A comparative analysis reveals weak relationships between ecological factors and beta diversity of stream insect metacommunities at two spatial levels

Abstract

The hypotheses that beta diversity should increase with decreasing latitude and increase with spatial extent of a region have rarely been tested based on a comparative analysis of multiple datasets, and no such study has focused on stream insects. We first assessed how well variability in beta diversity of stream insect metacommunities is predicted by insect group, latitude, spatial extent, altitudinal range, and dataset properties across multiple drainage basins throughout the world. Second, we assessed the relative roles of environmental and spatial factors in driving variation in assemblage composition within each drainage basin. Our analyses were based on a dataset of 95 stream insect metacommunities from 31 drainage basins distributed around the world. We used dissimilarity-based indices to quantify beta diversity for each metacommunity and, subsequently, regressed beta diversity on insect group, latitude, spatial extent, altitudinal range, and dataset properties (e.g., number of sites and percentage of presences). Within each metacommunity, we used a combination of spatial eigenfunction analyses and partial redundancy analysis to partition variation in assemblage structure into environmental, shared, spatial, and unexplained fractions. We found that dataset properties were more important predictors of beta diversity than ecological and geographical factors across multiple drainage basins. In the within-basin analyses, environmental and spatial variables were generally poor predictors of variation in assemblage composition. Our results revealed deviation from general biodiversity patterns because beta diversity did not show the expected decreasing trend with latitude. Our results also call for reconsideration of just how predictable stream assemblages are along ecological gradients, with implications for environmental assessment and conservation decisions. Our findings may also be applicable to other dynamic systems where predictability is low.

Global patterns in the metacommunity structuring of lake macrophytes: regional variations and driving factors

“…Single study regions inherently have region-specific environmental gradients (i.e., context dependency) which limits our abilities to draw comprehensive conclusions regarding how these gradients structure local communities across multiple regions and globally (Kraft et al 2011; Heino et al 2015a). To overcome this problem, we studied community–environment relationships of lake macrophytes at two metacommunity scales (i.e., within region and across regions) using data sets from 16 regions on six continents.…”

“…To investigate which characteristics structure the variability in macrophyte community structure across all regions (multiple metacommunities), we summarized regional environmental information within convex hulls encompassing the minimum area containing all surveyed lakes within each of the 16 regions (Heino et al 2015a; Alahuhta et al 2017a). For each study region, we defined elevation range within the convex hull (m), area of the convex hull (km 2 ), latitude of the convex hull (from centroid), longitude of the convex hull (from centroid), and estimated the maximum age of the oldest lake within a particular study region (Table 1).…”

“…However, it is difficult to draw comprehensive conclusions regarding how these environmental gradients structure aquatic macrophyte communities, due to inconsistencies among the studies (e.g., differences in spatial scales, explanatory variables, and methods used). Thus, investigations executed with identical study designs across multiple study sites and regions are needed to enhance our understanding of the relationships between aquatic macrophytes and environmental gradients (e.g., Borer et al 2014; Heino et al 2015a; Alahuhta et al 2017a). …”

Simulating the role of connectivity in shaping stream insect metacommunities under colonization cycle dynamics

“…In the context of metacommunities, this concept provides the basis for interpreting patterns of biodiversity distribution by linking species occurrences through an array of spatial scales (from millimeters to thousands of kilometers) in highly complex networks. In aquatic ecology, part of the interest in the subject is due to its implications for understanding the forces that shape riverine metacommunities (Auerbach and Poff, 2011;Altermatt et al, 2013;Heino et al, 2003Heino et al, , 2015bRoque et al, 2010;Siqueira et al, 2012a) and for the monitoring, management and conservation of river networks (Economo, 2011;Siqueira et al, 2012bSiqueira et al, , 2014.…”

Achteruitgang insectenpopulaties in Nederland: trends, oorzaken en kennislacunes

“…Er zijn vele voorbeelden van interactie-effecten tussen drukfactoren, waarbij de ene drukfactor het effect van een andere drukfactor versterkt of juist afzwakt. Door deze complexiteit is het vaak lastig om de effecten van een specifieke omgevingsfactor te kwantificeren (Heino, Melo et al 2015;Kaunisto, Ferguson et al 2016;Massoud, Huisman et al 2018). …”