Species Delimitation: A Case Study in a Problematic Ant Taxon

Department of Entomology, University of Georgia, Athens, GA 30602, USA.
Systematic Biology (Impact Factor: 14.39). 03/2010; 59(2):162-84. DOI: 10.1093/sysbio/syp089
Source: PubMed


Species delimitation has been invigorated as a discipline in systematics by an influx of new character sets, analytical methods, and conceptual advances. We use genetic data from 68 markers, combined with distributional, bioclimatic, and coloration information, to hypothesize boundaries of evolutionarily independent lineages (species) within the widespread and highly variable nominal fire ant species Solenopsis saevissima, a member of a species group containing invasive pests as well as species that are models for ecological and evolutionary research. Our integrated approach uses diverse methods of analysis to sequentially test whether populations meet specific operational criteria (contingent properties) for candidacy as morphologically cryptic species, including genetic clustering, monophyly, reproductive isolation, and occupation of distinctive niche space. We hypothesize that nominal S. saevissima comprises at least 4-6 previously unrecognized species, including several pairs whose parapatric distributions implicate the development of intrinsic premating or postmating barriers to gene flow. Our genetic data further suggest that regional genetic differentiation in S. saevissima has been influenced by hybridization with other nominal species occurring in sympatry or parapatry, including the quite distantly related Solenopsis geminata. The results of this study illustrate the importance of employing different classes of genetic data (coding and noncoding regions and nuclear and mitochondrial DNA [mtDNA] markers), different methods of genetic data analysis (tree-based and non-tree based methods), and different sources of data (genetic, morphological, and ecological data) to explicitly test various operational criteria for species boundaries in clades of recently diverged lineages, while warning against over reliance on any single data type (e.g., mtDNA sequence variation) when drawing inferences.

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    • "Introduced populations of potentially invasive ants show marked differences in their biology compared with native populations, such as changes in behavior, social organization, reproductive biology, and genetic profile[10]. The intracolony genetic profile is seldom explored because genetic analyses of microsatellite markers in the genus Solenopsis using few individuals (between 1 and 10) per colony[11][13]may hide internal diversity and influence conclusions regarding the species' social and reproductive dynamics. In many cases, these studies require individual analyses of worker ants from the same colony[14]. "
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    ABSTRACT: The genus Solenopsis includes more than 100 species in the New World. When introduced, some spe-cies cause serious harm to the native wildlife and agriculture. Two forms of social organization are known in the genus, namely, monogyne and polygyne. Here, we present the genetic profile of a Sole-nopsis invicta Buren 1972 colony recorded in the central region of the city of São Paulo, São Paulo state, Brazil (23 ̊33'37.18"S; 46 ̊42'48.66"W) to describe allele diversity. Eight microsatellite loci were used for the analysis of 30 worker ants. The results show the presence of seven alleles genotyped at the same microsatellite locus. Because this is an unusual finding, all of the alleles were sequenced, and surprisingly, an eighth allele was identified. These data suggest that the intracolonial genetic pro-file of fire ants must be investigated more frequently because there may be unexpected, albeit un-known, genetic patterns for S. invicta that can help inform better control and management programs.
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    • "Although molecular analyses have been based largely on mitochondrial genes, it is increasingly acknowledgedF. EVANGELISTI ET AL. that species inference using mtDNA should be corroborated with information from nuclear loci (O'Meara, 2010;Ross et al., 2010), but conflicts can arise between mitochondrial and nuclear data because of different gene evolutionary histories (e.g.Bichain et al., 2007). In this work, two mitochondrial genes (COI and 12S) were employed to explore the taxonomic status of several nominal Cerithium species from the central Mediterranean Sea. "
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    • "This aims at bringing new knowledge and methods mainly from population biology, phylogenetics , ecology and biogeography into traditional taxonomy. From this point of view,recent advances have been made in the fields of zoology (e.g.Ross et al., 2010), botany (e.g.Barrett & Freudenstein, 2011), bryology (e.g.Medina et al., 2012) and mycology (e.g.Zamora et al., 2015). All these worksa n a are promoting a change of species recognition paradigm by which taxonomists are now realizing that the processes shaping speciation matter for species delimitation as well. "
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    ABSTRACT: Data from morphology, phylogenetics, genetic clustering, species delimitation methods, biogeography and ecology have been used to evaluate species boundaries within the Battarrea phalloides-stevenii complex. Evidences suggest the existence of three to four independent lineages that may constitute new species for science. Despite no further attempts have been made to describe new taxa, some practical guidelines are proposed in order to establish a consistent systematic framework for the study of this genus of Basidiomycota.
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