Manejo em cativeiro e biologia reprodutiva de duas espécies de Thrichomys (Rodentia: Echimyidae) provenientes do Piauí e do Mato Grosso do Sul

Abstract

We analyzed life history traits (reproductive biology and postnatal development) in natural populations and in captive-breed colonies of two sibling species of the South American rodeTlt Thrichomys (Caviomorpha: Echimyidae). T pachYlfrus inhabited marshlands of Pantanal, while T apereoides laurelltius lives in very dry rocky habitats in Brazilian Caatinga. Both species are natural hosts of Trypallosoma cruzi, agent of Chagas disease and may serve as experimeutal models in various parasitological studies. We established breeding colonies of these species. They carl be easi!y maintained in the standard laboratory conditions and breed alI over the year. They do not have any special dietary demands and can be fed by standard food pelIets designed for iaboratory mice. They produce precocious offspring that have iheir eyes and ears open, teeth erupted, fur welI developed and can nibble solid food in the first week of life. Previous studies considered the genus Thrichomys as monospecific, however, more recent studies showed cromossomic, molecular and morphometrics vaíiation betwçen populations. In this study we found significant differences between the species in growth rate and several reproductive traits (litter size, body mass at birth and weaning, sexual maturation). T apereoides laurentius, living in harsh environment has a higher reproductive potential. It has larger litter size, smalIer body mass of infants and higher growth rate than T pachyurus. The females of the former species reach sexual maturation earlier and with lower body mass. These differents strategies are apparently related to their different habitats.