Phenotypic evidence for hidden biodiversity in the <Emphasis Type="Italic">Merodon aureus</Emphasis> group (Diptera,Syrphidae) on the Balkan Peninsula: conservation implication

Cryptic species and phenotypic divergent units provided useful information about hidden biodiversity in the Merodon genus (Diptera, Syrphidae) on the Balkan Peninsula. Discrimination three cryptic species within both the M. aureus (M. aureus A, M. aureus B and M. aureus C) and M. cinereus (M. cinereus A, M. cinereus B and M. cinereus C) complexes was done by study of subtle wing variation (wing size and shape) using a geometric morphometric approach. Observed interspecific differentiation is generally in agreement with a previous study using molecular markers (allozyme loci, COI mtDNA). A considerable evolutionary and phenotypic intraspecies diversity of the M. aureus A, M. aureus B, M. aureus C, M. cinereus A, M. cinereus B, M. cinereus C and M. funestus species from the Balkan Peninsula has important implications for diagnosing biodiversity, including endemic and cryptic species. Observed phenotypic divergent units within the species might be considered as an evolutionary potential of the M. aureus group and used for defining conservation priorities. This study has contributed to the recognition of the value of wing traits in order to decipher the hidden diversity and evolutionary diversification.     

Genetic diversity of populations of <Emphasis Type="Italic">Merodon aureus</Emphasis> and <Emphasis Type="Italic">M. cinereus</Emphasis> species complexes (Diptera,Syrphidae): integrative taxonomy and implications for conservation priorities on the Balkan Peninsula

The genetic structure of 10 populations of the Merodon aureus group from the Balkan Peninsula was examined through allozyme electrophoresis and mitochondrial DNA sequencing of the cytochrome c oxidase subunit I (COI). Six diagnosable cryptic taxa were identified within the morphologically defined species M. aureus Fabricius, 1805 and M. cinereus (Fabricius, 1794), with clear separation of the populations (((M. aureus A + M. aureus B) + cinereus complex) + M. aureus C). The parsimony analysis of COI sequence data of the aureus–cinereus complex using Merodon avidus A species as an outgroup resulted in two main clades, (M. aureus A + M. aureus B) and ((M. aureus C + M. cinereus B + M. cinereus C) + M. cinereus A), which differed on average by 5.7%. The observed spatial distribution of the taxonomic diversity of the group suggested that these taxa originated from a common ancestral population in the Mediterranean. Identification of genetic uniqueness and genetic endemism emphasizes the importance of molecular markers and estimation of genetic diversity in recognition of conservation units. The primary goals of the conservation measures that we propose are the protection of phylogenetic lineages within the highly diverse M. aureus group taxa and conservation of the genetic variation through management of important areas.     

Evidence of a complex phylogeographic structure in the common dormouse,Muscardinus avellanarius (Rodentia: Gliridae)

This is the first mitochondrial phylogeography of the common dormouse, Muscardinus avellanarius (Linnaeus, 1758), a hibernating rodent strictly protected in Europe (Habitat Directive, annex IV; Bern Convention, annex III). The 84 individuals of M. avellanarius, sampled throughout the distributional range of the species, have been sequenced at the mitochondrial DNA gene (cytochrome b, 704 base pairs). The results revealed two highly divergent lineages, with an ancient separation around 7.7 Mya and a genetic divergence of 7.7%. Lineage 1 occurs in Western Europe (France, Belgium, and Switzerland) and Italy, and lineage 2 occurs in Central–Northern Europe (Poland, Germany, Latvia, and Lithuania), on the Balkan Peninsula, and in Turkey. Furthermore, these two lineages are subdivided into five sublineages genetically isolated with a strong geographical association. Therefore, lineage 1 branches into two further sublineages (Western European and Italian), whereas lineage 2 contained three sublineages (Central–Northern European, Turkish, and Balkan). We observed low genetic diversity within the sublineages, in contrast to the significant level of genetic differentiation between them. The understanding of genetic population structure is essential for identifying units to be conserved. Therefore, these results may have important implications for M. avellanarius conservation. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 648–664.     

