It was the day before my maternity leave started that I received an invite from the journal Proceedings of the Royal Society B to submit a reply to the comment by Heymann & Fuzessy. They criticized some of the work my co-authors and I published in early 2020, on the relationship between palm fruit colours and the diversity of trichromatic vision (the ability to distinguish red and green) in primates. See here for the original publication. Luckily, the journal allowed me a bit of time to think about a response while nursing my baby.
The main issue that Heymann & Fuzessy raised, was that there is little natural history information on the dependence of primates on palm fruits, especially in Africa. Therefore, they considered the macroecological and macroevolutionary analyses we performed in our original article unreliable. In our response, we argue that our macro analyses, which show a strong relationship between the spatial and temporal diversity of trichromatic primates and that of conspicuous (e.g. reddish) palm fruits (see figure below), are indeed only one piece of the puzzle, and multiple lines of evidence are needed to further resolve the question whether primates evolved trichromatic vision as an adaptation to detect conspicuous fruits. This includes more natural history information – the dataset of Heymann & Fuzessy was limited and incomplete, especially for Africa – , network analyses, co-phylogenetic methods, and macro approaches as we did here, and perform these across a range of taxonomic plant groups that may be important food sources for primates. Good ones to start with could be Moraceae (figs and relatives), Melastomataceae, Annonaceae.
I hope to further address the question on whether palm fruits are important to explain the distribution and diversity of frugivores (including primates) in my future research.
Original publication: https://royalsocietypublishing.org/doi/10.1098/rspb.2019.2731