Major shifts in biogeographic regions of freshwater fishes as evidence of the Anthropocene epoch

Abstract

Animals and plants worldwide are structured in global biogeographic regions, which were shaped by major geologic forces during Earth history. Recently, humans have changed the course of events by multiplying global pathways of introduction for nonindigenous species and propagating local species extirpations. Here, we report on how introductions and extirpations have changed the distributions of freshwater fishes worldwide and how it affected their natural biogeographic regions. We found major shifts in natural regions, with the emergence of an intercontinental region arising from the fusion of multiple faunas, which we named Pan-Anthropocenian Global North and East Asia (PAGNEA). The PAGNEA region is evocative of the Pangea supercontinent, as flows of introductions show that dispersal has become possible again across multiple continents, suggesting that human activities have superseded natural geological forces. Our results constitute evidence on the expected modification of biostratigraphic boundaries based on freshwater fish, which are abundant in the fossil record, thereby supporting the concept of the Anthropocene epoch.

Biological invasions are a population‐level rather than a species‐level phenomenon

“…Biological invasions have rapidly consolidated among the major threats of the Anthropocene, causing significant detrimental impacts to biodiversity, the functioning of ecosystem processes, and to socio‐economic stability (Diagne et al., 2021; Roy et al., 2023; Shackleton et al., 2019; Simberloff, 2013; Zhang et al., 2022). Both accidental and intentional introductions of non‐native species into new geographic regions, where they have no evolutionary history, can result in substantial adverse effects (Dudgeon, 2019; Leroy et al., 2023; Reid et al., 2019), including local displacement and extinction of native species through predation and competition, parasite and disease transmission, changes in ecosystem functioning, and—among other impacts—the disruption of systemic balances (Bacher et al., 2023; Lázaro‐Lobo et al., 2023; Soto et al., 2024). As biological invasions continue to escalate globally, understanding what enables populations of non‐native species to spread to new territories becomes crucial in devising effective strategies for the mitigation of their impacts (Heger et al., 2021; Richardson & Ricciardi, 2013).…”

A global analysis of the introduction pathways and characteristics associated with non-native fish species introduction, establishment, and impacts

“…Freshwater fishes are among the most introduced taxa, with non-native freshwater fishes now established in all biogeographical realms (Gozlan 2008;Leprieur et al 2008;Bernery et al 2022). The magnitude of introduced fishes is so significant that these biogeographical realms were irremediably altered, constituting evidence of the Anthropocene epoch (Leroy et al 2023). Invasive nonnative freshwater fish species have diverse impacts, ranging from local hybridization with native fish species, with the invasive rainbow trout (Oncorhynchus mykiss) and native westslope cutthroat trout (Oncorhynchus clarkii lewisi) in Canadian rivers (Muhlfeld et al 2009) being a well-known example.…”

Structural and functional effects of global invasion pressure on benthic marine communities—patterns, challenges and priorities

“…Biological invasions are a defining characteristic of global change and the Anthropocene epoch in general (Leroy et al, 2023;Lewis & Maslin, 2015;Ricciardi, 2007). Since the middle of the twentieth century, the number of species that have been detected outside their native historical range has increased dramatically across most of the world's terrestrial and aquatic ecosystems, in association with increased global trade and travel (Bailey et al, 2020;Early et al, 2016;Seebens et al, 2018).…”