Coastal heathland succession influences butterfly community composition and threatens endangered butterfly species

Succession has a strong influence on species diversity and composition of semi-natural open terrestrial ecosystems. While several studies examined the effects of succession on butterflies in grassland and forest ecosystems, the response of heathland butterflies to succession had not been investigated so far. To address this issue we sampled butterfly abundance and environmental parameters on the Baltic island of Hiddensee (NE Germany) along a gradient of coastal heathland succession from grey dunes to birch forest. Our results provide evidence that succession of coastal heathland has a strong influence on butterfly diversity, abundance, and species composition. Thereby grass and tree encroachment present the main threats for heathland butterflies. Diversity and abundance of butterflies were highest in shrub-encroached heath directly followed by early stages of coastal heathland succession (dwarf-shrub heath, grey dune). Both observed threatened species (Hipparchia semele, Plebeius argus) were negatively affected by succession: abundance decreased with increasing vegetation density (both species) and grass cover (P. argus); consequently, the two later successional stages (shrub, birch forest) were not occupied. Our findings highlight the importance of the preservation of early stages of coastal heathland succession for endangered butterfly species. For coastal heathland management we therefore suggest to maintain early successional stages by sheep grazing, mowing or, in case of high nutrient contents, intensive techniques such as sod-cutting or choppering. To a lower extend shrub-encroached sites should also be present, which might be beneficial for overall species richness.     

Metapopulation structure and dynamics of an endangered butterfly

Recovery plans for endangered invertebrates will improve with a better understanding of population dynamics and structure. Some spatially distributed structures beyond the classic metapopulation, including highly integrated patchy populations and core-satellite, maybe better suited for the recovery of endangered populations. In this study we examined the population dynamics of the Karner blue butterfly, Lycaeides melissa samuelis (Nabokov) [Lepidoptera: Lycaenidae], which is federally endangered in the USA, at eleven sites at Fort McCoy, Wisconsin. Adult L. m. samuelis butterflies were surveyed approximately weekly at each site using a straight line transect method. We used autocorrelation and partial autocorrelation function to look for patterns in the population dynamic, and tested for density-dependent growth and weather factors as potential explanatory factors of the yearly variation. We found non-declining or stable Karner blue populations at all eleven sites at Fort McCoy, a long-term trend and an alternating generational cycle. The trend occurred at seven of the eleven sites and was synchronous, suggesting that Karner blue butterflies were not functioning as a classic metapopulation and maybe functioning as a patchy metapopulation. We also found density-dependent growth and a positive relationship between early summer precipitation and population growth from the spring to summer generation. We suggest that aiming to recover patchy metapopulations will reduce monitoring costs, simplify reserve design, and create more robust populations, which are more likely to persist into the future.     

Unprecedented long-term genetic monomorphism in an endangered relict butterfly species

Multi-locus monomorphism in microsatellites is practically non-existent, with one notable exception, the island fox (Urocyon littoralis dickeyi) population on San Nicolas island off the coast of southern California, having been called “the most monomorphic sexually reproducing animal population yet reported”. Here, we present the unprecedented long-term monomorphism in relict populations of the highly endangered Parnassius apollo butterfly, which is protected by CITES and classified as “threatened” by the IUCN. The species is disjunctly distributed throughout the western Palaearctic and has occurred in several small remnant populations outside its main distribution area. We screened 78 individuals from 1 such relict area (Mosel valley, Germany) at 16 allozyme and 6 microsatellite loci with the latter known to be polymorphic in this species elsewhere. From the same area, we also genotyped 55 museum specimens sampled from 1895 to 1989 to compare historical and present levels of genetic diversity. However, none of all these temporal populations yielded any polymorphism. Thus, present and historical butterflies were completely monomorphic for the same fixed allele. This is the second study to report multi-locus monomorphism for microsatellites in an animal population and the first one to prove this monomorphism not to be the consequence of recent factors. Possible explanations for our results are a very low long-term effective population size and/or a strong historic bottleneck or founder event. Since the studied population has just recovered from a recent population breakdown (second half of twentieth century) and no signs of inbreeding depression have been detected, natural selection might have purged the population of weakly deleterious alleles, thus rendering it less susceptible to the usual negative corollaries of high levels of homozygosity and low effective population size.     

Genetic consequences of an introduction-colonization process in an endangered butterfly species

From a theoretical point of view, the genetic consequences of foundation events are relatively well known but few field experimental data are available on this subject. At the beginning of the 1970s, a small number of Proclossiana eunomia females were released in a region where this glacial relict was absent. We report here the genetic aspects of the evolution of the populations generated by these translocations. Both enzyme electrophoresis and wing pattern morphometry disclosed a significant differentiation of the populations both with their mother population and within themselves. Field observations and enzyme data suggest a stepping-stone colonization process, but there is no significant isolation by distance at this stage of population establishment, as predicted by 32 model. Concerning phenotypic characters, there is a significant correlation between morphometric and geographical distances; this may be due to isolation by distance but the action of environmental gradients cannot be excluded. Our results show that this colonization, although induced with a low number of founders, was a success, despite a predicted loss of polymorphism.     

