An Integrative Method for Delimiting Cohesion Species: Finding the Population-Species Interface in a Group of Californian Trapdoor Spiders with Extreme Genetic Divergence and Geographic Structuring

Abstract

Here we present an objective, repeatable approach to delineating species when populations are divergent and highly structured geographically using the Californian trapdoor spider species complex Aptostichus atomarius Simon as a model system. This system is particularly difficult because under strict criteria of geographical concordance coupled with estimates of genetic divergence, an unrealistic number of population lineages would qualify as species (20 to 60). Our novel phylogeographic approach, which is generally applicable but particularly relevant to highly structured systems, uses genealogical exclusivity to establish a topological framework to examine lineages for genetic and ecological exchangeability in an effort to delimit cohesion species. Both qualitative assessments of habitat and niche-based distribution modeling are employed to evaluate selective regime and ecological interchangeability among genetic lineages; adaptive divergence among populations is weighted more heavily than simple geographical concordance. Based on these analyses we conclude that five cohesion species should be recognized, three of which are new to science.

Integrating DNA barcode data and taxonomic practice: Determination, discovery, and description

“…Yule models of stochastic lineage growth of Pons et al [100]) and likelihood ratio tests [101]. Statistical approaches for delimiting species are as varied and controversial as species concepts and criteria themselves [99,[102][103][104]. Although long abandoned by phylogenetic systematists for their statistical shortcomings, distance methods [105] have been resurrected in species delimitation methods used most commonly in DNA barcoding studies.…”

The Dynamic Discipline of Species Delimitation: Progress Toward Effectively Recognizing Species Boundaries in Natural Populations

“…Integrative methods for species delimitation fall across a broad spectrum, ranging from verbal and qualitative assessments of data classes to quantitative methods that allow different data types to contribute to statistical species delimitation (Yeates et al 2011). In most taxonomic studies utilizing both molecular and morphological data, expert opinion is eventually used to some degree to evaluate the final status of a candidate species (e.g., Bond and Stockman 2008). In this sense, many studies using evidence for independent data sources for delimiting species boundaries use an iterative approach (Yeates et al 2011) where species boundaries can be tested within a hypotheticodeductive framework with diverse datasets.…”

A toolbox for integrative species delimitation in Machilis jumping bristletails (Microcoryphia: Machilidae)

“…Integrative taxonomy (DeSalle et al, 2005;Padial et al, 2010;Schlick-Steiner et al, 2010) has proven to significantly improve the rigour of species delimitation in various animal taxa (SchlickSteiner et al, 2006;Fontaneto et al, 2007;Bond and Stockman, 2008;Macías-Hernández et al, 2008;Leaché et al, 2009;Bailey et al, 2010;Damm et al, 2010;Glaw et al, 2010;Lumley and Sperling, 2010;Ross et al, 2010;Steiner et al, 2010;Birky et al, 2011;Gurgel-Gonç alves et al, 2011;Moyal et al, 2011;Seppä et al, 2011). Multi-source approaches take advantage of complementarities amongst disciplines: It is assumed that the strength of any species delimitation hypothesis rises with the independence of the information sources , i.e.…”