Leptidea Sinapis Research Articles

Ecological Constraints on Female Fitness in a Phytophagous Insect

Although understanding female reproduction is crucial for population demography, determining how and to what relative extent it is constrained by different ecological factors is complicated by difficulties in studying the links between individual behavior, life history, and fitness in nature. We present data on females in a natural population of the butterfly Leptidea sinapis. These data were combined with climate records and laboratory estimates of life-history parameters to predict the relative impact of different ecological constraints on female fitness in the wild. Using simulation models, we partitioned effects of male courtship, host plant availability, and temperature on female fitness. Results of these models indicate that temperature is the most constraining factor on female fitness, followed by host plant availability; the short-term negative effects of male courtship that were detected in the field study were less important in models predicting female reproductive success over the entire life span. In the simulations, females with more reproductive reserves were more limited by the ecological variables. Reproductive physiology and egg-laying behavior were therefore predicted to be co-optimized but reach different optima for females of different body sizes; this prediction is supported by the empirical data. This study thus highlights the need for studying behavioral and life-history variation in orchestration to achieve a more complete picture of both demographic and evolutionary processes in naturally variable and unpredictable environments.

The geography of speciation in butterflies (Lepidoptera, Papilionoidea): an empirical test of theoretical models

Despite the fundamental role of speciation in formation of biodiversity, the genetic and ecological mechanisms related to this process, as well as the geography of speciation are still poorly known. In our research we have used methods of molecular phylogenetics and phylogeography to reconstruct the stages of speciation in two model groups of butterflies. Phylogeographic analysis showed that speciation in Agrodiaetus blues started in allopatry. An additional age-range correlation test also revealed a pattern consistent with allopatric speciation. However, the formation of new wing colors, the characters most important for maintenance of pre-zygotic reproductive isolation, was shown to occur after transition from allopatry to sympatry. Analysis of karyotypes, mitochondrial and nuclear molecular markers in the Wood White butterfly Leptidea sinapis L. showed that clinal speciation may have occurred in this case; this process is theoretically possible but difficult to document.

Unexpected layers of cryptic diversity in wood white Leptidea butterflies

Uncovering cryptic biodiversity is essential for understanding evolutionary processes and patterns of ecosystem functioning, as well as for nature conservation. As European butterflies are arguably the best-studied group of invertebrates in the world, the discovery of a cryptic species, twenty years ago, within the common wood white Leptidea sinapis was a significant event, and these butterflies have become a model to study speciation. Here we show that the so-called 'sibling' Leptidea actually consist of three species. The new species can be discriminated on the basis of either DNA or karyological data. Such an unexpected discovery challenges our current knowledge on biodiversity, exemplifying how a widespread species can remain unnoticed even within an intensely studied natural model system for speciation.

Unprecedented within-species chromosome number cline in the Wood White butterfly Leptidea sinapis and its significance for karyotype evolution and speciation

BackgroundSpecies generally have a fixed number of chromosomes in the cell nuclei while between-species differences are common and often pronounced. These differences could have evolved through multiple speciation events, each involving the fixation of a single chromosomal rearrangement. Alternatively, marked changes in the karyotype may be the consequence of within-species accumulation of multiple chromosomal fissions/fusions, resulting in highly polymorphic systems with the subsequent extinction of intermediate karyomorphs. Although this mechanism of chromosome number evolution is possible in theory, it has not been well documented.ResultsWe present the discovery of exceptional intraspecific variability in the karyotype of the widespread Eurasian butterfly Leptidea sinapis. We show that within this species the diploid chromosome number gradually decreases from 2n = 106 in Spain to 2n = 56 in eastern Kazakhstan, resulting in a 6000 km-wide cline that originated recently (8,500 to 31,000 years ago). Remarkably, intrapopulational chromosome number polymorphism exists, the chromosome number range overlaps between some populations separated by hundreds of kilometers, and chromosomal heterozygotes are abundant. We demonstrate that this karyotypic variability is intraspecific because in L. sinapis a broad geographical distribution is coupled with a homogenous morphological and genetic structure.ConclusionsThe discovered system represents the first clearly documented case of explosive chromosome number evolution through intraspecific and intrapopulation accumulation of multiple chromosomal changes. Leptidea sinapis may be used as a model system for studying speciation by means of chromosomally-based suppressed recombination mechanisms, as well as clinal speciation, a process that is theoretically possible but difficult to document. The discovered cline seems to represent a narrow time-window of the very first steps of species formation linked to multiple chromosomal changes that have occurred explosively. This case offers a rare opportunity to study this process before drift, dispersal, selection, extinction and speciation erase the traces of microevolutionary events and just leave the final picture of a pronounced interspecific chromosomal difference.

