Frugivoria em Myrteae (Myrtaceae) nas Américas

Abstract

Myrtaceae is one of the most species-rich families among angiosperms and plays a crucial ecological role in tropical regions, particularly in the Americas, where it is represented by the tribe Myrteae. This group exhibits a wide diversity of fleshy fruits that serve as resources for fauna, relying on frugivores for seed dispersal. This plant-animal interaction impacts the evolutionary success of both lineages, and it is expected that fruit selection by frugivores may explain the high species diversity within this tribe. Based on this premise, we divided this dissertation into two chapters. The first chapter aimed to review the consumption of Neotropical Myrteae fruits by animals through a systematic literature search using the Web of Science, Scopus, and SciELO databases, as well as additional references cited in these studies. We found 324 sources of information. The research covered 18 countries from Mexico to southern South America, with a high concentration of studies in Brazil (188 out of 324; 58%). We recorded a total of 1,858 frugivory interactions, involving 200 Myrteae species and 292 frugivore species (152 bird species, 106 mammals, 17 fishes, 8 ants, 8 reptiles, and 1 crustacean). Of this total, 722 interactions were unique records between identified species (i.e., excluding duplicate records found in different studies and records where one or both species were unidentified at the species level). Approximately 40% of the studies recorded interactions involving Myrteae species with some level of taxonomic uncertainty (species or genus). The interactions occurred with at least 19 genera of Myrteae, with Eugenia being the most studied, appearing in 165 studies (51% of the total). This genus also had the most studied species, at least 65, and the most recorded interactions (541 in total, with 371 involving identified animal species). In the second chapter, we filtered the initial database for interactions where both plant and animal taxonomy were known at the species level and focused only on vertebrates (since interactions with ants and crustaceans are exceptions in the dispersal patterns of Myrteae). We then characterized the associations between fruit and seed traits and their frugivores, testing the hypothesis of seed dispersal syndromes and their impact on Myrteae speciation. From 225 studies, we found 1,019 interactions (697 unique) involving 254 vertebrate species and 163 Myrteae species. Primates consumed 79 Myrteae species (127 unique interactions), while birds consumed 42 species (221 unique interactions), with other vertebrates playing a lesser role in the group's dispersal. The majority of Myrteae species produced small, black fruits with a single seed, which were dispersed by all visiting groups, particularly birds. The second most important group of fruits included large, yellow, multi-seeded fruits, characteristic of the genera Psidium and Campomanesia, which were more frequently visited by primates. Other dispersal syndromes were unclear, with significant overlap in fruit and seed traits consumed by birds and mammals. Even when mammals were subdivided by order, dispersal syndromes were not evident in Myrteae. Additionally, we found a sampling bias in frugivory studies, with a high concentration of data from the Paraná domain region. To remove a potential biogeographic effect, network metrics were calculated only for this domain (105 Myrteae species, 139 animal species, 568 interactions, 422 unique interactions). The network exhibited modularity, but without an evident pattern associated with fruit functional traits or the animals consuming them. Few modules displayed notable characteristics, such as the absence of small fruits in module 1, exclusivity of mammals in module 5, and a predominance of birds and small fruits in modules 8 and 9. This lack of clear patterns was likely due to many interactions occurring with low frequency, obscuring the identification of more general patterns. Many important interactions occurred with primates, some of which acted as connector species and module hubs, including endangered species such as Brachyteles arachnoides, Leontopithecus caissara, and L. chrysopygus, highlighting their importance in maintaining natural forest regeneration in this province. In a scenario of high threats, these species would be the first to disappear, affecting the conservation of these environments. We also found a trend, although not significant, that lineages producing large and yellow fruits tend to have lower speciation rates. While lineages producing small, black fruits, consumed by all frugivore groups, exhibit more varied speciation rates, with only these lineages showing higher speciation rates within the Myrteae tribe. The database generated in this dissertation advances our knowledge of frugivory interactions in Myrteae in the Americas, identifies knowledge gaps, and suggests directions for future studies. Moreover, the analysis of the interaction network from a macroevolutionary perspective provided insights into how fruit selection by frugivores may have shaped the evolution and diversification patterns in plants.