Life

Developmental robustness and species diversity: A special issue of Annals of Botany

Magnolia flowers
Flowers from the same Magnolia tree have different numbers of perianth organs, indicative of a low degree of robustness in perianth organ number determination.
Photos by Susanne Schilling.

J.B.S. Haldane is often quoted to have said that ‘God has an inordinate fondness for beetles’. Arguably, Haldane himself would not have accepted this as an explanation for the enormous number of beetle species – they make up some 25 – 30 % of all described animals. However, Haldane’s statement demonstrates that we still lack a satisfying explanation for an oddity in the tree of life: it is only a few taxa that contribute disproportionately strongly to species diversity, whereas other taxa contain relatively few species. This observation is by no means restricted to the animal kingdom; if Haldane would have been a botanist, he may have said that god (like most of us humans) has an inordinate fondness for flowering plants – these make up some 85 – 90 % of all described plant species. The question is obvious: Why are there so many flowering plant species but so few gymnosperm species? Likewise, one may ask: Why are there so many orchid, daisy and grass but so few early diverging angiosperm species? A number of explanations have been suggested over the years: the age of clades, evolutionary innovations and co-evolution may all well have contributed to the success (in terms of species number) of some taxa over others. But as obvious as some of these explanations might be for certain groups – for example, co-evolution with pollinators may well have accelerated the radiation of orchids – they fail to explain other cases of species diversity: co-evolution with pollinators can hardly explain why there are more than 10,000 species of mainly wind-pollinated grasses, for example.

However, one striking observation is that successful taxa appear to be morphologically rather uniform: all orchid flowers share a basic floral bauplan, the same applies to grasses or daisies (and also beetles have a highly standardized body plan). Highly standardized or uniform structures may be an indication for a high degree of developmental robustness. Thus, in contrast to what one may intuitively assume, robust developmental processes might facilitate rather than prevent the evolution of species diversity.

We started exploring the relationship between species diversity and developmental robustness on a symposium at the Euro Evo Devo 2014 conference in Vienna that was supported by the Annals of Botany. However, we are still far from understanding the relevance of robustness for species diversity. On account of this, a Special Issue on that topic will appear in the Annals of Botany. Authors already committed to contribute to this Special Issue are Peter Endress (Zürich), Angela Hay (Cologne), Matthew Wills (Bath), Koichi Fujimoto (Osaka), and Veronica Grieneisen (Norwich).

This is an open call for submission of manuscripts on developmental robustness, biodiversity and the relationship between the two for consideration for the Special Issue. We intend to have a mixture of papers treating the topic from the perspective of developmental genetics, evolutionary biology, plant morphology, paleobiology and systems biology. If you have a manuscript that you would like us to consider, please send an outline (Title, Authors and 250 to 500 words) until the end of 2014 to annalsbotany@le.ac.uk. If agreed, the full paper would need to be submitted by 31 March 2015, in order to enter the full review process.

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