Andrea Grill

Hybridization and speciation

Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near‐instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky–Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock‐on effects on speciation both within and outside regions of hybridization.

Molecular phylogeography of European Sciurus vulgaris: refuge within refugia?

The red squirrel (Sciurus vulgaris) is a well‐known forest animal distributed all over Europe. Still, we are far from having a firm knowledge of the species’ phylogeography. This study investigates the genetic differentiation of S. vulgaris across the species’ Eurasian range, using sequence data from the mitochondrial DNA gene (D‐loop, 252 base pairs, cytochrome b, 359 base pairs), and eight variable autosomal microsatellite loci genotyped for 236 individuals. The results reveal the presence of two main mitochondrial phylogroups. The first clade comprises the individuals from the region of Calabria in southern Italy, belonging to the subspecies S. v. meridionalis, while the second clade contains the remainder of the studied individuals. Bayesian analysis of microsatellite genotypes resulted in three main clusterings corresponding to the three S. vulgaris subspecies: infuscatus, meridionalis and fuscoater. Geographical distribution of mtDNA haplotypes and mismatch analysis suggest a common refugium for the red squirrel across most of its present range from which expansion happened rather rapidly. The genotype mixing of italicus with northern populations could be a residual of postglacial expansion. The lack of mixing between the Calabrian lineage and the rest of European red squirrel haplotypes can be seen as evidence for distinct histories throughout the Pleistocene. Calabrian mtDNA probably diverged in an ice age contraction and remained isolated from the neighbouring squirrel populations until very recent times.

Conservation management for Orthoptera in the Dadia reserve, Greece

The diversity patterns, the ecological structure and the typical species of the orthopteran assemblage in the Dadia reserve are investigated. The reserve was designed to protect the black vulture (Aegypius monachus) and other raptors. A total of 39 orthopteran species were found, including Paranocarodes chopardi, a pamphagid species with very restricted distribution. All species can be represented in a network of six complementary habitats, including open oak woodlands, agricultural fields separated with hedges, humid grasslands, as well as serpentine grasslands. The buffer zone of the reserve is far more important for Orthoptera conservation than the core areas, which host most of the black vulture nests. Management focusing on raptors is in general compatible with conservation of Orthoptera. We suggest the maintenance of forest openings in the buffer zone, the maintenance of forest heterogeneity, the enhancement of periodical livestock grazing, and the use of nine indicator species and Paranocarodes chopardi in the reserve monitoring program

Diversity patterns in butterfly communities of the Greek nature reserve Dadia

Traditionally, nature reserves have been centered mainly around areas that are important for vertebrate diversity. This practice has not gone unchallenged and may be a suboptimal choice for overall conservation planning. To investigate this problem, we sampled butterfly species richness in a nature reserve in north eastern Greece that was originally established for the protection of birds of prey. Patterns of butterfly species richness and abundance were investigated by means of transect walks across a range of the seven predominant habitat types (wet and dry meadow, pine, oak and mixed forest, grazed, and agricultural land). Data analysis, including ANOVA and DCA (detrended correspondence analysis), revealed that the main gradients in butterfly species richness (low to high) were from sites dominated by the pine forest matrix of the core areas of the reserve, to peripheral sites in landscapes of mixed or oak forest, and from sites with little human impact to more disturbed areas with high grazing pressure. Species of conservation interest were concentrated at sites of low human impact. Ten of them are endemic to Europe and/or threatened in Europe. In this respect, the most important species are Lycaena ottomanus, Thymelicus acteon, and Pseudophilotes vicrama which are declining all over Europe. Our results suggest that (1) traditional agricultural practices in areas surrounded by forest can be considered as important management tools in butterfly conservation, (2) highest butterfly species richness is found in the periphery of the reserve rather than in the core areas, and (3) for butterfly conservation the zones surrounding the strictly protected areas are equally important as the core areas.

Butterfly, spider, and plant communities in different land-use types in Sardinia, Italy

Butterfly, spider, and plant species richness and diversity were investigated in five different land-use types in Sardinia. In 16 one-hectare plots we measured a set of 15 environmental variables to detect the most important factors determining patterns of variation in species richness, particularly endemicity. The studied land-use types encompassed homogeneous and heterogeneous shrublands, shrublands with tree-overstorey, Quercus forest and agricultural land. A total of 30 butterfly species, among which 10 endemics, and 50 spider (morpho)species, were recorded. Butterfly and spider community composition differed according to land-use type. The main environmental factors determining diversity patterns in butterflies were the presence of flowers and trees. Spiders reacted mainly to habitat heterogeneity and land-use type. Traditional land-use did not have adverse effects on the diversity of butterflies, spiders, or plants. The number of endemic butterfly species per treatment increased with total species richness and altitude. Butterfly and spider richness did not co-vary across the five land-use types. Butterflies were, however, positively associated with plant species richness and elevation, whereas spiders were not. Conclusively, butterflies did not appear to be good indicators for spider diversity and species richness at the studied sites.

