Behavioural Adaptation of a Bird from Transient Wetland Specialist to an Urban Resident

Dramatic population increases of the native white ibis in urban areas have resulted in their classification as a nuisance species. In response to community and industry complaints, land managers have attempted to deter the growing population by destroying ibis nests and eggs over the last twenty years. However, our understanding of ibis ecology is poor and a question of particular importance for management is whether ibis show sufficient site fidelity to justify site-level management of nuisance populations. Ibis in non-urban areas have been observed to be highly transient and capable of moving hundreds of kilometres. In urban areas the population has been observed to vary seasonally, but at some sites ibis are always observed and are thought to be behaving as residents. To measure the level of site fidelity, we colour banded 93 adult ibis at an urban park and conducted 3-day surveys each fortnight over one year, then each quarter over four years. From the quarterly data, the first year resighting rate was 89% for females (n = 59) and 76% for males (n = 34); this decreased to 41% of females and 21% of males in the fourth year. Ibis are known to be highly mobile, and 70% of females and 77% of males were observed at additional sites within the surrounding region (up to 50 km distant). Our results indicate that a large proportion of ibis have chosen residency over transience both within the study site and across the broader urban region. Consequently the establishment of refuge breeding habitat should be a priority localised management may be effective at particular sites, but it is likely to have an impact across the broader population.     

用组合模型综合比较的方法分析气候变化对朱鹮潜在生境的影响

气候变化的不确定性和物种与环境关系的不确定性使气候变化生物学的研究充满变数。为了降低不确定性,人们开始用组合模型综合比较的方法研究物种对气候变化的响应。以朱鹮(Nipponia nippon)为研究对象,介绍组合模型综合比较方法的特点。朱鹮曾经高度濒危,目前种群大小在迅速恢复中;然而其分布区依旧狭小,气候变化可能是朱鹮面临的新威胁。应用BIOMOD模型中的9种模型,选择了每年的最低温和最高温、温度的季节性变异、每年的总降水量和降水的季节性变异共5个气候因子,依据WorldClim气候数据的CGCM2气候模型的A2a排放情形,计算了朱鹮当前(1950—2000年)的适宜生境和2020年、2050年、2080年3个阶段的潜在生境范围。结果表明朱鹮潜在生境将逐渐北移,生境中心脱离现在的保护区。因此,制定朱鹮的长期保护策略是必要的。9个模型在预测结果上、变量权重上和拟合优度的指标上都有差异,反映了模型本身的不确定性。气候变化的生物学效应比较复杂,应用多个模型进行综合比较,可以尽可能地减少模型所导致的误差。     

Genomic signatures of near-extinction and rebirth of the crested ibis and other endangered bird species

Background

Nearly one-quarter of all avian species is either threatened or nearly threatened. Of these, 73 species are currently being rescued from going extinct in wildlife sanctuaries. One of the previously most critically-endangered is the crested ibis, Nipponia nippon. Once widespread across North-East Asia, by 1981 only seven individuals from two breeding pairs remained in the wild. The recovering crested ibis populations thus provide an excellent example for conservation genomics since every individual bird has been recruited for genomic and demographic studies.

Results

Using high-quality genome sequences of multiple crested ibis individuals, its thriving co-habitant, the little egret, Egretta garzetta, and the recently sequenced genomes of 41 other avian species that are under various degrees of survival threats, including the bald eagle, we carry out comparative analyses for genomic signatures of near extinction events in association with environmental and behavioral attributes of species. We confirm that both loss of genetic diversity and enrichment of deleterious mutations of protein-coding genes contribute to the major genetic defects of the endangered species. We further identify that genetic inbreeding and loss-of-function genes in the crested ibis may all constitute genetic susceptibility to other factors including long-term climate change, over-hunting, and agrochemical overuse. We also establish a genome-wide DNA identification platform for molecular breeding and conservation practices, to facilitate sustainable recovery of endangered species.

