A random model for mapping imprinted quantitative trait loci in a structured pedigree: an implication for mapping canine hip dysplasia

Genetic imprinting may have played a more notable role in shaping embryonic development of plants, animals, and humans than previously appreciated. Quantitative trait loci that are imprinted (iQTL) exert monoallelic effects, depending on the parent of origin, which is an exception to the laws of Mendelian genetics. In this article, we present a modified random effect-based mapping model to use in a genome-wide scan for the distribution of iQTL that contribute to genetic variance for a complex trait in a structured pedigree. This model, implemented with the maximum likelihood method, capitalizes on a network of relatedness for maternally and paternally derived alleles through identical-by-descent sharing, thus allowing for the discrimination of the genetic variances due to alleles derived from maternal and paternal parents. The model was employed to map iQTL responsible for canine hip dysplasia in a multihierarchical canine pedigree, founded with seven greyhounds and six Labrador retrievers. Of eight significant QTL detected, three, located on CFA1, CFA8, and CF28, were found to trigger significant parent-of-origin effects on the age of femoral capital ossification measured at the left and right hips of a canine. The detected iQTL provide important candidate regions for fine-mapping of imprinted genes and for studying their structure and function in the control of complex traits.     

Seasonality in diet and breeding success of the Jackass PenguinSpheniscus demersus

Summary Jackass Penguins breed throughout the year but show seasonal preferences. I examined the hypothesis that most birds breed at a time when reproductive potential is most fully realised. By using the numbers of Jackass Penguins returning to the island per 24 hour period as an index of the number of birds breeding, I found that most penguins on the island bred when chick growth was maximal and chick mortality was minimal. The diet of Jackass Penguins was determined by stomach pumping 556 birds. More than 95% of their diet, by weight, consisted of pelagic schooling fish. The local abundance of these fish seemed to determine the breeding success of the Jackass Penguin.

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Jahreszeitliche Unterschiede in Nahrung und Bruterfolg des BrillenpinguinsSpheniscus demersus

Zusammenfassung Brillenpinguine brüten zwar das ganze Jahr hindurch, zeigen aber jahreszeitliche Präferenzen. Ich prüfte die Hypothese, daß die meisten Vögel zu der Zeit nisten, wenn der höchste Bruterfolg realisiert werden kann. Die Anzahl pro 24-h-Perioden auf die Insel rückkehrender Pinguine wurde als Index für den Brutbestand betrachtet. Tatsächlich brüteten am meisten Vögel dann, als Wachstum maximal und Kükensterblichkeit minimal waren. Die Nahrung wurde durch Magenspülungen bei 556 Individuen ermittelt. Pelagische Schwarmfische machten mehr als 95 Gewichtsprozente aus. Anscheinend bestimmte die lokale Häufigkeit dieser Fische den Bruterfolg.