Defining Conservation Units Research Articles

Endangered subspecies of the Reed Bunting (Emberiza schoeniclus witherbyi and E. s. lusitanica) in Iberian Peninsula have different genetic structures

In the Iberian Peninsula, populations of two subspecies of the Reed Bunting Emberiza schoeniclus have become increasingly fragmented during the last decades when suitable habitats have been lost and/or the populations have gone extinct. Presently, both subspecies are endangered. We estimated the amount of genetic variation and population structure in order to define conservation units and management practices for these populations. We found that the subspecies lusitanica has clearly reduced genetic variation in nuclear and mitochondrial markers, has a drastically small effective population size and no genetic differentiation between populations. In contrast, the subspecies witherbyi is significantly structured, but the populations still hold large amounts of variation even though the effective population sizes are smaller than in the non-endangered subspecies schoeniclus. We suggest several management units for the Iberian populations. One unit includes subspecies lusitanica as a whole; the other three units are based on genetically differentiated populations of witherbyi. The most important genetic conservation measure in the case of lusitanica is to preserve the remaining habitats in order to at least maintain the present levels of gene flow. In the case of the three management units within witherbyi, the most urgent conservation measure is to improve the habitat quality to increase the population sizes.

Applying molecular genetic tools to tiger conservation

The utility of molecular genetic approaches in conservation of endangered taxa is now commonly recognized. Over the past decade, conservation genetic analyses based on mitochondrial DNA sequencing and microsatellite genotyping have provided powerful tools to resolve taxonomy uncertainty of tiger subspecies, to define conservation units, to reconstruct phylogeography and demographic history, to examine the genetic ancestry of extinct subspecies, to assess population genetic status non-invasively, and to verify genetic background of captive tigers worldwide. The genetic status of tiger subspecies and populations and implications for developing strategies for the survival of this charismatic species both in situ and ex situ are discussed.

Reconsideration for conservation units of wildPrimula sieboldiiin Japan based on adaptive diversity and molecular genetic diversity

Primula sieboldii E. Morren is a perennial clonal herb that is widely distributed in Japan, but in danger of extinction in the wild. In a previous study, we revealed the genetic diversity of the species using chloroplast and nuclear DNA and used this information to define conservation units. However, we lacked information on adaptive genetic diversity, which is important for long-term survival and, thus, for the definition of conservation units. In order to identify adaptive traits that showed adaptive differentiation among populations, we studied the genetic variation in six quantitative traits within and among populations for 3 years in a common garden using 110 genets from five natural populations from three regions of Japan. The number of days to bud initiation was adaptive quantitative trait for which the degree of genetic differentiation among populations (QST) was considerably larger than that in eight microsatellite markers (FST). The relationship between this trait and environmental factors revealed that the number of days to bud initiation was negatively correlated, with the mean temperature during the growing period at each habitat. This suggests that adaptive differentiation in the delay before bud initiation was caused by selective pressure resulting from temperature differences among habitats. Our results suggest that based on adaptive diversity and neutral genetic diversity, the Saitama population represents a new conservation unit.

Geographic variation in Northwest Atlantic fin whale (Balaenoptera physalus) song: Implications for stock structure assessment

Passive acoustic data are increasingly being used as a tool for helping to define marine mammal populations and stocks. Fin whale (Balaenoptera physalus) songs present a unique opportunity to determine interstock differences. Their highly stereotyped interpulse interval has been shown to vary between geographic areas and to remain stable over time in some areas. In this study the structure of songs recorded at two geographically close feeding aggregations in the Gulf of St. Lawrence (GSL) and Gulf of Maine (GoM) was compared. Recordings were made from September 2005 through February 2006 in the GSL and intermittently between January 2006 and September 2007 at two locations in the GoM. 6257 pulse intervals corresponding to 19 GSL and 29 GoM songs were measured to characterize songs from both areas. Classification trees showed that GSL songs differ significantly from those in the GoM. The results are consistent with those derived from other stock structure assessment methodologies, such as chemical signature and photoidentification analysis, suggesting that fin whales in these areas may form separate management stocks. Song structure analysis could therefore provide a useful and cost-efficient tool for defining conservation units over temporal and geographical scales relevant to management objectives in fin whales.

