Modelling distributional trends to inform conservation strategies for endangered species

Aim: Species loss has increased significantly over the last 1000 years and is ultimately attributed to the direct and indirect consequences of increased human population growth across the planet. A growing number of species are becoming endangered and require human intervention to prevent their local extirpation or complete extinction. Management strategies aimed at mitigating a species loss can benefit greatly from empirical approaches that indicate the rate of decline of a species providing objective information on the need for immediate conservation actions, e.g. captive breeding; however, this is rarely employed. The current study used a novel method to examine the distributional trends of a model endangered species, the freshwater pearl mussel, Margaritifera margaritifera (L.).
Location: United Kingdom and Republic of Ireland.
Methods: Using species presence data within 10-km grid squares since records began three-parameter logistic regression curves were fitted to extrapolate an estimated date of regional extinction.
Results: This study has shown that freshwater pearl mussel distribution has contracted since known historical records and outlier populations were lost first. Within the United Kingdom and Republic of Ireland, distribution loss has been greatest in Scotland, Northern Ireland, Wales and England, respectively, with the Republic of Ireland containing the highest relative proportion of M. margaritifera distribution, in 1998.
Main conclusions: This study provides empirical evidence that this species could become extinct throughout countries within the United Kingdom within 170 years under the current trends and emphasizes that regionally specific management strategies need to be implemented to prevent extirpation of this species.

Restrospective genetic monitoring of the threatened Yellow marsh saxifrage (Saxifraga hirculus) reveals genetic erosion but provides valuable information for conservation strategies

Aim: Retrospective genetic monitoring, comparing genetic diversity of extant populations with historical samples, can provide valuable and often unique insights into evolutionary processes informing conservation strategies. The Yellow marsh saxifrage (Saxifraga hirculus) is listed as ‘critically endangered’ in Ireland with only two extant populations. We quantified genetic changes over time and identified genotypes in extant populations that could be used as founders for reintroductions to sites where the species is extinct.

Location: Ireland.

Methods: Samples were obtained from both locations where the species is currently found, including the most threatened site at the Garron Plateau, Co. Antrim, which held only 13 individuals during 2011. Herbarium samples covering the period from 1886 to 1957 were obtained including plants from the same area as the most threatened population, as well as three extinct populations. In total, 422 individuals (319 present-day and 103 historical) were genotyped at six microsatellite loci. Species distribution modelling was used to identify areas of potentially suitable habitat for reintroductions.

Results: Level of phenotypic diversity within the most threatened population was significantly lower in the present-day compared with historical samples but levels of observed heterozygosity and number of alleles, whilst reduced, did not differ significantly. However, Bayesian clustering analysis suggested gradual lineage replacement over time. All three measures of genetic diversity were generally lower at the most threatened population compared with the more substantial extant populations in Co. Mayo. Species distribution modelling suggested that habitat at one site where the species is extinct may be suitable for reintroduction.

Main conclusions: The dominant genetic lineage in the most threatened population is rare elsewhere; thus, care needs to be taken when formulating any potential reintroduction programme. Our findings highlight both the need for genetic monitoring of threatened populations, but also for its swift implementation before levels of diversity become critically low.

How can a knowledge of the past help to conserve the future? Biodiversity conservation and the relevance of long-term ecological studies

This paper evaluates how long-term records could and should be utilized in conservation policy and practice. Traditionally, there has been an extremely limited use of long-term ecological records (greater than 50 years) in biodiversity conservation. There are a number of reasons why such records tend to be discounted, including a perception of poor scale of resolution in both time and space, and the lack of accessibility of long temporal records to non-specialists. Probably more important, however, is the perception that even if suitable temporal records are available, their roles are purely descriptive, simply demonstrating what has occurred before in Earth’s history, and are of little use in the actual practice of conservation. This paper asks why this is the case and whether there is a place for the temporal record in conservation management. Key conservation initiatives related to extinctions, identification of regions of greatest diversity/threat, climate change and biological invasions are addressed. Examples of how a temporal record can add information that is of direct practicable applicability to these issues are highlighted. These include (i) the identification of species at the end of their evolutionary lifespan and therefore most at risk from extinction, (ii) the setting of realistic goals and targets for conservation ‘hotspots’, and (iii) the identification of various management tools for the maintenance/restoration of a desired biological state. For climate change conservation strategies, the use of long-term ecological records in testing the predictive power of species envelope models is highlighted, along with the potential of fossil records to examine the impact of sea-level rise. It is also argued that a long-term perspective is essential for the management of biological invasions, not least in determining when an invasive is not an invasive. The paper concludes that often inclusion of a long-term ecological perspective can provide a more scientifically defensible basis for conservation decisions than the one based only on contemporary records. The pivotal issue of this paper is not whether long-term records are of interest to conservation biologists, but how they can actually be utilized in conservation practice and policy.

