Dear list-mates,
I would thank your input to explaining polychaete brooding species in the
sublitoral of an oceanic island, La Gomera, Spain.
We are finding a local cosmopolism of spionids, syllids and onuphids, and
are wondering on the occurrence of species not relying on planktonic
larvae for dispersal, mainly onuphids (Aponuphis bilineata, Onuphis
eremita) and a high number of syllid species.
Only Bhaud & Duchene (1994) have given some evidence that swappings
between benthopelagic and benthic development are common among
polychaete fauna and may have taken place several times in the evolution
of species to date. On evolutive grounds, he has argued that benthic
development may have been possibly adopted by some polychaete
populations faced with environmental constraints like massive loss of larvae
by dispersal through water currents (Bhaud 1988). This condition is
particularly dramatic in the sublitoral of oceanic islands, but the possibility
that some dominant brooding species occurring in La Gomera (e.g. A.
bilineata and most syllid species) have undergone such reproductive shifts
is obviously only speculative. Besides, vicariant populations of Eupolymnia
nebulosa from the Mediterranean and the North Atlantic have been found to
use differing reproductive strategies in order to minimise larval loss (Bhaud
& Duchene 1994), but further research needs to be taken to confirm if
other polychaete species populations are plastic enough to resort to either
benthopelagic or benthic development in function of the constraints of their
habitat, oceanic islands standing as fairly appropriate environments to
address this issue.
Do you have any research evidence that those reproductive swappings
have taken place in syllid and onuphid polychaete families? Ideas are very
welcome indeed.
Thanks.
Salva
<salherra at smtp.ctv.es>
-----------------------------------------------
Working-@ addresss: salherra at ull.es
_____________________________
Salvador Herrando-Perez
Tenerife University, Spain
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