INVESTIGADORES
RAYA REY Andrea Nelida
artículos
Título:
Geographical variation in egg size dimorphism in rockhopper penguins
Autor/es:
DEMONGIN L; POISBLEAU M; RAYA REY A; SCHIAVINI A; QUILLFELDT P; EENS M; STRANGE I
Revista:
POLAR BIOLOGY
Editorial:
Springer-Verlag
Referencias:
Año: 2010 vol. 33 p. 469 - 476
ISSN:
0722-4060
Resumen:
Abstract All crested penguins present a unique reversed
hatching asynchrony: the larger second-laid egg (B-egg)
hatches before the smaller Wrst-laid egg (A-egg). Although
both eggs often hatch, the A-chick generally dies of starvation
within days after hatching. However, within rockhopper
penguins, the population at the Falkland Islands is
unique in that some birds manage to raise both chicks.
Although it has been suggested that the egg size dimorphism
between A- and B-eggs may explain how long both
eggs and chicks survive, this hypothesis has never been
explicitly tested. We expect that both eggs are retained
longer in the less dimorphic clutches than in the more
dimorphic ones. In this paper, we have compiled egg measurements
for three rockhopper penguin species (Eudyptes
chrysocome, E. Wlholi and E. moseleyi) in order to compare
the intra-clutch egg size dimorphism among these species.
Furthermore, we have collected new data to compare egg
size dimorphism between two populations of E. chrysocome
(Falkland Islands versus Staten Island). A-egg
volumes are more variable between species and populations
than B-egg volumes. E. chrysocome and especially the
population from the Falkland Islands produces the largest
A-eggs and the least dimorphic eggs. Nevertheless, as
diVerences in A-egg volumes between species and between
the populations of Falkland Islands and Staten Island are
stronger and more signiWcant than diVerences in egg dimorphism,
we suggest that A-egg volume, more than egg
dimorphism, could be one of the factors inXuencing the
prevalence of twins. A large A-egg and/or reduced egg
dimorphism is probably necessary to enable rockhopper
penguins to raise two chicks, but other reasons may also be
involved which enable them to keep both eggs and chicks.