Using community phylogenetics to assess phylogenetic structure in the Fitzcarrald region of Western Amazonia

Jack M Craig,James S Albert,Hernán Ortega,Prosanta Chakrabarty,Roberto E Reis,Tiago P Carvalho,Valerie Derouen,Victor A Tagliacollo,Paulo Petry

doi:10.1590/1982-0224-2020-0004

Abstract

ABSTRACT Here we explore the use of community phylogenetics as a tool to document patterns of biodiversity in the Fitzcarrald region, a remote area in Southwestern Amazonia. For these analyses, we subdivide the region into basin-wide assemblages encompassing the headwaters of four Amazonian tributaries (Urubamba, Yuruá, Purús and Las Piedras basins), and habitat types: river channels, terra firme (non-floodplain) streams, and floodplain lakes. We present a robust, well-documented collection of fishes from the region including 272 species collected from 132 field sites over 63 field days and four years, comprising the most extensive collection of fishes from this region to date. We conduct a preliminary community phylogenetic analysis based on this collection and recover results largely statistically indistinguishable from the random expectation, with only a few instances of phylogenetic structure. Based on these results, and of those published in other recent biogeographic studies, we conclude that the Fitzcarrald fish species pool accumulated over a period of several million years, plausibly as a result of dispersal from the larger species pool of Greater Amazonia.

Highlights

The global diversity of freshwater fishes is highest in the rivers of the Neotropics, from where 6,080 fish species are currently described (5,607 from South America alone), comprising about 18% of all known fish species, and about 9% of all vertebrate species combined (Reis et al, 2016; Van der Sleen, Albert, 2017; Dagosta, de Pinna, 2019)
We present a study exploring the phylogenetic structure of freshwater assemblages, taking as a representative fauna the Fitzcarrald region of southeastern Peru, a broad (~400,000 km2), low elevation (200–500 m) structural arch located in southwestern Amazonia (Fig. 1)
We explored the phylogenetic structure of each assemblage using two indices calculated using the picante package in R (Kembel et al, 2010): Mean Phylogenetic Distance (MPD) which estimates the average phylogenetic relatedness between all possible pairs of taxa in a local assemblage and Mean Nearest Taxon Distance (MNTD) which estimates the mean phylogenetic relatedness between each taxon in an assemblage and its nearest relative (Kembel et al, 2010)

Summary

INTRODUCTION

The global diversity of freshwater fishes is highest in the rivers of the Neotropics, from where 6,080 fish species are currently described (5,607 from South America alone), comprising about 18% of all known fish species, and about 9% of all vertebrate species combined (Reis et al, 2016; Van der Sleen, Albert, 2017; Dagosta, de Pinna, 2019). To explore the phylogenetic structure of assemblages in the river basins and habitats of the Fitzcarrald region, we apply the emerging method of community phylogenetics (Losos, 1996; Webb et al, 2002, 2008; Strauss et al, 2006; Cavender-Bares et al, 2009). The results of this study and future community phylogenetic work in Neotropical freshwaters holds the potential to better assess the common assumptions that competition, habitat filtering, and habitat conservatism influence assemblage formation, the latter of which has already been subjected to some scrutiny using community phylogenetic methods (Pearse et al, 2014)

MATERIAL AND METHODS

RESULTS

DISCUSSION