Systematics of Clupeiformes and testing for ecological limits on species richness in a trans-marine/freshwater clade

Abstract

Clupeiformes (herring, sardines, shad, anchovies and allies) are a globally distributed clade with nearly 400 marine, freshwater, and diadromous species. Although best known as filter feeding fishes that form large schools, this group occupies a diverse array of trophic guilds and habitats. Theory suggests that species richness in clades is modulated by ecological limits, which results in diversity-dependent clade growth, a pattern that most clades exhibit. As a trans-marine/freshwater clade that has undergone repeated transitions between marine and freshwaters, Clupeiformes are an excellent system for investigating the interplay between ecological diversity and macroevolutionary dynamics. In this study we review the systematics of Clupeiformes and explore discordance in phylogenetic relationships and divergence times between mitochondrial and nuclear loci. We then use comparative methods to test whether ecological limits regulate diversity in Clupeiformes. We find discordance in phylogenetic relationships at various taxonomic scales, but also considerable agreement between genomes. Our results suggest that trans-marine/freshwater clades are able to circumvent ecological limits on clade growth at regional, but not on local scales. Our study demonstrates that phylogenies are a critical link between ecology and macroevolutionary dynamics, and suggests habitat transitions can play a key role in shaping diversity patterns, particularly in the neotropics.

Speciation rate and the diversity of fishes in freshwaters and the oceans

“…My tabulation of marine‐freshwater transitions (Appendix S1) is highly incomplete and should not be considered an exhaustive list; I do not distinguish multiple freshwater invasions (and potentially, reverse transitions) in a number of groups with complex histories of trait evolution. These groups include gobiiform, mugiliform, atheriniform and clupeiform fishes; several have already been the topic of dedicated analyses (Betancur‐R et al, 2012; Bloom & Egan, 2018; Bloom et al, 2013). Appendix S1 also indicates whether a given origin is associated with a freshwater "radiation", which is defined here as diversification of a presumed freshwater ancestor into four or more species that exclusively inhabit freshwater and for which multiple independent freshwater colonizations from marine ancestors are unlikely.…”

Habitat transitions alter the adaptive landscape and shape phenotypic evolution in needlefishes (Belonidae)

“…In addition, considering all phylomorphospace configurations in Figures 2 and 3, freshwater taxa are more morphologically diverse than marine taxa. This demonstrates that habitat transitions have promoted diversification of body shapes and size, as well as faster rates of shape and size evolution in belonids overall perhaps due to release of ecological limits on clade diversification in novel habitats (Betancur‐R et al, 2012; Bloom & Egan, 2018).…”

Mode of miniaturisation influences body shape evolution in New World anchovies (Engraulidae)

“…Alternatively, Thomas et al (2009) argued that extreme body size is not driven by islands per se, but rather that when a lineage colonises an island, it is the novel environment in general that promotes phenotypic evolution. Anchovies colonised freshwater rivers of South America 20-30 MBP (Bloom & Lovejoy, 2017;Bloom & Egan, 2018;Egan et al, 2018), which preceded or was synchronous with the Pebas mega-wetland (Hoorn et al, 2010;Wesslingh & Hoorn, 2010). The Pebas mega-wetland was a dynamic ecosystem that may have created a novel environment that set the stage for diversification of some Neotropical freshwater fishes, including freshwater anchovies (Bloom & Lovejoy, 2017).…”