Past and present distribution of the cryptic species Leptidea sinapis and L. reali (Lepidoptera: Pieridae) in Poland and its implications for the conservation of these butterflies

Using a large sample of museum and newly collected specimens of the cryptic butterfly species Leptidea sinapis and L. reali, identified/confirmed based on genital characters, the patterns in their geographical distributions, historical changes in range and briefly also their habitat associations in Poland, were investigated. Leptidea sinapis occurs mainly in the lowland and upland parts of the country and is rarer than L. reali, which is widespread throughout Poland, including the mountains. In the first half of the 20th century, the range of L. sinapis included the whole of Poland, whereas currently it is confined to eastern and southern regions. Historical records of the distribution of L. reali are concentrated in southern and central Poland. Currently it is recorded from localities throughout Poland. Leptidea reali is recorded most frequently in meadows and shows no clear preference for a particular level of humidity, while L. sinapis is found mainly in woodland and xerothermic habitats. The two species are syntopic within the present range of L. sinapis, which is now a declining and local species, whereas L. reali is now common and widespread.

Evidence-based National Recovery Plan for Leptidea sinapis (wood white butterfly) in Southern Britain

We present a key part of the evidence base used to develop a National Recovery Plan for Leptidea sinapis a declining and threatened species in Britain. Knowledge of the current sites has been updated along with the macro- and micro-habitat resource requirements of the species and its autecology to set the basis for a conservation strategy for 2010 and beyond. The three main findings are that: L. sinapis uses a greater diversity of biotopes within and between sites than was previously thought; population dynamics are complex with 2–3 year peaks and troughs of annual abundance indices and two generations per year throughout its range; and dispersal ability is also greater than previously stated. This evidence has been used to develop an Action Plan for 2010 and beyond. The importance of landscape-scale management and effective collaboration between scientists, land managers and volunteers is emphasised.

Leptidea sinapis (Wood White butterfly) egg-laying habitat and adult dispersal studies in Herefordshire

The Wood White butterfly Leptidea sinapis, a UK BAP Priority species, is present in a number of Forestry Commission woodlands in the West Midlands and these constitute an important part of the national resource of this butterfly. A joint SITA Trust funded project between the Forestry Commission and Butterfly Conservation (linking with the National Wood White Conservation Project) is researching the use of habitat by Leptidea sinapis within these sites with regard to targeting conservation management. Two aspects of this research are presented: the results of a mark-recapture study and an analysis of egg-laying habitat. Mark-recapture results show considerable movement between areas of concentrations of adults and between egg-laying areas, with males moving further and faster than females. Movements do occur across potential habitat barriers. Egg locations were found by following females and by searching for eggs. The habitat used for egg-laying is extremely variable even within a site. A number of foodplants species are used and habitat ranges from low height foodplants within bare ground to a foodplant height of over 1 m within thick vegetation and scrub. These results are being integrated into an ongoing project to restore Leptidea sinapis habitat within managed Forestry Commission woodlands.

Host plant preference and performance of the sibling species of butterflies Leptidea sinapis and Leptidea reali: a test of the trade-off hypothesis for food specialisation

A large proportion of phytophagous insect species are specialised on one or a few host plants, and female host plant preference is predicted to be tightly linked to high larval survival and performance on the preferred plant(s). Specialisation is likely favoured by selection under stable circumstances, since different host plant species are likely to differ in suitability-a pattern usually explained by the "trade-off hypothesis", which posits that increased performance on a given plant comes at a cost of decreased performance on other plants. Host plant specialisation is also ascribed an important role in host shift speciation, where different incipient species specialise on different host plants. Hence, it is important to determine the role of host plants when studying species divergence and niche partitioning between closely related species, such as the butterfly species pair Leptidea sinapis and Leptidea reali. In Sweden, Leptidea sinapis is a habitat generalist, appearing in both forests and meadows, whereas Leptidea reali is specialised on meadows. Here, we study the female preference and larval survival and performance in terms of growth rate, pupal weight and development time on the seven most-utilised host plants. Both species showed similar host plant rank orders, and larvae survived and performed equally well on most plants with the exceptions of two rarely utilised forest plants. We therefore conclude that differences in preference or performance on plants from the two habitats do not drive, or maintain, niche separation, and we argue that the results of this study do not support the trade-off hypothesis for host plant specialisation, since the host plant generalist Leptidea sinapis survived and performed as well on the most preferred meadow host plant Lathyrus pratensis as did Leptidea reali although the generalist species also includes other plants in its host range.

