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Abstract The Nippostrongylinae is a group of strongylid nematodes that includes species typically associated with coprophagous mammals; in the New World, it is represented by 82 species within 11 genera. Two main morphological features, the synlophe and the caudal bursa, are used to evaluate the characteristics that allow identification and classification of the organisms in the taxon. However, the analysis of these characters often requires a partial or total destruction of specimens and therefore morphological variation is studied in only a very small subset of organisms per species. To evaluate the phylogenetic signal from these characteristics, we use genetic data to reconstruct the first phylogeny for the Nippostrongylinae using nuclear and mitochondrial genes and include representatives of the most common and diverse genera. The reconstructed phylogeny features five distinct clades and allows us to identify three non-monophyletic taxa includingCarolinensis, VexillataandHassalstrongylus. From these,Carolinensis s. l. is divided into four genera includingCarolinensis, Boreostrongylus, Neoboreostrongylusn. gen. andTepalcuaneman. gen.Stunkardionemais resurrected to includeVexillata noviberiaeandHassalstrongylusis divided into two, establishingLovostrongylusn. gen. to include species that are closely related toGuerrerostrongylusandTrichofreitasia. Organisms in these three genera feature a caudal arrangement of type 2-2-1. Furthermore, species inHassalstrongylus sensu strictoare more closely related to species inMalvinemaandStilestrongylus. Our results reveal the existence of an additional unnamed genus and underscore the usefulness of framing morphological characters in a comparative framework. A key for genera from the Americas is proposed.
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Evaluation of spectral collection strategies for identification of Dalbergia spp. using handheld laser‐induced breakdown spectroscopy
Abstract The illegal timber trade has significant impact on the survival of endangered tropical hardwood species likeDalbergiaspp. (rosewood), a world‐wide protected genus from the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Due to increased threat toDalbergiaspp., and lack of action to reduce threats, port of entry analysis methods are required to identifyDalbergiaspp. Handheld laser‐induced breakdown spectroscopy (LIBS) has been shown to be capable of identifying species and establishing provenance ofDalbergiaspp. and other tropical hardwoods, but analysis methods for this work have yet to be investigated in detail. The present work investigates five well‐known algorithms—partial least squares discriminant analysis (PLS‐DA), classification and regression trees (CART),k‐nearest neighbor (k‐NN), random forest (RF), and support vector machine (SVM)—two training/test set sampling regimes, and data collection at two signal‐to‐noise (S/N) ratios to assess the potential for handheld LIBS analyses. Additionally, imbalanced classes are addressed. For this application, SVM and RF yield near identical results (though RF takes nearly 100 longer to compute), while the S/N ratio has a significant effect on model success assuming all else is equal. It was found that forming a training set with replicate low S/N analyses can perform as well as higher precision training sets for true prediction, even if the predicted samples have low signal to noise! This work confirms handheld LIBS analyzers can provide a viable method for classification of hardwood species, even within the same genus.
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- Award ID(s):
- 2003839
- PAR ID:
- 10412154
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Chemometrics
- Volume:
- 38
- Issue:
- 5
- ISSN:
- 0886-9383
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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