Biodiv Sci ›› 2002, Vol. 10 ›› Issue (2): 213-218.  DOI: 10.17520/biods.2002028

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Frugivores and their food plants: have they coevolved?

LIU Yong, CHEN Jin *   

  1. Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences,Mengla,Yunnan 666303
  • Received:2001-10-30 Revised:2002-01-07 Online:2002-05-20 Published:2002-05-20

Abstract: Whether a coevolutionary relationship exists between frugivores and their food plants has been argued for 30 years. Plant seeds dispersed by frugivores provide many advantages to plants, which may include escaping from the parents where seed or seedling predators are disproportionately abundant, colonizing new habitat patches and increasing gene flow. Simultaneously, frugivores obtain nutritional   
and energetic rewards as a consequence of digesting fruit pulp. The unique attributes of these two partners may give rise to a coevolutionary relationship. This concept stimulated studies on this field in early years. Some studies suggested that "diffuse coevolution" between plants and their dispersers might exist, whi   
ch may occur at the level of genus or family. Alternatively, the relationship may be one of just functional equivalence with no relationship to traditional taxonomy. It is also suggested that the evolution of seed dispersal systems is mainly determined by a few key dispersers and plants, which may control the evolution of related traits of other species. The defense scenario hypothesis, however,   
suggests that fleshy pulp of fruits was produced originally as a kind of defensive structure to protect seeds, only later becoming traits to promote seed dispersal. In recent years, many studies have suggested that the selective pressure between dispersers and plants is rather weak. Suitable sites for seed germination and seedling establishment are temporally and spatially unpredictable. Evolutio   
nary rates of herbivores and their food plants are unequal. High unpredictability and asymmetry of interaction, coupled with an important influence of abiotic factors, means that the influences of mutual selection pressures between plants and seed dispersers are greatly constrained. The evolutionary interaction between frugivores and plants in seed dispersal should be re evaluated. Attention shou   
ld be paid to the complexity and the diversity of the relationship between frugivores and plants. Comparative studies on the systematics of related species to evaluate the possible influence from the interaction of plants and their frugivores upon the specification of species may provide powerful evidence for coevolution. Furthermore, the influences of frugivore plant interactions on ecological dynamics and conservation will continue to be a hot topic.