Conservation genetics and species status of an endangered Australian dragon, <Emphasis Type="Italic">Tympanocryptis pinguicolla</Emphasis> (Reptilia: Agamidae)

We present a phylogenetic and morphological study of the grassland earless dragon, Tympanocryptis pinguicolla, an endangered habitat specialist that occurs in a few isolated populations in eastern Australia. Tympanocryptis pinguicolla occurred historically in Victoria in south-eastern Australia, but has not been seen since 1990, and current populations are known in New South Wales and Canberra in south-eastern Australia. Recently, new populations identified as T. pinguicolla were discovered on the Darling Downs, Queensland. Translocation of individuals between these populations has been suggested as a conservation management strategy to maintain genetic diversity. To address this issue, we undertook a phylogenetic study of all major populations of T. pinguicolla using a 1838 bp region of mitochondrial DNA, incorporating ND1, ND2, COI and eight tRNA genes. We incorporated specialized degraded-DNA techniques to amplify DNA from historical museum specimens, as no extant tissue was available for Victorian populations. Our results, which include morphological analysis, provide convincing evidence that populations currently identified as T.␣pinguicolla do not comprise a monophyletic species, as the populations from the Darling Downs are more closely related to T. tetraporophora than to T. pinguicolla. In addition, we find that there is a significant level of haplotype divergence between populations of T. pinguicolla, indicating that these lineages separated at least 1.5 mya. Our results suggest translocation may not be an appropriate management strategy and our findings that Darling Downs populations are not T.␣pinguicolla will significantly influence the conservation management of this species in Queensland.     

Moths in fragments: insights into the biology and ecology of the Australian endangered golden sun moth Synemon plana (Lepidoptera: Castniidae) in natural temperate and exotic grassland remnants

The conservation and management of endangered species requires an adequate understanding of their biology and ecology. Although there has been an increasing appreciation in Australia of the need for greater efforts to conserve insects, there is only limited information available that can be used to underpin conservation efforts. The endangered golden sun moth, Synemon plana (Lepidoptera: Castniidae) is a flagship species endemic to natural temperate grassland in south-eastern Australia. Most populations of this species are at considerable risk from habitat loss, weed invasion and inadequate management. Despite the considerable knowledge that exists about the species biology and ecology, efforts to improve the species conservation status are hampered because there are still critical gaps in our understanding of the species’ natural history. In particular, the ecology of the larvae is not known. Our study examined the abundance, population structure and reproductive biology of the moths in a broad sample of both natural temperate and exotic grassland remnants in and near Canberra in the Australian Capital Territory (ACT) in south-eastern Australia. The results fill critical gaps in the knowledge needed to achieve effective conservation management. From our findings, it is clear that the species inhabits grasslands dominated by a mixture of native wallaby grasses (Rytidosperma spp. (formerly Austrodanthonia)) and spear grasses (Austrostipa spp.). In contrast to earlier suggestions that S. plana is entirely confined to natural temperate grassland, mature and immature life stages of the species were also present in grasslands comprised entirely of the exotic Chilean needlegrass (Nassella neesiana). Most of the S. plana populations surveyed in the ACT were characterised by low relative abundance with only very few large populations being recorded. The conservation of exotic grasslands as substitute habitat for S. plana is discussed and suggestions regarding future monitoring and research of the species are provided.     

Explaining Rarity of the Dry Grassland Perennial Astragalus exscapus

In Central Europe several plant species of dry grasslands are particularly rare. Here I investigate whether habitat requirements, reproduction, and dispersal potential can contribute to the rarity of Astragalus exscapus (Fabaceae) growing in dry grassland habitats in dry regions of Europe. In addition, I question whether historic events might have contributed to the present-day rarity of A. exscapus. To assess habitat requirements of A. exscapus, vegetation composition and soil characteristics were studied in 37 populations in central Germany. Production and dispersal potential of seeds were investigated in 10 populations, and germination and recruitment were assessed in experimental plots in three populations. Vegetation of the habitats included most dry grassland community types occurring in the central German dry region indicating a broad ecological niche of the species within dry subcontinental grasslands. Soil characteristics of the habitats also spanned a wide range. Seed production was moderate. 98% of the seeds sown in the laboratory germinated whereas under natural conditions 20% of the seeds developed seedlings. Half of these seedlings survived for one year but only 4.5% for two years. 90% of the seeds were dispersed less than 50 cm distance indicating a low dispersal potential. I conclude that A. exscapus is mainly limited in dispersal but recruitment limitation might also be important in explaining its rarity. Furthermore, former climate change and postglacial reforestation of the area very likely contribute to the rarity of A. exscapus.     

