Phylogenetic signal, feeding behaviour and brain volume in Neotropical bats.

Comparative correlational studies of brain size and ecological traits (e.g. feeding habits and habitat complexity) have increased our knowledge about the selective pressures on brain evolution. Studies conducted in bats as a model system assume that shared evolutionary history has a maximum effect on the traits. However, this effect has not been quantified. In addition, the effect of levels of diet specialization on brain size remains unclear. We examined the role of diet on the evolution of brain size in Mormoopidae and Phyllostomidae using two comparative methods. Body mass explained 89% of the variance in brain volume. The effect of feeding behaviour (either characterized as feeding habits, as levels of specialization on a type of item or as handling behaviour) on brain volume was also significant albeit not consistent after controlling for body mass and the strength of the phylogenetic signal (λ). Although the strength of the phylogenetic signal of brain volume and body mass was high when tested individually, λ values in phylogenetic generalized least squares models were significantly different from 1. This suggests that phylogenetic independent contrasts models are not always the best approach for the study of ecological correlates of brain size in New World bats.

Class II DRB polymorphism and sequence diversity in two vesper bats in the genus Myotis.

Almost no studies have been done with respect to major histocompatibility complex (MHC) polymorphism and sequence diversity in bats, although they account for one in five living mammalian species. We analysed MHC Class II DRB polymorphism and sequence diversity in two Mexican verpertilionid bat species, the widespread continental species Myotis velifer and the narrowly distributed (and endangered) island endemic Myotis vivesi. We find extensive DRB polymorphism in the widespread M. velifer, similar to that commonly reported in other mammals. The geographically restricted M. vivesi by contrast shows only very limited polymorphism. We conclude that M. vivesi has undergone a dramatic loss of MHC polymorphism. The significance of this inference in light of other information on population structure and genetic diversity in this species is discussed.

Waldenström's macroglobulinemia is infrequent in Mexican Mestizos: experience of a hematological diseases referral center.

Along a 17-year period 7,373 patients were prospectively studied in a private practice Health facility; of these 11 were patients with Waldenström's macroglobulinemia; calculations from these data and previous publications show that this lymphoid malignancy represents in Mexico 0.18% of all hematologic malignancies, a figure 11 times lower than that described from caucasians. The median age was 65 years (range 31 to 84); there were 6 males and 5 females. Ten individuals were mexican mestizos, whereas one had a caucasian phenotype. The clinical features of the patients afflicted by the disease in Mexico were similar to those reported from caucasian populations. The median survival (SV) of the group of patients was 40 months, whereas the 42-month survival was 49%; the prognosis of the disease was relatively good despite the fact that complete remissions were unfrequent as a result of the treatment.