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The Yucatan Peninsula (YP) is a biotic province located in southeastern Mexico, delimited mainly by climatic variables. One endemic species of the YP is the Yucatan deer mouse Peromyscus yucatanicus . It is considered a member of the P. mexicanus species group, but some morphological characters and habitat preferences separate it from them. Herein, the DNA barcoding identification of P. yucatanicus , intraspecific relationships, and the level of genetic differentiation among its geographical distribution were examined. Sequences of the mitochondrial cytochrome c oxidase subunit 1 gene were used for the phylogenetic, demographic history, and genetic structure analysis. In addition, an ecological niche model was built and transferred to 6000 years ago in order to explore the current and past environmental suitability of the species. Results showed that P. yucatanicus was monophyletic and its phylogenetic relationships unresolved. Intraspecific analyses showed signatures of a scenario of demographic stability followed by population growth, and three genetic haplogroups were identified. Paleontological, paleoclimate, and the results presented here are useful to hypothesize that P. yucatanicus likely diverged in the Pleistocene and invaded the south of YP after the Last Glacial Period with the arrival of the current vegetation in the late Pleistocene—early-middle Holocene, and its demographic population was stable during the remaining Holocene epoch with slight growth at the late-middle Holocene resulting in the major precipitation changes that provided more plant coverage.

Post-dispersal, epiphyte seed predation is poorly documented. Our study on the in situ germination of two Tillandsia species in a deciduous forest in Yucatan, Mexico showed an average post-dispersal seed predation rate by the Yucatan deer mouse (Peromyscus yucatanicus) of 90%. Post-dispersal predation was thus more limiting than drought.

The protozoan parasite Trypanosoma cruzi is the causative agent of the Chagas disease, which is endemic in southeastern Mexico and is transmitted by the vector Triatoma dimidiata (triatomide). T. cruzi infect a great variety of domestic and wild mammals; rodents are considered one of the most important reservoirs of the parasite in the transmission cycles of T. cruzi. The objective of this study was to determine the frequency of T. cruzi infection and to determine the parasitic load in synanthropic and wild rodents from the rural community of southern Mexico. A total of 41 blood samples and 68 heart tissue samples were collected from various species of synanthropic (n= 48 in 2 species) and wild rodents (n= 35 in 5 species). DNA was extracted from samples to detect the presence of T. cruzi through quantitative PCR (qPCR). T. cruzi DNA was detected in the 9.75% of the blood samples of the synanthropic species (4/41) (14.28%) for Rattus rattus samples and 25% for Ototylomys phyllotis samples, with an average of parasitic load of 4.80 ± 1.17 parasites/μL. In the case of heart tissue samples, 10.29% were positive for T. cruzi (7/68) (8.7% for Rattus rattus, 40% for Peromyscus yucatanicus, and 42.8% for Ototylomys phyllotis) with an average parasite load of 3.15 ± 1.98 eq-parasites/mg. The active and chronic infection of T. cruzi in synanthropic or wild rodents of the rural community of southern Mexico evidences the natural infection in these reservoirs which contribute to maintaining the agent in the wild and domestic environments and can represent a risk of infection for the human population when the vector is present.

Cysticercus fasciolaris is the larval stage of the cestode Taenia taeniaeformis, whose definitive hosts are mainly cats. This larval stage uses a wide variety of small rodents, and occasionally birds and humans, as intermediate hosts. In the Yucatan, there are no reports of the presence of this cestode in animal populations. The aim of this study was to evaluate the occurrence of C. fasciolaris in rodent populations from the Cuxtal ecological reserve, Yucatan, Mexico. Trapping of rodents was conducted from October 2009 to April 2010 in 40 households in Molas, in which Sherman traps were placed both inside and outside backyards. Rodents were dissected to inspect the liver for the presence of the worm. To determine risk factors associated with infection, univariate analysis was performed using sex, age, species, trapping site, and season as independent variables. Variables with a P value <  0.2 were analysed using a logistic regression model. In this study, 411 individuals of six rodent species were trapped; Mus musculus was the most abundant (78%), followed by Rattus rattus (13%) and the wild species Peromyscus yucatanicus, Ototylomys phyllotis,Heteromys gaumeri and Reithrodontomys gracilis (9%). Only 7.5% (n = 31) of M. musculus and R. rattus were infected with C. fasciolaris (demonstrated by the presence of liver cysts) with a prevalence of 9.0% and 3.5%, respectively. Both adults and male mice were 4.33 and 3.46 (OR values) times more likely to have C. fasciolaris than juveniles and females respectively. We can conclude that in the Cuxtal Reserve, Yucatan, Mexico, the prevalence of C. fasciolaris is higher in M. musculus, and that adult males had a higher probability of infection. Wild species, mainly P. yucatanicus, were not found to be infected with the cestode, but its presence in the backyards of households could result in a potential risk of acquiring this infection.

There is not an experimental model of localized cutaneous leishmaniasis (LCL) caused by Leishmania (Leishmania) mexicana. The aim of the present study was to characterize the clinical and histological features of Peromyscus yucatanicus experimentally infected with L. (L.) mexicana. A total of 54 P. yucatanicus (groups of 18) were inoculated with 1x10(6) promastigotes of L. (L.) mexicana in the base of the tail. They were euthanized at three and six months post experimental infection. The control group was inoculated with RPMI-1640. The predominant clinical sign observed was a single ulcerated lesion in 27.77% (5/18) and in 11.11% (2/18) P. yucatanicus at three and six months respectively. The histological pattern described as chronic granulomatous inflammation with or without necrosis was found in 7/7 (100%) biopsies of euthanized P. yucatanicus at three (n = 5) and six (n = 2) months, respectively. These results resembled clinical and histological features caused by L. (L.) mexicana in humans, and support the possibility to employ P. yucatanicus as a novel experimental model to study LCL caused by this parasite. No existe un modelo experimental de la leishmaniosis cutánea localizada (LCL) causada por Leishmania (Leishmania) mexicana. El objetivo del presente estudio fue el de caracterizar los cuadros clínico e histológico de Peromyscus yucatanicus infectados experimentalmente con L. (L.) mexicana. Un total de 54 P. yucatanicus (grupos de 18) fueron inoculados en la base de la cola con 1x10(6) promastigotes de L. (L.) mexicana. A los 3 y 6 meses posteriores a la infección experimental fueron sacrificados. El grupo control fue inoculado con RPMI-1640. El signo clínico predominante fue una lesión única ulcerada en 27.77% (5/18) y en 11.11% (2/18) P. yucatanicus a los 3 y 6 meses respectivamente. El patrón histológico descrito como inflamación crónica granulomatosa con o sin necrosis se observó en 7/7 (100%) biopsias de los P. yucatanicus a los 3 (n=5) y 6 (n=2) meses respectivamente. Los resultados son similares a los cuadros clínico e histológico de la infección por L. (L.) mexicana en humanos, y apoyan la posibilidad de utilizar P. yucatanicus como un nuevo y original modelo para el estudio de la LCL causada por L. (L.) mexicana.

We report the first record of Yucatan deer mouse, Peromyscus yucatanicus, in Guatemala. The Yucatan deer mouse was restricted to Yucatán Peninsula, where it is considered a common species in deciduous to semi-evergreen tropical forests, and secondary growth forests. Two Yucatan deer mice were collected at Laguna Flor de Luna, Laguna del Tigre National Park, Guatemala, on April 1999. This new record constitutes a range extension of 116 km south of the nearest previously known locality at Escárcega, Campeche, Mexico.