Currently, the phylum Gastrotricha is divided into the orders Macrodasyida and Chaetonotida, with the structure of the myoepithelial pharynx being an important distinguishing feature. Macrodasyida currently has six recognized families, and Chaetonotida comprises seven families. However, within-group relationships are poorly understood. To arrive at a better understanding of gastrotrich systematics and phylogeny, we performed the first cladistic analysis of nearly all known gastrotrich genera using 71 morphological characters. Results suggest that the Gastrotricha is a monophyletic group (supported by 82% of bootstrap replications) with its most primitive taxa distributed among the families Dactylopodolidae and Neodasyidae. Monophyly of Macrodasyida and Chaetonotida was supported by 90% and 52% bootstrap replications, respectively. Within the Macrodasyida, the families Dactylopodolidae, Turbanellidae, Macrodasyidae, and Thaumastodermatidae all formed monophyletic clades. The families Planodasyidae and Lepidodasyidae were paraphyletic. Among the Chaetonotida, the marine family Xenotrichulidae was monophyletic, supported by 51% of bootstrap replications. A second clade containing all freshwater families was supported by 62% bootstrap values. However, Chaetonotidae were paraphyletic. Using this analysis as a framework, we now can explore possible patterns of evolution within it, and arrive at a consensus of the gastrotrich ground pattern. Moreover, in future molecular studies of metazoan phylogeny, we will be able to select gastrotrich species that are more appropriate representatives of the phylum.
The abundance and distribution of New England cottontails (NEC; Sylvilagus transitionalis) have been declining for several decades. Remnant populations in some regions are known to be vulnerable to extirpation but little is known about the status of populations in most areas. We conducted a survey of the historic range (ca. 1960) of NEC to determine the current distribution and relative status of extant populations. Because NEC were sympatric with eastern cottontails (S. floridanus) and snowshoe hares (Lepus americanus) in much of their historic range, identity of resident lagomorphs was based on DNA extracted either from tissue of captured cottontails or from fecal pellets of free‐ranging lagomorphs. We searched 2,301 patches of suitable habitat and detected NEC in 162. We identified 5 disjunct populations in approximately 14% of the historic range. Forest maturation and fragmentation are the most plausible explanations for the widespread decline of NEC. Contraction of the historic distribution was toward eastern and southern edges where a variety of anthropogenic disturbances (e.g., brushy edges of highways and railroad corridors and idle portions of agricultural fields) provided habitat. Land‐ownership patterns (dominated by small acreages) and land‐use activities (expanding development and limited forest management) within the currently occupied range of NEC suggest a continued decline of suitable habitats. As a result, we recommend efforts to enhance remaining populations of NEC that include responses at 2 spatial scales. At the population or landscape scale, current land uses should guide habitat manipulations that expand existing populations. At the regional scale, we recommend consideration should be given to increasing dispersal among remnant populations, possibly by generating “stepping stones” of suitable habitat. In addition to improving long‐term viability of NEC, other species of conservation concern that are dependent on early successional habitats will benefit from these efforts.
Using 28S ribosomal DNA sequences, we inferred the internal relationships of the order Polycladida. We identified morphological characters for clade support when possible. Monophyletic Acotylea and Cotylea were consistently recovered. In Acotylea, the superfamilies Stylochoidea, Cryptoceloidea and Leptoplanoidea were supported, with Stylochoidea representing the most basal acotylean lineage. In Leptoplanoidea, we united genera lacking a penis armature into the new family Notocomplanidae. Gnesiocerotidae was recovered as the most basal leptoplanoid lineage, and Stylochoplanidae and Notoplanidae were paraphyletic. Among cotyleans, Cestoplanidae, Diposthus popeae + Pericelis spp., Boniniidae, Pseudocerotidae and Prosthiostomidae formed clades. Genera in Euryleptidae were monophyletic, but the family itself was recovered with low support only. The established superfamilies Pseudocerotoidea, Euryleptoidea, Periceloidea and Chromoplanoidea are not supported. Pericelis has been moved to Diposthidae and Pericelidae has been abolished. A clade of Boniniidae + Theama spp. + Chromyella sp. was supported. In Pseudocerotidae, the number of male reproductive structures unites Pseudobiceros and Thysanozoon. Tytthosoceros has been abolished, with all currently described species now placed in Phrikoceros. Our results support several additional synonymies and taxonomic corrections. This new phylogeny provides an increased understanding of relationships in the order and offers a framework for future testing of hypotheses of character evolution and life-history strategies.
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