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Species Boundaries (species + boundary)
Selected AbstractsSpawning times, reproductive compatibilities and genetic structuring in the Acropora aspera group: evidence for natural hybridization and semi-permeable species boundaries in coralsMOLECULAR ECOLOGY, Issue 8 2002Madeleine J. H. Van Oppen Abstract Species boundaries among five sympatric coral species of the Indo-Pacific Acropora aspera group were examined by a combination of in vitro breeding trials, comparisons of spawning times and DNA sequence analysis of ribosomal DNA internal transcribed spacer (rDNA ITS) and 5.8S regions. The breeding trials showed that reproductive compatibility exists between at least some colonies of all the species pairs tested, suggesting a large potential for natural hybridization and introgression. The Acropora ITS regions exhibited extremely high levels of variability (up to ,62% for ITS1, ,11% for 5.8S and ,43% for ITS2), but most of the variation was shared among four of the five species, A. millepora, A. papillare, A. pulchra and A. spathulata, consistent with extensive introgression. Phylogenetic analyses did not resolve these four species as distinct clusters across a wide biogeographic region stretching from the southern Great Barrier Reef to Papua New Guinea. However, most colonies of the fifth species, A. aspera, constituted a distinct clade in phylogenetic analyses. This is consistent with our observations of a semi-permeable temporal barrier involving differences in spawning times between this and the other four species. Although the majority of colonies of all five species generally spawned within 90 min of each other, in two out of four years, gametes were absent prior to mass spawning episodes from at least some A. aspera colonies. Hence, our data suggest that transient reproductive barriers may be the result of year-to-year variation in the date of spawning and that this difference in spawning time contributes to the genetic structure detected among Acropora species in this group. Occasional leakage through the reproductive barrier was confirmed by the observation of A. aspera ×A. pulchra F1 hybrids, identified based on additivity of ITS sequences. [source] A morphometric analysis of the Bonatea speciosa complex (Orchidaceae) and its implications for species boundariesNORDIC JOURNAL OF BOTANY, Issue 3 2009Mariaan E. Ponsie Species boundaries in rapidly evolving lineages are often blurred, necessitating analysis of the full range of variation within a complex in order to identify traits that can be used to diagnose taxa. The delimitation of Bonatea speciosa (L. f.) Willd. has been controversial, as most, but not all, recent authors have included within the concept of this species several additional taxa that were formerly recognised at the species level, including Bonateaboltonii (Harv.) Bolus and Bonateaantennifera Rolfe. Morphological variation across the Bonateaspeciosa complex (Orchidaceae) was explored using principal component and cluster analysis. Scatter plots were used to identify characters that could potentially be used to diagnose taxa. These data support the recognition of three distinct species, B.speciosa, B.antennifera and B.boltonii, instead of a single entity. A taxonomic account of southern African taxa within the B. speciosa complex is presented. [source] Historical DNA from museum type specimens clarifies diversity of Asian leaf turtles (Cyclemys)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2008BRYAN L. STUART Species boundaries in Asian leaf turtles of the genus Cyclemys are difficult to define on the basis of morphology, primarily because many populations exhibit considerable ontogenetic variation in shell and head coloration. Two recent molecular phylogenetic hypotheses of Cyclemys species relationships, based largely on market and pet-trade samples of uncertain provenance, were highly incongruent. We used historical DNA methods to sequence fragments of the mitochondrial cytochrome b gene from eight type specimens of Cyclemys (including one collected by Alfred Russel Wallace), and phylogenetically placed these type sequences into the context of published cytochrome b variation. Our phylogenetic hypothesis supports the recognition of four named species (Cyclemys atripons, Cyclemys dentata, Cyclemys oldhamii, and C. pulchristriata), as well as a fifth species of unknown geographical provenance obtained from the Hong Kong pet trade. The type sequences show that previous molecular phylogenetic studies were hampered by misidentifications, supporting the notion that Cyclemys of unknown provenance are not reliably identified to species solely on the basis of morphology. