For 829 mammalian species, data on age at weaning or age at first solid food were analyzed with respect to body mass, phylogeny, habitat, diet, length of gestation, basal metabolism, and neonatal development. The primary influence on lactation length is female mass, but phylogenetic constraints are important. Thus, lactation can be characterized as short (earless seals and baleen whales), long ...

Nematodes of the family Heligmonellidae (Heligmosomoidea; Trichostrongylina) reside in the digestive tracts of rodents and lagomorphs. Although this family contains large numbers of genera and species, genetic information on the Heligmonellidae is very limited. We collected and isolated adult worms of three species in Japan that belong to the family Heligmonellidae, namely Heligmonoides specios...

Syncytins are envelope protein genes of retroviral origin that have been captured for a function in placentation. Two such genes have already been identified in simians, two distinct, unrelated genes have been identified in Muridae, and a fifth gene has been identified in the rabbit. Here, we searched for similar genes in the Laurasiatheria clade, which diverged from Euarchontoglires--primates,...

During the past several years, cytological, histochemical, and electron microscopic studies have been carried out on the placentas of several different species of mammals. In these studies, particular attention has been paid to the so called placental barrier; that is, the regions of the choriallantoic placenta in which the circulating fetal blood most closely approximates the maternal blood. W...

One year ago, JJ1 was Europe's most famous mammal. The male brown bear, also known by the more amiable name of 'Bruno', had wandered into Southern Germany from the Trentino in Italy. The appearance of this charismatic animal in a region where the last bear had been seen and killed 170 years ago seemed to fit a trend. Over the past ten years, wolves, elks, beavers and lynxes have been highly pub...

To the Editor: Tularemia is a bacterial zoonosis caused by the gram-negative, nonmotile coccobacillus Francisella tularensis, which is en-demic in lagomorphs in North America (1,2). Tularemia is considered a possible biological weapon of terrorism (Centers for Disease Control and Prevention [CDC] category A) because of its high infectivity, ease of dissemination , and considerable ability to ca...

Herbivory by rodents, lagomorphs and insects may locally constrain woody plant seedling establishment and stand development. Recruitment may therefore depend either upon plant tolerance of herbivory, or low herbivore abundance, during seedling establishment. We tested potential herbivory tolerance by quantifying growth, biomass allocation, and survival of defoliated Prosopis glandulosa seedling...