Long‐term land‐use changes and extinction of specialised butterflies

Abstract. 1 Land-use change in 450 ha in southern Sweden between 1814 and 2004 was recorded. Butterflies and burnet moths were surveyed in 1904–1913 and 2001–2005. 2 We explore if local extinctions were related to land-use changes and species attributes. 3 Land use changed drastically over the 190-year period, and the largest relative change occurred for hay meadows with late harvest, which decreased from 28% to 0%. The area changed from grasslands and grazed forests to being dominated by timber forests. Previous open grazed mixed woodlands changed to spruce plantations with clear-cuts. 4 Of the 48 resident butterfly and burnet moths found a century ago, 44% have become extinct. The extinct Aporia cratægi, Colias palaeno, and Leptidea sinapis were abundant 100 years ago and had their highest densities in flower-rich glades in forest, a habitat which no longer exists. 5 The butterfly extinctions could be predicted from species-specific attributes as a short flight length period (P < 0.02), narrow habitat breadth (P < 0.02), small distribution area in Europe (P = 0.033) and possibly larvae food plant nitrogen class (P < 0.06). In a multiple logistic regression, the flight length period was the only significant variable because the independent variables were intercorrelated. 6 We conclude that the most important factor explaining the high extinction rate is that flower-rich habitats have disappeared from both woodlands as well as from open farmlands. The most sensitive species are specialised species with a short summer flight which have gone extinct. Only the most unspecialised species still persist in the current landscape.

Distinguishing between Leptidea sinapis and L. reali (Lepidoptera: Pieridae) using a morphometric approach: impact of measurement error on the discriminative characters

A morphometric approach was used to test the possibility of discriminating between L. sinapis and L. reali by taking into account some new genitalic characters in addition to those used in previous surveys. Principal component analysis, performed on the size-and-shape data sets and on the size-adjusted data sets, has allowed two completely separate morphotypes to be detected, both in males and in females. Discriminant analysis has confirmed the separation of previously detected morphotypes and has correctly classified 100% of the specimens in both sexes with six discriminative characters being identified in males and two in females. However, some of these discriminative characters were not considered reliable enough because of the high associated measurement error and the scarce discriminative power. Reliable discriminative characters were: vinculum (≈ valve) width, length of phallus (≈ aedoeagus ≈ aedeagus), saccus and uncus in males and ductus bursae length in females. The main topics discussed are: a comparison of the discriminative characters with previous studies, the sources of measurement error and the devices used to reduce it, as well as the between and within-species variability of the characters.

Female mate choice determines reproductive isolation between sympatric butterflies

Animal courtship rituals are important for species recognition, and a variety of cues might be utilized to recognize conspecific mates. In this paper, we investigate different species-recognition mechanisms between two sympatric butterfly sister species: the wood white (Leptidea sinapis) and Real’s wood white (Leptidea reali). We show that males of both species frequently court heterospecific females both under laboratory and field conditions. The long-lasting elaborate courtships impose energetic costs, since the second courtship of males that were introduced to two subsequent conspecific females lasted on average only one fourth as long as the first courtship. In this paper, we demonstrate that premating reproductive isolation is dependent on female unwillingness to accept heterospecific mates. We studied female and male courtship behavior, chemical signaling, and the morphology of the sexually dimorphic antennae, one of the few male traits visible for females during courtship. We found no differences in ultraviolet (UV) reflectance and only small differences in longer wavelengths and brightness, significant between-species differences, but strongly overlapping distributions of male L. sinapis and L. reali antennal morphology and chemical signals and minor differences in courtship behavior. The lack of clear-cut between-species differences further explains the lack of male species recognition, and the overall similarity might have caused the long-lasting elaborate courtships, if females need prolonged male courtships to distinguish between con- and heterospecific suitors.

