Seasonality in the dung beetle community in a Brazilian tropical dry forest: Do small changes make a difference?

Abstract

Dung beetle (Coleoptera: Scarabaeoidea: Scarabaeinae) activity is influenced by rainfall seasonality. We hypothesized that rainfall might also play a major role in regulating the community structure of this group. In this study, we describe seasonal changes in the richness, composition, and structure of the Scarabaeinae community in a Brazilian tropical dry forest. A fragment of arboreal Caatinga was sampled using baited pitfall traps during the early dry season (EDS), late dry season (LDS), early wet season (EWS), and middle wet season (MWS). We compared the dung beetle community in each season in relationship to species richness, rank-dominance, curves, and composition. We collected 1352 Scarabaeinae individuals , belonging to 15 species. Dichotomius aff. laevicollis Felsche (Coleoptera: Scarabaeidae) was the dominant species, representing 73.89% of the individuals. There were no seasonal changes in the rank dominance curves; all had a single dominant species and a few species with low abundance, typical for arid areas. Estimated richness was highest in MWS, followed by EWS. Dry-season samples (EDS and LDS) had lower richness, with no significant difference between the dry seasons. Although species richness increased as the habitat became wetter, the difference between the wet and dry seasons was small, which differs completely from the findings of other studies in Neotropical dry forests, where almost all species cease activities in the dry season. Species composition changes were found in non-metric multidimensional scaling and sustained by analysis of similarity. All the seasons had pairwise differences in composition, with the exception of EDS and MWS, which indicates that the dung beetle community in this fragment requires more than three months of drought to trigger changes in species composition; this is probably due to small changes in the forest canopy. There was no difference in composition between EDS and MWS. As in other tropical dry forests, although to a lesser extent, the dung beetle community of this fragment responded to rainfall seasonality with changes in species composition and reduced species richness. Such responses, even to this lesser extent, may occur because of small changes in tree cover and minor microclimate changes.

Early successional dynamics of ground beetles (Coleoptera, Carabidae) in the tropical dry forest ecosystem in Colombia

“…Seasonality did not significantly influence the carabid beetle assemblage, even though numerous studies have shown seasonality to be important in dry forest beetles (e.g., Novais et al 2016 ; Pérez and Zaragoza 2016; Rangel-Acosta and Martínez-Hernández 2017 ; Noguera et al 2018 ). However, there are exceptions; for example dung beetle richness differences between wet and dry seasons in the Caatinga forest in Brazil were small ( Medina and Lopes 2014 ). A reason for the lack of a seasonality signal in our data may, again, be due to a deficit in precipitation during the 2015/6 El Niño southern oscillation.…”

Dung beetle β‐diversity across Brazilian tropical dry forests does not support the Pleistocene Arc hypothesis

“…Also, there are few studies on dung beetle fauna in TDFs in South America (Neves et al . 2010; Medina & Lopes 2014; Novais et al . 2016; Vieira et al .…”

“…These variables are important drivers of biological diversity during and after the LGM (Collevatti et al 2013;Arruda et al 2018). Also, there are few studies on dung beetle fauna in TDFs in South America (Neves et al 2010;Medina & Lopes 2014;Novais et al 2016;Vieira et al 2017), being most studies spatially limited. Therefore, there is a need to evaluate the dung beetle patterns across the TDFs distribution aiming to contribute to the ongoing debate on TDFs origin.…”

Recovery dynamics of carabid beetles (Coleoptera, Carabidae) in colombian tropical dry forest

“…Seasonality did not significantly influence the carabid beetle assemblage, even though numerous studies have shown seasonality to be important in dry forest beetles (e.g., Noguera et al 2018;. However, there are exceptions; for example dung beetle richness differences between wet and dry seasons in the Caatinga forest in Brazil were small (Medina & Lopes, 2014). A reason for the lack of a seasonality signal in our data may, again, be due to a deficit in precipitation during the 2015/6 El Niño southern oscillation.…”

“…Cerambycidae (Noguera-Martínez et al 2007;Noguera et al 2018;Noguera et al 2002;Toledo et al 2002), Scarabaeidae (Liberal et al 2011; and Staphylinidae (Jiménez-Sánchez et al 2009), but not for dung beetle richness in Brazil (Medina & Lopes, 2014), since differences between the wet and dry season are small. Insect seasonal patterns are affected by the relationship among community variables and rainfall (Jiménez-Sánchez et al 2009;Liberal et al 2011; or air humidity (García et al 2001;, demonstrating the important role of water for these organisms.…”