AFLP analysis shows high incongruence between genetic differentiation and morphology‐based taxonomy in a widely distributed tortoise

Morphology has traditionally been used to diagnose the taxa of various taxonomic ranks. However, there is growing evidence that morphology is not always able to reveal cryptic taxa, and that pronounced morphological variation could reflect phenotypic plasticity rather than evolutionary divergence. Spur‐thighed tortoises (the Testudo graeca complex), distributed in the western Palaearctic region, are characterized by high morphological variability and complicated taxonomy, which are under debate. Previous molecular studies using mainly mitochondrial DNA (mtDNA) sequences have revealed incongruence between genetic differentiation and morphology‐based taxonomy, suggesting that morphological variability is the result of phenotypic plasticity and stabilizing selection, which masks the true genealogies. In the present study, we used a range‐wide sampling and nuclear Amplified fragment length polymorphism (AFLP) markers to investigate genetic differentiation within the T. graeca complex. We found that spur‐thighed tortoises are differentiated into four geographically well‐defined AFLP groups: Balkans–Middle Eastern, western Mediterranean, Caucasian and central‐eastern Iranian. Compared with the distribution of mtDNA lineages, the groups are largely concordant, although the AFLP markers are less sensitive and distinguish fewer groups than do mtDNA sequences. The AFLP groups show an allopatric or parapatric distribution. The AFLP differentiation conflicts with the previously proposed morphology‐based taxonomy of the complex, suggesting that local adaptation to different environmental conditions may have led to the great extent of morphological variation within the same lineages. We propose a re‐evaluation of the taxa that were confirmed genetically using a thorough morphological analysis corrected for phenotypic plasticity. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

A new cytochrome b phylogroup of the common vole (Microtus arvalis) endemic to the Balkans and its implications for the evolutionary history of the species

The phylogeographic architecture of the common vole, Microtus arvalis, has been well‐studied using mitochondrial DNA and used to test hypotheses relating to glacial refugia. The distribution of the five described cytochrome b (cyt b) lineages in Europe west of Russia has been interpreted as a consequence of postglacial expansion from both southern and central European refugia. A recently proposed competing model suggests that the ‘cradle’ of the M. arvalis lineages is in western central Europe from where they dispersed in different directions after the Last Glacial Maximum. In the present study, we report a new cyt b lineage of the common vole from the Balkans that is not closely related to any other lineage and whose presence might help resolve these issues of glacial refugia. The Balkan phylogroup occurs along the southern distributional border of M. arvalis in central and eastern Bosnia and Herzegovina, Montenegro, and eastern Serbia. Further north and west in Slovenia, Bosnia and Herzegovina, and Serbia, common voles belong to the previously‐described Eastern lineage, whereas both lineages are sympatric in one site in Bosnia and Herzegovina. The Balkan phylogroup most reasonably occupied a glacial refugium already known for various Balkan endemic species, in contrast to the recently proposed model. South‐east Europe is an absolutely crucial area for understanding the postglacial colonization history of small mammals in Europe and the present study adds to the very few previous detailed phylogeographic studies of this region. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 788–796.     

Parallel evolution of insular Olea europaea subspecies based on geographical structuring of plastid DNA variation and phenotypic similarity in leaf traits

Strong geographical isolation within the distribution of a species may result in differentiated lineages exhibiting conspicuous phenotypic differences. In the present paper, we investigate whether plastid and phenotypic variation is geographically structured within the Olea europaea complex in Macaronesia, which comprises three subspecies separated by oceanic barriers: maroccana (south‐west Morocco), guanchica (Canary Islands) and cerasiformis (Madeira archipelago). Plastid variation showed a significant pattern of geographical structure (N_ST > G_ST = 0.56), because of the lack of shared haplotypes among subspecies and the presence of a single and private haplotype in the eastern Canary Islands. Such a clear molecular structure, however, was not reflected in a congruent pattern of phenotypic differentiation among taxa in leaf morpho‐functional traits. Despite the substantial genetic differentiation observed between the subspecies from Madeira and the Canary Islands, they displayed both higher leaf size (leaf area) and specific leaf area (leaf surface area‐to‐mass ratio) than their continental counterparts, probably as a result of oceanic conditions in subtropical environments. Unlike most of the plant groups previously studied in the Macaronesian region, the lineages of Olea illustrate how low phenotypic differentiation can be also related to a clear molecular differentiation in oceanic island enclaves. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 54–63.     