Habitat use of the endangered butterfly Euphydryas maturna and forestry in Central Europe

The knowledge of ecological requirements of declining butterflies of European woodlands remains limited, which hinders conservation management of their localities. This also applies for continentally threatened scarce fritillary Euphydryas maturna . On the basis of the largest data set on its habitat use ever collected in Central Europe, we analyse habitat requirements of its populations in Austria (A), the Czech Republic (Cz) and Germany (D). All studied populations inhabit open-canopy sites within woodlands, but larval survival decreases under full sun and preferred sites are relatively humid and sheltered. Nests of pre-hibernation larvae occur at terminal branches of Fraxinus excelsior , 1.5–3 m above the ground. Pre-hibernation mortality reaches 70% (Cz, D). Another limiting factor is quality of woodland vegetation: post-hibernation larvae consume a wide range of herbs and shrubs, and adult distribution is linked to nectar availability. The butterfly thus depends on highly heterogeneous early successional stages of deciduous woods, historically maintained by coppicing (Cz, D) and forest pasture (A). Restoration of these traditional methods offers the only chance for survival of E. maturna in Central Europe, and the butterfly may become a flagship for other threatened organisms of open-canopy woodlands.     

Patterns of genetic variation in isolated Danish populations of the endangered butterfly Euphydryas aurinia

In the present study, we report an investigation on molecular variation in the endangered univoltine butterfly Euphydryas aurinia (Rottemburg, 1775), a species heavily affected by habitat degradation and fragmentation in Denmark. Levels of genetic variation in extant populations were estimated using six variable number tandem repeat loci and were found to be low compared to other butterfly species with low migration rates. An analysis of genetic structure, based on both allele frequencies and genotype distributions, divided the entire sample into four distinct clusters. This was partially concordant with the a priori subdivision based on collection areas. An overall F_ST value of 0.16 (pairwise values ranging from 0.087–0.276) indicated restrictions of gene flow. Especially two populations had higher F_ST values than the others, suggesting their isolation, and showed signs of bottlenecks/founder events. One population deviated significantly from Hardy–Weinberg equilibrium, suggesting a possible Wahlund effect or the presence of null alleles. The results suggest habitat fragmentation, resulting in genetic drift and possibly inbreeding. Future management is therefore recommended to increase gene flow between the remaining populations while habitats are restored in order to increase carrying capacity. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 677–687.     

Nectar and hostplant scarcity limit populations of an endangered Oregon butterfly

As grassland habitats become degraded, declines in juvenile and adult food resources may limit populations of rare insects. Fender's blue butterfly (Icaricia icarioides fenderi), a species proposed for listing as endangered under the US Endangered Species Act, survives in remnants of upland prairie in western Oregon. We investigated the effects of limited larval hostplants and adult nectar sources on butterfly population size at four sites that encompass a range of resource densities. We used coarse and detailed estimates of resource abundance to test hypotheses relating resource quantity to population size. Coarse estimates of resources (percent cover of hostplant and density of nectar flowers) suggest that butterfly population size is not associated with resource availability. However, more detailed estimates of resources (density of hostplant leaves and quantity of nectar from native nectar sources) suggest that butterfly population size is strongly associated with resource availability. The results of this study suggest that restoring degraded habitat by augmenting adult and larval resources will play an important role in managing populations of this rare butterfly. Received: 20 June 1998 / Accepted: 25 November 1998     

濒危物种金斑喙凤蝶的行为特征及其对生境的适应性

金斑喙凤蝶(Teinopalpus aureus)1985年被IUCN列为红色名录种,1989年被我国列为一级保护种,此后便日益受到人们关注,然而,至今为止对其野外生存、行为及生境适应等认识仍很模糊。在广西金秀县大瑶山设定4个研究区域,以线路调查法计数成虫与幼期个体数,定点跟踪观察法记录成虫交配行为、产卵行为、幼虫取食行为等。结果显示:金斑喙凤蝶主要在湿季(4—10月底,月降水量>50 mm)生长、发育与繁殖后代。金斑喙凤蝶在行为上表现出对温度的主动选择性,幼虫在17—24℃时取食行为活跃,雄蝶在19—26℃时山顶行为活跃,均表现出中温选择性;然而,雌蝶多选择在正午时刻产卵,期间温度为27—30℃,表现出高温选择性。雄蝶活动对生境地形表现出主动选择性,(87.34±7.58)%(n=339)的雄蝶选择飞向山顶,他们每日上午6:00至11:00在山顶聚集,绕圈飞行或停息,而以山顶停息为主,占山顶活动时间的(77.87±19.32)%。雄蝶通常停息在山顶的高枝位叶片上或山顶周缘的叶片上,以便迅速发现并拦截飞经的雌蝶,获得交配机会。因而,金斑喙凤蝶在交配策略上主要采取雄蝶等候的方式。停息期间,雄蝶表现出明显的占区行为,首先停息在某一区域的雄蝶在领域权竞争中通常都是最后的胜利者,赢得领域,获得更多交配机会。野外观察发现,金斑喙凤蝶的天敌种类较多,野外存活率偏低,最后羽化率仅为38.9%(n=20)。对于存活个体而言,他们已明显进化形成一套复杂的防御体系,主要包括由保护色、颜色拟态、形状拟态等组建的初级防御体系和由眼斑展示、身体晃动、Y-腺伸出等组建的次级防御体系。另外,老熟幼虫多选择在林下层的灌木丛或竹丛的隐蔽枝条上化蛹,化蛹高度为(1.82±1.58)m(n=20),这种对化蛹场所的主动选择行为可提高其蛹期的防御能力。研究结果说明,在自然选择作用下,金斑喙凤蝶对其阔叶林生境的适应性行为特征非常明显,然而,生境破坏(砍伐等)或人类强度干扰(林下层垦殖等)将使这些适应性行为失效,并威胁到该珍稀蝴蝶种群的繁衍生息,甚至导致局部灭绝的发生。     

