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

Abstract

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 butchko sp. 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.

Caribbean golden orbweaving spiders maintain gene flow with North America

“…Trichonephila clavipes resembles the Caribbean pattern detected in the araneid Argiope argentata where island populations clearly interbreed (Agnarsson et al, ). At a higher taxonomic level and within the area of interest, the Caribbean Trichonephila contrasts the two tetragnathid lineages: Cyrtognatha is a relatively poor to intermediate disperser with significant species richness and high endemism, Tetragnatha is a dynamic disperser, with species apparently ranging from extremely good to relatively poor, and shows a high species richness and a mixed endemic to widespread mix of species (Čandek et al, , ).…”

Caribbean golden orbweaving spiders maintain gene flow with North America

“…Trichonephila clavipes resembles the Caribbean pattern detected in the araneid Argiope argentata where island populations clearly interbreed (Agnarsson et al 2016). At a higher taxonomic level and within the area of interest, the Caribbean Trichonephila contrasts the two tetragnathid lineages: Cyrtognatha is a relatively poor to intermediate disperser with significant species richness and high endemism, Tetragnatha is a dynamic disperser lineage, with species apparently ranging from extremely good to relatively poor, and shows a high species richness and a mixed endemic to widespread mix of species.…”

Evidence for Miocene overwater colonization in CaribbeanCyrtognathaspiders

“…As a means of biotic evolution on the Greater Antilles, the GAARlandia hypothesis allows for a combination of overland dispersal and subsequent vicariance and can be tested with the help of time calibrated phylogenies and fossils. While patterns of relationships that are consistent with predictions based on GAARlandia have been found in some lineages 44–48 it is not a good model for explaining the biogeographical history of others 27,29,49,50 .…”

“…Amongst island systems some of the best studied in terms of biogeographic research are Hawaii 6–8 , Galapagos 9–11 , Azores 12–14 , Canary 15–17 and Solomon 18–20 islands, as well as large continental fragments such as Madagascar 21–23 and New Zealand 24–26 . However, the Caribbean island system 27–30 is the single most ‘published’ island system in biogeography literature (Google Scholar title hits 237 compared with 195 for the second, New Zealand). The Caribbean Basin, also known as West Indies, lies in the tropical zone between South and North American continents, and to the east of the Gulf of Mexico.…”