Tropical Niche Conservatism Explains the Eocene Migration from India to Southeast Asia in Ochyroceratid Spiders

Abstract

Biological migrations between India and Southeast (SE) Asia provide an ideal system for exploring the effects of geology and climate on species ranges. Geologists have confirmed that the direct collision between India and Eurasia occurred in the Early Eocene, but most migrations occurred between the Indian subcontinent and SE Asia rather than the former and the southern margin of Eurasia. To explain this seemingly paradoxical disconnect between the routes of plate movement and biological migration, we studied the evolutionary history of the tropical spider family Ochyroceratidae based on 101 globally distributed species. We infer a robust dated phylogeny using both transcriptomic data and a data set of classical markers and relate these to biogeographic and climatic analyses. Our results indicate that the monophyly of Ochyroceratidae is strongly supported, and the divergence times suggest a Cretaceous Gondwanan origin of the family. Reconstructed biogeographic histories support a dispersal event from the Indian subcontinent to islands of SE Asia 55–38 Ma. Climatic analyses and the fossil record reveal that ochyroceratids are characterized by a high degree of tropical niche conservatism, and that the ancestor of the Indian and SE Asian clades originated in very warm, wet environments. Early Eocene tropical, perhumid climates in India, and SE Asia may have facilitated ochyroceratid migration, whereas the dry or seasonal climate extending from the eastern coast of China to Central Asia may have acted as a barrier, preventing dispersal. Our analyses suggest that climate plays a more important role than geology in biological migration from the Indian subcontinent to SE Asia, providing new insights into the Indian–Asian biogeographic link. [Biogeography; ecology; geological connections; macroevolution; paleoclimate.]

Molecular phylogeny of Megasternini terrestrial water scavenger beetles (Hydrophilidae) reveals repeated continental interchange during Paleocene‐Eocene thermal maximum

“…For example, it seems evident that the current diversity and distribution of the Megasternini was affected by the evolution of ecological traits, e.g., the larger or smaller ability to survive in a non‐tropical environment. Consequently, the phylogenetic niche conservatism (Wiens & Graham, 2005; Donoghue, 2008; Crisp et al ., 2009) needs to be taken into account for future analyses of the evolutionary history of the Megasternini (e.g., see Li et al ., 2020; Meseguer & Cordamine, 2020).…”

Niche Conservatism Drives the Elevational Diversity Gradient in Major Groups of Free-Living Soil Unicellular Eukaryotes

“…This hypothesis proposes that taxa retain their ecophysiological traits (e.g., thermal tolerance) over evolutionary time and that, therefore, they tend to remain in environments that exhibit the abiotic conditions within which they evolved [3]. This evolutionary trend has been proposed to explain why most modern taxa fail to disperse into new environments, offering an underlying explanation to the diversity patterns that we observe today in nature [4][5][6].…”

“…Accordingly, this hypothesis also predicts that diversity will decline towards exceedingly hot or cold (suboptimal) sites because the ancestral adaptation of modern taxa to moist (sub)tropical-like environments imposes a strong constraint on their ability to tolerate extremely high or low temperatures [3]. Others predictions of the PNC include a positive correlation between diversity and temperature [4,5,7], an increase in the size of taxa distribution ranges towards the colder end of an environmental gradient [10,11], giving place to a macroecological pattern known as the Rapoport effect [12]; and local communities structured by competition in warm sites and structured by habitat ltering in cold sites [3,13].…”

“…These predictions have been extensively tested in multicellular organisms, proving useful to explain their diversity patterns in terms of both ecological processes and historical contingencies (e.g., [4][5][6][7]). By contrast, these predictions have been investigated in few studies dealing with unicellular organisms, including bacteria (e.g., [8,14,15]) and protists such as testate amoebae [11].…”

Thirty-one new species of the spider genus Leclercera from Southeast Asia (Araneae, Psilodercidae)

“…To date, Psilodercidae includes a total of 165 species in 11 genera (WSC 2019), and the family has been shown to be monophyletic (Li and Li 2018). It is distributed in Southeast Asia, southern China, and parts of South Asia (WSC 2019, Li et al 2020. The number of species has ballooned to almost three times its size in the 21 st century, from only 53 species known by the end of 20 th century (Platnick 2000).…”