Beta Diversity along an Elevational Gradient at the Pico da Neblina (Brazil): Is Spider (Arachnida-Araneae) Community Composition Congruent with the Guayana Region Elevational Zonation?

André A Nogueira,Eduardo M Venticinque,Antonio D Brescovit,Gilmar Perbiche-Neves

doi:10.3390/d13120620

Abstract

Beta diversity is usually high along elevational gradients. We studied a spider community at the Pico da Neblina (Brazil), an Amazonian mountain which is one of the southern components of the Guayana region. We sampled six elevations and investigated if beta diversity patterns correspond to the elevational division proposed for the region, between lowlands (up to 500 m), uplands (500 m to 1500 m), and highlands (>1500 m). Patterns of dominance increased with elevation along the gradient, especially at the two highest elevations, indicating that changes in composition may be accompanied by changes in species abundance distribution. Beta diversity recorded was very high, but the pattern observed was not in accordance with the elevationaldivision proposed for the region. While the highlands indeed harbored different fauna, the three lowest elevationshad similar species compositions, indicating that the lowlands spider community extends into the uplands zone. Other measures of compositional change, such as similarity indices and species indicator analysis, also support this pattern. Our results, in addition to a revision of the literature, confirm the high diversity and endemism rates of montane spider communities, and we stress the importance of protecting those environments, especially considering the climate crisis.

Highlights

Montane biotas have always been a main source of interest for biologists
Diversity, and proportion of absolute singletons decreased with increasing elevation (Table 1), while the abundance and proportion of singletons by elevation showed a more variable pattern (Table 1)
Our results revealed very important changes in composition along the elevational gradient

Summary

Introduction

Montane biotas have always been a main source of interest for biologists. The drastic environmental changes observed in relatively short distances make mountain systems ideal for studies on diversity patterns [1,2,3,4] and for use as natural laboratories [5,6,7]. Due to the strong environmental gradients, montane biotas are characterized by large beta diversity values, with several compositional changes in their communities along the gradients. There is evidence of a gradual compositional change along elevational gradients [1,10,11,12] instead of important and localized discontinuities at a specific point. This could be attributed to the fact that some important environmental factors, such as temperature, decline continuously with elevation [13,14]. There are some empirical examples of more abrupt changes within elevational gradients [15,16]; evidence of well-defined elevational zonation of biotic communities

Methods

Results

Conclusion