Hi Folks,
A most interesting and interesting article discussing the problems with identifying stony corals, in particular, some species of Hawai’ian Montipora has recent been published.
The background for the article is that last year several parties petitioned to have 83 stony corals to be listed under the United States Endangered Species Act. The National Marine Fisheries Service (NMFS), a branch of the National Oceanic and Atmospheric Administration (NOAA) is charged with assessing the coral species in question to determine, among other things, if they actually are endangered. If the corals are listed, the act is supposed to provide some more protection for the species, and probably most importantly, designate critical habitat for these corals.
Of course, the whole “assessment” process ultimately depends upon somebody’s ability to identify individual colonies of coral species in question and that, in turn, depends upon the validity scientific description of those species. The basic fundamental issues are:
1) Is the given species well-enough described to be reliably identified? Keep in mind, that by being listed on the petition, at least somebody thinks the indivual colonies in that species can be identified.
2) If the species is identifable, can it be assessed to determine if it is endangered?
The article discussed in the Coral feature was officially published on 2 December, 2010, in the electronic (online and free access) peer-reviewed journal, PLoS One:
Forsman ZH, Concepcion GT, Haverkort RD, Shaw RW, Maragos JE, et al. (2010) Ecomorph or Endangered Coral? DNA and Microstructure Reveal Hawaiian Species Complexes: Montipora dilatata/flabellata/turgescens & M. patula/verrilli. PLoS ONE 5(12): e15021. doi:10.1371/journal.pone.
I urge you all to read, at least, the Abstract (= the authors’ short summery) of the article, but I am also a realist and realize that while a few of you will look at the Abstract, and some of you may actually read or download and save the article, most people who scan this blog probably won’t.
So…
Here is a brief summary of the summary – if you will, an abstracted abstract. And if this is creative document would it then be “abstract art?” Yeah, I know, “Boo!… hiss!”
The researchers examined the genetic codes for a relatively large number of well-known and well-characterised proteins found in the corals’ cells, as well, they also looked at how the subcellular structures called mitochondria vary genetically between the samples. They also microscopically compared, in fine detail, some of the visible physical structures of each specimen.
When added together, these different examinations revealed four distinct groupings of specimens (called “clades”), and when each specimen was identified with traditional taxonomic methods, the four clades contained these species: I) M. patula/M. verrilli, II) M. cf. incrassata, III) M. capitata, IV) M. dilatata/M. flabellata/M. cf. turgescens. So, sophisticated statistical analyses of skeletal microstructure and genetics separated specimens of 7 “species,” based on traditional taxonomy, into 4 groups that represent -probably- actual groups. I think whether or not one wants to consider that each of these groups represents a species is probably dependent on how one feels about this type of analysis. To me, yup, I’ll buy in to consideration of each group as representation of a species. The microcharacters of the size and shape of verrucae or papillae were the only reliable physical characters that could be used in identifying the groups, while gross features such as any aspect of colony-level morphology was so highly variable as to be useless.
The authors noted that previous studies on how observable structures in corals vary from specimen to specimen have revealed that fragments taken from the same colony can exhibit strikingly different growth forms if grown in different environments. Additionally, the extent of both genetic and morphological intraspecific variation in corals is poorly understood. This is clearly creates problems for assessment of species in the context of the Endangered Species Act as structurally-based taxonomy – not molecular or genetic information – is the current basis for estimating species distributions, abundance, and extinction risk.
This study identified no fixed genetic or fine-scale morphological differences between M. flabellata, M. cf. turgescens, and M. dilatata, or between M. patula and M. verilli; in other words, these 5 named species appear to be only 2 natural species. The authors noted that the geographic ranges of these groups are likely to extend beyond Hawai’i into the central Pacific and that individuals within “species” of these complexes are either actively interbreeding (which means they are not separate species), or they are from separate species that are very closely related (e.g., evolutionarily separated within the last one million years) and cannot be distinguished from one another. Now that these complexes have been identified, work is needed to determine if the nominal species within each complex freely interbreed.
Finally, the authors note:
Unfortunately, this study provides little guidance for determining if these specific species are valid and should be listed under the ESA, but perhaps more importantly; it highlights major gaps in the present understanding of species as opposed to population-level variation in corals. This study is an example of how knowledge of species boundaries in corals is not only necessary for understanding patterns and processes of biodiversity and evolution, but is essential for conservation.
In short, the article is a “fun read.”
One of the many take home messages is obviously that corals are exceptionally difficult critters to identify. Generally, if we choose the proper characters, we can identify them to genus. Beyond that… don’t even try. As it stands now, we have so few data across the range of most tropical stony reef-forming (and presumably, non-reef forming as well) corals, that distinguishing any specific species is an impossible task.
Enjoy the article!!
Cheers,
Tags: aquarium, genetics, genomic research, Hawai'i, laboratory research., marine biology, research article, scleractinia, taxonomy
This entry was posted on Friday, December 17th, 2010 at 07:42 and is filed under Reef Aquarium Questions Answered. You can follow any responses to this entry through the RSS 2.0 feed.
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