Relevance of genetics for conservation policies: the case of Minorcan cork oaks

Background and Aims

Marginal populations of widely distributed species can be of high conservation interest when they hold a significant or unique portion of the genetic diversity of the species. However, such genetic information is frequently lacking. Here the relevance of genetic surveys to develop efficient conservation strategies for such populations is illustrated using cork oak (Quercus suber) from Minorca (Balearic Islands, Spain) as a case study. Cork oak is highly endangered on the island, where no more than 67 individuals live in small, isolated stands in siliceous sites. As a consequence, it was recently granted protected status.

Methods

Two Bayesian clustering approaches were used to analyse the genetic structure of the Minorcan population, on the basis of nuclear microsatellite data. The different groups within the island were also compared with additional island and continental populations surrounding Minorca.

Key Results

Very high genetic diversity was found, with values comparable with those observed in continental parts of the species'' range. Furthermore, the Minorcan oak stands were highly differentiated from one another and were genetically related to different continental populations of France and Spain.

Conclusions

The high levels of genetic diversity and inter-stands differentiation make Minorcan cork oak eligible for specific conservation efforts. The relationship of Minorcan stands to different continental populations in France and Spain probably reflects multiple colonization events. However, discrepancy between chloroplast DNA- and nuclear DNA-based groups does not support a simple scenario of recent introduction. Gene exchanges between neighbouring cork oak stands and with holm oak have created specific and exceptional genetic combinations. They also constitute a wide range of potential genetic resources for research on adaptation to new environmental conditions. Conservation guidelines that take into account these findings are provided.     

Carabid beetle (Coleoptera: Carabidae) conservation in New Zealand

An overview of carabid beetles in the New Zealand conservation context is provided. Processes for threatened species recovery within the New Zealand Department of Conservation are outlined, and the Department’s two major beetle-related recovery documents (The Conservation Requirements for New Zealand’s Nationally Threatened Invertebrates, and The Carabid Beetle Recovery Plan) are discussed. A subjective consideration of the merits and drawbacks of both the documents, and the systems that support them, is presented, along with an option for the way forward for threatened species conservation in New Zealand.     

Chemical ecology and insect conservation: optimising pheromone-based monitoring of the threatened saproxylic click beetle Elater ferrugineus

Elater ferrugineus is a saproxylic click beetle inhabiting old deciduous trees in Europe. It is threatened throughout its area of distribution due to habitat loss. No efficient monitoring method has been available for this species, but observed attraction of females to (R)-(+)-γ-decalactone, which is a male-produced sex pheromone of its prey, the scarab beetle Osmoderma eremita, has led to the development of an odour lure for monitoring. In addition, four esters have recently been identified from the pheromone-producing gland in female E. ferrugineus, and a blend of these esters is highly attractive to conspecific males in the field, revealing an alternative odour-based method for monitoring this species. However, no rigorous analysis has been performed to check whether all four esters show biological activity in male E. ferrugineus, and whether its own sex pheromone is a more potent lure than the prey kairomone for monitoring of E. ferrugineus. In this study, we reinvestigated the E. ferrugineus sex pheromone, using electrophysiological and behavioural analyses, and found that only one of the esters, 7-methyloctyl (Z)-4-decenoate, is active. In addition, trapping experiments revealed that 7-methyloctyl (Z)-4-decenoate is a much more efficient attractant for male E. ferrugineus than the prey pheromone is for conspecific females, or any sex of O. eremita. With a very efficient odour lure at hand, novel information about current distribution, local population sizes, and dispersal ranges in E. ferrugineus can now be obtained, which can aid in conservation efforts to protect this threatened insect and its habitat.     

