The role of niche measures in explaining the abundance–distribution relationship in tropical lotic chironomids

Abstract

The positive relationship between species regional distribution and local abundance is one of the most ubiquitous patterns in ecology. Among the hypotheses proposed to explain the relationship, the niche breadth and the niche position (or habitat availability) hypothesis are the most investigated. An unappreciated issue, but that is likely to be important for the understanding the relationship is the nature of variables used to estimate niche measures. Here, we analyzed the form of this relationship in lotic chironomid genera and tested whether niche measures estimated from local and landscape variables explain the observed pattern. Analyses were based in 47 forested streams within Southeastern Brazil. From our data set, we randomly partitioned the data in two non-overlapping sets to estimate taxa distribution and abundance (Distribution Data; n = 23 sites) and to generate niche measures (Niche Data; n = 24). We repeated that process 1,000 times, and for each one, we generated niche breadth and position measures using in-stream and landscape variables and estimated abundance and distribution for each taxa. With these, we estimated the relationship between both abundance and distribution and niche measures using ordinary least-squares regressions. We found no relationship between niche position estimated from local variables and local abundance nor regional distribution. There was a negative relationship between niche position estimated from landscape and local abundance, and regional distribution. We found a positive relationship between niche breadth (local and landscape) and both local abundance and regional distribution. When the relationship was significant, both niche position and niche breadth explained less than a half of total variation in abundance and distribution. This suggests that not only niche-based processes, but also other mechanisms may be responsible for the abundance-distribution relationship in lotic chironomids. A novel finding of this study was that although there was much unexplained variability around the relationships, niche breadth was a better predictor of abundance and distribution than niche position. We suggest that future studies should investigate if spatial

The taxonomic distinctness of macroinvertebrate communities of Atlantic Forest streams cannot be predicted by landscape and climate variables, but traditional biodiversity indices can

“…Thus, although we estimated both pure environmental and spatial components in variation partitioning, our main intention was to use spatial variables as a way to control for inflated Type I error in assessing the environmental component. Together with previous studies about Atlantic Forest streams, these results indicate that by using local, landscape and spatial predictors (or a combination of them), we are usually able to explain around 40% or less of the of variation in macroinvertebrate abundance and distribution (Siqueira et al, 2009), taxa associations (Roque et al, 2010), diversity metrics ), common and rare taxa (Siqueira et al, 2012b) and functional diversity metrics (Colzani et al, 2013). Recent studies have tested the performance of taxonomic diversity and taxonomic distinctness in several systems and taxonomic groups.…”

“…Moreover, studies that have examined patterns of macroinvertebrates under a variety of measures of stream conditions in relation to land use at multiple scales report mixed influences (Allan, 2004). Thus, given the absence of specific information, we consider our exploratory approach an appropriate option for our purpose of estimating the effect of landscape processes on the structure of the macroinvertebrate community (see Roque et al, 2010;Siqueira et al, 2009Siqueira et al, , 2012b for a similar approach).…”

Temporal nestedness in Chironomidae and the importance of environmental and spatial factors in species rarity

“…Furthermore, although the definitions of rarity are necessarily arbitrary, there is a consensus that a species may be rare or common in relation to its numbers or distribution, and, despite some exceptions, the most widely distributed species tend to occur in higher abundances (Gaston, 1994). This indicates that there is a positive correlation between the abundance and frequency of occurrence (Blackburn et al, 2006;Siqueira et al, 2009), which was also demonstrated by the results for Chironomidae larvae according to our linear regression between these two variables.…”

Diversity of Non-Biting Midge Larvae Assemblages in the Jacuí River Basin, Brazil

“…Studies analyzing the environmental factors that influence the spatial distribution of their assemblages are being developed. Landscape factors such as altitude, area size, order of river segments, drainage basin, phytogeographical unit, riparian vegetation, environmental preservation of the area, temperature, and hydraulic conditions (lentic/lotic) (e.g., Rossaro 1991; Jacobsen et al 1997; Kleine and Trivinho-Strixino 2005; McKie et al 2005; Morrone 2006; Rossaro et al 2006; Roque et al 2007; Luoto 2009; Marziali et al 2009; Sonoda et al 2009; Roque et al 2010) are mentioned among the variables affecting assemblage distributions. However, studies conducted at larger spatial scales, with a geographical or regional ( sensu Sandin and Johnson 2004) approach, are rare.…”