Wing morphology is related to host plants in cactophilic Drosophila gouveai and Drosophila antonietae (Diptera,Drosophilidae)

A central issue in evolutionary biology is to understand the mechanisms promoting morphological evolution during speciation. In a previous study, we showed that the Neotropical cactophilic sibling species Drosophila gouveai and Drosophila antonietae can be reared in media prepared with their presumptive natural host plants (Pilosocereus machrisis and Cereus hildmaniannus) and that egg to adult viability is not independent of the cactus host. In the present study, we investigate the effects of ecological and genetic factors on interspecific divergence in wing morphology, in relation to the pattern of wing venation and phenotypic plasticity in D. gouveai and D. antonietae, by means of the comparative analysis of isofemale lines reared in the two cactus hosts. The species differed significantly in wing size and shape, although specific differences were mainly localized in a particular portion of the wing. We detected significant variation in form among lines, which was not independent of the breeding cactus, suggesting the presence of genetic variation for phenotypic plasticity and wing shape variation in both species. We discuss the results considering the plausible role of host plant use in the evolutionary history of cactophilic Drosophila inhabiting the arid zones of South America. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 655–665.     

Landscape genetic analysis of the tropical freshwater fish Mogurnda mogurnda (Eleotridae) in a monsoonal river basin: importance of hydrographic factors and population history

1. We performed spatial genetic analyses, incorporating landscape genetic methods using microsatellite data and phylogeographic analyses using mtDNA data, to identify the principal factors that determine population heterogeneity of the tropical freshwater fish, Mogurnda mogurnda, in the Daly River, northern Australia. We tested the individual and interactive effects of several environmental variables on spatial genetic patterns, including metrics relating to connectivity (i.e. stream distance, maximum stream gradient and elevation), habitat size (i.e. mean annual discharge) and a categorical variable relating to population history, as determined by mtDNA phylogeographic analyses. The Daly River is geomorphologically and hydrologically complex, and M. mogurnda has life history traits that limit its dispersal potential at river basin scales. Thus, we predicted that variables relating to connectivity would be the most important landscape factors driving population structure of the species. 2. Tree‐based phylogeographic analyses indicated four divergent mtDNA lineages within M. mogurnda in the Daly River, although three of the lineages were sympatric in various combinations and did not correspond with microsatellite groups identified by assignment tests. The allopatric mtDNA lineage detected in the uppermost part of the catchment was also identified as being highly differentiated by the microsatellite data, strongly suggesting that it may be a cryptic species. This site was therefore excluded from subsequent landscape genetic analyses. 3. Analyses of Molecular Variance indicated that M. mogurnda has a hierarchical population structure in the Daly River, thus supporting theoretical expectations that hierarchically arranged river habitats in dendritic systems impose hierarchal population structures on lotic species. 4. All landscape genetic analyses rejected stream distance, and supported stream gradient, as the major determinant of spatial genetic variation in M. mogurnda in the Daly River. Support for elevation as a determinant of spatial genetic patterns differed among the landscape genetic methods. Several of the landscape genetic methods also indicate that population history, including secondary contact between divergent and formerly allopatric genetic lineages, has a strong influence on spatial genetic patterns within M. mogurnda in the Daly River. 5. This study demonstrates the need to consider multiple environmental factors, especially factors relating to connectivity, and their interactions in spatial genetic analysis, rather than just geographic distance. Importantly, it demonstrates the need to account for population history and evolutionary divergences in landscape genetic analyses.     

