The karyotype of Peromyscus grandis (Rodentia:
Cricetidae)
THERYA, diciembre, 2013
Vol.4(3):575-580
DOI: 10.12933/therya-13-122
Cariotipo de Peromyscus grandis
(Rodentia: Criceidae)
Nicté Ordóñez-Garza1*, Vicki J. Swier3, John D. Hanson4,
Cibele G. Sotero-Caio1, and Robert D. Bradley1, 2
Abstract
Peromyscus grandis is a rodent whose distribution is restricted to the mountain ranges
of central Guatemala. This note represents the first report of karyotypic data for this
species. The karyotype (fundamental number = 58) closely resembles karyotypes of
other species of Peromyscus.
Keywords: chromosomes, Cricetidae, endemic, karyogram, Peromyscus mexicanus
group.
Resumen
Peromyscus grandis es un roedor cuya distribución está restricta a las montañas del centro
de Guatemala. Esta nota es el primer reporte de datos cariotípicos para esta especie.
El cariotipo (número fundamental = 58) resulta muy parecido al de otras especies de
Peromyscus.
Palabras clave: cariograma, Cricetidae, cromosomas, endémico, grupo Peromyscus
mexicanus
Introduction
Many species of rodents are endemic to the highlands of Mesoamerica (i.e. species of
Habromys, Microtus, Reithrodontomys, and Peromyscus- Hooper 1952; Conroy et al.
2001; Carleton et al. 2002; Dawson 2005). Although this region is considered one of
the biodiversity hotspots for conservation priorities (Myers et al. 2000), basic biological
information for many Mesoamerican rodents remains unknown. The P. mexicanus group
is among the most speciose and ecologically diverse species group within the genus
Peromyscus (Carleton 1989), and to date species limits and phylogenetic relationships
among taxa within the group are not well resolved (Rogers and Engstrom 1992; Bradley
et al. 2007; Ordóñez-Garza et al. 2010). Although most species within this group have
been shown to exhibit extreme karyotypic conservation with few taxa varying in their
(sex) chromosome composition (Smith et al. 1986; Peppers et al. 1999). Peromyscus
1
Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409. E-mail: nicte.ordonez-garza@ttu.edu
(NO-G), cibele.caio@ttu.edu (CGS-C) robert.bradley@ttu.edu (RDB).
2
Natural Science Research Laboratory, Museum of Texas Tech University, Lubbock, TX 79409. E-mail: robert.bradley@ttu.
edu (RDB).
3
Biomedical Sciences Department, Creighton University, Omaha, NE 68178. E-mail: vicki_swier@hotmail.com (VJS)
4
Research Testing Laboratory 104 Garfield Dr. Building #340, Lubbock, TX 79416. E-mail: j.delton.hanson@
researchandtesting.com (JDH)
*
Corresponding author.
KARYOTYPE OF PEROMYSCUS GRANDIS (RODENTIA:CRICETIDAE)
grandis is the only species within the P. mexicanus group for which chromosomal data
are unavailable. Herein, the karyotype of P. grandis is described and compared with
karyotypes of other closely related species of Peromyscus.
Material
and Methods
Sampling. Individuals of P. grandis were lived-trapped from natural populations in
Reserva Chelemhá, Alta Verapaz, Guatemala, 2,090 m, coordinates 15.3859 N and
-90.0062 W. Voucher specimens and tissues samples were deposited in the National
Museum of Natural History, Smithsonian Institution and the Natural Science Research
Laboratory, Museum of Texas Tech University and are listed in Appendix I.
