Ancient River Inference Explains Exceptional Oriental Freshwater Mussel Radiations

Abstract

The concept of long-lived (ancient) lakes has had a great influence on the development of evolutionary biogeography. According to this insight, a number of lakes on Earth have existed for several million years (e.g., Baikal and Tanganyika) and represent unique evolutionary hotspots with multiple intra-basin radiations. In contrast, rivers are usually considered to be variable systems, and the possibility of their long-term existence during geological epochs has never been tested. In this study, we reconstruct the history of freshwater basin interactions across continents based on the multi-locus fossil-calibrated phylogeny of freshwater mussels (Unionidae). These mussels most likely originated in Southeast and East Asia in the Jurassic, with the earliest expansions into North America and Africa (since the mid-Cretaceous) following the colonization of Europe and India (since the Paleocene). We discovered two ancient monophyletic mussel radiations (mean age ~51–55 Ma) within the paleo-Mekong catchment (i.e., the Mekong, Siam, and Malacca Straits paleo-river drainage basins). Our findings reveal that the Mekong may be considered a long-lived river that has existed throughout the entire Cenozoic epoch.

Molecular phylogeny of the Nearctic and Mesoamerican freshwater mussel genus Megalonaias

“…Although the higher-level classification of the Unionidae is unstable (Whelan et al, 2011;Pfeiffer & Graf, 2015;Lopes-Lima et al, 2016;Bolotov et al, 2017), it remains clear that the subfamily Ambleminae has experienced the most dramatic evolutionary radiation, representing over half of the species-level diversity of the family. The Ambleminae is distributed across much of North America, occupying most permanent freshwater habitats east of the Continental Divide of the Americas, from northern Canada south to the Isthmus of Panama.…”

A new Contradens from Laos (Bivalvia: Unionidae: Contradentini)

“…Although Southeast Asian fauna of freshwater bivalves has been subject of intense research efforts during the last five years (e.g. Zieritz et al 2016;Bolotov et al 2017aBolotov et al , 2017bBolotov et al , 2019Lopes-Lima et al 2017;Jeratthitikul et al 2019;Konopleva et al 2019), the fauna of Laos is still poorly known (Zieritz et al 2018).…”

“…For example, modern information on the population status and ecology is only available for a single species, Gibbosula laosensis (Lea, 1863) (Bivalvia: Margaritiferidae) (Bolotov et al 2014). Nevertheless, molecular data on freshwater mussels from Laos is presented in a few works (Pfeiffer and Graf 2015;Bolotov et al 2017aBolotov et al , 2017bLopes-Lima et al 2017) but the taxonomic placement of those sequences is still uncertain.…”

“…Contradens Haas 1911 is a widely distributed freshwater mussel genus, whose range covers the Mekong, Chao Phraya and Mae Klong basins, rivers of the Malay Peninsula and the Greater Sunda Islands (Zieritz et al 2016;Bolotov et al 2017aBolotov et al , 2017bPfeiffer et al 2018;Konopleva et al 2019). During recent decades some researchers attempt to revise the genus Contradens by means of an integrative taxonomic approach (Bolotov et al 2017b;Lopes-Lima et al 2017;Jeratthitikul et al 2019;Konopleva et al 2019).…”

Temperature‐driven selection on metabolic traits increases the strength of an algal–grazer interaction in naturally warmed streams

“…The two streams in our experiment are separated by approximately 500 m but differ in temperature by 11°C. Dispersal, gene flow and genetic divergence among populations in this species are strongly related to geographic distance (Johansson, Quintela, & Laurila, 2016), and R. balthica are known to disperse slowly, but regularly over short distances (Hoffman et al, 2006;Kappes & Haase, 2012), but rarely over long distances, where such events are usually associated with passive dispersal, for example, via association with vertebrates (Bolotov et al, 2017;Hansson & Akesson, 2014). Thus, our study, over a relatively small spatial scale (500 m), provides insight into how metabolic and resource acquisition traits in closely related natural populations have diverged in response to warming and is therefore directly relevant for understanding the effects of rapid climate change (Keller, Alexander, Holderegger, & Edwards, 2013;Meril€ a & Hendry, 2014;Richter-Boix, Teplitsky, Rogell, & Laurila, 2010).…”