Incongruous nuclear and mitochondrial phylogeographic patterns in two sympatric lineages of the wolf spider Pardosa astrigera (Araneae: Lycosidae) from China

We investigated the genetic structure of mitochondrial DNA (COI and 16S rRNA-tRNA(Leu(CUN))-ND1) and nuclear DNA (ITS2) variations among and within populations of Pardosa astrigera in China. Two phenotypes of males were recognized. They differed genetically also in the presence (type A) or absence (type B) of common insertions and deletions in ITS2. The concordance between mtDNA based phylogeny and the phenotypic variations of P. astrigera was weak. Haplotypes of type A did not form a monophyletic group. Instead they were found in three clades, in one of them mixed with type B haplotypes, most likely as a result of long-term and ongoing gene flow of mtDNA between the two phenotypic groups (M = 0.69). Pairwise sequence divergences of all data sets indicated that the genetic divergences between the two phenotypes fall within intraspecific range. Our results indicated that the P. astrigera populations in China consist of two sympatric lineages with male phenotypic variations. Patterns of mismatch distribution within lineages suggested long-term demographic stability in the lineage A, and growth in lineage B that expanded rapidly and recolonized from a southern refuge to the northern parts of China during the late-Pleistocene. On the basis of the estimated divergence time between the two lineages (0.18-0.41 Ma), we suggest that the dry-cold climate and the uplift of the Tibetan plateau during the mid-Pleistocene appear to have a determinating impact on the evolutionary history of P. astrigera in China.     

Repeated evolution of sympatric,palaeoendemic species in closely related,co‐distributed lineages of Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) across a sky‐island archipelago in Peninsular Malaysia

A time‐calibrated phylogenetic tree indicates that the evolution of sympatric, montane, endemic species from closely related, co‐distributed lineages of the Hemiphyllodactylus harterti group were not the result of rapid, forest‐driven, climatic oscillations of the Last Glacial Maximum, but rather the result of infrequent episodes of environmental fluctuation during the Late Miocene. This hypothesis is supported by genetic divergences (based on the mitochondrial gene ND2) between the three major lineages of the H. harterti group (17.5–25.1%), their constituent species (9.4–14.3%), and the evolution of discrete, diagnostic, morphological, and colour pattern characteristics between each species. Sister species pairs from two of the three lineages occur in sympatry on mountain tops from opposite sides of the Thai–Malay Peninsula, but the lineages to which each pair belongs are not sister lineages. A newly discovered species from Gunung Tebu, Terengganu State, H emiphyllodactylus bintik sp. nov. , is described. © 2015 The Linnean Society of London     

Molecular diversity of populations of the Merodon ruficornis group (Diptera, Syrphidae) on the Balkan Peninsula

Genetic diversity of 11 populations of the Merodon ruficornis group (Diptera, Syrphidae) on the Balkan Peninsula was quantified using allozyme electrophoresis and nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I. A total of 10 haplotypes of mtDNA were found in 22 analysed individuals. One haplotype was shared between M. loewi (from Pindos and Duba?nica Mts) and M. armipes, one confined to M. auripes (haplotype III) and M. armipes (VII) and three to M. trebevicensis (VIII, IX and X), M. ruficornis (I, II and IV) and M. loewi (V, VI and VII). Analysis of the population genetic structure parameters showed great differences among analysed species. Different levels of genetic variability suggested that a variety of biological, environmental and/or historical factors had influenced these hoverfly populations. The unweighted pair group method with arithmetic average dendrogram constructed using allozyme data suggested that M. loewi was the most divergent species in comparison with M. armipes, M. auripes, M. ruficornis and M. trebevicensis. Clear separation of the populations ((((M. armipes + M. auripes) + M. ruficornis) + M. trebevicensis) + M. loewi) was observed. The parsimony analysis of the M. ruficornis group using Merodon avidus as outgroup resulted in three equally parsimonious trees, and the strict consensus presented the following relationships ((((M. loewi + M. armipes) + (M. auripes)) + (M. trebevicensis)) + (M. ruficornis)))). The uncorrected interspecies pairwise sequence divergences ranged from 1.69% (between haplotype III of M. armipes and haplotype V of M. loewi) to 4.94% (between M. ruficornis and M. trebevicensis).     