Morphological and molecular evidence of a possible hybrid zone of Leptidea sinapis and L. reali (Lepidoptera: Pieridae)

Overlapping measurements in the length of the genitalia of Leptidea sinapis/reali collected in Slovenia triggered an investigation of a possible natural hybridization between these two well known sibling species of butterflies. Random polymorphic DNA (RAPD) was used to generate species specific markers and sequences of the cytochrome oxidase subunit one gene for determination of the progeny. RAPD's clustering and mitochondrial DNA (mtDNA) phylogeny were congruent with the taxonomic placement of specimens of both species, but slightly incongruent with the results of the analysis of genital morphology. Two specimens with L. reali genitalia measurements, but genetically belonging to L. sinapis, had species specific RAPD markers of both species indicating probable hybrid origin. All the specimens with genitalia of intermediate length were also genetically assigned to L. sinapis indicating a possible one way introgression as predicted from their genitalia morphology. Leptidea sinapis was found predominantly in xerothermic habitats in Slovenia, whereas L. reali was more of a generalist except in the sub-Mediterranean region where it is limited to humid meadows.

Generation-dependent female choice: behavioral polyphenism in a bivoltine butterfly

Climatic and biotic circumstances vary as seasons shift, and different cohorts of multivoltine species are likely subjected to different selection regimes. The bivoltine butterfly Leptidea reali (Réal's wood white; Lepidoptera: Pieridae) appears during May and June in central Sweden and has a partial second generation in late July. We manipulated both generations to appear simultaneously and performed laboratory mating experiments that showed the presence of a behavioral polyphenism in mating propensity, which is induced during the developmental stages. Females of the summer generation expressed higher mating propensities than spring generation females. Spring females showed an increase in mating propensity with increasing age, whereas summer females accepted most matings already when they were only 1 or 2 days old. It is likely that larval time constraints, a lower abundance of males and a lower risk of accepting a male of their univoltine sister species Leptidea sinapis (wood white), have relaxed selection on mate discrimination among summer generation females. A major challenge for future research is to further investigate the developmental pathways causing the polyphenism and the adaptive implications of cohort-dependent behaviors.

Diurnal butterflies (Lepidoptera, Rhopalocera) of the Solovetskie Islands (Northwestern Russia, the White Sea)

The species composition and diversity of Lepidoptera Rhopalocera were studied on the Solovetskie Islands during five years (2001–2005). Twenty-nine species of five families were recorded. The most abundant species are Leptidea sinapis, Boloria aquilonaris, Heodes virgaureae, Plebejus argus, Arcia eumedon, and Cyaniris semiargus. The fauna of these islands is poorer than local faunas of the continental northern taiga, forest-tundra, and southern tundra of Europe. The species diversity of insular assemblages of diurnal lepidopterans is lower in comparison with analogous continental assemblages. They are characterized by the mixed species composition, when species with different ecological preference occur within the same habitat.

Annual and Long-Term Changes in a Population of the Wood White Butterfly Leptidea sinapis

Annual and Long-Term Changes in a Population of the Wood White Butterfly Leptidea sinapis

The influence of shade on butterfly numbers in woodland rides, with special reference to the wood white Leptidea sinapis

Habitat selection by butterflies is examined by comparing the relative number of adults recorded in woodland rides with the overall level of direct shade, measured by hemispherical photography. Species that are typical of open grassland habitats were largely confined to the least shaded rides whilst other species were most abundant in either partially or heavily shaded rides. Overall, a far greater number of species occurred in the least shaded rides and only a few species actually preferred heavily shaded conditions. The apparent shade preferences of two species, Leptidea sinapis and Aphantopus hyperantus, were confirmed by local changes in their distribution over a period of several years when rides became increasingly shaded. Habitat selection by L. sinapis was also related to the abundance of certain resources, such as nectar sources and larval foodplants. The major factors which determine the level of direct shade in woodland rides (tree height, ride width and orientation) are discussed, and conclusions are drawn about the importance of ride management to the conservation of butterflies in woodland habitats.

Adaptive Versus Incidental Explanations for the Occurrence of Protandry in Butterfly, Leptidea sinapis L.

Adaptive Versus Incidental Explanations for the Occurrence of Protandry in Butterfly, Leptidea sinapis L.

ADAPTIVE VERSUS INCIDENTAL EXPLANATIONS FOR THE OCCURRENCE OF PROTANDRY IN A BUTTERFLY, LEPTIDEA SINAPIS L.