A mowing experiment to evaluate the influence of management on the activity of host ants of Maculinea butterflies

Maculinea butterflies obligatory parasitize certain species of Myrmica ants. Thus, the presence of the host ant species is a limiting factor for the survival of a Maculinea population. Here, we analyse the influence of vegetation structure and ground temperature on ant diversity and abundance on Maculinea habitats, with the final aim of identifying the environmental variables determining patterns of variation in species composition in order to recommend a mowing regime that will promote our three target species: Maculinea teleius, M. nausithous and M. alcon. Experimental plots with different mowing regimes were established at eight sites in South-Eastern Germany, a region which still contains a number of relatively large, stable populations of these threatened butterfly species. Among the seven different ant species recorded, four belong to the genus Myrmica (M. scabrinodis, M. rubra, M. ruginodis and M. vandeli). Among these, M. scabrinodis results most abundant at all sites. In a CCA analysis of environmental variables recorded at the studied plots, ant species diversity appears largely determined by litter cover, mean temperature, and mean grass cover. Mowing once a year, in the second half of September, after the larvae have left their host plants, enhances the abundance of Myrmica ants in the meadows, and would be the best management compromise for all three species.

Butterfly response to severe ENSO-induced forest fires in Borneo

Abstract.  1. Little is known about animal community response to severe El Niño Southern Oscillation (ENSO)‐induced fire events. Here the response of butterflies to the 1997/98 ENSO‐induced fire event in East Kalimantan (Indonesian Borneo) is assessed. In addition to the community‐wide study, a detailed assessment of the lycaenid Jamides celeno is made.

Endemism in Sardinia

The Tyrrhenian islands are known for their highly relictual fauna and flora and are one of the ten Mediterranean hotspots of plant diversity and endemism. There is little detailed information available on species’biogeography, and new species are still being discovered. This chapter is the first to put together information from several groups of organisms endemic to Sardinia (viz. plants, butterflies, amphibians, lizards, and beetles), with a particular focus on butterflies and amphibians. Reviewing recent literature, we describe distributional patterns and point to centers of endemicity, which we compare with the location and extent of existing protected areas in Sardinia, in order to assess their usefulness in protecting endemic species. Further, we discuss the geological history of the Mediterranean basin and relate geophysical events to molecular-based estimates of species’ divergence times to investigate when and how Sardinian endemics came to the island and describe scenarios of speciation that might have resulted from vicariance, dispersion, and human transportation. The divergence time estimates we summarize here support that the cladogenetic events leading to the Sardinian lineages of various taxa have occurred after the separation of the Sardo-Corsican microplate from the continental landmass and after the rotation of the Corso-Sardinian plate. Furthermore, there is evidence that the split of many Sardinian taxa has occurred after the marine regressions (± 5 mya). Areas of high endemism generally coincide with mountainous areas. The main centers of endemism in Sardinia are already included in a network of natural parks but these areas have not yet been officially accepted as protected areas by the Sardinian authorities. Giving them official status would be a step towards safeguarding the unique nature of Sardinia.

Applying the IUCN threat categories to island endemics: Sardinian butterflies (Italy)

European nature conservation documents, often reflect the charisma of a species rather than its actual degree of threat. The assessment of the threat status of 14 endemic Sardinian butterfly species, underlines that European nature legislation documents are incomplete. Pseudophilotes barbagiae and Lysandra coridon gennargenti (Lycaenidae) are identified as globally Vulnerable and are therefore proposed to be added to the Red Data Book of European butterflies as species of global conservation concern. A threat factor analysis identifies risks towards butterflies in Sardinia arising from increasing human activities. It is shown how the quantitative information used by the IUCN criteria, together with a qualitative assessment of human induced threat factors, could be combined to produce an objective standardised assessment that can be used also when only data on present distribution are available. Threats to Sardinian butterflies are highlighted and conservation measures proposed. The inclusion of Pseudophilotes barbagiae and Lysandra coridon gennargenti in Annex II and IV of the European Habitats Directive, and in Appendix II of the Bern Convention, is strongly recommended.

Genetic differentiation and natural hybridization between the Sardinian endemic Maniola nurag and the European Maniola jurtina.

The Mediterranean island of Sardinia is known for its multitude of unique genetic lineages. We view one of them in a larger phylogeographic context. The endemic Sardinian Meadow Brown butterfly, Maniola nurag, is restricted to the mountainous areas of the island, whereas its widespread close relative, Maniola jurtina, also occurs on the coast. At intermediate altitudes the species’ distributions overlap. There, a number of individuals exhibit phenotypic characteristics intermediate between the two species. We examined patterns of intra‐ and interpopulation variation in 10 M. nurag populations from Sardinia and 16 M. jurtina populations from Sardinia and continental Europe, as well as 17 intermediate individuals, sampled in 1999–2002, by means of allozyme markers, combining it with a morphometric analysis based on 18 wing‐characters of 52 males. At the 15 loci studied (aldolase, aat‐1, aat‐2, g6pdh, gpd, idh‐1, idh‐2, mdh‐1, mdh‐2, mpi, me, leu‐ala, pgi, pgm, and 6pgdh), 76 different alleles were detected, 63 of which were shared by M. nurag and M. jurtina. None of the loci was found to be alternatively fixed between the two species. In that respect, this study testifies to the difficulties that may arise when trying to identify hybrids from genotypic data. Levels of genetic variation in island populations (M. jurtina: HO = 0.137–0.189; M. nurag: HO = 0.141–0.270) were comparable to those of mainland M. jurtina (HO = 0.141–0.236). A Bayesian admixture analysis supported the hypothesis of mixed (hybrid) ancestry of individuals occurring at intermediate altitudes. Similarly, neighbour‐joining and unweighted pair‐group method with arithmetic averaging (UPGMA) analyses, as well as morphometrics hinted at the existence of a Maniola‐hybrid zone in Sardinia at intermediate altitudes. We discuss the results in the light of the phylogeography of other Sardinian taxa with the aim to reach a general understanding of the biogeographic history of this islands endemic species.