Genetic patterns in the Lathyrus pannonicus complex (Fabaceae) reflect ecological differentiation rather than biogeography and traditional subspecific division

The endangered European relict species complex Lathyrus pannonicus shows distinct morphological variation, reflected by the number of subspecies recognized, and complicated patterns of genetic variation. The traditionally recognized subspecies appear to possess different ecological preferences and disjunct distributions, particularly in the western range of the species. In this study, L. pannonicus was investigated by the correlation of distance matrices based on phytosociological, ecological, molecular and morphological data. Ecological characteristics of selected stands of L. pannonicus throughout Europe were assessed using ‘Ellenberg values’ of all the constituent taxa in phytosociological relevés. Genetic distances were calculated using recently developed methods to analyse high degrees of intra‐individual nuclear‐encoded internal transcribed spacer variability. We found that the remarkable genetic (and morphological) diversity in L. pannonicus could not be explained solely by the fragmentation of the distributional range. Instead, patterns of morphological and genetic differentiation were a reflection of the moisture regime in the sampled stands. Two major lineages could be identified: (1) a lineage adapted to dry conditions (Ellenberg indicator F‐value ≤ 3.5) and (2) a lineage preferring moist conditions (F‐value ≥ 4.5). Although both lineages occurred in close proximity in the Pannonian area, they appeared to be reproductively isolated in general. Further data are needed to determine whether these genetically and ecologically defined lineages, or ecospecies, within the L. pannonicus species complex can be formalized as (Linnaean) species or subspecies. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 402–421.     

Biased dispersal of Metrioptera bicolor,a wing dimorphic bush‐cricket

In the highly fragmented landscape of central Europe, dispersal is of particular importance as it determines the long‐term survival of animal populations. Dispersal not only secures the recolonization of patches where populations went extinct, it may also rescue small populations and thus prevent local extinction events. As dispersal involves different individual fitness costs, the decision to disperse should not be random but context‐dependent and often will be biased toward a certain group of individuals (e.g., sex‐ and wing morph‐biased dispersal). Although biased dispersal has far‐reaching consequences for animal populations, immediate studies of sex‐ and wing morph‐biased dispersal in orthopterans are very rare. Here, we used a combined approach of morphological and genetic analyses to investigate biased dispersal of Metrioptera bicolor, a wing dimorphic bush‐cricket. Our results clearly show wing morph‐biased dispersal for both sexes of M. bicolor. In addition, we found sex‐biased dispersal for macropterous individuals, but not for micropters. Both, morphological and genetic data, favor macropterous males as dispersal unit of this bush‐cricket species. To get an idea of the flight ability of M. bicolor, we compared our morphological data with that of Locusta migratoria and Schistocerca gregaria, which are very good flyers. Based on our morphological data, we suggest a good flight ability for macropters of M. bicolor, although flying individuals of this species are seldom observed.     

Phylogenetic analysis,taxonomic revision,and dental ontogeny of the Cretaceous Zhelestidae (Mammalia: Eutheria)

Iphisa elegans Gray, 1851 is a ground‐dwelling lizard widespread over Amazonia that displays a broadly conserved external morphology over its range. This wide geographical distribution and conservation of body form contrasts with the expected poor dispersal ability of the species, the tumultuous past of Amazonia, and the previously documented prevalence of cryptic species in widespread terrestrial organisms in this region. Here we investigate this homogeneity by examining hemipenial morphology and conducting phylogenetic analyses of mitochondrial (CYTB) and nuclear (C‐MOS) DNA sequence data from 49 individuals sampled across Amazonia. We detected remarkable variation in hemipenial morphology within this species, with multiple cases of sympatric occurrence of distinct hemipenial morphotypes. Phylogenetic analyses revealed highly divergent lineages corroborating the patterns suggested by the hemipenial morphotypes, including co‐occurrence of different lineages. The degrees of genetic and morphological distinctness, as well as instances of sympatry among mtDNA lineages/morphotypes without nuDNA allele sharing, suggest that I. elegans is a complex of cryptic species. An extensive and integrative taxonomic revision of the I. elegans complex throughout its wide geographical range is needed. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 361–376.     