Conservation genetics of the endangered grassland earless dragon Tympanocryptis pinguicolla (Reptilia: Agamidae) in Southeastern Australia

The grassland earless dragon, Tympanocryptis pinguicolla, islisted as endangered throughout its range. A recent taxonomic studybased on both morphological and allozyme data elevatedpinguicolla from a subspecies of T. lineata to fullspecies status, but the allozyme data showed considerabledifferentiation among pinguicolla populations. To investigatethe magnitude and nature of these differences with an independent dataset, we targeted key pinguicolla populations and sequenced anapproximately 900 base pair DNA fragment of the mitochondrial genomethat includes half of the ND4 gene and three tRNA genes. We obtainedsequence data from 21 individuals drawn from the three T.pinguicolla populations, included representatives of two otherTympanocryptis species and used an Amphibolurusspecies as an outgroup. Seven mitochondrial haplotypes were found amongthe 21 T. pinguicolla samples – two in the AustralianCapital Territory (ACT) and five in the Cooma region, Phylogeneticsignal in the data sets was extremely strong and a variety ofphylogenetic analyses of the data all resulted in the same single fullyresolved tree. There are 37 unique differences in the ND4 gene betweenthe ACT and Cooma populations. This translates into genetic differencesof between 5.76% and 6.23% between the two populations. Incomparison to studies on other reptile groups in which the same fragmentof DNA was used, the differences found between the ACT and Coomapopulations are more in line with species-level differences thandifferences within a single species and suggests that these populationsshould be considered separate taxonomic units.     

How many conservation units are there for the endangered grassland earless dragons?

Species are the most commonly recognised unit for conservation management, yet significant variation can exist below the level of taxonomic recognition and there is a lack of consensus around how a species might be defined. This definition has particular relevance when species designations are used to apportion conservation effort and when definitions might be made through legislation. Here, we use microsatellite DNA analyses to test the proposition that the last remaining populations of the endangered grassland earless dragon (Tympanocryptis pinguicolla) harbour substantial cryptic genetic variation. Our study provides strong evidence that long historical isolation and the recent impacts of urbanization, have led to genetic differentiation in microsatellite DNA allele frequencies and high numbers of private alleles among three genetic clusters. This differentiation is partially concordant with previous mitochondrial DNA analyses, which show the two regions (Canberra and Monaro) where this species exists, to be reciprocally monophyletic, but differs through the identification of a third genetic cluster that splits a northern Canberra cluster from that of southern Canberra. Our data also identify a stark contrast in population genetic structure between clusters such that high levels of genetic structure are evident in the highly urbanised Canberra region but not in the largely rural Monaro region. We conclude that this species, like many reptiles, harbours considerable cryptic variation and currently comprises three distinct and discrete units. These units could be classified as separate species for the purpose of conservation under the relevant Australian and international Acts drawing management appropriate to that status.     

High population differentiation in the rock-dwelling land snail (<Emphasis Type="Italic">Trochulus caelatus</Emphasis>) endemic to the Swiss Jura Mountains

Understanding patterns of genetic structure is fundamental for developing successful management programmes for isolated populations of threatened species. Trochulus caelatus is a small terrestrial snail endemic to calcareous rock cliffs in the Northwestern Swiss Jura Mountains. Eight microsatellite loci were used to assess the effect of habitat isolation on genetic population structure and gene flow among nine populations occurring on distinct cliffs. We found a high genetic differentiation among populations (mean F _ST = 0.254) indicating that the populations are strongly isolated. Both allelic richness and effective population size were positively correlated with the size of the cliffs. Our findings support the hypothesis that T. caelatus survived on ice-free cliffs during the Pleistocene glacier advancements from the Alps. Due to the establishment of beech and pine forest under recent, temperate climate conditions, dispersal between cliffs is no longer possible for rock-dwelling snails such as T. caelatus. Our results provide basic data for developing a conservation action plan for this endangered gastropod species.     

