Spiders on a Hot Volcanic Roof: Colonisation Pathways and Phylogeography of the Canary Islands Endemic Trap-Door Spider Titanidiops canariensis (Araneae, Idiopidae)

Abstract

Studies conducted on volcanic islands have greatly contributed to our current understanding of how organisms diversify. The Canary Islands archipelago, located northwest of the coast of northern Africa, harbours a large number of endemic taxa. Because of their low vagility, mygalomorph spiders are usually absent from oceanic islands. The spider Titanidiops canariensis, which inhabits the easternmost islands of the archipelago, constitutes an exception to this rule. Here, we use a multi-locus approach that combines three mitochondrial and four nuclear genes to investigate the origins and phylogeography of this remarkable trap-door spider. We provide a timeframe for the colonisation of the Canary Islands using two alternative approaches: concatenation and species tree inference in a Bayesian relaxed clock framework. Additionally, we investigate the existence of cryptic species on the islands by means of a Bayesian multi-locus species delimitation method. Our results indicate that T. canariensis colonised the Canary Islands once, most likely during the Miocene, although discrepancies between the timeframes from different approaches make the exact timing uncertain. A complex evolutionary history for the species in the archipelago is revealed, which involves two independent colonisations of Fuerteventura from the ancestral range of T. canariensis in northern Lanzarote and a possible back colonisation of southern Lanzarote. The data further corroborate a previously proposed volcanic refugium, highlighting the impact of the dynamic volcanic history of the island on the phylogeographic patterns of the endemic taxa. T. canariensis includes at least two different species, one inhabiting the Jandia peninsula and central Fuerteventura and one spanning from central Fuerteventura to Lanzarote. Our data suggest that the extant northern African Titanidiops lineages may have expanded to the region after the islands were colonised and, hence, are not the source of colonisation. In addition, T. maroccanus may harbour several cryptic species.

Pre‐Pleistocene geological events shaping diversification and distribution of primitively segmented spiders on East Asian margins

“…Our results suggest that restricted gene flow following barrier formation is the dominant force governing the historical and current‐day genetic boundaries among and within islands, which indicates the broad‐scale impact of the pre‐Pleistocene tectonic events on codistributed continental insular lineages. Together with a few well‐known phylogenetically old terrestrial arachnid lineages such as harvestmen (Boyer et al ., ; Clouse & Giribet, ) and myglomorph spiders (Opatova & Arnedo, ,b), liphistiids are a rare example of dispersal‐limited organisms occupying continental islands where overwater dispersal is evidently absent. Hence, their phylogenetic history can be treated as independent tests of geological history.…”

“…3, Table S3), multiple isolated genetic lineages (Figs 2,3,5 & 6), and stable populations (Table S5), suggesting that these lineages diversified well before the Pleistocene glaciations and that their matching phylogeographical patterns have been shaped by late Cenozoic geological events, some of which are yet unknown. Deep genetic structuring is known in mygalomorph spiders that share phenotypic and ecological traits with liphistiids (Bond et al, 2001;Opatova & Arnedo, 2014b). In contrast, the population genetic structures of Heptathela lineages of Kyushu and the Amami group exhibit lower genetic diversity reflected by high haplotype diversity and low nucleotide diversity indices (Table S5), simpler haplotype networks (Fig.…”

“…Arachnids with ancient origins, limited dispersal abilities, and restricted habitats are good models for testing historical biogeographical hypotheses (Boyer et al ., ; Clouse & Giribet, ; Hedin et al ., ; Opatova & Arnedo, ,b), and these include the primitively segmented spiders, family Liphistiidae (Xu et al ., ). Liphistiids belong to the suborder Mesothelae dating back at least to the late Carboniferous with an Euramerian origin (295 Ma, Bristowe, ; Platnick & Gertsch, ; Selden, ; Haupt, ).…”

Sky island diversification meets the multispecies coalescent – divergence in the spruce‐fir moss spider (Microhexura montivaga, Araneae, Mygalomorphae) on the highest peaks of southern Appalachia

“…; Castalanelli et al . ; Opatova & Arnedo ), whether such dispersal limitation applies in the small‐bodied (adult total length <6 mm), web‐building Microhexura is currently unknown. A second goal was to explore the use of multilocus species delimitation methods in this naturally fragmented system.…”

“…burrow-dwelling trapdoor spiders) display remarkable microgeographic genetic differentiation (e.g. Bond & Stockman 2008;Hedin et al 2013;Satler et al 2013;Castalanelli et al 2014;Opatova & Arnedo 2014), whether such dispersal limitation applies in the small-bodied (adult total length <6 mm), webbuilding Microhexura is currently unknown. A second goal was to explore the use of multilocus species delimitation methods in this naturally fragmented system.…”