Is the Species Flock Concept Operational? The Antarctic Shelf Case

Abstract

There has been a significant body of literature on species flock definition but not so much about practical means to appraise them. We here apply the five criteria of Eastman and McCune for detecting species flocks in four taxonomic components of the benthic fauna of the Antarctic shelf: teleost fishes, crinoids (feather stars), echinoids (sea urchins) and crustacean arthropods. Practical limitations led us to prioritize the three historical criteria (endemicity, monophyly, species richness) over the two ecological ones (ecological diversity and habitat dominance). We propose a new protocol which includes an iterative fine-tuning of the monophyly and endemicity criteria in order to discover unsuspected flocks. As a result nine « full » species flocks (fulfilling the five criteria) are briefly described. Eight other flocks fit the three historical criteria but need to be further investigated from the ecological point of view (here called « core flocks »). The approach also shows that some candidate taxonomic components are no species flocks at all. The present study contradicts the paradigm that marine species flocks are rare. The hypothesis according to which the Antarctic shelf acts as a species flocks generator is supported, and the approach indicates paths for further ecological studies and may serve as a starting point to investigate the processes leading to flock-like patterning of biodiversity.

Epimeria of the Southern Ocean with notes on their relatives (Crustacea, Amphipoda, Eusiroidea)

“…Excluding the sub-Antarctic/low Antarctic subgenus Metepimeria, for which no molecular data was available, Antarctic Epimeria do form a clade Verheye et al 2016b;Verheye et al 2017), which has been interpreted as a species flock (Lecointre et al 2013). This Antarctic Epimeria clade exhibits a higher species richness and morphological diversity than all known Epimeria species from all the other oceans combined.…”

Understanding processes at the origin of species flocks with a focus on the marine Antarctic fauna

“…Since the assessment of endemicity and speciosity is necessarily linked to a given geographic area, we here group the first three criteria of Lecointre et al . (). Our criteria for a monophletic group (i.e.…”

“…One question is therefore whether there is underlying unity beneath the SF concept [based on the detection criteria of Lecointre et al . ()]: for example, is there a syndrome, i.e. a significant statistical association among the SEC, ED and HD criteria or is there a single underlying cause leading, in theory, to the joint fulfillment of these three criteria?…”

The hypothesis of adaptive radiation in evolutionary biology: hard facts about a hazy concept

“…Naming the clade resulting from an AR is also challenging. In some cases, the term "species flock" has been invoked, referring to a clade whose constituting species occur in an isolated area and show differential adaptations to diverse ecological conditions (Lecointre et al 2013;Meyer 2005 and references therein). Although there is no agreement to date on what exactly defines an AR, the literature on this subject is very abundant (e.g., Erkens et al 2012;Givnish 1997;Olson and Arroyo-Santos 2009;Rundell and Price 2009 and references therein).…”