Assessing the conservation status of the freshwater pearl mussel in the North of Ireland - Relevance of growth and age characteristics

In order to conserve the freshwater pearl mussel in Ireland, populations that have a high risk of extinction must he identified and given priority for conservation. Growth of freshwater pearl mussels has been found to vary among populations on a wide geographic scale as well as on a local scale. Populations having a high growth constant (k), because of the small size of individuals and their shorter life-span and thus lower reproductive output, may be more likely to become extinct than those which have a low k and hence larger size and greater reproductive output. This study attempts to estimate the growth constant (k) in rivers in Donegal and Northern Ireland based on measuring lire largest shell in each population. Large differences in values of k were found among rivers and these are discussed in relation to catchment bedrock types and the identification of conservation priorities. Appropriate conservation strategies are recommended for Margaritifera margaritifera populations in the north of Ireland.

The conservation of bees: a global perspective

Bees are major pollinators of Angiosperms and therefore their apparent decline is of importance for humans and biodiversity. We synthesise results of 12 recent reviews to provide a global picture of the threats they face. Habitat loss is the major threat to bee diversity, whilst invasive species, emerging diseases, pesticide use, and climate change also have the potential to impact bee populations. We suggest that future conservation strategies need to prioritise (i) minimising habitat loss, (ii) making agricultural habitats bee-friendly, (iii) training scientists and the public in bee taxonomy and identification, (iv) basic autecological and population genetic studies to underpin conservation strategies, (v) assessing the value of DNA barcoding for bee conservation, (vi) determining the impact of invasive plants, animals, parasites and pathogens, and (vii) integrating this information to understand the potential impact of climate change on current bee diversity.

Conservation genetics of Ireland's sole population of the River water crowfoot (Ranunculus fluitans Lam.)

Populations of many freshwater species are becoming increasingly threatened as a result of a wide range of anthropogenically mediated factors. In the present study, we wanted to assess levels and patterns of genetic diversity in Ireland's sole population of the River water crowfoot (Ranunculus fluitans), which is restricted to a 12 km stretch of a single river, to assist the formation of conservation strategies. Analysis using amplified fragment length polymorphism (AFLP) indicated comparable levels of genetic diversity to those exhibited by a more extensive population of the species in England, and revealed no evidence of clonal reproduction. Allele-specific PCR analysis of five nuclear single nucleotide polymorphisms (SNPs) indicated no evidence of hybridization with its more abundant congener Ranunculus penicillatus, despite previous anecdotal reports of the occurrence of hybrids. Although the population currently exhibits healthy levels of genetic diversity and is not at risk of genetic assimilation via hybridization with R. penicillatus, it still remains vulnerable to other factors such as stochastic events and invasive species. © 2013 Elsevier B.V. All rights reserved.

Mammals and agri-environment schemes: hare haven or pest paradise?

1. Agri-environment schemes (AESs) are designed to create landscape-scale improvements in biodiversity. While the specific aims of AESs do not always include the enhancement of species of conservation concern, associated conservation strategies, such as the UK Biodiversity Action Plan, often rest on the assumption that AESs enhance environmental conditions and thereby improve the conservation status of target species. However, there is little evidence for the general efficacy of AESs in this respect. 2. To evaluate the effects of the Environmentally Sensitive Area (ESA) scheme, a widespread AES in Northern Ireland, a spotlight survey of the relative abundance of three mammal species, Irish hare Lepus timidus hibernicus, European rabbit Oryctolagus cuniculus and red fox Vulpes vulpes, was conducted. Of these, the Irish hare is a priority species for conservation action and the focus of a species action plan, while rabbit and fox are commonly considered agricultural pests. The effects of ESA designation and habitat on each species were assessed at 150 ESA and 50 non-ESA sites, matched for landscape characteristics. 3. The ESA scheme had no demonstrable effect on the abundance of Irish hares, and this agri-environment scheme did not target the landscape and habitat variables associated with hares. 4. In contrast, the abundance of rabbits and foxes was significantly greater within ESAs than the wider countryside. Agricultural factors such as reduced livestock stocking density, reduced overgrazing and field boundary enhancements may create more favourable conditions for both species. Aside from the implications for farm economics, the proliferation of rabbit populations within conservation areas may raise issues concerning the grazing of important plant communities, while increases in fox populations may adversely affect ground-nesting birds and other animal species of conservation concern. 5. Synthesis and applications: The abundance of rabbits and foxes corroborates recent work that suggests AESs may benefit common species but can not be relied upon to encourage rarer species. The Irish hare species action plan relies on agri-environment schemes to enhance the species’ status and realize the target of increasing the hare population by 2010 by promoting suitable habitat. However, the ESA scheme is unlikely to help in achieving these objectives. Targeted and evidence-based agri-environment prescriptions are clearly required in order to ensure the realization of species-specific conservation targets.

