Sympatry between species of Juliomys (Rodentia: Sigmodontinae) along an altitudinal gradient in the Serra da Bocaina National Park

Ana Cláudia Delciellos,Ana Carolina Loss,Marcia Aguieiras,Lena Geise,Gabriela Colombo De Mendonça,Oscar Rocha-Barbosa

doi:10.1590/1676-0611-bn-2020-0958

Abstract

Abstract The altitudinal gradient found in the Atlantic Forest may play a role in establishing sympatry areas between congeneric species of sigmodontine rodents. For some genera with cryptic species, the elucidation of spatial patterns of distribution may be useful to understand reproductive isolation and speciation patterns, as well as spatial and temporal factors determining the boundaries of species’ geographical distributions. Here we evaluated the occurrence of sympatry between Juliomys species along an altitudinal gradient in the Serra da Bocaina National Park (SBNP). Additionally, we review the occurrence of J. rimofrons and add new records of species occurrence in the SBNP, aided by karyological and molecular data. The study was carried out at four sites in the SBNP, which ranged between 770 and 1,200 m a.s.l. We captured 24 Juliomys specimens. Six out of 24 specimens were collected and karyotyped. For J. pictipes, the karyotype had a 2n of 36 and a FN of 34, and for J. ossitenuis 2n of 20 and FN of 36. Seventeen out of 24 Juliomys specimens were used in the cytochrome b phylogeny: 12 specimens grouped with J. pictipes and five with J. ossitenuis. Additionally, a specimen previously identified as J. rimofrons (MN 77793) clustered together with J. pictipes. Juliomys pictipes and J. ossitenuis were found in sympatry in two out of four sites in altitudes higher than 1,000 m a.s.l.. Our karyological and molecular data provided the detection of two Juliomys species in the SBNP for the first time (J. pictipes and J. ossitenuis) and disregarded the previous record of J. rimofrons. Our record of sympatry between J. pictipes and J. ossitenuis represents the fifth known record of sympatry between these species up to date.

Highlights

Juliomys encompasses Neotropical arboreal rodent species endemic to the southeastern Atlantic Forest of Brazil, with its northernmost distribution limited by the Doce River, in the state of Minas Gerais (González et al 2015)
Twenty-four from these 1,222 specimens (2%) belong to the genus Juliomys, and six from these 24 specimens were collected, karyotyped and prepared as voucher specimens: three females (MN 81841, MN 81843, and MN 83190) were identified as J. pictipes, and two males and one female (MN 81807, MN 81847, and MN 81852) as J. ossitenuis (Table 1)
The karyological and molecular analyses carried out provided the detection of two Juliomys species in the Serra da Bocaina National Park (SBNP) for the first time: J. pictipes and J. ossitenuis

Summary

Introduction

Juliomys encompasses Neotropical arboreal rodent species endemic to the southeastern Atlantic Forest of Brazil, with its northernmost distribution limited by the Doce River, in the state of Minas Gerais (González et al 2015). Thenceforth, three additional species were described for the genus: Juliomys rimofrons Oliveira & Bonvicino, 2002, Juliomys ossitenuis Costa, Pavan, Leite & Fagundes, 2007, and more recently Juliomys ximenezi Christoff, Vieira, Oliveira, Gonçalves, Valiati & Tomasi, 2016 (Christoff et al 2016). Juliomys was formally included in the tribe Wiedomyini Reig, 1980, which includes Wiedomys, Wilfredomys, and Phaenomys (Gonçalves et al 2020). Juliomys includes cryptic species, not recognized in the field by their external morphological characters (Christoff et al 2016). The few existing studies that differentiated species through external morphological characters found different morphological patterns in different localities, suggesting possible geographical variation in some of the characters commonly used (Pavan & Leite 2011, Aguieiras et al 2013)

Methods

Results

Conclusion