Chromosome data. Karyotypes were prepared under field conditions at Reserva
Chelemhá, following the standard bone marrow technique of Lee and Elder (1980) as
modified by Baker et al. (2003). At least five metacentric spreads were examined and
photographed per individual and the diploid (2n) and fundamental numbers of autosomal
arms (FN) were determined for each individual. Karyograms were initially constructed
by arranging bi-armed chromosomes based on size (largest to smallest); inferences
of homology were then made using the chromosomal morphology depicted in the
Committee for Standardization of Chromosomes of Peromyscus (1977) and Greenbaum
et al. (1994) and were compared to karyotypes and FNs previously reported for the P.
mexicanus species group (Hsu and Arrighi 1986; Smith et al. 1986; Bradley and Ensink
1987; Peppers et al. 1999).
Results
Karyotypic data. Karyotypes were obtained from two individuals of P. grandis from
Reserva Chelemhá, Alta Verapaz, Guatemala and 16 individuals of P. mexicanus from
five localities in Honduras (see Appendix I). Comparison to the standard karyotype
for Peromyscus (Committee for Standardization of Chromosomes of Peromyscus 1977;
Greenbaum et al. 1994) using chromosomal size as a reference, revealed that P. grandis
possessed six pairs of biarmed chromosomes (presumably pairs 1, 2, 3, 9, 22, and 23),
a large sub-telocentric X, and a small acrocentric Y. The remaining autosomes are
acrocentric (see Fig. 1a).
Discussion
Although the chromosomal data depicted herein are based on standard karyotypes (nondifferentially stained), many inferences can be made relative to the G-banded datasets
depicted in Greenbaum et al. (1994) and those pertaining to the P. mexicanus species
groups (see below). The karyotype of P. grandis (2n = 48, FN = 58) resembled that
described for other members of the P. mexicanus species group (Robbins and Baker
1981; Rogers et al. 1984; Stangl and Baker 1984; Smith et al. 1986; Peppers et al. 1999)
examined to date, with two exceptions. First, Bradley and Ensink (1987) reported a FN
= 56 karyotype for individuals of P. m. saxatilis from El Hatillo, Honduras. The karyotype
of P. m. saxatilis appears to be missing chromosomal material above the centromere in
the 3rd largest pair of chromosomes, leading Bradley and Ensink (1987) to conclude that
it was acrocentric. P. grandis possesses a minute, but visible, amount of chromosomal
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Vol.4(3):575-580
Ordóñez-Garza et al.
material above the centromere on the 3rd largest pair of chromosomes. To further examine
this apparent discrepancy, we examined the karyotypes of 17 individuals of P. m. saxatilis
collected from five localities in Honduras (Appendix I). All possessed a FN = 58 similar
to that proposed for P. grandis. It is not known whether the FN = 56 form reported in
Bradley and Ensink (1987) was a result of over contracted chromosomal material in P.
m. saxatilis, population variation restricted to El Hatillo, Honduras, or if it represented a
unique taxonomic character.
Figure 1. Non-differentially
stained karyotypes for P.
grandis from Guatemala (a)
and P. mexicanus saxatilis
from Honduras (b) depicting
chromosomal morphology.
The
presumptive
sex
chromosomes in the insert
in (a) were obtained from
a male P. grandis (USNM
569910) and have the same
morphology and relative
size as the representative of
P. mexicanus saxatilis (TTU
104358)
The second difference observed in the karyotype of P. grandis, relative to its sister
taxon, P. guatemalensis (Ordóñez-Garza et al. 2010) and other members of the P.
mexicanus species group involves minor differences in the morphology of the X and Y
chromosomes. In P. grandis, the X chromosome, presumably is large and subtelocentric;
whereas the Y chromosome is exceptionally small, acrocentric, and resembles that of P.
guatemalensis, P. mexicanus, P. stirtoni, and P. zarhynchus (Rogers et al. 1984; Smith
et al. 1986; Peppers et al. 1999). In general, the karyotype of P. grandis agrees with the
conclusions of Smith et al. (1986) that karyotypic conservatism is consistent throughout
the P. mexicanus species group as envisioned by Musser and Carleton (2005).