Conclusions

These findings demonstrate common genomic signatures of population decline across avian species and pave a way for further effort in saving endangered species and enhancing conservation genomic efforts.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-014-0557-1) contains supplementary material, which is available to authorized users.     

COMPARATIVE ETHOLOGY OF THE CICONIIDAE. THE WOOD-STORKS (GENERA MYCTERIA AND IBIS)*

This paper reports on an 11-year study of the comparative behaviour of the four species of wood-storks. All species were studied under natural conditions at breeding colonies in the U.S.A., East Africa, India, and Indonesia. In addition, observations were made on hand-reared young of two species (Mycteria americana and Ibis ibis). Various aspects of signal (display) and non-signal behaviour are described. The most common ritualised display away from the nest is the Forward Threat. At the neBt, the following displays are seen, mainly during courtship and pair-formation: Aerial Clattering Threat, Forward Clattering Threat, Snap Display, Anxiety Stretch, Flying Around, Gaping, Balancing Posture, Swaying Twig-Grasping, Display Preening, Up-Down, and Copulation Clattering. Each of these patterns is described in the text and many of them are illustrated. The four species treated here are similar to each other in most behaviour patterns. They do show some quantitative differences in courtship displays, particularly in the Up-Down, a common “greeting” display shown to the mate at the nest. The behavioural and morphological evidence now available does not justify the separation of M. americana into a monotypic genus, and I suggest that all four wood-storks be combined in the genus Mycteria. Thus, the wood-storks include: M. americana, M. cinerea, M. ibis, and M. leucocephala.     

Public attitudes and willingness to pay toward the conservation of Crested Ibis: Insights for management

In order to better design conservation programs to conserve threatened species, social, economic and political factors must be carefully considered. The wild population of the endangered Crested Ibis (Nipponia nippon) is currently only distributed in Yangxian County, Shaanxi province of China, and as the gradual dispersal of its population from the mountains to the plains, the possibility of human-wildlife interaction has increased, which poses certain challenges for conservation and management. Here, we used a questionnaire to investigate public attitudes and willingness to pay (WTP) toward Crested Ibis conservation, and to evaluate relevant influencing factors, with a view to providing recommendations for its management. The results showed that local residents strongly support the conservation of ibis and factors like education level, income, residential area, perception for ibis and prior experiences significantly affected their support for conservation. Results also indicated that the annual WTP was US$18.28 per household, and the potential value of donations is about US$2.45 million per year for Crested Ibis conservation. Regression analysis indicated that income, perception for ibis, prior experience, support for conservation and environmental attitudes had a significant effect on WTP. The comparison between the original research value of the ibis and the predicted value from the Meta-regression analysis function indicated that the benefit transfer values are able to inform policy decisions. Our results can be applied not only to the design of tailored outreach programs and management policies for the Crested Ibis, but also to facilitate conservation and management of other endangered species by encouraging decision makers to use benefit transfer models for the rapid valuation in the absence of species economic information.     

Quarnet Inference Rules for Level-1 Networks

An important problem in phylogenetics is the construction of phylogenetic trees. One way to approach this problem, known as the supertree method, involves inferring a phylogenetic tree with leaves consisting of a set X of species from a collection of trees, each having leaf-set some subset of X. In the 1980s, Colonius and Schulze gave certain inference rules for deciding when a collection of 4-leaved trees, one for each 4-element subset of X, can be simultaneously displayed by a single supertree with leaf-set X. Recently, it has become of interest to extend this and related results to phylogenetic networks. These are a generalization of phylogenetic trees which can be used to represent reticulate evolution (where species can come together to form a new species). It has recently been shown that a certain type of phylogenetic network, called a (unrooted) level-1 network, can essentially be constructed from 4-leaved trees. However, the problem of providing appropriate inference rules for such networks remains unresolved. Here, we show that by considering 4-leaved networks, called quarnets, as opposed to 4-leaved trees, it is possible to provide such rules. In particular, we show that these rules can be used to characterize when a collection of quarnets, one for each 4-element subset of X, can all be simultaneously displayed by a level-1 network with leaf-set X. The rules are an intriguing mixture of tree inference rules, and an inference rule for building up a cyclic ordering of X from orderings on subsets of X of size 4. This opens up several new directions of research for inferring phylogenetic networks from smaller ones, which could yield new algorithms for solving the supernetwork problem in phylogenetics.     

