Geographic variation in sexual selection and implications for speciation in the Barn Swallow

Barn Swallows(Hirundo rustica), a group of passerine birds comprised of six closely related subspecies, are well known throughout their nearly worldwide distribution, in part because of their close association with human settlements.A tractable species for both individual-based and population-level studies, Barn Swallows are a prominent model system in evolutionary, ecological, and behavioral research. Here we review work on sexual selection and population divergence in this species complex, focusing on comparative studies among populations and subspecies.We summarize variation in the targets of mate choice and in the information conveyed by sexually selected traits, and conclude that the benefits advertised by different traits may vary geographically. Finally, we consider the role of sexual selection as a driver of population divergence in this widespread and phenotypically variable species complex.     

Intraperitoneal injection of methyridine

Extract

Sir,—Having read with interest the letter by R. H. Hiscock in the Veterinar'y Record (Vet. Rec. (1962), 74: 1140), I would like to record a similar experience, using the same product on some “tail end” Jersey calves, five to six months of age, which weighed between 100 lb and 160 lb each. They were very poor calves indeed.