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 131,141. [source] WHEN VICARS MEET: A NARROW CONTACT ZONE BETWEEN MORPHOLOGICALLY CRYPTIC PHYLOGEOGRAPHIC LINEAGES OF THE RAINFOREST SKINK, CARLIA RUBRIGULARISEVOLUTION, Issue 7 2004Ben L. Phillips Abstract Phylogeographic analyses of the fauna of the Australian wet tropics rainforest have provided strong evidence for long-term isolation of populations among allopatric refugia, yet typically there is no corresponding divergence in morphology. This system provides an opportunity to examine the consequences of geographic isolation, independent of morphological divergence, and thus to assess the broader significance of historical subdivisions revealed through mitochondrial DNA phylogeography. We have located and characterized a zone of secondary contact between two long isolated (mtDNA divergence > 15%) lineages of the skink Carlia rubrigularis using one mitochondrial and eight nuclear (two intron, six microsatellite) markers. This revealed a remarkably narrow (width<3 km) hybrid zone with substantial linkage disequilibrium and strong deficits of heterozygotes at two of three nuclear loci with diagnostic alleles. Cline centers were coincident across loci. Using a novel form of likelihood analysis, we were unable to distinguish between sigmoidal and stepped cline shapes except at one nuclear locus for which the latter was inferred. Given estimated dispersal rates of 90,133 m X gen,1/2 and assuming equilibrium, the observed cline widths suggest effective selection against heterozygotes of at least 22,49% and possibly as high as 70%. These observations reveal substantial postmating isolation, although the absence of consistent deviations from Hardy-Weinberg equilibrium at diagnostic loci suggests that there is little accompanying premating isolation. The tight geographic correspondence between transitions in mtDNA and those for nuclear genes and corresponding evidence for selection against hybrids indicates that these morphologically cryptic phylogroups could be considered as incipient species. Nonetheless, we caution against the use of mtDNA phylogeography as a sole criterion for defining species boundaries. [source] Molecular systematics of the speciose Indo-Pacific soft coral genus, Sinularia (Anthozoa: Octocorallia)INVERTEBRATE BIOLOGY, Issue 4 2009Catherine S. McFadden Abstract. The speciose tropical soft coral genus Sinularia traditionally has been divided into five intrageneric taxonomic groups based on variation in a single morphological character: the shape of the club sclerites (calcite skeletal elements) embedded in the surface tissues of the colony. To test the phylogenetic utility of this system of classification, we used a 735-bp fragment of the octocoral-specific mitochondrial msh1 gene to construct a molecular phylogeny that included 80 of the ,150 recognized morphospecies of Sinularia. The msh1 phylogeny recovered five well-supported clades, but they were not congruent with the traditional intrageneric taxonomic groups. Mapping of characters onto the tree suggested that the five major clades plus several additional sub-clades of Sinularia can be distinguished based on a suite of four morphological characters; these include the presence of sclerites in the tentacle, collaret, and point regions of the polyps, in addition to the shape of the club sclerites in the surface tissues. The overall growth form of the colony also distinguishes some clades. Polyp sclerites have for the most part been overlooked taxonomically in Sinularia, and as a result information on these characters is lacking or is incorrect in many species descriptions. As has been the case in other recent studies of lower metazoan groups, construction of a molecular phylogeny has led us to recognize the phylogenetic and taxonomic importance of previously overlooked morphological characters. A revised taxonomic key that includes these characters is already improving our ability to discriminate species boundaries, and facilitating description of new Sinularia species. [source] Phylogenetic relationships within the tropical soft coral genera Sarcophyton and Lobophytum (Anthozoa, Octocorallia)INVERTEBRATE BIOLOGY, Issue 4 2006Catherine S. McFadden Abstract. The alcyonacean soft coral genera Sarcophyton and Lobophytum are conspicuous, ecologically important members of shallow reef communities throughout the Indo-West Pacific. Study of their ecology is, however, hindered by incomplete knowledge of their taxonomy: most species cannot be identified in the field and the two genera cannot always be distinguished reliably. We used a 735-bp fragment of the octocoral-specific mitochondrial protein-coding gene msh1 to construct a phylogeny for 92 specimens identified to 19 species of Lobophytum and 16 species of Sarcophyton. All phylogenetic methods used recovered a tree with three strongly supported clades. One clade included only morphologically typical Sarcophyton species with a stalk distinct from the polypary, poorly formed club-shaped sclerites in the colony surface, and large spindles in the interior of the stalk. A second clade included only morphologically typical Lobophytum colonies with lobes and ridges on the colony surface, poorly formed clubs in the colony surface, and interior sclerites consisting of oval forms with regular girdles of ornamental warts. The third distinct clade included a mix of Sarcophyton and Lobophytum nominal species with intermediate morphologies. Most of the species in this mixed clade had a polypary that was not distinct from the stalk, and the sclerites in the