Habitat preferences and conservation of the marbled jewel beetle Poecilonota variolosa (Buprestidae)

Detailed knowledge on habitat requirements is a key to successful conservation actions. The marbled jewel beetle Poecilonota variolosa (Buprestidae) has a wide global distribution but populations are often scarce and typically fragmented. In Sweden it is monophagous on aspen Populus tremula and is classified as near threatened on the Swedish Red List due to its rapid population decline. This study aimed to investigate habitat preferences and regional-scale distribution patterns of P. variolosa in southern Sweden in order to suggest conservation measures. Aspen trees in four study areas in the province of Småland were surveyed for exit holes during late summer 2011. The occurrence and number of exit holes (both new and old ones) per tree were compared between study areas and habitat types, and were related to the sun exposure and bark thickness of individual trees. Further, the occurrence of new and older exit holes was related to tree sun exposure and bark thickness. The most preferred habitat types were aspens on clear-cuts, followed by roadside aspens, aspens in pastures, and aspens in closed forest. Thick bark and high sun exposure were consistently significant as predictors for both occurrence and number of new exit holes per tree. The majority of exit holes were located towards south. Our results indicate several useful management measures: to retain aspen on clear-cuts, to cut alongside roads and around some selected coarse aspens in closed forests and in pastures.     

Evolution of beetle bioluminescence: the origin of beetle luciferin

Bioluminescence, the conversion of chemical energy into light in living organisms, is dependent on two principal components, an enzyme luciferase and the substrate luciferin. In beetles, the enzyme luciferase has been extensively studied, with signi?cant enzymological, sequence and structural data now available. Furthermore, the enzyme has been employed in a remarkable number of important applications, from microbial detection and medical imaging to GM gene expression studies. However, there is little information regarding the biosynthesis of beetle luciferin, and here we review the literature and speculate as to its evolutionary origins. Luciferin consists of a benzothiazole moiety attached to a thiazole carboxylic acid moiety, the former being rarely observed in nature but the latter being observed in a broad range of biologically derived molecules. Benzothiazoles are, however, observed in melanogenesis and we speculate as to whether this may be relevant to the understanding of luciferin biosynthesis in beetles. This review examines recent novel insights into beetle luciferin recycling and we assess a range of possible biosynthetic mechanisms. Copyright © 2004 John Wiley & Sons, Ltd.     

Effects of trap baits and height on stag beetle and flower chafer monitoring: ecological and conservation implications

The implementation of conservation actions requires a reliable assessment of presence and/or abundance of targeted species. This is particularly difficult for rare and elusive species. In this study the use of bottle traps and the effects of two potential baits in relation to height in the trees were tested to detect presence and assess abundance of stag beetles (Lucanidae) and flower chafers (Scarabaeidae, Cetoniinae), an important component of forest biodiversity. The study was carried out in a flood-plain forest of northern Italy. Forty-eight handcrafted traps were assigned to two height categories (1.5–2 m and 10–20 m) and three kinds of bait: (i) red wine, white wine and sugar, (ii) red wine, beer and mashed banana, (iii) no bait, as control. Fieldwork lasted 8 weeks, with 32 surveys, from May to July. Overall, we recorded 399 captures of the following species: Dorcus parallelipipedus, Lucanus cervus, Cetonia aurata, Protaetia speciosissima, P.affinis, P. morio and P. cuprea. Traps baited with red wine, white wine and sugar showed the highest detection probabilities for all the species. A clear preference for the canopy layer (traps between 10 and 20 m high) was shown by all species except for D. parallelipipedus which was mostly captured between 1.5 and 2 m of height. The study period was long enough to improve ecological knowledge on species phenology, but not enough to include the whole phenology for all of them. The method allowed the assessment of population size only for flower chafers as the number of stag beetles captures was too low.     

Population structure and its implications for conservation of the great silver beetle Hydrophilus piceus in Britain