Microhabitats choice in intertidal gastropods is species-, temperature- and habitat-specific

Understanding how behavioural adaptations can limit thermal stress for intertidal gastropods will be crucial for climate models. Some behavioural adaptations are already known to limit desiccation and thermal stresses as shell-lifting, shell-standing, towering, aggregation of conspecifics or habitat selection. Here we used the IRT (i.e. infrared thermography) to investigate the thermal heterogeneity of a rocky platform, with four different macrohabitats (i.e. bare rock, rock with barnacles, mussels and mussels incrusted by barnacles) over four thermally contrasted months. We investigated the body temperature of Littorina littorea and Patella vulgata found on this platform and the temperature of their microhabitat (i.e. the substratum within one body length around of each individual). We also considered the aggregation behaviour of each species and assessed the percentage of thermal microhabitat choice (i.e choice for a microhabitat with a temperature different than the surrounding substrate). We did not find any aggregation of L. littorea on the rocky platform during the four studied months. In contrast, P. vulgata were found in aggregates in all the studied periods and within each habitat, but there was no difference in body temperature between aggregated and solitary individuals. These two gastropods species were preferentially found on rock covered by barnacles in the four studied months. The presence of a thermal microhabitat choice in L. littorea and P. vulgata is habitat-dependent and also season-dependent. In June, July and November the choice was for a microhabitat with temperatures lower than the temperatures of the surrounding substrate whereas in December, individuals choose microhabitats with higher temperatures than the temperatures of their substratum. Taken together, these results suggest that gastropods species are able to explore their environment to find sustainable thermal macrohabitats and microhabitats and adapt this behaviour in function of the conditions of temperatures.     

Differential physiological responses to prey availability by the great egret and white Ibis

In long-lived species, the balance between the benefits of reproduction and the costs from reduced survival or productivity is particularly challenging in dynamic environments like wetlands, where food levels vary greatly year to year. Some wetland species exhibit changes in reproductive strategies in response to food availability but whether physiological responses function in a similar manner is unclear. We compared the pre-breeding physiological responses (fecal corticosterone [FCORT], heat shock protein 60 [HSP60], and mass) of 2 species of wading birds with contrasting foraging strategies (great egret [Ardea alba], an exploiter, and white ibis [Eudocimus albus], a searcher) during years with contrasting levels of prey availability. Both species were in good physiological condition, with low levels of HSP60 and FCORT, during a year with high prey availability (2006). In a contrasting year with lesser prey availability (2007), HSP60 and FCORT concentrations indicated that ibis physiological condition was reduced, whereas egrets showed little change. Egrets and male ibis increased body mass, whereas female ibis decreased mass, in the year with low prey availability. Although poorly understood, we hypothesize that the differential response between female ibis and the others is associated with differential investment strategies based on long-term costs of reproduction. Model results identified prey availability and the 2-week water recession rate as the primary habitat variables that were associated with the physiological condition of white ibises, whereas great egret physiological condition was influenced mostly by 2-week water recession rate. Our results support the hypothesis that prey availability and hydrological factors play crucial roles in regulating populations of wading birds in the Florida Everglades. The results of this study show a more complete pathway by which hydrologic patterns affect wading birds, and it suggests that ibis are more sensitive to habitat conditions than are egrets. This information can be used to refine species models designed to evaluate water management scenarios and will improve our ability to manage and restore wetland ecosystems © 2012 The Wildlife Society.     

