Naive use of molecular data may lead to ambiguous conclusions, especially within the context of "cryptic" species. Here, we integrated molecular and morphometric data to evaluate phylogenetic relationships in the widespread terrestrial micro-snail genus, Euconulus. We analyzed mitochondrial (16S + COII) and nuclear (ITS1 + ITS2) sequence across 94 populations from Europe, Asia and North America within the nominate species E. alderi, E. fulvus and E. polygyratus, and used the southeastern USA E. chersinus, E. dentatus, and E. trochulus as comparative outgroups. Phylogeny was reconstructed using four different reconstruction methods to identify robust, well-supported topological features. We then performed discriminant analysis on shell measurements between these genetically-identified species-level clades. These analyses provided evidence for a biologically valid North American "cryptic" species within E. alderi. However, while highly supported polyphyletic structure was also observed within E. fulvus, disagreement in placement of individuals between mtDNA and nDNA clades, lack of morphological differences, and presence of potential hybrids imply that these lineages do not rise to the threshold as biologically valid cryptic species, and rather appear to simply represent a complex of geographically structured populations within a single species. These results caution that entering into a cryptic species hypothesis should not be undertaken lightly, and should be optimally supported along multiple lines of evidence. Generally, post-hoc analyses of macro-scale features should be conducted to attempt identification of previously ignored diagnostic traits. If such traits cannot be found, i.e. in the case of potentially "fully cryptic" species, additional criteria should be met to propound a cryptic species hypothesis, including the agreement in tree topology among both mtDNA and nDNA, and little (or no) evidence of hybridization based on a critical analysis of sequence chromatograms. Even when the above conditions are satisfied, it only implies that the cryptic species hypothesis is plausible, but should optimally be subjected to further careful examination.
- MeSH
- analýza hlavních komponent MeSH
- buněčné jádro genetika MeSH
- fylogeneze MeSH
- hlemýždi klasifikace genetika MeSH
- pravděpodobnostní funkce MeSH
- respirační komplex IV klasifikace genetika MeSH
- RNA ribozomální 16S klasifikace genetika MeSH
- sekvence nukleotidů MeSH
- sekvenční analýza DNA MeSH
- sekvenční seřazení MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Cryptic genetic diversity and erroneous morphological species determination represent frequent problems in biodiversity research. Here, examination of 138 specimens of Synodontis (Mochokidae, Siluriformes) from the Nile River and Lake Turkana revealed the presence of both S. schall-like and S. frontosus-like morphotypes, with a phenotypic gradient between them. We concluded phylogenetic and population genetic analyses based on two mitochondrial and one nuclear marker including 131 coxI (565 bp), 96 cytb (973 bp) and 19 RAG2 (896 bp) sequences from the Nile-Turkana population, plus additional GenBank data of Synodontis spp. Whilst nuclear data were inconclusive, mitochondrial sequences suggested that both morphotypes and intermediate forms are conspecific. The results imply probable synonymy of S. frontosus with S. schall. Conversely, a strong biogeographical signal was revealed among widely distributed and supposedly conspecific S. schall-like catfish of the Nilo-Sudanian ichthyological province. Synodontis schall sensu stricto (=Eastern clade), as defined by type locality in the Nile, is apparently restricted to the eastern part of the Nilo-Sudanian ichthyological province (e.g. Nile, Turkana, Chad). Synodontis schall Western clade (Senegambia, Niger, Chad) most probably represents a cryptic taxon, unrecognized thus far due to the absence of distinctive morphological differences.
- MeSH
- Bayesova věta MeSH
- biodiverzita * MeSH
- cytochromy b klasifikace genetika MeSH
- fylogeneze MeSH
- haplotypy MeSH
- populační genetika MeSH
- respirační komplex IV klasifikace genetika MeSH
- sumci klasifikace genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The degree of host specificity, its phylogenetic conservativeness and origin are virtually unknown in Eimeria. This situation is largely due to the inadequate sample of eimerian molecular data available for reliable phylogenetic analyses. In this study, we extend the data set by adding 71 new sequences of coccidia infecting 16 small-mammal genera, mostly rodents. According to the respective feasibility of PCR gene amplification, the new samples are represented by one or more of the following genes: nuclear 18S rRNA, plastid ORF 470, and mitochondrial COI. Phylogenetic analyses of these sequences confirm the previous hypothesis that Eimeria, in its current morphology-based delimitation, is not a monophyletic group. Several samples of coccidia corresponding morphologically to other genera are scattered among the Eimeria lineages. More importantly, the distribution of eimerians from different hosts indicates that the clustering of eimerian species is influenced by their host specificity, but does not arise from a cophylogenetic/cospeciation process; while several clusters are specific to a particular host group, inner topologies within these clusters do not reflect host phylogeny. This observation suggests that the host specificity of Eimeria is caused by adaptive rather than cophylogenetic processes.
- MeSH
- druhová specificita MeSH
- Eimeria klasifikace fyziologie MeSH
- feces parazitologie MeSH
- fylogeneze * MeSH
- fyziologická adaptace genetika MeSH
- hlodavci parazitologie MeSH
- hostitelská specificita MeSH
- interakce hostitele a parazita MeSH
- kokcidióza parazitologie veterinární MeSH
- nemoci hlodavců parazitologie MeSH
- plastidy genetika MeSH
- protozoální DNA klasifikace genetika MeSH
- respirační komplex IV klasifikace genetika MeSH
- RNA ribozomální 18S klasifikace genetika MeSH
- sekvenční analýza DNA MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Reliable phylogenetic reconstruction, as a framework for evolutionary inference, may be difficult to achieve in some groups of organisms. Particularly for lineages that experienced rapid diversification, lack of sufficient information may lead to inconsistent and unstable results and a low degree of resolution. Coincidentally, such rapidly diversifying taxa are often among the biologically most interesting groups. Aphids provide such an example. Due to rapid adaptive diversification, they feature variability in many interesting biological traits, but consequently they are also a challenging group in which to resolve phylogeny. Particularly within the family Aphididae, many interesting evolutionary questions remain unanswered due to phylogenetic uncertainties. In this study, we show that molecular data derived from the symbiotic bacteria of the genus Buchnera can provide a more powerful tool than the aphid-derived sequences. We analyze 255 Buchnera gene sequences from 70 host aphid species and compare the resulting trees to the phylogenies previously retrieved from aphid sequences, only. We find that the host and symbiont data do not conflict for any major phylogenetic conclusions. Also, we demonstrate that the symbiont-derived phylogenies support some previously questionable relationships and provide new insights into aphid phylogeny and evolution.
- MeSH
- bakteriální geny * MeSH
- biologická evoluce MeSH
- Buchnera klasifikace genetika MeSH
- DNA bakterií klasifikace genetika MeSH
- druhová specificita MeSH
- fylogeneze * MeSH
- genetické markery MeSH
- hmyzí proteiny klasifikace genetika MeSH
- mšice klasifikace genetika mikrobiologie MeSH
- respirační komplex IV klasifikace genetika MeSH
- symbióza MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