4 ◦C and beyond: what did this mean for biodiversity in the past?

How do the predicted climatic changes (IPCC, 2007) for the next century compare in magnitude and rate to those that Earth has previously encountered? Are there comparable intervals of rapid rates of temperature change, sea-level rise and levels of atmospheric CO2 that can be used as analogues to assess possible biotic responses to future change? Or are we stepping into the great unknown? This perspective article focuses on intervals in time in the fossil record when atmospheric CO2 concentrations increased up to 1200 ppmv, temperatures in mid- to high-latitudes increased by greater than 4 ?C within 60 years, and sea levels rose by up to 3 m higher than present. For these intervals in time, case studies of past biotic responses are presented to demonstrate the scale and impact of the magnitude and rate of such climate changes on biodiversity. We argue that although the underlying mechanisms responsible for these past changes in climate were very different (i.e. natural processes rather than anthropogenic), the rates and magnitude of climate change are similar to those predicted for the future and therefore potentially relevant to understanding future biotic response. What emerges from these past records is evidence for rapid community turnover, migrations, development of novel ecosystems and thresholds from one stable ecosystem state to another, but there is very little evidence for broad-scale extinctions due to a warming world. Based on this evidence from the fossil record, we make four recommendations for future climate-change integrated conservation strategies.

The pitfall with PIT tags: Marking freshwater bivalves for translocation induces short-term behavioural costs

Tagging animals is frequently employed in ecological studies to monitor individual behaviour, for example postrelease survival and dispersal of captive-bred animals used in conservation programmes. While the majority of studies focus on the efficacy of tags in facilitating the relocation and identification of individuals, few assess the direct effects of tagging in biasing animal behaviour. We used an experimental approach with a control to differentiate the effects of handling and tagging captive-bred juvenile freshwater pearl mussels, Margaritifera margaritifera, prior to release into the wild. Marking individuals with passive integrated transponder (PIT) tags significantly decreased their burrowing rate and, therefore, increased the time taken to burrow into the substrate. This effect was contributed to, in part, by the detrimental impacts of handling, which also significantly affected activity, burrowing ability and the time taken for each individual to emerge and start probing the substrate. Disturbance during handling and tagging may lead to indirect mortality after release by increasing the risk of predation or dislodgement during flooding, thereby potentially compromising any conservation strategy contingent on population supplementation or reintroduction. This is the first study to demonstrate that handling and PIT tagging has a detrimental impact on invertebrate behaviour. Moreover, our results provide useful information that will inform freshwater bivalve conservation strategies.

The importance of reproductive strategies in population genetic approaches to conservation: an example from the marine angiosperm genus Zostera

Knowledge of the levels of genetic diversity maintained in natural populations can play a central role in conservation programmes, particularly in threatened habitats or species. Fluctuations in population size can lead to loss of variation and, consequently, increase the risk of extinction. We have examined whether such a genetic bottleneck has occurred in populations of two species in the seagrass genus Zostera, which are believed to have been affected by an outbreak of wasting disease at the start of the last century. A test for heterozygote excess at five nuclear microsatellite loci did not suggest the occurrence of a genetic bottleneck, but analysis of seven chloroplast microsatellite loci and sequence data from two regions did suggest a bottleneck in the chloroplast genome. Extremely low levels of between-population diversity suggest that all subpopulations can be treated as a single management unit for each species. Comparable levels of nuclear genetic diversity were found in the three populations of the primarily sexual Zostera marina var. angustifolia studied but a wider range of within-population diversity was found in Zostera noltii, which displays both. sexual and vegetative reproductive strategies. This may be due to an increase in sexual recruitment due to localised fresh water inflow into the study site near to the most diverse population. Such populations should be prioritised as source material for any replanting or remediation due to natural or anthropogenic loss of Zostera beds in the area.

Predominance of genetic monogamy by females in a hammerhead shark, Sphyrna tiburo: Implications for shark conservation.