www.mastozoologiamexicana.org
577
KARYOTYPE OF PEROMYSCUS GRANDIS (RODENTIA:CRICETIDAE)
Acknowledgments
We thank R. J. Baker for advice with field karyotyping techniques. Field and collecting
equipment were provided by the USGS Patuxent Wildlife Research Center at National
Museum of Natural History, Smithsonian Institution (N. Woodman), Museo de Historia
Natural de la Universidad de San Carlos de Guatemala, and Natural Science Research
Laboratory at Museum of Texas Tech University. We thank Consejo Nacional de Areas
Protegidas (CONAP) and the people of the Reserva Chelemhá for granting collecting
permits. Partial funding was provided by UTMB (C. F. Fulhorst), NSRL (by J. Sowell),
Walter and Judy Bulmer, Ralph P. and Mary Eckerlin, Sharon Parsons, and John O. Matson.
Baker, r. J., M. J. HaMilton, and d. a. ParisH. 2003. Preparations of mammalian
karyotypes under field conditions. Occasional Papers, Museum of Texas Tech
University 228:1-8.
Bradley, r. d., and J. ensink. 1987. Karyotypes of five cricetid rodents from Honduras.
Texas Journal of Science 39:171-175.
Bradley, r. d., n. d. durisH, d. s. rogers, J. r. Miller, M. d. engstroM, and C. W.
kilPatriCk. 2007. Toward a molecular phylogeny for Peromyscus: evidence from
mitochondrial cytochrome-b sequences. Journal of Mammalogy 88:1146-1159.
Carleton, M. d. 1989. Systematics and evolution. Pp. 7-142, in Advances in the study
of Peromyscus (Kirkland, Jr. G. L., and J. N. Layne, eds.). Texas Tech University
Press. Lubbock, EE.UU.
Carleton, M. d., o. sánCHez, and g. urBano-Vidales. 2002. A new species of Habromys
(Muroiea: Neotominae) from México, with generic review of species definitions
and remarks on diversity patterns among Mesoamerican small mammals restricted
to humid montane forests. Proceedings of the Biological Society of Washington
115:488-533.
CoMMittee for standardization of CHroMosoMes of PeroMysCus. 1977. Standardized
karyotype of deer mice, Peromyscus (Rodentia). Cytogenetics and Cell Genetics
19:38-43.
Conroy C. J., y. Hortelano, f. a. CerVantes, and J. a. Cook. 2001. The phylogenetic
position of southern relictual species of Microtus (Muridae: Rodentia) in North
America. Mammalian Biology 66:332-344.
daWson, W. d. 2005. Peromyscine biogeography, Mexican topography and Pleistocene
climatology. Pp: 145--156 in Contribuciones Mastozoológicas en homenaje
a Bernardo Villa (V. Sánchez-Codero, and R. A. Medellín, eds.). Instituto de
Biología, Universidad Nacional Autónoma de México, Comisión Nacional para el
Conocimiento y Uso de la Biodiversidad. Ciudad de México, Mexico.
greenBauM, i. f., s. J. gunn, s. a. sMitH, B. f. MCallister, d. W. Hale, r. J. Baker, M. d.
engstroM, M. J. HaMilton, W. s. Modi, l. W. roBBins, d. s. rogers, o. g. Ward,
W. d. daWson, f. f. B. elder f.f., M. r. lee, s. P. PatHak, and f. B. stangl, Jr. 1994.
Cytogenetic nomenclature of deer mice, Peromyscus (Rodentia): revision and
review of the standardized karyotype. Cytogenetics and Cell Genetics 66:181195.
578
THERYA
Vol.4(3):575-580
References
Ordóñez-Garza et al.
Hafner M. s., W. l. gannon, J. salazar-BraVo, and s. t alVarez-Castañeda. 1997.
Mammal collections in the western hemisphere: a survey and directory of existing
collections. American Society of Mammalogists, Lawrence, EE. UU.
