Genotypes B and C are endemic in European nonpsittacine birds, which may represent an important part of the zoonotic reservoir for human psittacosis cases.
From this perspective, the extent of dosage compensation of Z-linked genes in birds may be seen to represent a trade-off between the costs and benefits of restoring the original balance between male and female sex chromosome and autosome expression levels (discussed later).
The avian influenza that killed 1000 or more migratory birds at Lake Qinghai in western China in mid-May may represent a new and more lethal form of the HN51 virus, Chinese researchers report.
Previous studies have shown that apoB, which is related to Vtgs [89] [91], is also incorporated in the yolk of birds [92], and may represent a neo-functional product of gene duplication.
Haemosporidia represent only one class of parasite to which island birds may be differentially exposed.
Given the striking pattern of similar and rapid effects across four common and widespread species, including a volant bird, intense urbanization may represent the most severe form of fragmentation, with minimal effective movement through the urban matrix.
Birds are not segregated by species, and <200 birds may be housed together in individual pens.
Biologically, values of k < 1 suggest a lower threshold of attraction to sites, which may represent birds occasionally choosing slightly less populous sites when the number of individuals in the patch is high.
In addition, the role of persistent infection in organs of infected birds cannot be excluded, which may represent a further infection overwintering mechanism when coupled with the predation by other bird species, as, for example, those belonging to Corvidae or Falconidae families [ 91].