colony surface were clubs with well-defined heads. Within the Sarcophyton clade, specimens identified as Sarcophyton glaucum belonged to six very distinct genetic sub-clades, suggesting that this morphologically heterogeneous species is actually a cryptic species complex. Our results highlight the need for a complete taxonomic revision of these genera, using molecular data to help confirm species boundaries as well as to guide higher taxonomic decisions. [source] Patterns in diversity of anurans along an elevational gradient in the Western Ghats, South IndiaJOURNAL OF BIOGEOGRAPHY, Issue 5 2007Rohit Naniwadekar Abstract Aim, To examine patterns in anuran species richness along an elevation gradient and identify factors that govern anuran species richness on a tropical elevational gradient. Location, Sampling for anurans was carried out in Kalakad Mundanthurai Tiger Reserve (KMTR) in the southern Western Ghats, India. Methods, Night-time sampling for anuran species richness was carried out from 20 November 2004 to 20 April 2005, during the north-east monsoon and dry seasons, using transects (50 × 2 m) and visual encounter surveys along the streams. The entire gradient was classified into thirteen 100-m elevation zones. Sampling at the alpha (single drainage basin) level was carried out in the Chinnapul River drainage basin (40,1260 m a.s.l.) and at the gamma (landscape) level in four drainage basins. Additionally, published records were used to arrive at an empirical species richness (S) for the entire landscape. Mid-Domain Null software was used to test for the possible influence of geometric constraints on anuran species at both the alpha and gamma levels. The influence of area under each elevation zone on empirical S was tested. The pattern in anuran species richness along the elevational gradient was investigated using: (1) species boundaries in each elevation zone and their habitat correlates, (2) abiotic factors as predictor variables, (3) mean snout vent lengths of anurans, and (4) correlation between the matrices of distance in the elevation zones based on microhabitat parameters and species composition. Cluster analysis on species presence,absence in the elevation zones was used to categorize the entire gradient into high, middle and low elevations. In these three elevation categories, pattern in composition of species was examined for endemism in Western Ghats,Sri Lanka biodiversity hotspot, uniqueness to an elevation zone, adaptations of adults and modes of breeding. Results, Species richness at the alpha level increased linearly with elevation, while at the gamma level there were three peaks. Maximum species richness was observed at the highest elevation (1200 m) at both the alpha and the gamma levels. The observed patterns differed significantly from mid-domain null predictions. The multi-modal pattern in species richness was a consequence of overlapping species range boundaries. Soil temperature was the best single measure in explaining the majority of variation in species richness at the alpha level (r2 = 0.846, P < 0.01). However, soil moisture was the best predictor when both the alpha and the gamma sites were pooled (r2 = 0.774, P < 0.01). Anuran body size decreased with an increase in elevation. The highest proportions of endemic and unique species were found at high elevations (> 700 m). The proportion of arboreal anurans increased from low to high elevation. Anurans exhibiting direct development were predominantly found at high elevations. Main conclusions, Geometric constraints did not influence anuran species richness along the elevational gradient. Overlapping range boundaries influenced species richness at the gamma level. Abiotic factors such as soil temperature and moisture influenced anuran species richness in the mountain range. The ,Massenerhebung effect' could be responsible for range restriction and endemism of anurans, differences in guilds and mode of reproduction. These findings highlight the importance of cloud forests for endemic anurans. [source] Differentiation of morphology, genetics and electric signals in a region of sympatry between sister species of African electric fish (Mormyridae)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2008S. LAVOUÉ Abstract Mormyrid fishes produce and sense weak electric organ discharges (EODs) for object detection and communication, and they have been increasingly recognized as useful model organisms for studying signal evolution and speciation. EOD waveform variation can provide important clues to sympatric species boundaries between otherwise similar or morphologically cryptic forms. Endemic to the watersheds of Gabon (Central Africa), Ivindomyrus marchei and Ivindomyrus opdenboschi are morphologically similar to one another. Using morphometric, electrophysiological and molecular characters [cytochrome b sequences and amplified fragment length polymorphism (AFLP) genotypes], we investigated to what extent these nominal mormyrid species have diverged into biological species. Our sampling covered the known distribution of each species with a focus on the Ivindo River, where the two taxa co-occur. An overall