Effects of different indices and pairwise methods on the longitudinal pattern of β diversity of stream fish assemblages

Abstract

Beta diversity is the key and central issue of theoretical and applied ecological questions, including those regarding spatial variation along gradients and conservation biodiversity. In contrast to the alpha diversity of stream fish assemblages, little concern has been reached regarding the factor affecting of spatial variation in beta diversity along longitudinal gradients, which may be modified by scale, indices of beta diversity and pairwise methods. To understand the spatial patterns and processes in the species composition of stream fish assemblages along the river continuum, we need to disentangle the influence of different beta diversity indices and pairwise methods on the longitudinal patterns of beta diversity. In this study, we chose four beta diversity indices (Jaccard, Sørensen, Simpson and additive partitioning) and two pairwise methods (mean beta diversity between the focal assemblage and all other assemblages; beta diversity between focal and immediate neighbouring assemblages downstream) to quantify the spatial pattern of fish beta diversity along the river continuum. We found that (1) although the four diversity indices differed in emphasis, they showed the same pattern of spatial variation in the longitudinal gradients of the river; (2) the same diversity index using different pairwise methods calculation may result in completely different spatial patterns; (3) beta diversity indices and pairwise may not have a significant effect on the ecological application of beta diversity, at least in community assembly. In conclusion, the results of our study suggest that at least in the longitudinal gradient of the river there may not be much difference in quantifying the spatial variation of beta diversity; however, pairwise methods between sampling sites need to be chosen according to specific research objectives.

Increasing fish biodiversity in high elevation Albertan lakes in response to global environmental change over the past 50 years

“…Specifically, by mapping the temporal changes of alpha diversity, it is possible to identify the biodiversity hotspots that experience major species losses, such as Primrose Lake, which should be prioritized in the conservation context (Fugère et al, 2016). On the other hand, the relationship between environmental stressors and ecological patterns involving local species introductions and extirpations can be investigated by measuring the changes in beta diversity (Socolar et al, 2016;Sarker et al, 2019;Zhang et al, 2022). Long-term studies of biodiversity are integral at providing valuable insights to evaluate the impacts of environmental disturbance on aquatic communities, thereby subsequently allowing us to predict the consequences of global environmental change on our freshwater communities.…”

Effects of seining effort on estimates of fish diversity in a sand-bed river

“…Following Wiens ( 1989 ), these studies held the extent of the investigation constant and increase the number of grains (sampling sites) to determine sampling effort. However, increased grain resolution (within-site sampling intensity) can increase detection probability, in turn affecting the accuracy and precision of these biodiversity indices, patterns of rarity, and estimates of functional diversity (Cao et al, 2002 ; Pritt & Frimpong, 2014 ; Zhang et al, 2022 ). Under sampling can presumably lead to biased estimates of biodiversity indices (Beck et al, 2013 ) and may even affect patterns of β -diversity (Marathe et al, 2021 ).…”