Size Doesn't Matter: Integrative Taxonomy Shows Crepidula adunca and Crepidula norrisiarum Have Overlapping Shell Sizes and Broadly Concordant Distributions.

AbstractThe calyptraeids Crepidula adunca and Crepidula norrisiarum, both direct developers, are abundant in the shallow waters of the northeastern Pacific. They have long been considered as two allopatric species that live on different hosts and differ in body size. In this study, we rigorously test this historical hypothesis by assessing molecular taxonomy, museum records, new morphological and host observations, and population genetic structure along the northeast Pacific coast. Results show that, contrary to previous understanding, the distributions of the two species largely overlap and that size does not effectively distinguish them, especially in the northern part of the range where the nominal "C. adunca" has been studied. Newly recognized northern occurrences of C. norrisiarum demonstrate that both species have similar, disrupted distributions that range from British Colombia through southern California. Neither species is reported to occur on the outer shores of southern Washington or Oregon, the exception being records of C. adunca at Cape Arago, Oregon. Despite this apparent geographic gap, neither species shows appreciable genetic differentiation between the northern and southern parts of its ranges. Despite body size having been used to distinguish these species, our observations do not support body size as a species-specific trait; rather, they support a new hypothesis that body size variation reflects regional differences in host use and host availability.

A new integrative framework for large-scale assessments of biodiversity and community dynamics, using littoral gastropods and crabs of British Columbia, Canada.

Improving our understanding of species responses to environmental changes is an important contribution ecologists can make to facilitate effective management decisions. Novel synthetic approaches to assessing biodiversity and ecosystem integrity are needed, ideally including all species living in a community and the dynamics defining their ecological relationships. Here, we present and apply an integrative approach that links high-throughput, multicharacter taxonomy with community ecology. The overall purpose is to enable the coupling of biodiversity assessments with investigations into the nature of ecological interactions in a community-level data set. We collected 1195 gastropods and crabs in British Columbia. First, the General mixed Yule-coalescent (GMYC) and the Poisson Tree Processes (PTP) methods for proposing primary species-hypotheses based on cox1 sequences were evaluated against an integrative taxonomic framework. We then used data on the geographic distribution of delineated species to test species co-occurrence patterns for nonrandomness using community-wide and pairwise approaches. Results showed that PTP generally outperformed GMYC and thus constitutes a more effective option for producing species-hypotheses in community-level data sets. Nonrandom species co-occurrence patterns indicative of ecological relationships or habitat preferences were observed for grazer gastropods, whereas assemblages of carnivorous gastropods and crabs appeared influenced by random processes. Species-pair associations were consistent with current ecological knowledge, thus suggesting that applying community assembly within a large taxonomical framework constitutes a valuable tool for assessing ecological interactions. Combining phylogenetic, morphological and co-occurrence data enabled an integrated view of communities, providing both a conceptual and pragmatic framework for biodiversity assessments and investigations into community dynamics.

The placement of Gyrodactylus salmonis (Yin & Sproston) in the molecular phylogeny of studied members of the Gyrodactylus wageneri-group parasitizing salmonids.

The molecular phylogeny of Gyrodactylus salmonis from brook charr, Salvelinus fontinalis, rainbow trout, Oncorhynchus mykiss, cutthroat trout, O. clarkii, and Atlantic salmon, Salmo salar, in Canada is presented using sequences from ITS-rDNA and the mitochondrial COX 1 gene. Sequence variation among G. salmonis specimens from the different North American hosts was consistent with within-species variation reported for other Gyrodactylus. Sequence data are compared to those from other members of the wageneri group parasitizing salmoniform fishes in northern Europe (G. derjavini, G. derjavinoides, G. lavareti, G. salaris, G. salvelini, G. teuchis and G. truttae) and Asia (G. brachymystacis). Sequence divergence between G. salmonis and the recently described G. salvelini on Arctic charr, Salvelinus alpinus, in Finland was consistent with within-species levels of variation in Gyrodactylus; however, phylogenetic analyses and morphological comparisons provided evidence of their distinctiveness such that they appear to be sister species. They grouped with G. lavareti (a parasite of a coregonid) to form a clade separate from European and Asian species of the wageneri lineage known from salmonid fish. Further study of gyrodactylids from across salmonid, coregonid and thymallid fish in the northern hemisphere would shed more light on the phylogeography of these parasites and serves as an important backdrop to understanding the evolution of their emergent virulence.

A molecular identification system for grasses: a novel technology for forensic botany.

Our present inability to rapidly, accurately and cost-effectively identify trace botanical evidence remains the major impediment to the routine application of forensic botany. Grasses are amongst the most likely plant species encountered as forensic trace evidence and have the potential to provide links between crime scenes and individuals or other vital crime scene information. We are designing a molecular DNA-based identification system for grasses consisting of several PCR assays that, like a traditional morphological taxonomic key, provide criteria that progressively identify an unknown grass sample to a given taxonomic rank. In a prior study of DNA sequences across 20 phylogenetically representative grass species, we identified a series of potentially informative indels in the grass mitochondrial genome. In this study we designed and tested five PCR assays spanning these indels and assessed the feasibility of these assays to aid identification of unknown grass samples. We confirmed that for our control set of 20 samples, on which the design of the PCR assays was based, the five primer combinations produced the expected results. Using these PCR assays in a 'blind test', we were able to identify 25 unknown grass samples with some restrictions. Species belonging to genera represented in our control set were all correctly identified to genus with one exception. Similarly, genera belonging to tribes in the control set were correctly identified to the tribal level. Finally, for those samples for which neither the tribal or genus specific PCR assays were designed, we could confidently exclude these samples from belonging to certain tribes and genera. The results confirmed the utility of the PCR assays and the feasibility of developing a robust full-scale usable grass identification system for forensic purposes.