Cryptic Speciation Patterns in Iranian Rock Lizards Uncovered by Integrative Taxonomy

While traditionally species recognition has been based solely on morphological differences either typological or quantitative, several newly developed methods can be used for a more objective and integrative approach on species delimitation. This may be especially relevant when dealing with cryptic species or species complexes, where high overall resemblance between species is coupled with comparatively high morphological variation within populations. Rock lizards, genus Darevskia, are such an example, as many of its members offer few diagnostic morphological features. Herein, we use a combination of genetic, morphological and ecological criteria to delimit cryptic species within two species complexes, D. chlorogaster and D. defilippii, both distributed in northern Iran. Our analyses are based on molecular information from two nuclear and two mitochondrial genes, morphological data (15 morphometric, 16 meristic and four categorical characters) and eleven newly calculated spatial environmental predictors. The phylogeny inferred for Darevskia confirmed monophyly of each species complex, with each of them comprising several highly divergent clades, especially when compared to other congeners. We identified seven candidate species within each complex, of which three and four species were supported by Bayesian species delimitation within D. chlorogaster and D. defilippii, respectively. Trained with genetically determined clades, Ecological Niche Modeling provided additional support for these cryptic species. Especially those within the D. defilippii-complex exhibit well-differentiated niches. Due to overall morphological resemblance, in a first approach PCA with mixed variables only showed the separation between the two complexes. However, MANCOVA and subsequent Discriminant Analysis performed separately for both complexes allowed for distinction of the species when sample size was large enough, namely within the D. chlorogaster-complex. In conclusion, the results support four new species, which are described herein.     

Planning for optimal conservation of geographical genetic variability within species

Systematic Conservation Planning (SCP) involves a series of steps that should be accomplished to determine the most cost-effective way to invest in conservation action. Although SCP has been usually applied at the species level (or hierarchically higher), it is possible to use alleles from molecular analyses at the population level as basic units for analyses. Here we demonstrate how SCP procedures can be used to establish optimum strategies for in situ and ex situ conservation of a single species, using Dipteryx alata (a Fabaceae tree species widely distributed and endemics to Brazilian Cerrado) as a case study. Data for the analyses consisted in 52 alleles from eight microsatellite loci coded for a total of 644 individual trees sampled in 25 local populations throughout species’ geographic range. We found optimal solutions in which seven local populations are the smallest set of local populations of D. alata that should be conserved to represent the known genetic diversity. Combining these several solutions allowed estimating the relative importance of the local populations for conserving all known alleles, taking into account the current land-use patterns in the region. A germplasm collection for this species already exists, so we also used SCP approach to identify the smallest number of populations that should be further collected in the field to complement the existing collection, showing that only four local populations should be sampled for optimizing the species ex situ representation. The initial application of the SCP methods to genetic data showed here can be a useful starting point for methodological and conceptual improvements and may be a first important step towards a comprehensive and balanced quantitative definition of conservation goals, shedding light to new possibilities for in situ and ex situ designs within species.     

Can Soil Seed Banks Serve as Genetic Memory? A Study of Three Species with Contrasting Life History Strategies

We attempted to confirm that seed banks can be viewed as an important genetic reservoir by testing the hypothesis that standing (aboveground) plants represent a nonrandom sample of the seed bank. We sampled multilocus allozyme genotypes from three species with different life history strategies: Amaranthus retroflexus, Carduus acanthoides, Pastinaca sativa. In four populations of each species we analysed the extent to which allele and genotype frequencies vary in consecutive life history stages including the summer seed bank, which has been overlooked up to now. We compared the winter seed bank (i.e., seeds collected before the spring germination peak), seedlings, rosettes, the summer seed bank (i.e., seeds collected after the spring germination peak) and fruiting plants. We found that: (1) All three species partitioned most of their genetic diversity within life history stages and less among stages within populations and among populations. (2) All genetic diversity parameters, except for allele frequencies, were similar among all life history stages across all populations in different species. (3) There were differences in allele frequencies among life history stages at all localities in Amaranthus retroflexus and at three localities in both Carduus acanthoides and Pastinaca sativa. (4) Allele frequencies did not differ between the winter and summer seed bank in most Carduus acanthoides and Pastinaca sativa populations, but there was a marked difference in Amaranthus retroflexus. In conclusion, we have shown that the summer seed bank is not genetically depleted by spring germination and that a majority of genetic diversity remains in the soil through summer. We suggest that seed banks in the species investigated play an important role by maintaining genetic diversity sufficient for recovery rather than by accumulating new genetic diversity at each locality.     