Small‐scale population‐genetic differentiation in the New Zealand caddisfly Orthopsyche fimbriata and the crayfish Paranephrops planifrons

A portion of the cytochrome c oxidase I gene in the caddisfly Orthopsyche fimbriata and in the crayfish Paranephrops planifrons was used to evaluate population genetic differentiation and define conservation units at small spatial scales among neighbouring catchments in the central‐west North Island of New Zealand. Hierarchical analysis of populations from 14 streams found 20 haplotypes in O. fimbriata and 23 haplotypes in P. planifrons. Haplotype diversity was high in most catchments. In O. fimbriata, c. 55% of genetic diversity was distributed among catchments and c. 45% within streams; haplotypes were shared across catchments with only the most northern and southern catchments, separated by c. 100 km, not sharing haplotypes. Paranephrops planifrons had a greater proportion of the total genetic diversity distributed between catchments (c. 72%) and much less within streams (c. 18%); most catchments had unique haplotypes, with only one shared among neighbouring catchments. As a strong disperser, O. fimbriata may have crossed catchments, over evolutionary timescales, but recent deforestation over ecological timescales may prevent ongoing gene flow. In contrast, weak dispersers such as P. planifrons, have no inter‐catchment dispersal, except where there are downstream freshwater connections. Translocation of populations may be necessary to restore areas and should preferably be from within catchments.

Geographic variation in northwest Atlantic fin whale (Balaenoptera physalus) song: Implications for stock structure assessment.

Passive acoustic data are increasingly being used as a tool for helping to define marine mammal populations and stocks. Fin whale (Balaenoptera physalus) songs present a unique opportunity to determine interpopulation differences. Their highly stereotyped interpulse interval has been shown to vary between geographic areas and to remain stable over time in some areas. In this study, the structure of songs recorded at two geographically close feeding aggregations in the Gulf of St. Lawrence (GSL) and Gulf of Maine (GoM) was compared. Recordings were made from September 2005 to June 2006 in the GSL and intermittently between January 2006 and September 2007 at two locations in the GoM. 6257 pulse intervals corresponding to 19 GSL and 29 GoM songs were measured to characterize songs from the three locations. Classification trees showed that GSL songs differ significantly from those in the GoM. The results are consistent with those derived from the other stock structure assessment methodologies, such as chemical signature and photoidentification analysis, suggesting that fin whales in these areas may form separate management stocks. Song structure analysis could therefore provide a useful and cost-efficient tool for defining conservation units over the temporal and geographical scales relevant to management objectives.

Historical DNA reveals the phylogenetic position of the extinct Alpine lynx

AbstractDuring the last two centuries, lynx populations have undergone severe declines and extinctions in Europe. The Alpine lynx, once distributed across the whole Alpine arc, became extinct due to direct human prosecution and deprivation of its main prey in the 1930s. Similar to the Iberian lynx Lynx pardinus, its taxonomy has been subject to several controversies. Moreover, knowing the taxonomic status of the Alpine lynx will help to define conservation units of extant lynx populations in Europe. In this study, we investigated two mitochondrial DNA regions in museum specimens (n=15) representing the autochthonous Alpine population and in samples from extant Eurasian lynx Lynx lynx populations in Europe and Asia (n=17). Phylogenetic analysis (cytochrome b, 345 bp) placed the Alpine lynx within the Eurasian lynx lineage. Among all individuals examined, seven different haplotypes (control region, 300 bp) were observed but no unique Alpine haplotype was discovered. Haplotypes of the extinct Alpine population were identical to previously described haplotypes in Scandinavian lynx signifying a recent genetic ancestry with current European populations. Moreover, our genetic data suggest two distinct glacial refugia for the Carpathian and Balkan population. Overall this study demonstrates that historical DNA from extinct populations can help to disentangle the phylogenetic relationships and historical biogeography of taxa with only a limited number of extant populations remaining.

Reproductive isolation, evolutionary distinctiveness and setting conservation priorities: The case of European lake whitefish and the endangered North Sea houting (Coregonus spp.)

BackgroundAdaptive radiation within fishes of the Coregonus lavaretus complex has created numerous morphs, posing significant challenges for taxonomy and conservation priorities. The highly endangered North Sea houting (C. oxyrhynchus; abbreviated NSH) has been considered a separate species from European lake whitefish (C. lavaretus; abbreviated ELW) due to morphological divergence and adaptation to oceanic salinities. However, its evolutionary and taxonomic status is controversial. We analysed microsatellite DNA polymorphism in nine populations from the Jutland Peninsula and the Baltic Sea, representing NSH (three populations, two of which are reintroduced) and ELW (six populations). The objectives were to: 1) analyse postglacial recolonization of whitefish in the region; 2) assess the evolutionary distinctiveness of NSH, and 3) apply several approaches for defining conservation units towards setting conservation priorities for NSH.ResultsBayesian cluster analyses of genetic differentiation identified four major groups, corresponding to NSH and three groups of ELW (Western Jutland, Central Jutland, Baltic Sea). Estimates of historical migration rates indicated recolonization in a north-eastern direction, suggesting that all except the Baltic Sea population predominantly represent postglacial recolonization via the ancient Elbe River. Contemporary gene flow has not occurred between NSH and ELW, with a divergence time within the last 4,000 years suggested from coalescence methods. NSH showed interbreeding with ELW when brought into contact by stocking. Thus, reproductive isolation of NSH was not absolute, although possible interbreeding beyond the F1 level could not be resolved.ConclusionFishes of the C. lavaretus complex in the Jutland Peninsula originate from the same recolonization event. NSH has evolved recently and its species status may be questioned due to incomplete reproductive isolation from ELW, but it was shown to merit consideration as an independent conservation unit. Yet, application of several approaches for defining conservation units generated mixed outcomes regarding its conservation priority. Within the total species complex, it remains one among many recently evolved unique forms. Its uniqueness and high conservation priority is more evident at a local geographical scale, where conservation efforts will also benefit populations of a number of other endangered species.