HooPer, e. t. 1952. A systematic review of harvest mice (Genus Reithrodontomys) of
Latin America. Miscellaneous Publications, Museum of Zoology, University of
Michigan, 77:1-255.
Hsu, t. C., and f. e. arrigHi. 1986. Chromosomes of Peromyscus (Rodentia, Cricetidae).
I. Evolutionary trends in 20 species. Cytogenetics 7:417-446.
lee, M. r., and f. f. B. elder. 1977. Karyotypes of eight species of Mexican rodents
(Muridae). Journal of Mammalogy 58:479-487.
lee, M. r., and f. f. B. elder. 1980. Yeast stimulation of bone marrow mitosis for
cytogenetic investigations. Cytogenetics and Cell Genetics 26:36-40.
Myers, n., r. a. MitterMeier, C. g. MitterMeier, g. a. B. da fonseCa, and J. kent. 2000.
Biodiversity hotspots for conservation priorities. Nature 403:853-858.
Musser, g. g., and M. d. Carleton. 2005. Superfamily Muroidea. Pp. 894-1531 in
Mammal Species of the World (Wilson, D. E. and Reeder, D. M. eds.). , Third
Edition. The Johns Hopkins University Press. Baltimore, EE.UU.
ordóñez-garza, n., J. o. Matson, r. e. strauss, r. d. Bradley, and J. salazar-BraVo.
2010. Concordant patterns of phenotypic and genetic variation in three species of
endemic Mesoamerican Peromyscus (Rodentia, Cricetidae). Journal of Mammalogy
91:848-859.
PePPers, J. a., J. g. oWen, and r. d. Bradley. 1999. The karyotype of Peromyscus stirtoni
and its implications on chromosomal evolution in the Peromyscus mexicanus
species group. The Southwestern Naturalist 44:109-112.
roBBins, l. W., and r. J. Baker. 1981. An assessment of the nature of rearrangements
in eighteen species of Peromyscus (Rodentia: Cricetidae). Cytogenetics and Cell
Genetics 31:194-202.
rogers, d. s., i. f. greenBauM, s. J. gunn, and M. d. engstroM. 1984. Cytosystematic value
of chromosomal inversion data in the genus Peromyscus (Rodentia: Cricetidae).
Journal of Mammalogy 65:457-465.
sMitH, s., r. d. Bradley, and i. f. greenBauM. 1986. Karyotypic conservatism in the
Peromyscus mexicanus group. Journal of Mammalogy 7:584-586.
stangl, f. B., Jr., and r. J. Baker. 1984. Evolutionary relationships in Peromyscus:
congruence in chromosomal, genic, and classical data sets. Journal of Mammalogy
65:643-654.
Sometido: 23 de abril de 2013
Revisado: 12 de septiembre de 2013
Aceptado: 23 de octubre de 2013
Editor asociado: Jesús Maldonado
Diseño gráfico editorial: Gerardo Hernández
www.mastozoologiamexicana.org
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Appendix I
Specimens examined. For each specimen, the collection locality, and museum catalogue
number (abbreviations for museum acronyms follow Hafner et al. 1997) are provided in
parentheses. Abbreviations are as follows: Museum of Texas Tech University (TTU), and
United States National Museum (USNM).
Peromyscus grandis. GUATEMALA: Alta Verapaz; Chelemhá Reserve, Yalijux Mountain
(569843, 569910 USNM).
Peromyscus mexicanus. HONDURAS: Atlántida; Lancetilla Botanical Garden (84454
TTU). Colón; Trujillo, Parque Nacional Capiro y Calentura (104186, 104187, 104188,
104189, 104242, 104244, 104246 TTU); La Ceiba; Laboratorio de la Secretaría de
Agricultura y Ganadería (103967, 103968 TTU). Comayagua; Parque Nacional Cerro
Azul Meámbar (104357, 104358 TTU). Francisco Morazán; Parque Nacional La Tigra
(83731, 83732, 83733, 837340 TTU).
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