Using surrogate data in population viability analysis: the case of the critically endangered cranberry fritillary butterfly

Population viability analyses (PVA) are central tools for the management of threatened populations. However, the parameterisation of effective PVA models is very demanding in high quality data, which are often impossible to collect on endangered populations. Here we propose the use of a generalisation strategy to bypass this limitation: management measures for an endangered metapopulation of the cranberry fritillary butterfly in the Netherlands are evaluated with RAMAS/GIS by using parameters estimated from a healthier metapopulation in Belgium. The Belgian metapopulation seems viable, with stable abundance and number of local populations, despite their erratic dynamics, whereas the Dutch metapopulation shows a continuous decline in the course of time, with many vacant habitat patches. Simulations of various scenarios indicated that (1) large scale restoration of habitat patches would be necessary to ensure long-term survival of the species in the Netherlands as not enough suitable habitats are currently remaining; and that (2) global warming is expected to put a major threat on both metapopulations by reducing the growth rate of this glacial relict species, and/or increasing environmental stochasticity (amplified climatic variations).     

Exploring the implications of recreational disturbance on an endangered butterfly using a novel modelling approach

Site and wildlife managers globally are under increasing pressure to implement management strategies that address the negative implications of outdoor recreational activities on wildlife. For many rare and isolated species any anthropogenic activities that cause disturbance could potentially be detrimental to existing populations. Understanding how non-consumptive recreation can influence a species may therefore be critical to its preservation. We developed a novel approach to specifically address this need. Using a combination of field surveys and simulation modelling exercises, we (1) explored the responses of endangered Karner blue butterflies (Lycaeides melissa samuelis) to recreation, (2) assessed whether such responses influenced oviposition rate and/or host plant choice and (3) tested alternative management strategies that could alleviate the negative impacts of recreation. Our field surveys confirmed that Karner blues were sensitive to recreational disturbance. Butterflies flushed at similar speeds and distances from recreationists (2.2 m at 0.17 m/s), as they would from natural threats, such as predators (2.2 m at 0.19 m/s). Incorporating female response parameters into a simulation model revealed that regular disturbance could reduce egg laying potential and significantly restrict host plant choice, which in turn, could impact the butterfly’s population dynamics. However, we established that it was possible to effectively offset the implications of recreational disturbance using our simulation modelling approach. For example, extending Karner blue breeding habitat from trails and other public rights of way has the potential to alleviate such disturbance. Our study demonstrates that the potential impact of recreation on species of conservation concern should not be overlooked.     

广西大瑶山濒危物种金斑喙凤蝶(广西亚种)的形态学、生物学特征

金斑喙凤蝶Teinoplpus aureus Mell分布于亚洲东南部沿海地区,已报道有5个地理亚种。在世界保护协会(IUCN)2004年濒危物种红色名录中金斑喙凤蝶被列为DD(Data deficient)物种,在我国动物保护名录(1989)中在我国动物保护名录(1989)中被列为一级保护物种被列为一级保护物种。自从1923年以来,由于数据欠缺,尤其是生物学方面的数据,使得金斑喙凤蝶的研究工作一直难以深入开展,保护工作更是难以做到实处。作者于2003年3月至2005年11月在广西大瑶山开展了对金斑喙凤蝶(广西亚种)的自然形态学、生物学研究,通过野外实地观察、跟踪与记录等方法,结果首次揭示:在大瑶山金斑喙凤蝶1年发生2代,少数1年1代,以蛹越冬。成虫活动时间为每年的4月上旬至6月上旬和8月上旬至9月中旬,雌虫产卵方式为散产,通常为"一枝一叶一卵"式。已确认其寄主植物有两种:光叶拟单性木兰(Parakmeria nitida)与广东含笑(Michelia chapensis)。幼虫共5龄,老熟幼虫离开寄主植物,在林下层各类植物上化蛹。文章首次对金斑喙凤蝶物种在自然栖境中的形态学、生物学特征进行详尽描述。     

A strong decline of the endangered Apollo butterfly over 20 years in the archipelago of southern Finland

Journal of Insect Conservation - Insect groups are declining worldwide; Lepidoptera are among the taxa most affected in terrestrial ecosystems. The main drivers of these declines are a diverse set...