Glacial survival and local adaptation in an alpine leaf beetle

The challenge in defining conservation units so that they represent evolutionary entities has been to combine both genetic properties and ecological significance. Here we make use of the complexity of the European Alps, with their genetic landscape shaped by geographical barriers and postglacial colonization, to examine the correlation between ecological and genetic divergence. Montane species, because of the fragmentation of their present habitat, constitute extreme cases in which to test if genetically distinct subgroups based on neutral markers are also ecologically differentiated and show local adaptation. In the leaf beetle Oreina elongata, populations show variation in host plant use and a patchy distribution throughout the Alps and Apennines. We demonstrate that despite very strong genetic isolation (F(ST) = 0.381), variation in host plant use has led to differences in larval life-history traits between populations only as a secondary effect of host defence chemistry, and not through physiological adaptation to plant nutritional value. We also establish that populations that are more ecologically different in terms of larval performance are also more genetically divergent. In addition, morphological variation used to define subspecies appears to be mirrored in the population genetics of this species, resulting in almost perfect clustering based on microsatellite data. Finally, we argue from their strong genetic structure and congruent distribution that the subspecies of O. elongata were divided among the same glacial refugia within the Alps that have been proposed for alpine plants.

Molecular, quantitative and abiotic variables for the delineation of evolutionary significant units: case of sandalwood (Santalum austrocaledonicum Vieillard) in New Caledonia

Various approaches have been developed to define conservation units for plant and animal species. In this study we combined nuclear microsatellites (from a previous published study) and chloroplast microsatellites (assessed in the present study), leaf and seed morphology traits and abiotic variables (climate and soil) to define evolutionary significant units (ESU) of Santalum austrocaledonicum, a tree species growing in New Caledonia. Results for chloroplast microsatellites showed that the total population heterozygosity was␣high, (H cp = 0.84) but varied between islands. Differentiation was strong in the total population (F stcp = 0.66) but also within the main island Grande Terre (F stcp = 0.73) and within Iles Loyaute (F stcp = 0.52), highlighting a limited gene flow between populations. These results confirmed those obtained with nuclear microsatellites. The cluster analysis on molecular markers discriminated two main groups constituted by the populations of Grande Terre and the populations of Iles Loyaute. A principal component analysis of leaf and seed morphology traits singled out the populations of Iles Loyaute and the western populations of Grande Terre. Quantitative genetic analyses showed that the variation between populations was under genetic control (broad sense heritability close to 80%). A high correlation between rainfall and morphological traits suggested an impact of climate on this variation. The integration of these results allows to define two ESUs, one corresponding to Grande Terre and Ile des Pins and the other the Iles Loyaute archipelago. This study stresses the need to restore some populations of Grande Terre that are currently threatened by their small size.

Conservation units in north-eastern populations of the Alpine newt (Triturus alpestris)

Genetic variation in 19 populations of the alpine newt, Triturus alpestris, was assessed at the north-eastern margin of its range (southern Poland). Allozyme variation at five polymorphic loci was used in order to evaluate the degree of intrapopulational variation and interpopulational differentiation and define conservation units. Three management units were established on the basis of significant differences in allele frequencies. These correspond to three separate mountain ranges, i.e. the Carpathian, Sudetes and Holy Cross Mts. Contemporary gene flow between them is limited. In the extensively sampled Carpathian Mts, genetic structure is less pronounced, although still significant. Among population differentiation may be attributed to genetic drift in accordance with the isolation by distance model. The consequences of recent changes in land use in Central and Eastern Europe for low vagility and genetically structured organisms are discussed.