Patterns of genetic and morphometric differentiation in Melitaea (Mellicta) athalia (Lepidoptera: Nymphalidae)

Patterns of genetic and morphometric differentiation were surveyed in Melitaea (Mellicta) athalia populations of the Carpathian Basin. This species has a wide distribution and exists under a wide variety of ecological conditions. It has two ecotypes in Hungary: with either one or two broods per year. It is of particular interest to reveal the main factors driving differentiation patterns in this species. Samples in our study were obtained from five Hungarian and one Transylvanian (Romanian) regions. Enzyme polymorphism, wing characters and male external genitalia were analysed using traditional morphometric methods. Statistical methods were optimized to compare morphological and genetic data. The results of genetic surveys revealed a clear regional pattern of differentiation in M. athalia. Moreover, the results of principal component analysis, Bayesian clustering and the dendrogram all suggested that the regions can be classified into two groups corresponding to the East or West zones of the Carpathian Basin. In contrast, differentiation between the two ecotypes was less expressed in the genetic variation of M. athalia. Results of the analyses conducted on phenotypic variation also suggested a regional pattern for both sets of morphometric characters (wings and external genitalia). At the same time, neither East–West regional division nor ecotype differentiation was detected in the morphometric studies. In sum, our analyses confirmed that both genetic and phenotypic variations of M. athalia exhibit a regional pattern rather than the differentiation between the two ecotypes. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

The genus Troglophilus Krauss, 1879 (Orthoptera: Rhaphidophoridae) in the west Balkans

We present a revision of the genus Troglophilus in the western part of the Balkan Peninsula based on morphological and genetic analysis, and provide distribution data for the species. The results of these analyses reduced the number of the known taxa within the genus Troglophilus in this area to five valid species: Troglophilus cavicola ( Kollar, 1833 ), Troglophilus neglectus Krauss, 1879 , Troglophilus ovuliformis Karny, 1907 , Troglophilus brevicauda Chopard, 1934, and Troglophilus lazaropolensis Karaman, 1958. A new species Troglophilus zorae sp. nov. is described and Troglophilus neglectus serbicus Maran, 1958, Troglophilus neglectus vlasinensis Maran, 1958, Troglophilus bukoviki Karaman, 1968 and Troglophilus pretneri Us, 1970 are synonymized. The distribution pattern of the western Balkan species supports a general east?west migration route. We also determined the centres of origin and spreading directions of particular species according to the distribution of the taxa and the structure of the haplotypes. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 1035–1063.     

Complex patterns of morphological and mtDNA variation in Lacerta perspicillata (Reptilia; Lacertidae)

Lacerta perspicillata is a north-west African lacertid lizard that shows considerable intraspecific variation, with three subspecies described on the basis of colour pattern and body size. Recent observations of a population containing two morphological forms and more than one deep genetic lineage, as well as an apparent lack of concordance between forms and genetic lineages, suggest that the complexity is greater than previously thought. To analyse and quantify this variation, we studied the variability within this species at two levels: (1) external morphology (multivariate analysis of scalation, body dimensions, and colour pattern) and (2) mtDNA (sequencing and single-strand confirmation polymorphism analysis). Fifty-two individuals were studied at Taza, northern Morocco. Two morphological groupings (ostensibly representing two previously described subspecies) and two deep mtDNA lineages were detected at this site, with complete correspondence between the two. This, together with an apparent lack of hybrids, would normally support respective full species recognition. However, analysis of 98 individuals from other populations demonstrated that the situation is highly complex with the same genetic lineages having reversed morphotypes in other areas, making such a designation difficult. Across the other studied populations, we found no support for any of the currently recognized subspecies. The lack of congruence between mtDNA lineages and morphometric patterns (in some cases) and the morphological similarity among lizards from different lineages suggest ecophenotypic convergence or multiple introgressive hybridization. The study highlights the tremendous complexity that may exist within a taxon and the inadequacy of older alpha-taxonomy based designations in describing it.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 479–490.     

