Miguel L. Munguira

DNA barcode reference library for Iberian butterflies enables a continental-scale preview of potential cryptic diversity

How common are cryptic species - those overlooked because of their morphological similarity? Despite its wide-ranging implications for biology and conservation, the answer remains open to debate. Butterflies constitute the best-studied invertebrates, playing a similar role as birds do in providing models for vertebrate biology. An accurate assessment of cryptic diversity in this emblematic group requires meticulous case-by-case assessments, but a preview to highlight cases of particular interest will help to direct future studies. We present a survey of mitochondrial genetic diversity for the butterfly fauna of the Iberian Peninsula with unprecedented resolution (3502 DNA barcodes for all 228 species), creating a reliable system for DNA-based identification and for the detection of overlooked diversity. After compiling available data for European butterflies (5782 sequences, 299 species), we applied the Generalized Mixed Yule-Coalescent model to explore potential cryptic diversity at a continental scale. The results indicate that 27.7% of these species include from two to four evolutionary significant units (ESUs), suggesting that cryptic biodiversity may be higher than expected for one of the best-studied invertebrate groups and regions. The ESUs represent important units for conservation, models for studies of evolutionary and speciation processes, and sentinels for future research to unveil hidden diversity.

Comparing relative model fit of several species-accumulation functions to local Papilionoidea and Hesperioidea butterfly inventories of Mediterranean habitats

When compiling an inventory of hyperdiverse taxa, it is impossible to record the total number of species during fieldwork. To ensure the accuracy of species-richness data it is necessary to assess the reliability of inventories. Accumulation curves are an easy method for doing this and are extensively described in the literature. In this study, we compare the relative fit of various models of species-accumulation functions for six local butterfly inventories, evaluating them by a consideration of the values of the fit, coefficient of determination and sum-of-squares, and the residual patterns and Akaike’s Information Criterion. In general, complex functions, such as the Weibull or Chapman-Richards, performed better than simpler and more widely used models (e.g., the Clench and negative exponential models). The performance of models varied among sampling plots, indicating the influence of factors such as land use and community structure. Thus, although the application of more complex models should replace the use of simple ones, further research into the factors affecting model fit of accumulation functions is necessary.

Use of space and resources in a Mediterranean population of the butterfly Euphydryas aurinia

Abstract Population parameters of a central Spanish population of the marsh fritillary butterfly, Euphydryas aurinia (Rott.), were studied between 1990 and 1991. Numbers were very similar in the two study years, but adult emergence was delayed 15 days in the second year as a consequence of variation in weather conditions. The nectar sources used by adults were different in the two years and were correlated with the most abundant plants available during the flight period. Adult abundance was correlated with the presence of the larval foodplant (Lonicera periclymenum) in open woodland and was higher where this habitat was mixed with open areas, where nectar sources abound. Estimates of male population numbers were higher than those of females, suggesting that males used wider ranges than females, or a higher residence rate for males. Nevertheless mobility did not differ significantly between the sexes. The conservation of the species in central Spain depends on maintaining patches of oak woodlands, important for the presence of larval foodplants. Large numbers of the butterfly in the Natural Park study area are favoured by traditional management including charcoal production and extensive grazing by cattle and goats.

Population modelling of the spatial interactions between Maculinea rebeli their initial foodplant Gentiana cruciata and Myrmica ants within a site