Biphasic Retention of One-Trial Learning in a Clonal Fish (<Emphasis Type="Italic">Poecilia formosa</Emphasis>)

Most species used for behavioural studies are bisexual. Sexual dimorphism determines genotypic diversity and behavioural variation within a species. The relative contribution of a genome to a specific behaviour is for the most part indiscernible, but gene changes can alter behaviour in many different ways¹. Within a species, strain differences can contribute to behavioural differences and many less clearly systematic behaviours, such as the aptitude to learn or to recall, may be genetically determined². Genotypic diversity, on the other hand, obscures gene correlates of behaviour because each organism brings a unique repertoire of behaviours to the experimental situation. Against this, learning research has found basic phenomena of learning and memory to be valid across many vertebrate species. In an effort to reduce genotypic and behavioural variability in studying memory processing, we have used a unisexual clonal fish, Poecilia formosa, as suggested by Agranoff and Davis³.     

First steps to restructuring the problematic genus Lasiotocus Looss, 1907 (Digenea: Monorchiidae) with the proposal of four new genera

Lasiotocus Looss, 1907 is the largest genus within the Monorchiidae Odhner, 1911, with 52 species currently considered valid. Species belonging to this genus exhibit wide morphological variation and it is likely that many of them belong in other genera; however, testing the validity of the group has been hampered by a lack of molecular sequence data, especially for the type-species. Here, we report the first DNA sequences for Lasiotocus mulli (Stossich, 1883) Odhner, 1911, the type-species of the genus, and only the sixth Lasiotocus species to be sequenced. Sequences were generated for three ribosomal DNA markers, the ITS2, 18S and 28S regions, and for one mitochondrial DNA marker, the cox1 region. Phylogenetic analyses show that the six sequenced species form four clearly distinct clades, each of which we argue require separate genera. On the basis of these relationships and review of the morphology of all species in the genus, we propose a system of six genera. Four genera, Lasiotocus, the resurrected concept of Ancylocoelium Nicoll, 1912, Infundiburictus n. gen., and Sinistroporomonorchis n. gen., represent the four molecular clades. Two genera, Paralasiotocus n. gen. and Alloinfundiburictus n. gen., are proposed on the basis of morphology only. Ancylocoelium is resurrected for Ancylocoelium typicum Nicoll, 1912, Infundiburictus is erected for Lasiotocus arrhichostoma Searle, Cutmore & Cribb, 2014, Sinistroporomonorchis is erected for Lasiotocus glebulentus Overstreet, 1971and Lasiotocus lizae Liu, 2002, Paralasiotocus is erected for Lasiotocus okinawaensis Machida, 2011, and Alloinfundiburictus is erected for Lasiotocus cacuminatus Nicoll, 1915. Of the 52 species presently recognised in Lasiotocus, 43 are distributed among these genera; nine are considered species inquirendae or are transferred to other genera. We think it likely that more genera will be required for the species reviewed here but more sequence data are essential to further refine the classification.     