pattern of congruence among datasets suggests that I. opdenboschi and I. marchei are mostly distinct. Electric signal analysis showed that EODs of I. opdenboschi tend to have a smaller initial head-positive peak than those of I. marchei, and they often possess a small third waveform peak that is typically absent in EODs of I. marchei. Analysis of sympatric I. opdenboschi and I. marchei populations revealed slight, but significant, genetic partitioning between populations based on AFLP data (FST , 0.04). Taken separately, however, none of the characters we evaluated allowed us to discriminate two completely distinct or monophyletic groups. Lack of robust separation on the basis of any single character set may be a consequence of incomplete lineage sorting due to recent ancestry and/or introgressive hybridization. Incongruence between genetic datasets in one individual, which exhibited a mitochondrial haplotype characteristic of I. marchei but nevertheless fell within a genetic cluster of I. opdenboschi based on AFLP genotypes, suggests that a low level of recent hybridization may also be contributing to patterns of character variation in sympatry. Nevertheless, despite less than perfect separability based on any one dataset and inconclusive evidence for complete reproductive isolation between them in the Ivindo River, we find sufficient evidence to support the existence of two distinctive species, I. opdenboschi and I. marchei, even if not ,biological species' in the Mayrian sense. [source] Combining mitochondrial DNA sequences and morphological data to infer species boundaries: phylogeography of lanceheaded pitvipers in the Brazilian Atlantic forest, and the status of Bothrops pradoi (Squamata: Serpentes: Viperidae)JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2001G. Puorto Phylogeographic studies using mitochondrial DNA sequence information are frequently used as the principal source of evidence to infer species boundaries. However, a critical analysis of further evidence is essential to test whether different haplotype clades identify different species. We demonstrate a hypothesis-testing approach, using a combination of phylogeographic methods, multivariate morphometrics and matrix association tests, to investigate species boundaries in eastern Brazilian pitvipers conventionally assigned to the species Bothrops leucurus and B. pradoi. Two basal haplotype clades with partly overlapping geographical distributions are identified, which could either represent two partly sympatric species, or multiple haplotypes within one organismal lineage. We use partial Mantel matrix association tests to verify whether generalized morphology, or any of four supposedly diagnostic characters for the two species, show any association with mtDNA variation. Negative results lead to the conclusion that the haplotype clades do not denote independently evolving organismal lineages, and do not constitute separate species under any criterion. [source] Species discovery in marine planktonic invertebrates through global molecular screeningMOLECULAR ECOLOGY, Issue 5 2010ERICA GOETZE Abstract Species discovery through large-scale sampling of mitochondrial diversity, as advocated under DNA barcoding, has been widely criticized. Two of the primary weaknesses of this approach, the use of a single gene marker for species delineation and the possible co-amplification of nuclear pseudogenes, can be circumvented through incorporation of multiple data sources. Here I show that for taxonomic groups with poorly characterized systematics, large-scale genetic screening using a mitochondrial DNA marker can be a very effective approach to species discovery. Global sampling (120 locations) of 1295 individuals of 22 described species of eucalanid copepods identified 15 novel evolutionarily significant units (ESUs) within this marine holoplanktonic family. Species limits were tested under reciprocal monophyly at the mitochondrial (mt) gene 16S rRNA, and 13 of 15 lineages were reciprocally monophyletic under three phylogenetic inference methods. Five of these mitochondrial ESUs also received moderate support for reciprocal monophyly at the independently-inherited nuclear gene, internal transcribed spacer 2 (ITS2). Additional support for the utility of mt DNA as a proxy for species boundaries in this taxon is discussed, including results from related morphological and biogeographic studies. Minimal overlap of intra-ESU and inter-ESU 16S rRNA genetic distances was observed, suggesting that this mt marker performs well for species discovery via molecular screening. Sampling coverage required for the discovery of new ESUs was found to be in the range of >50 individuals/species, well above the sampling intensity of most current DNA Barcoding studies. Large-scale genetic screening can provide critical first data on the presence of cryptic species, and should be used as an approach to generate systematic hypotheses in groups with incomplete taxonomies. [source] Defining reproductively isolated units in a cryptic and syntopic species complex using mitochondrial and nuclear markers: the brooding brittle star, Amphipholis