Within-patch mobility and flight morphology reflect resource use and dispersal potential in the dryad butterfly Minois dryas

Knowledge of mobility is essential for understanding animal habitat use and dispersal potential, especially in the case of species occurring in fragmented habitats. We compared within-patch movement distances, turning angles, resting times, and flight-related morphological traits in the locally endangered butterfly, the dryad (Minois dryas), between its old populations occupying xerothermic grasslands and newly established ones in wet meadows. We expected that the latter group should be more mobile. Individuals living in both habitat types did not differ in their body mass and size, but those from xerothermic grasslands had wider thoraxes and longer wings, thus lower wing loading index (defined as body mass to wing length ratio). The majority of movements were short and did not exceed 10 m. Movement distances were significantly larger in males. However, there was no direct effect of habitat type on movement distances. Our results suggest that the dryads from xerothermic grasslands have better flight capabilities, whereas those from wet meadows are likely to invest more in reproduction. This implies that mobility is shaped by resource availability rather than by recent evolutionary history. Lower female mobility may have negative implications for the metapopulation persistence because only mated females are able to (re)colonise vacant habitat patches efficiently. Conservation efforts should thus be focused on maintaining large habitat patches that prevent stochastic local extinctions. Furthermore, the recommendation of promoting the exchange of individuals among patches through improving matrix permeability, as well as assisted reintroductions of the species into suitable vacant habitats should also improve its conservation.     

Genetic Diversity and Spatial Genetic Structure of the Grassland Perennial Saxifraga granulata along Two River Systems

Due to changes in land use, the natural habitats of an increasing number of plant species have become more and more fragmented. In landscapes that consist of patches of suitable habitat, the frequency and extent of long-distance seed dispersal can be expected to be an important factor determining local genetic diversity and regional population structure of the remaining populations. In plant species that are restricted to riparian habitats, rivers can be expected to have a strong impact on the dynamics and spatial genetic structure of populations as they may enable long-distance seed dispersal and thus maintain gene flow between fragmented populations. In this study, we used polymorphic microsatellite markers to investigate the genetic diversity and the spatial genetic structure of 28 populations of Saxifraga granulata along two rivers in central Belgium. We hypothesized that rivers might be essential for gene flow among increasingly isolated populations of this species. Genetic diversity was high (H_S = 0.68), which to a certain extent can be explained by the octoploid nature of S. granulata in the study area. Populations along the Dijle and Demer rivers were also highly differentiated (G” _ST = 0.269 and 0.164 and D _EST = 0.190 and 0.124, respectively) and showed significant isolation-by-distance, indicating moderate levels of gene flow primarily between populations that are geographically close to each other. Along the river Demer population genetic diversity was higher upstream than downstream, suggesting that seed dispersal via the water was not the primary mode of dispersal. Overall, these results indicate that despite increasing fragmentation populations along both rivers were highly genetically diverse. The high ploidy level and longevity of S. granulata have most likely buffered negative effects of fragmentation on genetic diversity and the spatial genetic structure of populations in riparian grasslands.     

Negative effects of habitat degradation and fragmentation on the declining grassland plant Trifolium montanum

