Did a Miocene–Pliocene island isolation sequence structure diversification of funnel web spiders in the Taiwan‐Ryukyu Archipelago?

Abstract

Aim We tested the competing hypotheses concerning the relative importance of Pleistocene versus Miocene-Pliocene geological events for the formation of endemism in an Asian archipelago using the Macrothele taiwanensis (Hexathelidae) species group.Location Taiwan-Ryukyu Archipelago.Methods We estimated phylogenetic trees from cytochrome oxidase I subunit (COI) and 16S rRNA (16S) gene regions and employed Bayesian ancestral range reconstructions to investigate previously debated models of lineage diversification in the Taiwan-Ryukyu Archipelago. To evaluate alternative geological timeframes for their importance in shaping the genetic structure of funnel web spiders, we used five time calibration schemes to estimate timing of divergence, infer ancestral distributions, and to reconstruct historical demographic changes in each lineage. We tested taxonomic boundaries with two species delimitation procedures.Results Our results indicate a north-to-south isolation sequence of the M. taiwanensis group: the Amami lineage diverged first, then Yaeyama, and finally the Taiwanese lineages. Divergence time estimation and population demographic change analyses indicate that Pleistocene climate fluctuations minimally impacted the genetic structure of these spiders. Instead, estimated divergence events correspond to Miocene-Pliocene geological events, strongly supporting a much older timeframe for diversification. The results of species delimitation analyses coincide well with morphological differences observed among the island populations, reinforcing inferred species boundaries, and at least three potential cryptic species were statistically detected within Taiwan.Main conclusions Miocene-Pliocene geological events appear to have contributed disproportionately to diversification in the M. taiwanensis species group. The clear association between geographical area, genetic structure and statistical species delimitation strongly supports an interpretation of allopatric speciation. We advocate comparing our results with those derived from additional study organisms with similar life histories to further explore the Miocene-Pliocene diversification hypothesis.

Geographical and temporal origins of terrestrial vertebrates endemic to Taiwan

“…The temporal patterns of these colonization events based on the meta-analysis were strikingly consistent with those resulting from the DEC models (compare Figure 3a to b), indicating that the major colonization wave into Taiwan may have occurred c. 5-6 Ma. Further evidence supporting this important timing of colonization events can be found in other lineages, such as invertebrates (Shih, Hung, Schubart, Chen, & Chang, 2006;Su et al, 2016), freshwater fish (Chiang, Lin, Shao, & Hsu, 2010) and plants (Chou et al, 2011;Ito et al, 2017;Matuszak et al, 2016). Collectively, the highly supported congruency provided robust biogeographical evidence that extant Taiwanese species have colonized from neighbouring land masses since the early Pliocene (c. 5 Ma), which is highly coincident with the estimated geological age of Taiwan (Sibuet & Hsu, 2004;Teng, 1990).…”

“…5–6 Ma. Further evidence supporting this important timing of colonization events can be found in other lineages, such as invertebrates (Shih, Hung, Schubart, Chen, & Chang, ; Su et al., ), freshwater fish (Chiang, Lin, Shao, & Hsu, ) and plants (Chou et al., ; Ito et al., ; Matuszak et al., ). Collectively, the highly supported congruency provided robust biogeographical evidence that extant Taiwanese species have colonized from neighbouring land masses since the early Pliocene ( c .…”

“…Brown et al, 2013;Crottini et al, 2012;de Bruyn et al, 2014;Stelbrink, Albrecht, Hall, & von Rintelen, 2012). Nevertheless, studies on East Asian islands are comparatively limited, and due to the distinct geological contexts, the biogeographical patterns on East Asian islands are rather distinct (Li, Fu, & Lei, 2011;Komaki et al, 2017;Su, Brown, Chang, Lin, & Tso, 2016;Yang, Komaki, Brown, & Lin, 2018).…”

Conceptual and statistical problems with the DEC+J model of founder‐event speciation and its comparison with DEC via model selection

“…Klaus et al ; Fuchs, Pons, and Bowie, 2017; Su et al. ). However, these studies alone do not account for the trending use of model selection noted above.…”

“…Numerous empirical studies have since followed this example and pitted DEC against DEC+J in testing hypotheses involving jump dispersal (e.g. Klaus et al 2016;Fuchs, Pons, and Bowie, 2017;Su et al 2016). However, these studies alone do not account for the trending use of model selection noted above.…”