Hybridization and transgressive exploration of colour pattern and wing morphology in Heliconius butterflies

Hybridization can generate novel phenotypes distinct from those of parental lineages, a phenomenon known as transgressive trait variation. Transgressive phenotypes might negatively or positively affect hybrid fitness, and increase available variation. Closely related species of Heliconius butterflies regularly produce hybrids in nature, and hybridization is thought to play a role in the diversification of novel wing colour patterns despite strong stabilizing selection due to interspecific mimicry. Here, we studied wing phenotypes in first‐ and second‐generation hybrids produced by controlled crosses between either two co‐mimetic species of Heliconius or between two nonmimetic species. We quantified wing size, shape and colour pattern variation and asked whether hybrids displayed transgressive wing phenotypes. Discrete traits underlain by major‐effect loci, such as the presence or absence of colour patches, generate novel phenotypes. For quantitative traits, such as wing shape or subtle colour pattern characters, hybrids only exceed the parental range in specific dimensions of the morphological space. Overall, our study addresses some of the challenges in defining and measuring phenotypic transgression for multivariate traits and our data suggest that the extent to which transgressive trait variation in hybrids contributes to phenotypic diversity depends on the complexity and the genetic architecture of the traits.     

Phenotypic evolution of an Atlantic Forest passerine (Xiphorhynchus fuscus): biogeographic and systematic implications

We studied the phenotypic variation of the Atlantic Forest passerine Xiphorhynchus fuscus (Aves: Dendrocolaptidae) with the broad aim of addressing whether the history and type of forest affected the evolution of endemic taxa. We also tested whether the different subspecies and genetic lineages of X. fuscus could be considered full species. We collected plumage and body size measurements and, in combination with genetic data, used multivariate tests to evaluate the working hypotheses. Our results, combined with previous biogeographic analyses, indicate that vicariant events have been important determinants in the evolution of phenotypic characters of X. fuscus, once genetic isolation was complete. Our analysis also suggests that forest heterogeneity and ecotones are important factors in the early evolution of Atlantic Forest taxa, perhaps via divergent selection. Forest instability during the Pleistocene was critical in the evolution of phenotypic traits. We confirm that the subspecies atlanticus should be considered a full species. Other lineages or populations are also phenotypically differentiated but we do not suggest considering them as full species. They share high levels of gene flow and are part of a continuous latitudinal cline of phenotypic variation. Our study suggests that not all the historic events in the Atlantic Forest that affected the evolution of genetic lineages also influenced the evolution of phenotypic characters in the same direction and intensity. Undoubtedly, natural selection played a major role in the evolution of Atlantic Forest organisms. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 1047–1066.     

Almost but not quite a subspecies: a case of genetic but not morphological diagnosability in Nicrophorus (Coleoptera: Silphidae)

Allopatric populations that show genetic differentiation but lack phenotypic diagnosability are difficult to classify. In 1946, Arnett described a new species of burying beetle (Silphidae: Nicrophorus) from Luzon Island, Philippines, Nicrophorus benguetensis. In 2002, Sikes et al., finding the species to be inconsistently diagnosable, synonymized N. benguetensis under Nicrophorus nepalensis Hope 1831. We rigorously and quantitatively test the validity of N. benguetensis using several different species delimitation criteria. We employed discrete and quantitative character‐based methods to test similarity criteria using linear morphometrics in a discriminant analysis framework, and percentage sequence divergences based on sequences from four mitochondrial DNA (mtDNA) genes (COI, COII, ND4 and ND5) and two nuclear genes [28S (D2 region) and CAD]. We also employed tree‐based methods to test phylogenetic criteria using mtDNA sequences and morphology with parsimony, Bayesian inference and maximum likelihood. The analysis of discrete phenotypic characters did not reliably diagnose N. benguetensis. The results of the discriminant analysis provided moderate support for the validity of N. benguetensis (71.4% of the specimens were properly classified). There is adequate genetic distance between N. benguetensis and its nearest neighbour for DNA barcoding to identify an unknown sequence, although this may be an artefact of the small sample size. Phylogenetic analyses of the morphological data, with and without the morphometric data, yielded unresolved trees. Molecular phylogenetic results found N. benguetensis to be monophyletic, but neither clearly rejected nor supported its validity. Two of our approaches using molecular data diagnosed N. benguetensis, but those that used phenotypic data did not exceed a 75% success rate. We conclude, therefore, that N. benguetensis, despite being a weakly distinct allopatric population, and deserving of additional study, should remain synonymized until further analysis suggests otherwise. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 311–333.