Speaker
Description
The largest animals in ecosystems (megafauna) can feed on mega-fruited plants (fruits diameter > 4 cm) and disperse massive loads of large seeds across long distances, thus playing a vital role in maintaining biotic connectivity and population structures of mega-fruited plants. However, it remains unclear how the global extinction of most megafauna since the late Quaternary (last ~10k years) affected mega-fruited plant populations. Here, we hypothesize that the loss of specialized megafaunal seed dispersers led to dispersal limitation of mega-fruited plants, resulting in high population genetic structure and decreases in population sizes and migration rates that coincided spatially and temporally with the decline and extinction of co-occurring megafauna. We focus on the megafaunal palm Hyphaene coriacea, which naturally occurs in savannas in Madagascar (where all seed-dispersing megafauna – e.g. giant lemurs, elephant birds – have gone extinct) and mainland Africa (where more intact elephant populations are still functioning as seed dispersers of H. coriaceae). Using RAD-seq from 22 populations and 151 individuals, we found that H. coriaceae population structure is shaped by extant and extinct fruit-eating and seed dispersing animals (frugivores), and we detected signatures of population size declines in both Malagasy and mainland African populations. This suggests that current and past interactions with megafauna have left signatures in the genome of megafruited plant populations, and reduced seed dispersal may have led to a loss of biotic connectivity and population size declines. Furthermore, alternative dispersal mechanisms, such as human-mediated dispersal and dispersal by surface runoff, may have substituted dispersal functions by past megafauna, explaining the persistence of H. coriaceae in Madagascar. These results provide important insights in the role of frugivores in maintaining seed dispersal and population structure of African plants, and how megafruited plants have been able to persist since the late Quaternary extinction of most primary seed dispersers.
| Status Group | Doctoral Researcher |
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