quelques abstract :
The perfect invader: a parthenogenic crayfish poses a new
threat to Madagascar’s freshwater biodiversity
In 2007 an unusual crayfish found in food
markets in the capital of Madagascar was prelimi-
narily identified as Procambarus ‘Marmorkrebs’: a
new world taxa and the only decapod known to
reproduce by parthenogenesis. We present informa-
tion on the identity, distribution and ecology of this
recent invader and attempt to evaluate the threat it
poses to Madagascar’s biodiversity and to liveli-
hoods. The species appears to be currently limited to
the area close to Antananarivo, but is being sold alive
on major transport routes. We present molecular
evidence of its taxonomic relationships and confirm
that the Procambarus present in Madagascar is
indeed the parthenogenic taxa. We investigate its
reproductive ecology and find Procambarus ‘Mar-
morkrebs’ to have an extremely high fecundity; more
than six times that of the native crayfish Astacoides.
The limited evidence we have suggests that this
species poses a serious threat to freshwater biodiver-
sity and that it is likely to damage human livelihoods
(through its impact on fishing and possibly rice
agriculture). More research is urgently needed but in
the meantime action is needed to reduce the rate of
spread before it is too late.
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Ecology: Parthenogenesis in an outsider crayfishIt has been rumoured
1that an unidentified decapod crustacean, a crayfish of marbled
appearance and of uncertain geographical origin that was introduced
into the German aquarium trade in the mid-1990s, is capable of
unisexual reproduction (parthenogenesis). Here we confirm that this
marbled crayfish ('
Marmorkrebs') is parthenogenetic under
laboratory conditions and use morphological and molecular analysis to
show that it belongs to the American Cambaridae family. Although
parthenogenesis is widespread among the Crustacea
2, and shrimp, lobsters, crayfish and crabs are otherwise versatile in their modes of reproduction
3, 4, 5,
it has not been reported before in decapods, the largest and
economically most important crustacean group. By virtue of its
parthenogenetic reproduction, the marbled crayfish emerges not only as
an interesting laboratory model but also as a potential ecological
threat in that it could outcompete native forms should even a single
specimen be released into European lakes and rivers.
_________________
Benoist,

"Les animaux ne demandent pas qu'on les aime, ils exigent qu'on leur foute la paix !"
Théodore Monod