MARDIGRAS: A New Project Begins!

Credit: © Hans Hillewaert

It's official! Starting today, I am a Marie Skłodowska-Curie Fellow, with a project titled "MARDIGRAS: Elucidating MARine DIversity GRAdients with Empirical and Theoretical ModelS". I'm thrilled for the opportunity to take my experiences of the last few years working on biodiversity patterns in butterflies and birds, and puzzle through how to infer biodiversity patterns and their underlying mechanisms in marine fishes.

The aim of the project is to take a deep dive (sorry not sorry for the pun) into understanding worldwide biodiversity patterns for three groups of marine fishes (my beloved Gadiformes, aka codfishes; Scombriformes, aka mackerels and tunas; and Beloniformes, aka flyingfishes), develop a mechanistic model of how biodiversity patterns arise in marine systems, and then contrast diversity patterns among the three groups of fishes and with the mechanistic model.

While there is extensive macroecological literature on diversity gradients in terrestrial systems, especially regarding latitude, marine systems seem to be following a different set of rules. First, geographic patterns of diversity appear to be neither clear nor ubiquitous. Recently, Chaudhary et al. (2016) found a bimodal diversity curve with respect to latitude (that is, more species were found at middle latitudes than at the equator), whereas Rabosky et al (2018) found a unimodal curve with diversity concentrated at the equator (which is the expected pattern for terrestrial groups). Admittedly, these studies had different organismal foci and employed different methods, but this disparity is striking.

Second, the mechanisms underlying diversity patterns in marine systems appear to be quite different. Generally, in terrestrial systems it is thought that speciation is highest in the tropics, as this is where the most energy is concentrated (among other explanations). However, the aforementioned study by Rabosky and colleagues found that speciation (in marine fishes) was highest at high latitudes! Some of this may be attributable to the unique properties of ocean ecosystems compared to terrestrial ones. As such, one of my project goals is to adapt a mechanistic model that was developed for terrestrial tropical biodiversity (Rangel et al. 2018) and adapt it for the marine context, using diversity patterns in codfishes, mackerels, and flyingfishes to evaluate how realistic the model is.

Stay tuned as I make progress in this exciting area, either here or by following #mardigrasProj on Twitter!

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