There is growing interest in the mating systems of sharks and their relatives (Class Chondrichthyes) because these ancient fishes occupy a key position in vertebrate phylogeny and are increasingly in need of conservation due to widespread overexploitation. Based on precious few genetic and field observational studies, current speculation is that polyandrous mating strategies and multiple paternity may be common in sharks as they are in most other vertebrates. Here, we test this hypothesis by examining the genetic mating system of the bonnethead shark, Sphyrna tiburo, using microsatellite DNA profiling of 22 litters (22 mothers, 188 embryos genotyped at four polymorphic loci) obtained from multiple locations along the west coast of Florida. Contrary to expectations based on the ability of female S. tiburo to store sperm, the social nature of this species and the 100% multiple paternity observed in two other coastal shark species, over 81% of sampled bonnethead females produced litters sired by a single male (i.e. genetic monogamy). When multiple paternity occurred in S. tiburo, there was an indication of increased incidence in larger mothers with bigger litters. Our data suggest that sharks may exhibit complex genetic mating systems with a high degree of interspecific variability, and as a result some species may be more susceptible to loss of genetic variation in the face of escalating fishing pressure. Based on these findings, we suggest that knowledge of elasmobranch mating systems should be an important component of conservation and management programmes for these heavily exploited species.

Blood-derived dermal langerin+ dendritic cells survey the skin in the steady state.

Langerin is a C-type lectin receptor that recognizes glycosylated patterns on pathogens. Langerin is used to identify human and mouse epidermal Langerhans cells (LCs), as well as migratory LCs in the dermis and the skin draining lymph nodes (DLNs). Using a mouse model that allows conditional ablation of langerin(+) cells in vivo, together with congenic bone marrow chimeras and parabiotic mice as tools to differentiate LC- and blood-derived dendritic cells (DCs), we have revisited the origin of langerin(+) DCs in the skin DLNs. Our results show that in contrast to the current view, langerin(+)CD8(-) DCs in the skin DLNs do not derive exclusively from migratory LCs, but also include blood-borne langerin(+) DCs that transit through the dermis before reaching the DLN. The recruitment of circulating langerin(+) DCs to the skin is dependent on endothelial selectins and CCR2, whereas their recruitment to the skin DLNs requires CCR7 and is independent of CD62L. We also show that circulating langerin(+) DCs patrol the dermis in the steady state and migrate to the skin DLNs charged with skin antigens. We propose that this is an important and previously unappreciated element of immunosurveillance that needs to be taken into account in the design of novel vaccine strategies.

Endothelial Nox4 NADPH oxidase enhances vasodilatation and reduces blood pressure in vivo.

OBJECTIVE: Increased reactive oxygen species (ROS) production is involved in the pathophysiology of endothelial dysfunction. NADPH oxidase-4 (Nox4) is a ROS-generating enzyme expressed in the endothelium, levels of which increase in pathological settings. Recent studies indicate that it generates predominantly hydrogen peroxide (H(2)O(2)), but its role in vivo remains unclear. METHODS AND RESULTS: We generated transgenic mice with endothelium-targeted Nox4 overexpression (Tg) to study the in vivo role of Nox4. Tg demonstrated significantly greater acetylcholine- or histamine-induced vasodilatation than wild-type littermates. This resulted from increased H(2)O(2) production and H(2)O(2)-induced hyperpolarization but not altered nitric oxide bioactivity. Tg had lower systemic blood pressure than wild-type littermates, which was normalized by antioxidants. CONCLUSION: Endothelial Nox4 exerts potentially beneficial effects on vasodilator function and blood pressure that are attributable to H(2)O(2) production. These effects contrast markedly with those reported for Nox1 and Nox2, which involve superoxide-mediated inactivation of nitric oxide. Our results suggest that therapeutic strategies to modulate ROS production in vascular disease may need to separately target individual Nox isoforms.

Conundrums in Conservation: Complexity in Control

The departure point for this investigation is to highlight the centrality of regulation theory as a praxis in planning enforcement. The value of the conceptual framework is demonstrated by application in the problematic arena of conservation regulatory compliance, where there is currently a dearth of investigation. It is evidenced that this thematic approach provides a lens to scrutinise problematic areas of control and provides a deeper understanding of the difficulties faced by planning enforcement operational practice generally and heritage regimes specifically. The utility of the proposed mechanism is that it remedies the current well documented pitfalls of disjointed, piecemeal strategies by providing a framework for robust, coherent decision making not only in planning but in the wider regulatory arena.