Nestedness and degree distributions are necessarily linked in mutualist   systems
  Replacement of papers q-bio/0605026 and q-bio/0607043 by a single manuscript (q-bio/0701029) follows suggestions from a magazine's referee 
Enrique Burgos, Horacio Ceva, Roberto P.J. Perazzo, Mariano Devoto,   Diego Medan, Martin Zimmermann, Mariana Delbue