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Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	The reduction of primaries and the evolutionary change of wing form
Auteurs :	B. Stephan, Auteur
Type de document :	Article
Dans :	Journal of Ornithology (143(3) JUL 2002)
Article en page(s) :	287-302
Langues:	Anglais
Résumé :	This paper is a critical evaluation of the theories purporting to explain the different number of primaries, which Stegmann (1962) first associated with the evolutionary change of wing form. The change in the number of primaries in the metacarpal section was the result of individual variability. To some extent this variability has remained. Ancestrally there might have been 11 or 10 primaries, 7 or accordingly 6 metacarpal primaries. In a very few species the number of primaries is standardized at 11, in most species at 10 and in Indicatoridae only at 9, and accordingly 5 metacarpal primaries. Distally no primaries are reduced. The position of the four distal primaries does not change. A shift of primaries from proximal to distal does not take place. Certain processes of reduction in the distal section are connected with the reduction of the claw and the claw limb (phal. 3) of the long finger (Digit. II), which follow their own laws, and are not primarily connected with a change in the wing form. The remicle (Re) is not a rudiment (Ru) of a primary, a well developed great feather, but from the outset a small stiff feather belonging to the row of primaries stabilising this part of the wing. If the outer vane of the distal primary or the very reduced distal primary takes over this function, then the Re will be reduced and omitted. With the change of an ancestral or a round wing to a pointed wing,,the,,R)e may grow in size. The Re fills up the space in front of the distal primary, which is left out by the outer vane of this feather. The change of the wing form in connection with a change of the flying mode may lead to enlargement or to reduction of the size of distal primaries. The outermost distal primary is always preserved and not without function. One part of Stegmann's theory - the change of the wing form, which leads to the reduction of size of the distal primary and which is partly responsible for the reduction of the remicle - retains its validity, but does not explain the reduction of the number of metacarpale primaries.

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