Hybridization in Acropora

Hernandez Edwin coral_giac at yahoo.com
Fri Feb 14 22:45:18 EST 2003

Dear Pedro and fellow listers.

Just a minor observation following Pedro's posting on
rapidly changing Acropora palmata morphology.

Here in Puerto Rico, I've seen in two locations on the
northern coast at Arrecife La Ocho, also known as El
Escambron (San Juan), and at Vega Baja Beach (about
20-25 km west of San Juan) high densities of A.
palmata colonies with mixed phenotypes.

These colonies are growing on very shallow (0.5-1.5 m)
and highly turbulent habitats. Most of the colonies
show typical A. palmata branches in the colony
portions under less turbulent microhabitats (lower
part of the colony). But, those colony portions
exposed to the prevalent turbulent conditions (upper
branches) show typical A. prolifera forms.

I've always thought that these "hybrid" morphs are the
result of local environmental factors. Their
distribution is limited only to the most turbulent
zone. Thus, it would be interesting to look at the
genetics of these known A. prolifera hybrids and those
A. prolifera-looklike palmatas.

Is this sudden increase in branchiness a strategy to
dissipate high energy from incoming waves? Or is it
simply a reproductive strategy to rapidly colonize,
disperse and dominate shallow turbulent reef zones? Or
is it an strategy of some genetic variants to try to
fix their genes by producing larger numbers of weaker
fragments, which will inebitably will fragment and
disperse, thus rapidly dispersing genetic clones

Moreover, this process that Pedro just described under
aquarium conditions, which might be the same one that
could explain my observations under field conditions,
should be tested as a potential A. palmata propagation
and restoking method.

If palmata branches can exhibit such a rapid increase
in branchiness under stronger water movement, then,
wouldn't it be feasable either to propagate corals
under flowing tank or field conditions by allowing
single branches to rapidly produce a high number of
new branches which can be cut and transplanted to
repeat the process?  Just a though...



Edwin A. Hernandez-Delgado, Ph.D.
University of Puerto Rico
Department of Biology
Coral Reef Research Group
P.O. Box 23360
San Juan, P.R. 00931-3360
Tel (787) 764-0000, x-4855; Fax (787) 764-2610

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