A spatial computer simulation model has been developed to assist our understanding of the ways in which Maculinea butterflies depend upon the spatial distribution and abundance of their initial foodplant and their Myrmica host ant. It was initially derived for the Maculinea rebeli-Myrmica schencki-Gentiana cruciata system. It relates the population processes of the competing host and other ant species to an underlying gradient of habitat quality and incorporates the impact of adopted Maculinea caterpillars on the growth and survival of individual ant nests. The model was initially calibrated for a large site in the Spanish Pyrenees, but has since been successfully tested on 12 French sites and another in Spain. On such sites, with M. rebeli present, there is a close relationship between Maculinea population density and the density of the early larval foodplant G. cruciata. Optimum gentian density is estimated to be about 1500 plants ha-1 on sites with the natural clumping of gentians found. However, any site management which added extra gentians, especially if filling the gaps, is predicted to reduce the Maculinea population. Meta-population studies of single species have shown that the size and spatial arrangement of patches of assumed uniformly ‘suitable’ habitat can influence their population dynamics and persistence. Our modelling suggests that the spatial pattern of ‘suitable’ habitat of varied quality within a single site can influence the local butterfly population size and perhaps also persistence. Despite being free-ranging over the whole area, the butterflys dynamics may depend on the arrangement of habitat quality at a finer spatial scale, due to its interactions with ant species possessing narrower habitat niches and more localized dispersal.

Field evidence and model predictions of butterfly-mediated apparent competition between gentian plants and red ants

Abstract In recent spatial models describing interactions among a myrmecophilous butterfly Maculinea rebeli , a gentian Gentiana cruciata and two competing species of Myrmica ant, we predicted that apparent competition should exist between gentians (the food of young M. rebeli caterpillars) and Myrmica schencki , which supports M. rebeli in its final instar. Here we extend and quantify model predictions about the nature of this phenomenon, and relate them to ecological theory. We predict that: (i) Within sites supporting the butterfly, fewer M. schencki colonies occur in sub-areas containing gentians than in identical habitat lacking this plant. (ii) Where G. cruciata and M. schencki do co-exist, the ant colonies will be less than half the size of those living > 1.5 m from gentians; (iii) The turnover of M. schencki colonies will be much greater than that of other Myrmica species in nest sites situated within 1.5 m of a gentian. All three predictions were supported in the field on 3–6 sites in two mountain ranges, although the exact strength of the apparent competition differed from some model predictions. Field data were also consistent with predictions about apparent mutualisms between gentians and other ants. We suggest that apparent competition is likely to arise in any system in which a specialist enemy feeds sequentially on two or more species during its life-cycle, as occurs in many true parasite-host interactions. We also predict that more complex patterns involving other Myrmica species and G. cruciata occur in our system, with apparent competition existing between them in some sub-areas of a site being balanced by apparent mutualism between them in other sub-areas.

Morphology and morphometry of Lycaenid eggs (Lepidoptera: Lycaenidae)

A morphological study with the use of scanning electron microscope of 67 species of Iberian Lycaenidae is presented. The study covers all the genera present in the area and shows an extraordinary variation in chorionic characters that allows egg diagnosis for most species. A morphometric study showed that the eggs from the sample have sizes that are correlated with adult size, but some species showed larger egg size than expected. Species hibernating at the egg stage proved to have on average larger sizes than those overwintering at other stages, probably because this trait might be favourable to endure the adverse conditions taking place during the winter. A cladistic analysis was performed using morphologic and morphometric characters from the egg with the result of poor discriminant power. However, some formal taxonomic groups such as the genera Lycaena and Satyrium were supported by our analysis due to specific apomorphic characters.

Morphological and chemical analysis of male scent organs in the butterfly genus Pyrgus (Lepidoptera: Hesperiidae)

Chemical communication in the family Hesperiidae (Lepidoptera) is practically unstudied, even though this group includes approximately 4,000 species and represents a fifth of the world’s butterfly fauna. We present the first comparative morphological and chemical analysis of scent organs for nine species in the genus Pyrgus, the most species-rich hesperiid genus in the Palearctic region. Our results show that the morphology of the two main male scent organs—the costal fold and the tibial tufts—does not differ between species. The chemical analyses detected a total of 125 different compounds exclusively present in these organs. We document great interspecific differences and much narrower intraspecific variability in the chemical profiles. The dynamics of chemical versus genetic distances indicate two different phases: a faster (but more variable) initial chemical divergence at lower genetic divergences (probably related to speciation) and a slower but more constant differentiation (drift). As a result most species can be identified based on their chemical profiles, except for a closely related species pair (P. malvae/P. malvoides) for which hybridisation is common in the contact zone. Our results suggest that the Hesperiidae is a group with great potential for the study of chemical communication that deserves further attention.

