Spintharus flavidus in the Caribbean – a 30 million year biogeographical history and radiation of a ‘widespread species’
- Published
- Accepted
- Subject Areas
- Biodiversity, Biogeography, Taxonomy, Zoology
- Keywords
- Spintharus, GAARLandia, Theridiidae, Evolution, Caribbean, Adaptive Radiation, Dispersal, zoology, Arachnology
- Copyright
- © 2015 Dziki et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2015. Spintharus flavidus in the Caribbean – a 30 million year biogeographical history and radiation of a ‘widespread species’. PeerJ PrePrints 3:e1332v1 https://doi.org/10.7287/peerj.preprints.1332v1
Abstract
The Caribbean island biota is characterized by high levels of endemism, the result of an interplay between colonization opportunities on islands and effective oceanic barriers among them. A relatively small percentage of the biota is represented by ‘widespread species’, presumably taxa for which oceanic barriers are ineffective. Few studies have explored in detail the genetic structure of widespread Caribbean taxa. The cobweb spider Spintharus flavidus Hentz, 1850 (Theridiidae) is one of two described Spintharus species and is unique in being widely distributed from northern N. America to Brazil and throughout the Caribbean. As a taxonomic hypothesis, Spintharus “flavidus” predicts maintenance of gene flow among Caribbean islands, a prediction that seems contradicted by known S. flavidus biology, which suggests limited dispersal ability. As part of an extensive survey of Caribbean arachnids (project CarBio), we conducted the first molecular phylogenetic analysis of S. flavidus with the primary goal of testing the ‘widespread species’ hypothesis. Our results, while limited to three molecular loci, reject the hypothesis of a single widespread species. Instead this lineage seems to represent a radiation with at least 16 species in the Caribbean region. Nearly all are short range endemics with several distinct mainland groups and others being single island endemics. While limited taxon sampling, with a single specimen from S. America, constrains what we can infer about the biogeographical history of the lineage, clear patterns still emerge. Consistent with limited overwater dispersal, we find evidence for a single colonization of the Caribbean about 30 million years ago, coinciding with the timing of the GAARLandia landbridge hypothesis. In sum, S. “flavidus” is not a single species capable of frequent overwater dispersal, but rather a 30 my old radiation of single island endemics that provides preliminary support for a complex and contested geological hypothesis.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
specimen table
Table S1. List of specimens included in this study.
data matrix
Supplementary material. Data matrix with the three concatenated loci