Changes in land use have resulted in a strong decline in the plant diversity of nutrient-poor grasslands, but little is known about the combined effects of habitat degradation and fragmentation on populations of individual species. We studied these effects on stage structure, recruitment, reproduction and offspring fitness in populations of the declining perennial grassland plant Trifolium montanum in central Germany. Density and survival probability of juvenile plants decreased with light competition, measured as leaf area index (LAI) above T. montanum plants, resulting in aged populations with few juvenile plants at unmanaged sites with higher LAI. Reproduction of T. montanum was not related to LAI, but increased strongly with local density, suggesting pollinator limitation in fragmented populations with a low density of flowering plants. In the common garden, the survival of sown offspring increased with mean seed size, whereas seed production of offspring decreased with isolation, and in strong contrast to previous studies, also decreased with size and density of the population of origin. This could be due to increased inbreeding because of pollination between closely related neighbouring plants in dense and large populations. Our results indicate that both habitat degradation and fragmentation have negative effects on populations of T. montanum, but affect different phases of the life cycle. In the short term, the effects of habitat degradation are more important than those of fragmentation, and populations of T. montanum are primarily threatened by an increase in light competition in unmanaged sites, which rapidly affects the dynamics of the populations. The observed opposite effects of habitat fragmentation on reproduction and offspring fitness indicate that the effects of population size, density and isolation on plant fitness and population viability may be complex.     

Scale-dependent diversity effects of seed dispersal by a wild herbivore in fragmented grasslands

Dispersal limitation between habitat fragments is a known driver of landscape-scale biodiversity loss. In Europe, agricultural intensification during the twentieth century resulted in losses of both grassland habitat and traditional grassland seed dispersal vectors such as livestock. During the same period, populations of large wild herbivores have increased in the landscape. Usually studied in woodland ecosystems, these animals are found to disperse seeds from grasslands and other open habitats. We studied endozoochorous seed dispersal by roe deer (Capreolus capreolus) in fragmented grasslands and grassland remnants, comparing dispersed subcommunities of plant species to those in the established vegetation and the seed bank. A total of 652 seedlings of 67 species emerged from 219 samples of roe deer dung. This included many grassland species, and several local grassland specialists. Dispersal had potentially different effects on diversity at different spatial scales. Almost all sites received seeds of species not observed in the vegetation or seed bank at that site, suggesting that local diversity might not be dispersal limited. This pattern was less evident at the landscape scale, where fewer new species were introduced. Nonetheless, long-distance dispersal by large wild herbivores might still provide connectivity between fragmented habitats within a landscape in the areas in which they are active. Finally, as only a subset of the available species were found to disperse in space as well as time, the danger of future biodiversity loss might still exist in many isolated grassland habitats.     

Mobility and microhabitat utilization in a flightless wetland grasshopper, Chorthippus montanus (Charpentier, 1825)

Wetlands are among the most threatened habitat types on our planet. Their decline will probably even intensify under climate change. Many biota are strongly dependent on wetlands, including a large number of invertebrate species. The populations of such hygrophilous species become increasingly disconnected due to the ongoing fragmentation of their habitats. This is particularly true for species with reduced dispersal capacities, such as flightless insects. We studied mobility, population size and microhabitat utilization in a population of an endangered grasshopper species, the Water-meadow Grasshopper, Chorthippus montanus. Our mark-recapture study revealed that the cumulative movement distance of the adults was on average 23.5?m with a maximum of 104?m. The microhabitat analysis showed that both sexes of C. montanus preferred warmer patches with greater radiation than measured at control sites. Niche overlap among sexes was stronger than expected by chance, while niche overlap between insects and controls showed the opposite pattern. Our results suggest that C. montanus is strongly restricted to its habitat and is probably not able to cross larger distances through unsuitable vegetation. Hence, we assume that the populations of this flightless insect species are strongly isolated. However, the effect of the rare macropterous morph of C. montanus on gene flow remains unknown. Wetland restoration is crucial to reconnect the existing wetland patches in Central Europe and thereby reduce the negative effects of habitat fragmentation on wetland species.     

The potential key seed-dispersing role of the arboreal marsupial Dromiciops gliroides

Marsupial seed dispersal is a rare phenomenon, although it may be ecologically significant in southern South America. The marsupial Dromiciops gliroides is endemic to the northern part of the temperate forest of South America. Here we describe the food habits and examine the potential role of D. gliroides as a seed disperser. We evaluated the diet of this marsupial in its natural habitat and in captivity. Dromiciops gliroides is omnivorous showing high consumption of a diversity of fruits. In captivity, D. gliroides consumed fruits from 80% of 22 native plant species we examined. Experiments conducted with fruits from two common understory shrubs show that seed passage through the digestive tract of D. gliroides enhances germination. Our results suggest that this species may have an important role as a seed disperser in the temperate forest of South America, which might offset a scarcity of frugivorous bird species.     

