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Vol. 52, 2013
Pattern of chromosomal changes in ‘beta’ Anolis (Norops group) (Squamata:
Polychrotidae) depicted by an ancestral state analysis
Riccardo
Castiglia1*, Oscar Flores-Villela2, Alexandra
Maria Ramos Bezerra3,4, Antonio Muñoz5 and
Ekaterina Gornung1
1Dipartimento
di Biologia e Biotecnologie ‘Charles Darwin’, Università di Roma ‘La
Sapienza’, via A. Borelli 50, Rome 00161, Italy
2Museo de Zoología, Facultad de Ciencias, Universidad
Nacional Autónoma de México, A.P. 70-399, Coyoacán, Mexico, DF 04510,
Mexico
3Departamento de Zoologia, Universidade de Brasília,
IB, Brasilia, DF 70910-900, Brazil
4Current address: Laboratório de Biologia e
Parasitologia de Mamíferos Silvestres Reservatórios, IOC-FIOCRUZ, Rio
de Janeiro CEP 21045-900, Brazil
5El Colegio de la Frontera Sur - San Cristóbal de las
Casas Carr. Panamericana y Av. Periférico Sur s/n 29290, San Cristóbal
de las Casas, Chiapas, Mexico
Abstract
Background: Neotropical lizards,
genus Anolis (Polychrotidae), with nearly 380 species, are members of
one of the most diversified genera among amniotes. Herein, we present
an overview of chromosomal evolution in ‘beta’ Anolis (Norops group) as a baseline
for future studies of the karyotypic evolution of anoles. We evaluated
all available information concerning karyotypes of Norops, including
original data on a recently described species, Anolis unilobatus. We used the phylogeny
of Norops based on DNA sequence data to infer the main pattern of
chromosomal evolution by means of an ancestral state analysis (ASR).
Results: We identified 11 different karyotypes, of
which 9 in the species had so far been used in molecular studies. The
ASR indicated that a change in the number of microchromosomes was the
first evolutionary step, followed by an increase in chromosome numbers,
likely due to centric fissions of macrochromosomes. The ASR also showed
that in nine species, heteromorphic sex chromosomes most probably
originated from six independent events.
Conclusions: We observed an overall
good correspondence of some characteristics of karyotypes and species
relationships. Moreover, the clade seems prone to sex chromosome
diversification, and the origins of five of these heteromorphic sex
chromosome variants seem to be recent as they appear at the tip nodes
in the ancestral character reconstruction. Karyotypic diversification
in Norops provides an opportunity to test the chromosomal speciation
models and is expected to be useful in studying relationships among
anole species and in identifying cryptic taxa.
Key words: Anole; Anolis; Chromosomal
evolution; Cytogenetics; Norops; Sex chromosomes; Systematics.
*Correspondence: E-mail: castiglia@uniroma1.it
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