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

Abstract

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.

Fruit syndromes in Viburnum: correlated evolution of color, nutritional content, and morphology in bird-dispersed fleshy fruits

“…It may have evolved a black fruit color in the Old World and then become extinct there after moving to North America, but more parsimoniously it evolved black-synchronous fruits after entering North America (possibly mimicking the black fruits of Porphyrotinus species, which were already present at that time in North America). Multiple cases of dispersal to a new region followed by fruit color evolution have been documented in other angiosperms; e.g., from red to black in Gaultherieae [79] and from black to red in Empetrum [80]. Our analyses show that this has been rare in Viburnum.…”

“…Recent work on Gaultherieae [79] also addressed fruit color evolution, focusing on links between biogeography and fruit color. Their findings suggest that different fruit colors may have different propensities for dispersal, specifically that red fruits are more likely to disperse long distances and then evolve new fruit colors in situ.…”

The dispersal syndrome hypothesis: How animals shaped fruit traits, and how they did not

“…While most recent studies are phylogenetically informed in the sense that they statistically corrected for the non‐independence of species (Hodgkison et al, 2013; Lomascolo et al, 2010; Lomáscolo & Schaefer, 2010; Nevo, Razafimandimby, et al, 2018; Nevo et al, 2019; Nevo & Valenta, 2018; Nevo, Valenta, et al, 2018; Valenta et al, 2016), reconstructions of the evolution of fruit traits, especially in the context of interaction with animals, are still rare. A handful of recent studies have examined the relationships between fruit traits such as size and colour to plant migration and diversification (Lu et al, 2019; Onstein et al, 2017, 2018, 2019). These approaches can be particularly useful in identifying the conditions in which fruit traits evolved, and to what extent they evolved in concert, bringing about extant combinations of traits.…”

Phylogenomics, biogeography, and evolution of the blue‐ or white‐fruited dogwoods (Cornus)—Insights into morphological and ecological niche divergence following intercontinental geographic isolation

“…In two of the disjunct clades (2 and 3), the eastern North American species make blue or white fruits, whereas the eastern Asian species make black fruits. Fruit color is a defining feature of disperser syndromes, with pale yellow and green fruits attracting mammals and vibrant colors such as red, black, and blue attracting birds (Valenta et al, 2013;Duan et al, 2014;Nevo et al, 2018;Lu et al, 2019). Although little research has been conducted to assess the mechanisms driving fruit color variation in Cornus, the findings relating to Viburnum may shed light on biogeography and fruit color.…”