been studied in Hungary so far. The population in the Carpathian Basin can be considered as a range edge population. Yet, studying and conserving breeding population at the edge of the species’ range is important for the evolutionary potential of the species. In the present study, we examined Scops Owl populations situated on both sides of the Hungarian-Slovenian border. Although breeding density is significantly higher in Slovenia than in Hungary, we found no difference in the ecological diversity of the Goričko Nature Park (GNP), Slovenia and Vas County, Hungary. We found that both the proportion and total edge length of dry grasslands and intensively managed mesic grasslands were lower in Hungary. Similarly, market gardens were present in a larger proportion in GNP. These landscape features all indicate that the complex cultivation is still pronounced in GNP, favouring the Sops Owl as less intensive cultivation modes, like rural market gardens and grasslands play a key role in its habitat selection. Points with Scops Owl observations appeared to be closer to settlements than randomly generated points. They also were observed farther from primary roads than from secondary roads. This is in accordance with other studies revealing that these nocturnal birds avoid noisy roads. We briefly discuss why conserving range edge populations is important, and how time and effort optimised species conservation measures should accompany landscape protection at the political level.

Conserving populations at the edge of their geographic range: the endangered Caspian red deer (Cervus elaphus maral) across protected areas of Iran

Large ungulate populations around the world are declining, experience range loss or even go extinct. Ecological theory predicts that a species’ vulnerability is greater at the edges of its geographic range compared to its core. However, edge populations may still be successfully managed inside reserves when the drivers of declines are addressed with priority. Our aim was to evaluate the status of Caspian red deer in Iran and address the importance of law enforcement and landscape connectivity between reserves. Using systematic occurrence records and ranger-based censuses, we applied multiple methods to model the Caspian red deer’s distribution, quantify population trajectory metrics and predict landscape connectivity. Additionally, we ran generalized linear models in a Bayesian approach to assess the importance of ranger stations and connectivity on population abundance. We estimated the population at 747 (CI 95% 604–890) individuals being confined to 21 areas, reflecting a decline by 59% compared to an estimate in 1977 with declining trajectories in 98% of reserves. The number of ranger stations was the only factor correlating with its population abundance. Moreover, extirpation and range loss mostly occurred in the periphery of its Iranian distribution, and we detected five stepping stone areas in the center of the range. Our study suggests that under conditions of heavy poaching and competition with livestock, conservation urgently needs to focus on increased law enforcement and improvement of habitat quality to stop declines and prevent extinction of this large ungulate in Iran.