Communication via sex pheromones within and among Arrenurus spp. mites (Acari: Hydrachnida; Arrenuridae)

We present direct experimental evidence of pheromone use in six species of Arrenurus and indirect evidence for four species, including members of the subgenera Megaluracarus, Truncaturus, and Arrenurus. Water in which females were housed elicited arrestant behaviour in males, males oriented to the source, and at least some individuals in each species assumed the male readiness posture, a precursor to coupling. Most species responded to water treated with conspecific females, but there was also interspecific sex pheromone responsiveness. Arrenurus manubriator and A. megalurus demonstrated reciprocal pheromone cross-attractancy. Males of A. major, A. marshallae, and A. birgei responded to water from females of related species from within their subgenera. Arrenurus apetiolatus males failed to respond to conspecific female-treated water, but the same water elicited arrestant behaviour and orientation in A. manubriator. Heterospecific reactions to female-conditioned water were limited to cases involving members of the same species group and were not seen between species representing different species groups or different subgenera. The species for which cross-attractancy has been demonstrated commonly co-occur in nature, so apparently these pheromones are of limited value for species recognition. Shared reaction to sex pheromones provides additional evidence for inferring close phylogenetic relationship among species, and thus far, corresponds with morphological evidence based on adult males and larvae.     

Why the crested ibis declined in the middle twentieth century

The crested ibis (Nipponia nippon) had declined severely from a common species to only two pairs in last century. To analyze the declining process, we established a GIS database with historical occurrences of the crested ibis based on published literatures, and layers of environmental factors such as elevation, wetland, and human activities. We compared the environmental factors at the occurrence sites in different periods to quantify the changes of habitat use across time. To address the spatial deviation of the occurrences and check the effect of measuring scale on habitat use, we calculated the environmental factors in a serial measuring scales from 1 to 161 × 161 km². Our results indicated that the crested ibis traditionally lives in habitat with higher wetland density and higher human impact, then it gradually moved to areas with higher elevation and lower human impact in last century. In 1980–2000 the crested ibis stayed at a very high elevation, lower wetland density and lower human impact as possible consequences of human activities such as using fertilizer and pesticide, drying the over wintering rice paddies, and direct hunting. Our quantitative analysis of the habitat use matched well the previous published statements (which have no numerical evidences) on the declination of the crested ibis. We suggest to reestablish the habitat with traditional farming practice that the bird has adapted as a major solution for applications such as conservation planning and reintroduction.     

Tetanocera elata (Diptera: Sciomyzidae) Larvae Feed on Protected Slug Species Geomalacus maculosus (Gastropoda: Arionidae): First Record of Predation

The Family Sciomyzidae (Diptera) is one of the best studied groups of malacophagous insects containing some of the most important enemies of slugs. Larvae of the fly Tetanocera elata are known obligate feeders on slugs both as parasitoids and predators. We tested whether predatory larvae of T. elata can feed on the protected slug species Geomalacus maculosus, for which there appear to be no published records of natural enemies. Using an infra-red video camera, we recorded the behaviour of third instar T. elata in the presence of: 1) a single specimen of G. maculosus and 2) one specimen each of G. maculosus and Deroceras reticulatum, a known slug prey of T. elata. We describe the behaviour of the larvae where they killed and consumed G. maculosus and D. reticulatum in experiments 1 and 2 respectively. Since T. elata has been suggested as a potential biocontrol agent of pestiferous slugs, the possibility of predation on the protected species G. maculosus is discussed from this perspective.     

The Organization of Genetic Diversity in the Parthenogenetic Lizard CNEMIDOPHORUS TESSELATUS

The parthenogenetic lizard species Cnemidophorus tesselatus is composed of diploid populations formed by hybridization of the bisexual species C. tigris and C. septemvittatus, and of triploid populations derived from a cross between diploid tesselatus and a third bisexual species, C. sexlineatus. An analysis of allozymic variation in proteins encoded by 21 loci revealed that, primarily because of hybrid origin, individual heterozygosity in tesselatus is much higher (0.560 in diploids and 0.714 in triploids) than in the parental bisexual species (mean, 0.059). All triploid individuals apparently represent a single clone, but 12 diploid clones were identified on the basis of genotypic diversity occurring at six loci. From one to four clones were recorded in each population sampled. Three possible sources of clonal diversity in the diploid parthenogens were identified: mutation at three loci has produced three clones, each confined to a single locality; genotypic diversity at two loci apparently caused by multiple hybridization of the bisexual species accounts for four clones; and the remaining five clones apparently have arisen through recombination at three loci. The relatively limited clonal diversity of tesselatus suggests a recent origin. The evolutionary potential of tesselatus and of parthenogenetic forms in general may be less severely limited than has generally been supposed.     

