48 research outputs found
Diário de uma expedição de Pirara ao Upper Corentyne, e dali a Demerara
Tradução de Journal of an Expedition from Pirara to the Upper Corentyne, and from thence to Demerara, de Robert H. Schomburgk
Male pygmy hippopotamus influence offspring sex ratio
Pre-determining fetal sex is against the random and equal opportunity that both conceptus sexes have by nature. Yet, under a wide variety of circumstances, populations shift their birth sex ratio from the expected unity. Here we show, using fluorescence in situ hybridization, that in a population of pygmy hippopotamus (Choeropsis liberiensis) with 42.5% male offspring, males bias the ratio of X- and Y-chromosome-bearing spermatozoa in their ejaculates, resulting in a 0.4337±0.0094 (mean±s.d.) proportion of Y-chromosome-bearing spermatozoa. Three alternative hypotheses for the shifted population sex ratio were compared: female counteract male, female indifferent, or male and female in agreement. We conclude that there appears little or no antagonistic sexual conflict, unexpected by prevailing theories. Our results indicate that males possess a mechanism to adjust the ratio of X- and Y-chromosome-bearing spermatozoa in the ejaculate, thereby substantially expanding currently known male options in sexual conflict
Taxonomic status and conservation relevance of the raccoons (Procyon spp.) of the West Indies
III.—A description of some new species of fishes from the sea surrounding the Island of Barbados
Volume: 2Start Page: 11End Page: 2
The history of Barbados; comprising a geographical and statistical description of the island; a sketch of the historical events since the settlement; and an account of its geology and natural productions.
Twelve views in the interior of Guiana : from drawings executed by Mr. Charles Bentley, after sketches taken during the expedition carried on in the years 1835 to 1839, under the direction of the Royal Geographical Society of London, and aided by Her Majesty\u27s government /
The history of Barbados; comprising a geographical and statistical description of the island; a sketch of the historical events since the settlement; and an account of its geology and natural productions.
Contains 8 original lithographs, including added title page.Mode of access: Internet