squamata (Ophiuroidea)MOLECULAR ECOLOGY, Issue 7 2008E. BOISSIN Abstract At a time when biodiversity is threatened, we are still discovering new species, and particularly in the marine realm. Delimiting species boundaries is the first step to get a precise idea of diversity. For sympatric species which are morphologically undistinguishable, using a combination of independent molecular markers is a necessary step to define separate species. Amphipholis squamata, a cosmopolitan brittle star, includes several very divergent mitochondrial lineages. These lineages appear totally intermixed in the field and studies on morphology and colour polymorphism failed to find any diagnostic character. Therefore, these mitochondrial lineages may be totally interbreeding presently. To test this hypothesis, we characterized the genetic structure of the complex in the French Mediterranean coast using sequences of mitochondrial DNA (16S) and for the first time, several nuclear DNA markers (introns and microsatellites). The data revealed six phylogenetic lineages corresponding to at least four biological species. These sibling species seem to live in syntopy. However, they seem to display contrasted levels of genetic diversity, suggesting they have distinct demographic histories and/or life-history traits. Genetic differentiation and isolation-by-distance within the French Mediterranean coasts are revealed in three lineages, as expected for a species without a free larval phase. Finally, although recombinant nuclear genotypes are common within mitochondrial lineages, the data set displays a total lack of heterozygotes, suggesting a very high selfing rate, a feature likely to have favoured the formation of the species complex. [source] Shifting distributions and speciation: species divergence during rapid climate changeMOLECULAR ECOLOGY, Issue 3 2007BRYAN C. CARSTENS Abstract Questions about how shifting distributions contribute to species diversification remain virtually without answer, even though rapid climate change during the Pleistocene clearly impacted genetic variation within many species. One factor that has prevented this question from being adequately addressed is the lack of precision associated with estimates of species divergence made from a single genetic locus and without incorporating processes that are biologically important as populations diverge. Analysis of DNA sequences from multiple variable loci in a coalescent framework that (i) corrects for gene divergence pre-dating speciation, and (ii) derives divergence-time estimates without making a priori assumptions about the processes underlying patterns of incomplete lineage sorting between species (i.e. allows for the possibility of gene flow during speciation), is critical to overcoming the inherent logistical and analytical difficulties of inferring the timing and mode of speciation during the dynamic Pleistocene. Estimates of species divergence that ignore these processes, use single locus data, or do both can dramatically overestimate species divergence. For example, using a coalescent approach with data from six loci, the divergence between two species of montane Melanoplus grasshoppers is estimated at between 200 000 and 300 000 years before present, far more recently than divergence estimates made using single-locus data or without the incorporation of population-level processes. Melanoplus grasshoppers radiated in the sky islands of the Rocky Mountains, and the analysis of divergence between these species suggests that the isolation of populations in multiple glacial refugia was an important factor in promoting speciation. Furthermore, the low estimates of gene flow between the species indicate that reproductive isolation must have evolved rapidly for the incipient species boundaries to be maintained through the subsequent glacial periods and shifts in species distributions. [source] Spawning times, reproductive compatibilities and genetic structuring in the Acropora aspera group: evidence for natural hybridization and semi-permeable species boundaries in coralsMOLECULAR ECOLOGY, Issue 8 2002Madeleine J. H. Van Oppen Abstract Species boundaries among five sympatric coral species of the Indo-Pacific Acropora aspera group were examined by a combination of in vitro breeding trials, comparisons of spawning times and DNA sequence analysis of ribosomal DNA internal transcribed spacer (rDNA ITS) and 5.8S regions. The breeding trials showed that reproductive compatibility exists between at least some colonies of all the species pairs tested, suggesting a large potential for natural hybridization and introgression. The Acropora ITS regions exhibited extremely high levels of variability (up to ,62% for ITS1, ,11% for 5.8S and ,43% for ITS2), but most of the variation was shared among four of the five species, A. millepora, A. papillare, A. pulchra and A. spathulata, consistent with extensive introgression. Phylogenetic analyses did not resolve these four species as distinct clusters across a wide biogeographic region stretching from the southern Great Barrier Reef to Papua New Guinea. However, most colonies of the fifth