Why is fruit colour so variable? Phylogenetic analyses reveal relationships between fruit-colour evolution, biogeography and diversification

Aim Are different fruit colours related to large‐scale patterns of dispersal, distribution and diversification? Here, we investigate this question for the first time, using phylogenetic approaches in the tribe Gaultherieae (Ericaceae). We test relationships between fruit colour and (a) biogeographic dispersal, (b) elevational and latitudinal species distributions and (c) rates of diversification. Location Global. Time period Recent to 30 million years ago. Major taxa studied The plant tribe Gaultherieae in the family Ericaceae (blueberries and relatives). Methods We estimated a new time‐calibrated phylogeny for Gaultherieae. Data on fruit colours and geographic distributions for each species were compiled from published sources and field observations. Using phylogenetic methods, we estimated major dispersal events across the tree and the most likely fruit colour associated with each dispersal event, and tested whether dispersal between major biogeographic regions was equally likely for different fruit colours, and whether dispersal distances were larger for certain colours. We then tested the relationships between fruit colours and geographic variables (latitude, elevation) and diversification rates. Results Large‐scale dispersal events were significantly associated with red‐fruited lineages, even though red‐fruited species were relatively uncommon. Further, different fruit colours were associated with different elevations and latitudes (e.g. red at lower elevations, violet at lower latitudes, white at higher elevations). Violet colour was related to increased diversification rates, leading to more violet‐fruited species globally. Main conclusions Overall, we show that different fruit colours can significantly impact the large‐scale dispersal, distribution and diversification of plant clades. Furthermore, the interplay between biogeography and fruit‐colour evolution seems to generate “taxon cycles” in fruit colour that may drive variation in fruit colour over macroevolutionary time‐scales.CAS Strategic Priority Research Program, Grant/Award Number: XDB31000000; National Natural Science Foundation China, Grant/Award Number: 41671052, 31100163, 31270272, 31320103919 and U1502261; Applied Fundamental Research Foundation of Yunnan Province, Grant/Award Number: 2017FB072; the Hundred‐Talent Program of Kunming Medical University, Grant/Award Number: 60117190444 and 60118090109; the U.S. National Science Foundation, Grant/Award Number: DEB-0717711, DEB-0717744 and DEB-1655690; the National Geographic Society, Grant/Award Number: 4-03-9329; the CAS President's International Fellowship Initiative, Grant/Award Number: 2010T2S05 and 2017VCA0024; ARC DECRA fellowship, Grant/Award Number: DE150101773; Marsden grants, Grant/Award Number: 16UOA-277 and 18-UOA-03