Diversidade genética e fenotípica no gênero Ectatomma
Ectatomma is a genus of ants belonging to Ectatomminae, currently located in the Formicoid group. With 15 recognized species, the genus includes relatively large ants endemic to the Neotropical Region. These species are relatively common in diverse areas such as wet forest, savannah, and dry forest habitats below 1500 m in altitude. Most of them are generalist predators but they also consume fruit pulp, honey and plant nectars. The wide variation in their environmental performance, foraging strategies and diet explains their abundance in the Neotropics. The first review of this genus was done by William Brown Jr. in 1958, who recognized the difficulties in delimiting some Ectatomma species. Some of these problems were partly solved by Kugler and Brown, who suggested some synonymies and recognized 12 species. Arias-Penna re-described E. confine; Almeida described two species from Brazil, E. vizotoi and E. suzanae, and Feitosa et al. described the first social parasitic Ectatomma, E. parasiticum from Mexico. While there are currently 15 Ectatomma described species, recent studies have shown that this variability is underestimated due to cryptic species or insufficient sampling. In this chapter, we synthesize from the literature and our own experience data on phenotypic variation, ecological and life traits and genetics. Morphological variation is known for E. tuberculatum, E. goninion and E. ruidum over their geographic distribution. As in other ants, this kind of variation has been the principal source of taxonomic inflation. The challenge with this taxon is to find a correct delimitation of the species, using several sources of data, including morphology, chemistry, genetics and biology. Phenotypic variation can also be expressed by differences in behaviours or life history traits between species, and we here present some features common to or, by contrast, specific to some Ectatomma. The nests of all the species of the genus Ectatomma are terricolous, even those of species exhibiting arboricolous habits. Generally, they exhibit the same pattern; a simple architecture with a single entrance hole opening directly on the ground surface and leading to a gallery, which connects with successive chambers (4-12 according to the species) deeper in the ground (0.68-3.60 m according to the species). The structure of the nests seems to vary depending on the environment and probably with the season, colony size and the structure of the soil. The patterns of nest distribution appear to vary according to the species (overdispersion; random distribution; aggregated pattern; patchy distribution). Polydomy occurs in E. tuberculatum and possibly in E. brunneum and E. opaciventre. Polygynous colonies have been detected in seven of the 15 Ectatomma species (E. ruidum, E. tuberculatum, E. parasiticum, E. brunneum, E. permagnum, E. planidens (referred to as E. edentatum), and E. vizottoi). However, data based on genetic markers to investigate details of the socio-genetic structure of the colonies have only been obtained in E. tuberculatum and E. ruidum, for which we developed specific microsatellite loci. Although Ectatomma is a widespread and common genus in the Neotropics, their taxonomy is surprisingly poorly known, with several issues unanswered, such as: the delimitation of some species or cryptic species complexes (as in E. tuberculatum and E. ruidum); the interpretation of infra- vs inter-specific variation (as in E. goninion); the problem of paraphyly (as in the E. tuberculatum / E. parasiticum pair); and also the status of species described by Almeida in (E. vizotoi and E. suzanae). Hopefully work in progress, including the molecular phylogeny of the genus, will throw light on species delimitation, biogeography, and evolution of some biological traits such as microgyny and parasitism.
| Main Authors: | , , , |
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| Format: | Texto biblioteca |
| Language: | por |
| Subjects: | Ectatomma tuberculatum, Ectatomma goninion, Ectatomma ruidum, Hormigas, Variación genética, Hábitat (Ecología), |
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