species, A. aspera, constituted a distinct clade in phylogenetic analyses. This is consistent with our observations of a semi-permeable temporal barrier involving differences in spawning times between this and the other four species. Although the majority of colonies of all five species generally spawned within 90 min of each other, in two out of four years, gametes were absent prior to mass spawning episodes from at least some A. aspera colonies. Hence, our data suggest that transient reproductive barriers may be the result of year-to-year variation in the date of spawning and that this difference in spawning time contributes to the genetic structure detected among Acropora species in this group. Occasional leakage through the reproductive barrier was confirmed by the observation of A. aspera ×A. pulchra F1 hybrids, identified based on additivity of ITS sequences. [source] A morphometric analysis of the Bonatea speciosa complex (Orchidaceae) and its implications for species boundariesNORDIC JOURNAL OF BOTANY, Issue 3 2009Mariaan E. Ponsie Species boundaries in rapidly evolving lineages are often blurred, necessitating analysis of the full range of variation within a complex in order to identify traits that can be used to diagnose taxa. The delimitation of Bonatea speciosa (L. f.) Willd. has been controversial, as most, but not all, recent authors have included within the concept of this species several additional taxa that were formerly recognised at the species level, including Bonateaboltonii (Harv.) Bolus and Bonateaantennifera Rolfe. Morphological variation across the Bonateaspeciosa complex (Orchidaceae) was explored using principal component and cluster analysis. Scatter plots were used to identify characters that could potentially be used to diagnose taxa. These data support the recognition of three distinct species, B.speciosa, B.antennifera and B.boltonii, instead of a single entity. A taxonomic account of southern African taxa within the B. speciosa complex is presented. [source] Population and species boundaries in the South American subterranean rodent Ctenomys in a dynamic environmentBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010PATRICIA MIROL Subterranean rodents of the genus Ctenomys are an interesting system to assess the effects of habitat instability on the genetic structure of populations. The perrensi group is a complex of three species (C. roigi, C. perrensi and C. dorbignyi) and several forms of uncertain taxonomic status, distributed in the vicinity of the Iberá wetland in Argentina. Because of limited availability of suitable dry habitat, Ctenomys populations are distributed patchily around a vast mosaic of marshes, swamps and lagoons and become connected or isolated over time, depending particularly on the precipitation regime. Genetic variation at 16 microsatellite loci in 169 individuals collected in the area revealed eight clusters of populations which are thought to be evolutionary units, but which do not fit previous species limits. We interpret this lack of congruence between taxonomy and genetic structure as the result of a dynamic population structure. Where populations become connected, hybridization is possible. Where populations become isolated, rapid genetic divergence may occur. In the perrensi group, it appears that both of these factors disrupt the association between different genetic and morphological characters. The study of multiple characters is crucial to the understanding of the recent evolutionary history for dynamic systems such as this. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 368,383. [source] Combining molecular, morphological and ecological data to infer species boundaries in a cryptic tropical pitviperBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2006KATE L. SANDERS Few operational methods exist for delimiting species boundaries, and these usually require sampling strategies that are unrealistic for widespread organisms that occur at low densities. Here we apply molecular, morphological and ecological species delimitation criteria to a wide-ranging, fragmented group of Asian green pitvipers, the Popeia popeiorum complex. A mitochondrial DNA phylogeny for the group indicates two well-differentiated clades, corresponding mainly to northern and southern parts of its range. Strong phylogeographical structure within each clade suggests isolation in forest refugia during the Pliocene and a southward colonization of the Sunda islands during the Pleistocene. Multivariate analysis of morphological characters reveals a generally conserved pattern of geographical variation, incongruent with the recovered phylogenetic history. We compare groups delineated by mtDNA variation to morphological and ecological divisions in the complex, and discuss the implications of these for the taxonomy of the group. Discordance between species boundaries inferred from different criteria suggests that combining independent sources of data provides the most reliable estimation of species boundaries in organisms that are difficult to sample in large numbers. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 343,364. [source] | ||||||||||