The critical role of natural history museums in advancing eDNA for biodiversity studies: a case study with Amazonian fishes.

Ichthyological surveys have traditionally been conducted using whole-specimen, capture-based sampling with varied but conventional fishing gear. Recently, environmental DNA (eDNA) metabarcoding has emerged as a complementary, and possible alternative, approach to whole-specimen methodologies. In the tropics, where much of the diversity remains undescribed, vast reaches continue unexplored, and anthropogenic activities are constant threats; there have been few eDNA attempts for ichthyological inventories. We tested the discriminatory power of eDNA using MiFish primers with existing public reference libraries and compared this with capture-based methods in two distinct ecosystems in the megadiverse Amazon basin. In our study, eDNA provided an accurate snapshot of the fishes at higher taxonomic levels and corroborated its effectiveness to detect specialized fish assemblages. Some flaws in fish metabarcoding studies are routine issues addressed in natural history museums. Thus, by expanding their archives and adopting a series of initiatives linking collection-based research, training and outreach, natural history museums can enable the effective use of eDNA to survey Earth's hotspots of biodiversity before taxa go extinct. Our project surveying poorly explored rivers and using DNA vouchered archives to build metabarcoding libraries for Neotropical fishes can serve as a model of this protocol.

Phylogeography of a good Caribbean disperser: Argiope argentata (Araneae, Araneidae) and a new 'cryptic' species from Cuba.

The Caribbean islands harbor rich biodiversity with high levels of single island endemism. Stretches of ocean between islands represent significant barriers to gene-flow. Yet some native species are widespread, indicating dispersal across oceans, even in wingless organisms like spiders. Argiope argentata (Fabricius, 1775) is a large, charismatic, and widespread species of orb-weaving spider ranging from the United States to Argentina and is well known to balloon. Here we explore the phylogeography of Argiope argentata in the Caribbean as a part of the multi-lineage CarBio project, through mtDNA haplotype and multi-locus phylogenetic analyses. The history of the Argiope argentata lineage in the Caribbean goes back 3-5 million years and is characterized by multiple dispersal events and isolation-by-distance. We find a highly genetically distinct lineage on Cuba which we describe as Argiope butchkosp. n. While the argentata lineage seems to readily balloon shorter distances, stretches of ocean still act as filters for among-island gene-flow as evidenced by distinct haplotypes on the more isolated islands, high FST values, and strong correlation between intraspecific (but not interspecific) genetic and geographic distances. The new species described here is clearly genetically diagnosable, but morphologically cryptic, at least with reference to the genitalia that typically diagnose spider species. Our results are consistent with the intermediate dispersal model suggesting that good dispersers, such as our study species, limit the effect of oceanic barriers and thus diversification and endemism.

Linking of digital images to phylogenetic data matrices using a morphological ontology.

Images are paramount in documentation of morphological data. Production and reproduction costs have traditionally limited how many illustrations taxonomy could afford to publish, and much comparative knowledge continues to be lost as generations turn over. Now digital images are cheaply produced and easily disseminated electronically but pose problems in maintenance, curation, sharing, and use, particularly in long-term data sets involving multiple collaborators and institutions. We propose an efficient linkage of images to phylogenetic data sets via an ontology of morphological terms; an underlying, fine-grained database of specimens, images, and associated metadata; fixation of the meaning of morphological terms (homolog names) by ostensive references to particular taxa; and formalization of images as standard views. The ontology provides the intellectual structure and fundamental design of the relationships and enables intelligent queries to populate phylogenetic data sets with images. The database itself documents primary morphological observations, their vouchers, and associated metadata, rather than the conventional data set cell, and thereby facilitates data maintenance despite character redefinition or specimen reidentification. It minimizes reexamination of specimens, loss of information or data quality, and echoes the data models of web-based repositories for images, specimens, and taxonomic names. Confusion and ambiguity in the meanings of technical morphological terms are reduced by ostensive definitions pointing to features in particular taxa, which may serve as reference for globally unique identifiers of characters. Finally, the concept of standard views (an image illustrating one or more homologs in a specific sex and life stage, in a specific orientation, using a specific device and preparation technique) enables efficient, dynamic linkage of images to the data set and automatic population of matrix cells with images independently of scoring decisions.