1. The great silver water beetle Hydrophilus piceus is one of the largest aquatic insects in Europe. In Britain it is rare and endangered, and confined to a small number of low-lying marshes. Very little is known about the beetle populations in any of these areas, or the connectivity between them.
2. To investigate the population structure of H. piceus in Britain, four polymorphic microsatellite loci were identified and characterized. The genome of this beetle seems to have few microsatellites but contains a high proportion of a larger repeated sequence.
3. All six of the main British populations (Somerset, Lewes, Pevensey, Romney, North Kent and Norfolk) showed substantial genetic diversity at the microsatellite loci. However, estimates of effective population size at one site (Pevensey) were remarkably low, at <10 adults for the period 2004–05.
4. Most of the genetic diversity was partitioned within rather than among the populations, although there was, nevertheless, significant genetic sub-structuring. Almost all population pairwise F _st estimates were significantly different from zero, and there was a clear isolation-by-distance effect. Assignment tests and cluster analyses demonstrated interpopulation relationships largely consistent with their geographical separations.
5. Hydrophilus disperses by flight, and records from moth traps indicated that there was no month in which the beetles never flew, but that flight activity was highest in the spring.
6. The genetic data highlight the need to maintain or regenerate habitat connectivity within flying distance for H. piceus , and to sustain large areas of suitable breeding marshes.     

Modelling geographic distribution and detecting conservation gaps in Italy for the threatened beetle Rosalia alpina

Presence-only models can aid conservation and management of threatened, elusive species. We developed a Maxent model for the rare cerambycid beetle Rosalia longicorn Rosalia alpina L. in Italy and neighbouring regions and identified the variables best explaining the species’ occurrence on a large scale. Once successfully validated, we used the model to (a) evaluate the current degree of fragmentation of R. alpina range in Italy; and (b) quantify the amount of the Italian territory with the highest probability of beetle presence within the existing national conservation areas (Natura 2000 network, parks and reserves). Low (<0.5) probability scores of R. alpina presence corresponded to 89% of the total area considered, whereas high scores (>0.9) covered only 2.5%. R. alpina was predicted to occur mostly in broadleaved deciduous forest at 1000–1700 m a.s.l. with warm maximum spring temperatures and May and November precipitation >80 mm. We found a high degree of fragmentation; gaps were mainly covered with farmland or other unsuitable habitat. Over 52% of potential habitat is unprotected. While the Natura 2000 network protects 42% of potential habitat, parks and reserve covers less than 29%. To preserve R. alpina, we urge to create, or restore, forest corridors to bridge the otherwise impermeable gaps our model detected and grant protection to the still largely unprotected area of the Italian territory e.g. by including it in further Natura 2000 sites. Models such as ours may also help focus field surveys in selected areas to save resources and increase survey success.     

An aquatic ecotone and its significance in conservation

Aquatic invertebrates were sampled throughout an area of transition between a well-established reservoir and a perennial stream in the KwaZulu-Natal Midlands of South Africa. The visibly obvious separation of stream and reservoir was not reflected by the invertebrates. Communities overlapped in species, ranging from fast-flowing stream and moderate-flowing stream, through a transitional ecotone, which ran along the exposed reservoir edge and stream edges, to sheltered edges of reservoir and stream then to open reservoir. These features reflected the degree of water movement (whether from waves or riffles) and type of substratum, rather than visibly lotic or lentic conditions. The main aquatic ecotone between the open reservoir and the main stream was therefore not at the mouth of the stream but along the edges of both systems. The centre of the reservoir and centre of the stream, although physically connected, were quite different in their invertebrates and were separate patches with a sharp boundary. They were faunistically connected through the communities of the edge ecotone. The ecotone acted like a semi- permeable membrane to the drifting stream fauna with movement back again apparently mostly in the air, suggesting a patchy metapopulation model. Both the river continuum and boundary concepts were applicable to this multi-system. The ecotone did not show any edge effect and accords more with the variegation than fragmentation model. The great difference in patterns of pelagic, littoral and terrestrial communities has important implications for zoning of water bodies for different conservation and recreation activities.     

Extinction filters and current resilience: the significance of past selection pressures for conservation biology

There is now little reasonable doubt about the scale of the present extinction crisis: recent and ongoing rates of species loss exceed background levels by two to three orders of magnitude. Nevertheless, species differ widely in their vulnerability to current threats. Growing evidence from both palaeontology and conservation biology suggests that past events may help to explain this variation. Communities appear far more resilient to particular threats if they have faced similar challenges in the past. This intuitive but poorly reported phenomenon has potentially far-reaching implications for attempts to focus conservation efforts on those areas most at risk from contemporary human activity.     

