Recruitment to the reef
column spacer Recruitment to the reef
 
 

Asexual reproduction

 
Asexual reproduction of gorgonians is considered in this section. Click on an icon to learn about asexual reproduction in other reef organisms. hot buttons for asexal reproduction section of BCCR website hot-button icon for linking to the topic of asexual reproduction in seaweeds in BCCR website hot-button icon for linking to the topic of asexual reproduction in sponges in BCCR website hot-button icon for linking to the topic of asexual reproduction in gorgonians in BCCR website hot-button icon for linking to the topic of asexual reproduction in corals/zoanthids in BCCR website hot-button icon for linking to the topic of asexual reproduction in seastars in BCCR website hot-button icon for linking to the topic of asexual reproduction in tunicates in BCCR website
 
 
seahorse dive leader for BIOLOGY OF CARIBBEAN CORAL REEFS website photograph of a broken gorgonian taken from a video

"You wouldn't think that gorgonians would fragment, but some species are actually quite fragile. If broken bits lodge somewhere quiet, like these ones, then any of them have a chance to regrow." - Grand Cayman Island, 2001

NOTE possibly the sea-rod gorgonian Eunicea sp.

 
 

Asexual reproduction: gorgonians

 

In the San Blas Islands off of Panama, the gorgonian Plexaura, known for its extreme fragility, commonly reproduces by fragmention. In one part of the reef, over 90% of the small colonies within a 100 meter-square area were found to have grown from fragments of a single parent colony...in other words, clones of the parent.

How is this known? How can the small gorgonians be identified as clones: that is, having originated from a single parent? One possible method is to isolate and identify nucleotide sequences in DNA from the different fragments and compare them for degrees of similarity. The drawback to this method is that it is time-consuming and expensive. As well, many parent colonies of the same species would have to be sampled to ascertain natural variability in the species.

Another possibility is to test for cross-fragment fertilisation potential. Because all fragments from a given individual would be the same sex, if you found that all were male, or all female, it could suggest a single parentage. However, a problem might arise if the original fragments happened to be produced by several males or several females in the area. This could lead to incorrectly assuming that the youngsters were clones because they were of the same sex. Lasker & Coffroth 1985 Proc 5th Int Coral Reef Symp 4: 331.

photograph of gorgonian Plexaura
Black sea-rod Plexaura sp. 0.25X
photograph of naturally fused gorgonians

Instead, the authors used a tissue-histocompatibility method. This involved simply tying together sample fragments of gorgonians and monitoring them over time. If they fuse it is strong evidence that the fragments come from the same "parent" individual; that is, they are genetically idential clonemates. In fact, the authors identified larger histocompatibility groups made up of more than one suspected genotype, which made interpretation of what was going on somewhat more difficult.

Another possibility, that the small colonies are just the offspring produced from eggs from a single individual, was dismissed by the authors on the bases that: 1) if this had happened the youngsters would have differed genetically (e.g., would have been of different sexes, and so on) and, hence, would have had different histocompatibilities, and 2) because gorgonians are "broadcast" spawners with eggs that are known to float for up to 12h, the offspring would be more likely to end up hundreds or even thousands of meters away. Lasker & Coffroth 1985 Proc 5th Int Coral Reef Symp 4: 331.

 
  RETURN TO TOP
   
hot button for sponges section on spawning/metamorphosis/dispersal hot button for corals section on spawning/metamorphosis/dispersal hot button for snails section on spawning/metamorphosis/dispersal hot button for sea urchins & relatives section on spawning/metamorphosis/dispersal hot button for fishes section on spawning/metamorphosis/dispersal hot-button icon for linking to the topic of spawning, larval development, & dispersal of larvae in BCCR hot-button icon for linking to the topic of settlement & metamorphosis during early life in BCCR hot-button icon for linking to the topic of survival during early life in BCCR