Managing coastal grasslands for an endangered wader species can give positive results only when expanding the area of open landscape

The rapid loss of wetlands during the 20^th century has caused a severe decline in the biota associated with these habitats. In Europe, the loss of wet grasslands has seriously affected breeding waders, whose numbers have halved in the past 50 years and remaining populations are facing fragmented, low quality habitats. To improve the remaining sites as breeding grounds for these birds, the exact habitat requirements of the species need to be known. Our study was carried out in Boreal Baltic coastal grasslands in Estonia, where land abandonment has been the main reason behind waders’ population declines in the past decades. Hence, we focus on partially overgrown fields, aiming to ascertain habitat characteristics determining the breeding site selection of meadow birds, especially the endangered Southern Dunlin (Calidris alpina schinzii).We studied the breeding site selection of four wader species (Southern Dunlin, Common Redshank (Tringa totanus), Northern Lapwing (Vanellus vanellus) and Common Snipe (Gallinago gallinago)) in 23 coastal grasslands over two years. We analysed seven habitat characteristics which could influence the breeding habitat selection of these species.Our study demonstrates that breeding sites of all studied wader species are located closer to wet areas and coastline and further away from woodland. Also, the height of the ground level has an impact on the breeding probability, with lower areas favoured. Concerning the Southern Dunlin, our results show that on sites where the species was absent, suitable breeding sites, regarding the distance from woodland edge, were absent. Thus, reforestation of grasslands may be the key reason behind the poor population status of the species. We also demonstrated that proximity of reed beds did not influence the breeding site selection of waders – a result which contradicts current wet grassland management suggestions.Expanding the open landscape, maintaining a large quantity of wet features suitable for foraging and preventing overgrowth of coastline and lower parts of the meadow makes the habitat optimal for breeding waders. Concerning the growth of the population size and spatial distribution of the Southern Dunlin, removal of woodlands adjacent to grasslands is crucial.     

Which plant traits predict species loss in calcareous grasslands with extinction debt?

Aim Habitat loss and degradation pose a major threat to biodiversity, which can result in the extinction of habitat characteristic species. However, many species exhibit a delayed response to environmental changes because of the slow intrinsic dynamics of populations, resulting in extinction debt. We assess directly the changes in habitat characteristic species composition by comparing historical (1923) and current inventories in highly fragmented grasslands. We aim to characterize the species that constitute extinction debt in European calcareous grasslands. Location Europe, Estonia, 59–60° N, 24–25° E. Methods We related eleven life‐history traits and selected habitat preferences to local extinctions of populations in grasslands where extinction debt has been largely paid. Traits were chosen to describe species dispersal and persistence abilities and were quantified from databases. Results The studied grasslands have lost 90% of their area and 30% of their characteristic plant populations in 90 years. Species more prone to local population extinction were characterized by shorter life span, self‐pollination, a lack of clonal growth, fewer seeds per shoot, lower average height, lower soil nitrogen preference and higher requirements for light, indicating a limited ability to tolerate the range of changes in biotic and abiotic conditions of the sites. Locally extinct populations were also characterized by wind‐dispersed seeds, lower seed weight and lower terminal velocity of seeds, suggesting that species strategies for long‐distance dispersal are not favoured in highly fragmented landscapes. Thus, both increased habitat isolation and decreased habitat quality are important in determining local population extinction. Main conclusions Populations more prone to local extinction were characterized by a number of life‐history traits, demonstrating a greater extinction risk for species with poorer abilities for local persistence and competition. Our results can be applied to less degraded grasslands where the extinction debt is not yet paid to determine those species most susceptible to future extinction.     

