INVESTIGADORES
LOPEZ Laura Susana
artículos
Título:
A hypothesis about the origin of sperm storage in the Eubrachyura, the effects of seminal receptacle structure on mating strategies and the evolution of crab diversity: how did a race to be first become a race to be last?
Autor/es:
MC LAY, COLIN; LÓPEZ GRECO, LAURA SUSANA
Revista:
ZOOLOGISCHER ANZEIGER
Editorial:
ELSEVIER GMBH
Referencias:
Año: 2011 vol. 250 p. 378 - 406
ISSN:
0044-5231
Resumen:
The origins and evolution of sperm storage in Brachyura are enigmatic: sperm is either stored
in seminal receptacles, accessable via the vulvae on the sixth thoracic sternite, or in
spermathecae at the border between the seventh and eighth sternites. Crabs with
spermathecae are collectively refered to as podotremes while crabs with seminal
receptacles belong to the Eubrachyura. The position of gonopores is the primary basis for
subdividing the Eurachyura into the Heterotremata (female vulvae + males with coxal
gonopores) and Thoracotremata (female vulvae + males with sternal gonopores). We present
a hypothesis about the evolution of seminal receptacles in eubrachyuran female crabs and
argue that the sternal gonopore has been internalized into chitin-lined seminal receptacles and
the vulva is in fact a secondary aperture. The loss of some or all of the ancestral chitinous
seminal receptacle lining was linked to ventral migration of the oviduct connection. Male and
female strategies are to maximize gamete fertilization. The most important variable for
females is sperm supply, enhanced by long-term storage made possible by the seminal
receptacle. To maximize their fertilization rates males must adapt to the structure of the
seminal receptacle to ensure that their sperm are close to the oviduct entrance. The major
evolutionary impetus for female mating strategies was derived from the consequences of
better sperm conservation and the structure of the seminal receptacle. The advantages were
all to the females because their promiscuity and sperm storage allowed them to produce more
genetically variable offspring, thereby enhancing variation upon which natural selection
could act. We extend our arguments to Brachyura as a whole and offer a unifying explanation
of the evolution of seminal receptacles, comparing them with the spermathecae found in
Podotremata: they were independent solutions to the same problem: maintaining spermsperm
supply during evolutionary carcinization.