Comparative study of the morphology of stridulatory organs of the Iberian lycaenid butterfly pupae (Lepidoptera).

We compared the pupal stridulatory organs of 35 species and one subspecies of Iberian Lycaenidae using scanning electron microscopy. The studied species belong to the tribes Theclini, Eumaeini, Lycaenini, and Polyommatini. Nine species do not show stridulatory organs on the pupae but all other species possess them. Stridulatory organs are formed by a stridulatory plate (pars stridens) placed on the fifth abdominal segment and a file (plectron) in the sixth abdominal segment. The plate has tubercles in the Theclini and Lycaenini, tubercles, ridges, or undulations in the Eumaenini, and tubercles, teeth, or unspecialized structures in the Polyommatini. Morphological differences can be found in the files of the different tribes, regarding the number of teeth, their form and size. Cuticular formations of the organs were studied on a surface of 2,500 µm2 and the average of ridges, tubercles, and teeth was measured searching for relevant taxonomic information. Stridulatory organs were thought to be an adaptation to myrmecophily but we show that they are present both in myrmecophilous and nonmyrmecophilous species; therefore, we suggest that this trait probably did not evolve in relation with myrmecophily, but may be used to enhance relationships with ants. J. Morphol. 275:414–430, 2014.

Ecology and recovery plans for the four Spanish endangered endemic butterfly species

Data compiled during three fieldwork seasons and habitat models provided the tools to produce Species recovery plans for the endangered and endemic butterflies in Spain: Polyommatus violetae, P. golgus, Agriades zullichi, and Euchloe bazae. The distribution of each species has been updated with new field records. For E. bazae and P. violetae the known distribution records increased 33% and 8%, respectively. Detailed habitat descriptions, based on fieldwork data, are given for the four species and models show relatively small and fragmented habitat patches for P. violetae, P. golgus, and P. zullichi. Those areas might be particularly sensitive under a climate change scenario. Habitat of the four species is very specialized and mainly consists of open areas with grassland or scrub vegetation. Population densities are provided for the first time for these species and show low numbers for E. bazae, particularly in the area around Baza in SE Spain. 25 to 54% of the populations were apparently not threatened. For the rest, apparent habitat suitability threats were abandonment for E. bazae and P. violetae, trampling for A. zullichi, and overgrazing for P. golgus. Recovery plans included aspects on legislation, habitat management, precautionary measures (limit new developments and land use changes), research, and public awareness campaigns. Suggested habitat management actions are: (1) support extensive grazing and prevent overgrazing; (2) reduce the effect of trampling by visitors in mountain areas; and (3) woodland and scrub clearing of abandoned areas and pine plantations to improve the quality of grassland habitats.

Multivariate analysis techniques in the study of the male genitalia of Pyrgus bellieri (Oberthür 1910) and P alveus (Hübner 1803) (Lepidoptera: Hesperiidae): species discrimination and distribution in the Iberian Peninsula

Abstract We used statistical multivariate analyses to study two morphologically similar species: Pyrgus bellieri and P. alveus. Ten different variables were measured in the male genitalia, and the results tested with Principal Component Analysis which showed a clear cut separation between the two species later confirmed by Discriminant Analysis. The discerning variables were the length of cuiller and the length of uncus that are inversely proportional in the two species. The classification functions for each species have been worked out resulting in the possibility to identify any individual just using some parameters in the male genitalia. The presence of P. bellieri in the Iberian Peninsula is confirmed and 18 literature citations of the species are rejected while 13 new ones are given. The resulting distribution in the Peninsula is restricted to 32 UTM squares (10 km) in the NE, all of them in Catalonia and in the Province of Huesca (Aragón). The study highlights the validity of statistical multivariate analysis techniques, using variables taken from the male genitalia, to discriminate species with identification problems.