KEYNOTE ADDRESS: CONSERVATION GENETICS OF FRESHWATER ORGANISMS

This manuscript serves as a summary of both the importance of genetics in conservation, and the range of methodological approaches available. Two somewhat distinct realms of conservation genetics are outlined. The first theoretically rests upon the field of population genetics, and primarily concerns itself with the conservation of genetic diversity within and among populations, both in the wild and captivity. Basic concepts such as heterozygosity, genetic drift, and effective population size are discussed in the framework of freshwater conservation interests. Most importantly, it is emphasized that only multi-locus data sets, with adequate sample sizes are appropriate for answering a range of conservation-oriented questions with such population genetic approaches. The second area of research rests upon the fields of phylogenetics and phylogeography and concerns itself with systematics and the designation of conservation units. The somewhat popularised role of using trees based on mitochondrial DNA sequences and phylogeographic structure to define conservation units is described, but also criticized. In its place, a pluralistic approach should be undertaken, which takes into consideration both the socio-economic and legislative framework within which conservation units can be managed. Finally, despite much attention to the varying definition of conservation units, both theoretical and practical considerations support that the unit most important to conservation is the population.

KEYNOTE INVOLVEMENT OF GENETICS IN KNOWLEDGE, STOCK MANAGEMENT AND CONSERVATION OF AUSTROPOTAMOBIUS PALLIPES IN EUROPE

In the past, conservation programmes for a given species consisted in restoring the habitat and in translocating individuals without knowledge of their taxonomic status. Even if managers wanted to be informed, the “traditional taxonomy”, based on morphological characters, was discouraging because it could indicate several types of classification. This is the case for Austropotamobius pallipes, considered as a species complex. Today, conservation genetics aims to maintain, on one hand, the genetic specificity of populations (genetic integrity principle) and, on the other hand, the genetic diversity within and between populations (biodiversity principle), these basic principles being considered both at the level of protection measures and management measures. As an endangered species, A. pallipes is subjected to a loss of genetic diversity, a result of deterioration of water quality responsible for habitat fragmentation, with populations being confined to headwaters of the catchments. Consequently a certain degree of genetic variability must be maintained within the species because it governs the adaptation potential: the populations must be capable of responding to new environmental conditions. In A. pallipes, recent studies from several countries attempt to first describe the distribution of the present natural populations and secondly, by studying mitochondrial DNA, to clarify the taxonomy (number and identification of the present species and subspecies by phylogenetic inferences) and to assess the biogeographical history. These two preliminary steps are fundamental before defining conservation units and working at the catchment level, using highly polymorphic nuclear markers. The new approach has provided a good framework for research, with more frequent dialogues between geneticists and managers.

Adaptive evolutionary conservation: towards a unified concept for defining conservation units

Recent years have seen a debate over various methods that could objectively prioritize conservation value below the species level. Most prominent among these has been the evolutionarily significant unit (ESU). We reviewed ESU concepts with the aim of proposing a more unified concept that would reconcile opposing views. Like species concepts, conflicting ESU concepts are all essentially aiming to define the same thing: segments of species whose divergence can be measured or evaluated by putting differential emphasis on the role of evolutionary forces at varied temporal scales. Thus, differences between ESU concepts lie more in the criteria used to define the ESUs themselves rather than in their fundamental essence. We provide a context-based framework for delineating ESUs which circumvents much of this situation. Rather than embroil in a befuddled debate over an optimal criterion, the key to a solution is accepting that differing criteria will work more dynamically than others and can be used alone or in combination depending on the situation. These assertions constitute the impetus behind adaptive evolutionary conservation.

Adaptive evolutionary conservation: towards a unified concept for defining conservation units

Adaptive evolutionary conservation: towards a unified concept for defining conservation units

Defining conservation units in a rich and fragmented flora: implications for the management of genetic resources and evolutionary processes in south-west Australian plants

The south-west Australian flora shows a diverse array of evolutionary patterns and exceptionally high species diversity. A significant component of this flora consists of relictual species which often have naturally fragmented and geographically restricted distributions. Many of these species appear to apportion significant levels of genetic diversity among populations. Diversity at both the population and species level presents a major challenge to the development of appropriate conservation strategies for this flora. To be effective these strategies should not only aim to preserve current levels of species diversity, but also consider intraspecific variation and the evolutionary and ecological processes associated with the generation and maintenance of that variation. The identification and characterisation of conservation units, based on population genetic structure and phylogeographic patterns within species, provide a useful basis upon which more general conservation principals can be developed for the maintenance of these processes. Population genetic structure and phylogeographic studies are used to show how conservation units can be identified in Lambertia orbifolia, Acacia anomala, Stylidium coroniforme, Stylidium nungarinense and Banksia cuneata, and taxa from a range of other genera. Determining conservation units in these taxa defines not only suitable units for their conservation but also the appropriate geographical scale for management. These findings indicate the potential this approach can have in determining strategies and priorities for the conservation of the south-west Australian flora.