Africa as an evolutionary arena for large fruits

Abstract

Summary Strong paleoclimatic change and few Late Quaternary megafauna extinctions make mainland Africa unique among continents. Here, we hypothesize that, compared with elsewhere, these conditions created the ecological opportunity for the macroevolution and geographic distribution of large fruits. We assembled global phylogenetic, distribution and fruit size data for palms (Arecaceae), a pantropical, vertebrate‐dispersed family with > 2600 species, and integrated these with data on extinction‐driven body size reduction in mammalian frugivore assemblages since the Late Quaternary. We applied evolutionary trait, linear and null models to identify the selective pressures that have shaped fruit sizes. We show that African palm lineages have evolved towards larger fruit sizes and exhibited faster trait evolutionary rates than lineages elsewhere. Furthermore, the global distribution of the largest palm fruits across species assemblages was explained by occurrence in Africa, especially under low canopies, and extant megafauna, but not by mammalian downsizing. These patterns strongly deviated from expectations under a null model of stochastic (Brownian motion) evolution. Our results suggest that Africa provided a distinct evolutionary arena for palm fruit size evolution. We argue that megafaunal abundance and the expansion of savanna habitat since the Miocene provided selective advantages for the persistence of African plants with large fruits.

Genomic signatures of past megafrugivore‐mediated dispersal in Malagasy palms

“…beta diversity) and trait (e.g. fruit size) distributions (Blach‐Overgaard et al., 2013; Lim et al., 2020; Méndez, Viana, et al., 2022a; Wölke et al., 2023; Xu et al., 2023). Nevertheless, the extinction of all megafrugivores on Madagascar may affect current and future gene flow among vertebrate‐dependent plant populations, with potentially detrimental effects on the genetic diversity and adaptive potential of these species to climate change (Fricke et al., 2022).…”