Limited structure and widespread diversity suggest potential buffers to genetic erosion in a threatened grassland shrub Pimelea spinescens (Thymelaeaceae)

Pimelea spinescens is a critically endangered species of the temperate grasslands of southeastern Australia. Two subspecies are recognised. Subspecies, P. spinescens subsp. spinescens, formerly common and widespread, is found in isolated remnants of previously extensive grasslands. The second subspecies, subsp. pubiflora, is thought to have been historically rare with only two geographically-isolated extant populations. The grassland communities exist now as fragmented remnants representing <1 % of their extent prior to European settlement in the early 1800s. Conservation management strategies for species in these critically endangered ecosystems rely on an understanding of genetic diversity and population structure to ensure long-term evolutionary potential. We used chloroplast DNA (cpDNA) and microsatellite markers to examine the population genetic structure of both subspecies. Analysis of cpDNA revealed 14 haplotypes with high divergence between the single haplotype found in subsp. pubiflora and most remaining haplotypes restricted to subsp. spinescens. Microsatellites also indicated high genetic differentiation between subspecies but little evidence of sub-structuring within either subspecies. Results suggest that seed dispersal has not been as limited as previously thought. In this fragmented habitat, a lack of genetic structure suggests buffers to genetic erosion, with current patterns reflecting genetic diversity prior to fragmentation. Plant longevity and the presence of seed banks may contribute to the maintenance of these patterns, resulting in a lag between fragmentation and genetic erosion. Whilst factors such as longevity and seed banks may be preserving historic genetic diversity, management is required to ensure the maintenance of this diversity into the future.     

Restricted dispersal in a flying beetle assessed by telemetry

Many insects living in ancient trees are assumed to be threatened as a result of habitat loss and fragmentation. It is generally expected that species in habitats with low temporal variability in carrying capacity have lower degree of dispersal in comparison to those in more ephemeral habitats. As hollow trees are long-lived, species in that habitat are expected to be sensitive to habitat fragmentation, due to a low capacity to establish new populations far from present ones. Using radio telemetry, we studied the dispersal for a beetle, Osmoderma eremita, living in hollow trees. O. eremita exhibited philopatry and only dispersed over short ranges. About 82–88% of the adults remained in the tree where they were caught. All observed dispersal movements ended up in nearby hollow trees and 62% in the neighbouring hollow tree. These results corroborate the suggestion that habitat fragmentation may be detrimental to insects living in temporally stable but spatially variable habitats. In order to preserve such species, we propose that conservation efforts should be focused on maintaining or increasing the number of suitable trees in and near presently occupied stands.     

Strongly diverging population genetic patterns of three skipper species: the role of habitat fragmentation and dispersal ability

The fragmentation of landscapes has an important impact on the conservation of biodiversity, and the genetic diversity is an important factor for a populations viability, influenced by the landscape structure. However, different species with differing ecological demands react rather different on the same landscape pattern. To address this feature, we studied three skipper species with differing habitat requirements (Lulworth Skipper Thymelicus acteon: a habitat specialist with low dispersal ability, Small Skipper Thymelicus sylvestris: a habitat generalist with low dispersal ability, Essex Skipper Thymelicus lineola: a habitat generalist with higher dispersal ability). We analysed 18 allozyme loci for 1,063 individuals in our western German study region with adjoining areas in Luxembourg and north-eastern France. The genetic diversity of all three species were intermediate in comparison with other butterfly species. The F _ST was relatively high for T. acteon (5.1%), low for T. sylvestris (1.6%) and not significant for T. lineola. Isolation by distance analyses revealed a significant correlation for T. sylvestris explaining 20.3% of its differentiation, but no such structure was found for the two other species. Most likely, the high dispersal ability of T. lineola in comparison with T. sylvestris leads to a more or less panmictic structure and hence impedes isolation by distance. On the other hand, the isolation of the populations of T. acteon seems to be so strict that the populations develop independently. Although no general genetic impoverishing was observed for the endangered T. acteon, small populations had significantly lower genetic diversities than big populations, and therefore the high degree of isolation among populations might threaten its local and regional survival.     

