Historical connectivity and environmental filtering jointly determine the freshwater fish assemblages on Taiwan and Hainan Islands of China

Abstract

The biotas of Taiwan and Hainan Islands are of continental origin, but the manner with which historical and ecological factors shaped these insular species is still unclear. Here, we used freshwater fish as a model to fill this gap by quantifying the phylogenetic structure of the insular faunas and disentangling the relative contribution of potential drivers. Firstly, we used clustering and ordination analyses to identify regional species pools. To test whether the insular freshwater fish faunas were phylogenetically clustered or overdispersed, we calculated the net relatedness index (NRI) and the nearest taxon index (NTI). Finally, we implemented logistic regressions to disentangle the relative importance of species attributes (i.e. maximum body length, climatic niche dissimilarity, and diversification) and historical connectivity in explaining the insular faunas. Our results showed that the most possible species pools of Taiwan are Zhejiang and Fujian provinces, and those of Hainan are Guangdong and Guangxi provinces. These insular faunas showed random phylogenetic structures in terms of NRI values. According to the NTI values, however, the Taiwanese fauna displayed more phylogenetic clustering, while the Hainanese one was more overdispersed. Both the standard and phylogenetic logistic regressions identified historical connectivity and climatic niche dissimilarity as the two top explanatory variables for species assemblages on these islands. Our reconstruction of the paleo-connected drainage basins provides insight into how historical processes and ecological factors interact to shape the freshwater fish fauna of the East Asian islands.

Phylogeographic analysis revealed allopatric distribution pattern and biogeographic processes of the widespread pale chub Opsariichthys acutipinnis-evolans complex (Teleostei: Cyprinidae) in southeastern China

“…Samples from the northern part of the island, including the Danshuihe River and Shuangxi River, showed a close relationship with those sampled from the Qiangtangjiang/ Oujiang River (Figure 1D), while samples from northwestern part of the island derived from those sampled from Mulanxi River (Figure 1F). Geological and phylogeographical evidence have shown that a land bridge recurrently connected the Taiwan Island with the continental East Asia during the Quaternary glacial cycles, facilitating biotic interchanges between both sides (e.g., Wang et al, 2007;Chiang et al, 2010;Lin et al, 2022). The periodic emergence of the land bridge could be a plausible explanation for the multiple colonization routes at different time stages as some previous studies suggested (Yu, 1995;Wang et al, 2004;Chang et al, 2016).…”

Biogeography of Greater Antillean freshwater fishes, with a review of competing hypotheses

“…Excellent examples of immigration by primary freshwater fishes via continent–island drainage connections have been documented on the eastern coasts of Asia, where there are extensive continental shelves that allow for river‐drainage connections between the continent and islands during periods of low sea‐level (Voris, 2000). For instance, streams draining the islands of Hainan and Taiwan integrated with mainland drainages during Pleistocene sea‐level low stands and freshwater fishes populating both islands are a random subset of fishes available from mainland source pools (Lin et al ., 2023). This includes primary freshwater fishes, notably Cypriniformes (Chiang et al ., 2013; Ju et al ., 2018; Wang et al ., 2022; Chen & Jang‐Liaw, 2023).…”

Biogeography of Greater Antillean freshwater fishes, with a review of competing hypotheses

“…Excellent examples of immigration by primary freshwater fishes via continent-island drainage connections are documented on the eastern coasts of Asia, where there are extensive continental shelves that allow for river-drainage connections between the continent and islands during sea-level falls (Voris, 2000). For instance, streams draining the islands of Hainan and Taiwan integrated with mainland drainages during Pleistocene sea-level low stands and freshwater fishes populating both islands were a random subset of fishes available from mainland source pools (Lin et al, 2023). This included primary freshwater fishes, notably Cypriniformes (Chiang et al, 2013; Ju et al, 2018; Wang et al, 2022; Chen & Jang-Liaw, 2023).…”