title: Unexpected high diversity of galling insects in the Amazonian upper canopy: the savanna out there.
abstract: A relatively large number of studies reassert the strong relationship between galling insect diversity and extreme hydric and thermal status in some habitats, and an overall pattern of a greater number of galling species in the understory of scleromorphic vegetation. We compared galling insect diversity in the forest canopy and its relationship with tree richness among upland terra firme, várzea, and igapó floodplains in Amazonia, Brazil. The soils of these forest types have highly different hydric and nutritional status. Overall, we examined the upper layer of 1,091 tree crowns. Galling species richness and abundance were higher in terra firme forests compared to várzea and igapó forests. GLM-ANCOVA models revealed that the number of tree species sampled in each forest type was determinant in the gall-forming insect diversity. The ratio between galling insect richness and number of tree species sampled (GIR/TSS ratio) was higher in the terra firme forest and in seasonally flooded igapó, while the várzea presented the lowest GIR/TSS ratio. In this study, we recorded unprecedented values of galling species diversity and abundance per sampling point. The GIR/TSS ratio from várzea was approximately 2.5 times higher than the highest value of this ratio ever reported in the literature. Based on this fact, we ascertained that várzea and igapó floodplain forests (with lower GIA and GIR), together with the speciose terra firme galling community emerge as the gall diversity apex landscape among all biogeographic regions already investigated. Contrary to expectation, our results also support the "harsh environment hypothesis", and unveil the Amazonian upper canopy as similar to Mediterranean vegetation habitats, hygrothermically stressed environments with leaf temperature at lethal limits and high levels of leaf sclerophylly.
authors.affiliation: Coordenação de Ecologia, Instituto Nacional de Pesquisa da Amazonia (INPA), Manaus, Amazonas, Brazil; Fiocruz Rondônia, Laboratório de Entomologia, Porto Velho, Rondônia, Brazil.
authors.forename: Genimar R
authors.initials: GR
authors.lastname: Julião
authors.affiliation: Departamento de Ecologia, CB/Universidade Federal do Rio Grande do Norte, Campus Universitário, Lagoa Nova, Natal, RN, Brazil.
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Venticinque
authors.affiliation: Ecologia Evolutiva e Biodiversidade/DBG, C P 486, ICB/Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
authors.forename: G Wilson
authors.initials: GW
authors.lastname: Fernandes
authors.affiliation: Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, United States of America.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Price
mesh_terms: D000818:Animals; D044822:Biodiversity; D001938:Brazil; D065928:Forests; D065948:Grassland; D007313:Insecta / Q000145:classification*; D011157:Population Dynamics; D012621:Seasons; D012987:Soil; D014197:Trees / Q000145:classification*
chemical_list: D012987:Soil