Eight polymorphic microsatellite loci for the critically endangered crested ibis,Nipponia nippon (Ciconiiformes: Threskiornithidae)

The Chinese crested ibis, Nipponia nippon, is a critically endangered bird. The current population of this species has developed from four wild individuals rediscovered in 1981. Given its conservation status, there is considerable interest in assessing the genetic diversity and individual relatedness in this species. For this purpose, a set of eight polymorphic di‐ or trinucleotide microsatellite loci was developed for the crested ibis. The expected heterozygosity at these loci ranges from 0.01 to 0.50, with less than four alleles being observed at individual loci, a reflection of the serious population bottleneck experienced by this species.     

Delineating a New Heterothallic Species of Volvox (Volvocaceae,Chlorophyceae) Using New Strains of “Volvox africanus”

The volvocine algae represent an excellent model lineage in which to study evolution of female and male genders based on comparative analyses of related species. Among these species, Volvox carteri has been extensively studied as a model of an oogamous and complex organism. However, it may have unique derived features that are not present in other species of Volvox. Therefore, information regarding the characteristics of sexual reproduction of other species of Volvox is also important. In 1971, Starr studied four types of sexuality in several global strains identified as Volvox africanus; however, further taxonomic studies of these strains have been lacking, and strains of three of the four sexual types are not available. Here, we studied the morphology, sexual reproduction, and taxonomy of two V. africanus-like species isolated recently from Lake Biwa, Japan. These two species were very similar to two sexual types described by Starr in 1971: one producing dioecious sexual spheroids in heterothallic strains and the other forming both male spheroids and monoecious spheroids in a single strain. The former species produced zygotes with a reticulate cell wall, whereas a smooth zygote wall was observed in the latter species as in V. africanus previously reported from various localities around the world. Our multigene phylogenetic analysis demonstrated that these are sister species to each other. However, the presence of a compensatory base change in the most conserved region of the secondary structure of nuclear ribosomal DNA internal transcribed spacer-2, hybrid inviability demonstrated by intercrossing experiments, and morphological differences in the density of abutment between the gelatinous material of adjacent cells (individual sheaths) in the spheroid supported the recognition of the two species, V. africanus having a smooth zygote wall and V. reticuliferus Nozaki sp. nov. having a reticulate zygote wall.     

Orientation behaviour in the Grayling butterfly: thermoregulation or crypsis?

ABSTRACT.

• 1 Body orientation and wing tilting in Hipparchia semele (L.) have been explained previously both by the need for shadow-minimization (crypsis hypothesis) and by the need to regulate body temperature (thermoregulation hypothesis).
• 2 This study tests the thermoregulation hypothesis by quantifying butterfly orientation in relation to sun position, using vector analysis, and correlating the data with ambient temperature and time of day.
• 3 During sunshine, Graylings tend to present a maximal wing area to the sun's rays when the ambient temperature is relatively low, and a minimal area when it is high ('sunning’and‘heat-avoiding’positions respectively).
• 4 On cool sunny days, butterflies adopt sunning positions throughout the day, whereas on warm sunny days they adopt sunning positions during the outlying periods and heat-avoiding positions in the middle period of the day. Correlations between wing exposure and both ambient temperature and time of day are statistically significant for warm sunny days.
• 5 During overcast weather, butterfly orientation is very variable and possibly random.
• 6 Analysis of sunny day data supports the thermoregulation hypothesis. This is discussed in relation to other known types of thermoregulatory behaviour observed in this species: stilting, shade-seeking, ground-hugging and shivering.
• 7 Conversely, the results do not support the crypsis hypothesis.