In many butterflies males emerge before females (Petersen, 1892; Demoll, 1908; Berge and Rebel, 1910; Ford, 1945; Petersen, 1947; Forster, 1954; Newman, 1968). This phenomenon, here referred to as protandry, is also known from other insects (Petersen, 1892; Demoll, 1908; Petersen, 1947). At least two general classes of hypotheses can be invoked to explain the occurrence of protandry. First, the time difference per se in eclosion times may be the result of selective pressures on males and females to emerge at different times in relation to each other. This class of explanations is here called adaptive. Thus, for example, Wiklund and Fagerstr6m (1977) argue that sexual selection between males to maximize the number of matings leads to protandry. It has also been argued that sexual selection between females to minimize the risk of death prior to mating also leads to protandry (Ford,, 1945; Bowden, 1979; Wiklund and Fagerstrom, 1979). If eclosions are similarly distributed among males and females the optimal difference in eclosion time is similar for male and female strategies (Wiklund and Fagerstr6m, unpubl.). Another hypothesis claims that selection for outbreeding can explain the incidence of protandry in butterflies (Petersen, 1892) thus presupposing that males are better suited for dispersal than females. Second, the difference in eclosion times may be a byproduct of selection for other life history For example, in many butterflies males are smaller than females (which may be adaptive per se) and thus as an byproduct of the size difference between the sexes. We call this class of explanations for the occurrence of protandry incidental. Recently Lewontin (1977, 1978a, 1978b) and Gould and Lewontin (1979) have stressed the importance of seriously considering non-adaptive or explanations for various traits. The aim of this paper is to report the results of experiments aimed at distinguishing between and incidental explanations for the occurrence of protandry in a butterfly, the Wood White Leptidea sinapis L. (Lepidoptera: Pieridae). (We are aware of the fact that the term is in part ambiguous. For example a trait can have a positive adaptive value without having been for [cf. Williams, 1966; Futuyma, 1979]. We therefore want to state explicitly that in this paper is used synonymously with selected for. ) The basis for our attempt to distinguish between these two classes of explanations is the occurrence of two developmental phenotypes in L. sinapis. By using different phenotypes (in this case two generations) of the same species we gain the advantage of comparing organisms with the same physiological constraints or Bauplan (cf. Gould and Lewontin, 1979) thus avoiding the problems of comparing different species that are always to some extent trapped in their particular evolutionary pasts (cf. Solbreck, 1978). Pertinent points in the biology of L. sinapis in Sweden follow. The insect overwinters in the pupal stage. In spring males emerge from the pupae a couple of days before females (Wiklund, 1977). Follow-

The Wood White Butterfly Leptidea sinapis and Its Nectar Plants: A Case of Mutualism or Parasitism?

The purpose of this study was to determine (1) the nectar plant utilization of a population of Leptidea sinapis L. by following individual adults in their natural habitat, and (2) whether L. sinapis pollinates the flowers visited by collecting insects immediately after their visiting flowers and identifying pollen grains on the proboscis, palpi, head and thorax. Approximately 90% of the flower visits were made to Viola canina, V. riviniana and Lathyrus montanus. Although the strong flower preference exhibited by L. sinapis would make it a suitable pollinator, it seems unlikely that any flowers were pollinated by the butterflies in view of their low pollen load (im = 3.0 grains/specimen). Thus, L. sinapis should be regarded as a parasite on its nectar plants. Since the feeding behaviour of L. sinapis is typical of most butterflies we advance the tentative hypothesis that butterflies as a group may have evolved to occupy a parasitic mode of life as adults, feeding on the nectar of flowers without pollinating them. If so the evolution of the long pliable proboscis of butterflies may have opened a whole new feeding niche for adult butterflies by making accessible not only the exposed nectar from unspecialized flowers but also the formerly hidden nectar from a vast variety of bee and bumblebee flowers. However, since the above hypotheses are based on little evidence from but one butterfly species a broad study is needed to test their validity.

Courtship Behaviour in Relation to Female Monogamy in Leptidea sinapis (Lepidoptera)

Courtship in butterflies is argued to serve two functions, viz. (1) to ensure conspecific matings, and (2) to provide a mechanism for deciding whether to mate or not once both sexes have recognized the other as being conspecific. Courtship in Leptidea sinapis L. is unique in two respects (1) virgin females always display a willingness signal when courted, and (2) courting males are completely noninsistent and never attempt to initiate copulation unless the female has signalled that she is receptive. All male/virgin female encounters resulted in copulation, whereas all male/already mated female courtships ended without mating. In consequence, the females are monogamous. In L. sinapis female monogamy is argued to be maintained by the females according to the following reasoning: (I) the females can ultimately decide whether or not mating will occur at courtship, (2) monogamy is beneficial to females on account of allowing maximum time expenditure for locating suitable host plants, and (3) male non-insistent courtship is thus neither advantageous nor disadvantageous so long as virgin females are willing to mate once they recognize a courting male as being conspecific.