Abstract
Changes in natural habitats for human use can alter the distribution of biodiversity, favoring species that are more tolerant to environmental disturbance. Usually, these species comprise clades of habitat generalists, which have biological mechanisms to colonize environments with different environmental conditions. However, such effects are still poorly understood for most biological groups, such as the Amazon odonates. Therefore, this study aims to evaluate the effects of land use along an environmental gradient on the phylogenetic and taxonomic diversity of Odonata in the Amazon. We tested the following hypotheses: In deforested areas (e.g., pasture for cattle, palm plantation, and logging), the Odonata community will be more taxonomically and phylogenetically impoverished than in forested areas. We assume that the modification of the natural habitat causes loss of specialist forest species and favors specialist species of open areas and/or habitat generalists. Data sampling was performed in 195 streams under different land-use types: livestock areas, palm monoculture, timber exploitation, and forest areas taken as reference sites. Our results showed that anthropogenic impacts affected the phylogenetic diversity of odonates and the increase in shrub vegetation was related to the increase in the phylogenetic diversity of communities. On the other hand, shrub vegetation is indicative of disturbed areas, where secondary vegetation predominates, with less canopy cover due to the absence or discontinuity of the native tree cover in these habitats. Nonetheless, species richness and abundance were not related to the effects of anthropogenic land use. Finally, our results suggest that the phylogenetic diversity of Amazonian odonates is related to riparian vegetation structure.
Highlights
When evaluating the effects of physical habitat variables on the phylogenetic diversity of the Odonata community, the coefficients showed that the metrics of wood debris volume and the percent mean canopy cover of small trees had a positive relationship with the phylogenetic diversity of Odonata
The variables of mean canopy cover of woody understory, mean canopy coverage and the proportion of mean primary vegetation by microbasin had a negative relationship with the phylogenetic diversity of Odonata, but none of these variables were significant in the models (Table 1)
Our results suggest that the expansion of anthropogenic land use over the natural landscape in the Brazilian Amazon affects the phylogenetic diversity of Odonata
Summary
The search to understand how species are distributed and what processes affect their distribution patterns has always been a major challenge for researchers addressing community ecology problems [1] This is due to the increasing rate of environmental changes, resulting in biodiversity loss and depletion of ecosystem services [2,3]. In this context, for assessing environmental changes, some groups such as odonates are remarkably good models for studies on ecological dynamics, behavior, and evolutionary biology [4,5,6]. The closer species are phylogenetically, the more likely that they will respond in a similar way to the environmental changes, both in function for ecosystem services and in response to environmental conditions [11,12,13]
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