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My lab:
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I missed the first part of the previous plenary lecture by Dan-Eric Nilsson on the evolution of eyes: "Animal vision: The simple beginning" But what I saw was a great showcase of first an overeview of eyes, eye genes and eye phylogeny and then a detailed account of the lense-eyes of box-jellyfish.
But now on to birdsong. The song of Bengalese finches is learned, only sung by males to court females and comparatively complex. The song consists of three syllables which are strung together stochastically according to certain rules of which syllable may follow which preceding syllable. Kazuo Okanoya told us that Bengalese finches are a white morph which is very popular in Japan. After import to Japan these finches were separated from the original strain (white-backed munias) for 500 years and constantly selected for the white color and for reproductive efficiency, but not for song. Nevertheless, the song between the two morphs now differs considerably. In contrast to the complex song of Bengalese finches, the original Munia song is very simple and repetitive.
Lesioning critical birdsong nuclei in the brain of the finches specifically alters the rules by which the syllables are strung together. Lesioning nucleus HVC renders the birdsong simple and repetitive. Electrophysiological recordings show that HVC activity matches with song complexity. Interestingly, nucleus HVC is reduced in size in Munia. Performing gene expression profiles on the birdsong nuclei revealed numerous differences between the two morphs.
To study where the differences in song between the morphs come from, he cross-fostered the two. It turned out that Bengalese finches are better to learn the Munia song compared to the other way around. If the animals are housed with a group of other finches so that they learn from a number of tutors, rather than a single one further increases song complexity. Looking at the tutors the young birds chose to learn from, it turned out that they preferred to learn their song from complex singers.
Female Bengalese finches respond to a new song with an increase in heart rate. Also nesting behavior in females shows a strong connection to song: complex songs lead to more nesting behavior than simple song. Interestingly, even Munia females prefer complex songs. This is starting to make sense as song complexity correlates with male body-size.

Posted on Friday 27 July 2007 - 18:56:29 comment: 0
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