The contribution of cacao agroforests to the conservation of lower canopy ant and beetle diversity in Indonesia

The ongoing destruction of tropical rainforests has increased the interest in the potential value of tropical agroforests for the conservation of biodiversity. Traditional, shaded agroforests may support high levels of biodiversity, for some groups even approaching that of undisturbed tropical forests. However, it is unclear to what extent forest fauna is represented in this diversity and how management affects forest fauna in agroforests. We studied lower canopy ant and beetle fauna in cacao agroforests and forests in Central Sulawesi, Indonesia, a region dominated by cacao agroforestry. We compared ant and beetle species richness and composition in forests and cacao agroforests and studied the impact of two aspects of management intensification (the decrease in shade tree diversity and in shade canopy cover) on ant and beetle diversity. The agroforests had three types of shade that represented a decrease in tree diversity (high, intermediate and low diversity). Species richness of ants and beetles in the canopies of the cacao trees was similar to that found in lower canopy forest trees. However, the composition of ant and beetle communities differed greatly between the agroforest and forest sites. Forest beetles suffered profoundly from the conversion to agroforests: only 12.5% of the beetle species recorded in the forest sites were also found in the agroforests and those species made up only 5% of all beetles collected from cacao. In contrast, forest ants were well represented in agroforests, with 75% of all species encountered in the forest sites also occurring on cacao. The reduction of shade tree diversity had no negative effect on ants and beetles on cacao trees. Beetle abundances and non-forest ant species richness even increased with decreasing shade tree diversity. Thinning of the shade canopy was related to a decrease in richness of forest ant species on cacao trees but not of beetles. The contrasting responses of ants and beetles to shade tree management emphasize that conservation plans that focus on one taxonomic group may not work for others. Overall ant and beetle diversity can remain high in shaded agroforests but the conservation of forest ants and beetles in particular depends primarily on the protection of natural forests, which for forest ants can be complemented by the conservation of adjacent shaded cacao agroforests.     

Mating refusal and its significance in females of the ladybird beetle, Harmonia axyridis

ABSTRACT. . Mating receptivity in females of the ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was studied with reference to internal and environmental conditions. Females sometimes reject copulation: they run away, or shake off the male and bend the abdomen upwards. Newly emerged females show a greater likelihood of accepting copulation with an advance in the stage of ovarian development, this being related to age. Females usually mate repeatedly, but frequently show refusal behaviour under unfavourable food conditions. Dissections reveal that females which accept copulation have a greater number of mature eggs in the ovary than do rejectors. Results also suggest that the food conditions are a major environmental factor, directly controlling mating receptivity.     

Status and conservation of an imperiled tiger beetle fauna in New York State,USA

New York has 22 documented species of tiger beetles (Coleoptera: Cicindelidae). Over half of these species are considered rare, at risk, or potentially extirpated from the state. These rare species specialize on three sandy habitat types under threat from human disturbance: beaches, pine barrens, and riparian cobble bars. In 2005, we began a status assessment of eight of New York’s rarest tiger beetles, examining museum records, searching the literature, and conducting over 130 field surveys of historical and new locations. Significant findings included (1) no detections of four of the eight taxa; (2) no vehicle-free beach habitat suitable for reintroducing Cicindela dorsalis dorsalis; (3) C. hirticollis at only 4 of 26 historical locations; (4) C. patruela patruela at only one site statewide; and (5) C. ancocisconensis at only 3 of 28 de novo survey sites. Additional species that might be declining deserve our attention, as do some threats to tiger beetle habitats, like lack of beach wilderness, fire suppression in pine barrens, and river damming. Rarity in tiger beetles is a result of varying ecologies, which suggest different conservation strategies. Future inventory and documentation of tiger beetle occurrences need to take into account the metapopulation structure and imperfect detectability of these rare insects.     

