﻿Comparative cytogenetics on eight Malagasy Mantellinae (Anura, Mantellidae) and a synthesis of the karyological data on the subfamily.

Marcello Mezzasalma,Fabio Maria Guarino,Angelica Crottini,Gaetano Odierna,Franco Andreone

doi:10.3897/compcytogen.v16.i1.76260

Comparative cytogenetics on eight Malagasy Mantellinae (Anura, Mantellidae) and a synthesis of the karyological data on the subfamily.

Marcello Mezzasalma, Fabio Maria Guarino + Show 3 more

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https://doi.org/10.3897/compcytogen.v16.i1.76260

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Abstract

We performed a molecular and cytogenetic analysis on different Mantellinae species and revised the available chromosomal data on this group to provide an updated assessment of its karyological diversity and evolution. Using a fragment of the mitochondrial 16S rRNA, we performed a molecular taxonomic identification of the samples that were used for cytogenetic analyses. A comparative cytogenetic analysis, with Giemsa’s staining, Ag-NOR staining and sequential C-banding + Giemsa + CMA + DAPI was performed on eight species: Gephyromantis sp. Ca19, G.striatus (Vences, Glaw, Andreone, Jesu et Schimmenti, 2002), Mantidactylus (Chonomantis) sp. Ca11, M. (Brygoomantis) alutus (Peracca, 1893), M. (Hylobatrachus) cowanii (Boulenger, 1882), Spinomantispropeaglavei “North” (Methuen et Hewitt, 1913), S.phantasticus (Glaw et Vences, 1997) and S. sp. Ca3. Gephyromantisstriatus, M. (Brygoomantis) alutus and Spinomantispropeaglavei “North” have a karyotype of 2n = 24 chromosomes while the other species show 2n = 26 chromosomes. Among the analysed species we detected differences in the number and position of telocentric elements, location of NOR loci (alternatively on the 6th, 7th or 10th pair) and in the distribution of heterochromatin, which shows species-specific patterns. Merging our data with those previously available, we propose a karyotype of 2n = 26 with all biarmed elements and loci of NORs on the 6th chromosome pair as the ancestral state in the whole family Mantellidae. From this putative ancestral condition, a reduction of chromosome number through similar tandem fusions (from 2n = 26 to 2n = 24) occurred independently in Mantidactylus Boulenger, 1895 (subgenus Brygoomantis Dubois, 1992), Spinomantis Dubois, 1992 and Gephyromantis Methuen, 1920. Similarly, a relocation of NORs, from the putative primitive configuration on the 6th chromosome, occurred independently in Gephyromantis, Blommersia Dubois, 1992, Guibemantis Dubois, 1992, Mantella Boulenger, 1882 and Spinomantis. Chromosome inversions of primitive biarmed elements likely generated a variable number of telocentric elements in Mantellanigricans Guibé, 1978 and a different number of taxa of Gephyromantis (subgenera Duboimantis Glaw et Vences, 2006 and Laurentomantis Dubois, 1980) and Mantidactylus (subgenera Brygoomantis, Chonomantis Glaw et Vences, 1994, Hylobatrachus Laurent, 1943 and Ochthomantis Glaw et Vences, 1994).

Highlights

Madagascar is one of the richest biodiversity hotspots and an ideal region to study evolutionary dynamics (Myers et al 2000; Ganzhorn et al 2001; Vences et al 2009)
A comparative cytogenetic analysis, with Giemsa’s staining, Ag-NOR staining and sequential C-banding + Giemsa + CMA + DAPI was performed on eight species: Gephyromantis sp
Merging our data with those previously available, we propose a karyotype of 2n = 26 with all biarmed elements and loci of NORs on the 6th chromosome pair as the ancestral state in the whole family Mantellidae

Summary

Introduction

Madagascar is one of the richest biodiversity hotspots and an ideal region to study evolutionary dynamics (Myers et al 2000; Ganzhorn et al 2001; Vences et al 2009). The last three decades have seen the flourishing of the use of molecular techniques, with numerous taxonomic and systematic studies that clarified the relationships among the major groups within this subfamily (Glaw et al 1998; Vences et al 1998; Richards et al 2000; Glaw and Vences 2006; Wollenberg et al 2011; Kaffenberger et al 2012) These tools have been used in the identification of candidate species (Vieites et al 2009; Perl et al 2014) and have later contributed to the formal description of many of them These tools have been used in the identification of candidate species (Vieites et al 2009; Perl et al 2014) and have later contributed to the formal description of many of them (e.g. Andreone et al 2003; Crottini et al 2011a; Cocca et al 2020; AmphibiaWeb 2021)

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