Habitat connectivity, more than species’ biology, influences genetic differentiation in a habitat specialist, the short-eared rock-wallaby (Petrogale brachyotis)

It is difficult to assess the relative influence of anthropogenic processes (e.g., habitat fragmentation) versus species’ biology on the level of genetic differentiation among populations when species are restricted in their distribution to fragmented habitats. This issue is particularly problematic for Australian rock-wallabies (Petrogale sp.), where most previous studies have examined threatened species in anthropogenically fragmented habitats. The short-eared rock-wallaby (Petrogale brachyotis) provides an opportunity to assess natural population structure and gene flow in relatively continuous habitat across north-western Australia. This region has reported widespread declines in small-to-medium sized mammals, making data regarding the influence of habitat connectivity on genetic diversity important for broad-scale management. Using non-invasive and standard methods, 12 microsatellite loci and mitochondrial DNA were compared to examine patterns of population structure and dispersal among populations of P. brachyotis in the Kimberley, Western Australia. Low genetic differentiation was detected between populations separated by up to 67?km. The inferred genetic connectivity of these populations suggests that in suitable habitat P. brachyotis can potentially disperse far greater distances than previously reported for rock-wallabies in more fragmented habitat. Like other Petrogale species male-biased dispersal was detected. These findings suggest that a complete understanding of population biology may not be achieved solely by the study of fragmented populations in disturbed environments and that management strategies may need to draw on studies of populations (or related species) in undisturbed areas of contiguous habitat.     

Comparative biogeography of the congener lilies Lilium distichum and Lilium tsingtauense in Korea

The main Korean mountain range (the so-called “Baekdudaegan”), which stretches from north to south across most of the Peninsula, has been thought to harbor glacial refugia for boreal and temperate plant species, where they likely found relatively stable habitats and maintained large population sizes. Under this scenario, high levels of genetic variation for plant populations can be anticipated. To test this hypothesis, we examined levels of allozyme diversity in the boreal herb Lilium distichum, which in Korea occurs largely along the Baekdudaegan and in its closely related congener L. tsingtauense, a temperate species that can occur from the coastal islands to high-altitude mountains in the Baekdudaegan. As expected, L. distichum harbored high levels of genetic variation within populations, and we found significant correlations between percentage of polymorphic loci (and allelic richness) and elevation. For L. tsingtauense we found moderate genetic variation, with its populations showing a significantly positive correlation between intra-population expected heterozygosity and elevation. Our results suggest that populations/species that occur within or near the main ridge of the Baekdudaegan probably endured the glacial periods in macrorefugia, whereas those populations/species located at low elevations (far away from mid- and high-elevation mountains) did it in microrefugia. Palaeodistribution modelling is in agreement with genetic data, indicating that the Baekdudaegan was suitable habitat for both species during the glacial (LGM) and interglacial periods (like the present). This study as well as the data from other studies compiled here provides strong evidence that the Baekdudaegan was a major refugial area for the East Asian flora throughout the Quaternary and, thus, meriting high priority for conservation biogeography.     

Extinction debt in a common grassland species: immediate and delayed responses of plant and population fitness

Changes in landscape structure and environmental conditions due to habitat fragmentation can have significant effects on plant populations. Decreasing genetic diversity and changing population structure can reduce plant fitness and influence the long-term persistence of populations. Dry calcareous grasslands in Estonia have witnessed a large decline in area within the last 80 years, but due to extinction debt, the species richness in these grasslands has not yet responded to this decline. In these calcareous grasslands, we studied genetic diversity, phenotypic performance and population characteristics of a common habitat-specialist grass, Briza media. A decrease in genetic diversity was associated with a decrease in plant reproductive output. In addition, we found that some fitness components of B. media showed a delayed response to landscape changes. Specifically, plant height and germination success were related to historical rather than to current landscape parameters, indicating a time-lagged response of plant performance to habitat fragmentation. Dependence on historical landscape structure may thus result in a future decline in population fitness even if habitat loss and fragmentation no longer continue. The documented effect of current environmental conditions, however, shows that fitness-related traits are already slowly adapting to the changing conditions. Our results indicate that even common habitat-specialist species can be susceptible to landscape changes and be threatened by decreased population performance in the future.