Analysis of the functional significance of linkage group conservation in Drosophila

Linkage groups, as defined by chromosome arms in Drosophila melanogaster, appear to have remained largely intact within the genus Drosophila and, possibly, within the higher Diptera per se. We hypothesized that linkage group conservation might have a functional basis (possibly related to interphase chromosome arrangement). To test this hypothesis, a series of autosomal 2–3 translocations were synthesized, creating many new linkage groups. A total of 167 2–3 translocations were recovered, cytologically analyzed to determine their polytene chromosome breakpoints, and tested for homozygous viability and fertility. The breakpoints associated with homozygous viable translocations were randomly distributed throughout the genome, indicating that the linear continuity of the linkage groups could be disrupted quite extensively. Inter se complementation crosses between homozygous lethal translocations having similar breakpoints further confirmed this result, documenting that, at least with respect to homozygous viability, the linear integrity of the autosomal linkage groups was not of major functional significance. Fertility analysis of the homozygous translocations also indicated that sterility could not be a single major factor. Having concluded that linkage group conservation is not based on important functional interactions between specific linked chromosomal segments, or due principally to the sterility of new linkages, the problem of linkage group conservation remains unsolved. Several possible selective factors are discussed, principally segregational load and inbreeding depression, which may contribute to the elimination of new linkage rearrangements.     

The maintenance of extensively exploited pastures within the Alpine mountain belt: implications for dung beetle conservation (Coleoptera: Scarabaeoidea)

The abandonment of marginal areas and the decline of traditional small-scale cattle-breeding is bringing about substantial changes in many areas of the Alpine mountain belt. Extensively exploited pastures, which were colonized by typical ecological communities, are now being replaced by shrublands and forests. In this paper, we evaluate the effectiveness of the maintenance of small pastures for dung beetle (Scarabaeoidea: Geotrupidae, Aphodiidae, Scarabaeidae) conservation in a protected area of the north-western Italian Alps. From July until September 2007, we studied the dung beetle coenosis in the main habitats of the mountain belt: beech forest, scots pine forest, mountain pine forest and pasture. Twenty-three species were sampled. We compared abundance, species richness, α-diversity, evenness and species turnover between the four habitat assemblages and performed a correspondence analysis based on dominance patterns of the three families. Two main ensembles were identified: a pasture ensemble, highly diverse and dominated by Scarabaeidae, and a closed habitats ensemble, less structured and dominated by Aphodiidae and Geotrupidae. Combining habitat specificity and fidelity, the IndVal method showed that half of the species collected made a strong habitat selection toward pasture, while only C. granarius (Aphodiidae) was a reliable indicator of woody areas. We therefore conclude that the loss of extensively exploited pastures may bring about fundamental changes in dung insect communities. In protected areas, a management policy intended to preserve the traditional, sustainable human activities within the mountain belt is highly recommended for the conservation of these insects.     

Xylophagous entomofauna in branches of oaks (Quercus spp.) and its significance for oak health in the Karst region of Slovenia

Samples of dying branches from 121 trees of Quercus pubescens, Q. cerris, and Q. petraea were taken from 102 sites in Seslerio autumnalis-Quercetum petraeae and Ostryo-Quercetum pubescentis forests. After nine months’ rearing in eclectors, branches were cut to 20-cm sections, and signs of infestation as well as larvae and adult insects were noted. We analysed 395 sections of branches from Q. pubescens, 125 sections from Q. cerris, and 85 sections from Q. petraea. We found 44 adult insects: 45% were from the Cerambycidae family (Callimus angulatus ssp. angulatus, Poecilium alni, and Exocentrus adspersus), 18% were from the Scolytinae subfamily (Scolytus intricatus, Xyleborus dispar), 4% from the Buprestidae family (Coraebus florentinus), 4.5% from the Cleridae family (Tilloidea unifasciata), and 28.5% from other families. In addition, 145 larvae were found: 50% from the Cerambycidae family, 39% from the Buprestidae family, 4% from the Scolytinae subfamily, and 7% from other families. Significant difference in the abundance of adult insects and larvae with regard to the diameter of branch sections and the host species were found. 78% of dying branches showed signs of infestation. Species of the Buprestidae, Scolytinae, and Cerambycidae represent important factors in the decline in oak vitality in the lower Karst region of Slovenia.