How are new species of coral identified?

[duberii]

The definition of a species is "a collection of organisms that are able to reproduce fertile offspring." I doubt that when a new specimen is found, taxonomists try to breed that coral with other corals to test for reproduction and then later test for viability. I know that identification of known species is usually done via looking at the skeleton, but the appearance of a skeleton isn't enough to declare a new species, right?

 

[mtfish]

Most stony corals are ID'ed through their skeletal shape. DNA profiles are also used to look at all sorts of things. Even bacteria and viruses associated with corals, but these can change under differing conditions. I am not a taxonomist by training and barely passed my coral reef ecology class many, many years ago, so take everything I say with a grain of salt!

 

[Smarkow]

I've always wondered this as well. I've read before about taking thin cross-sectional slices and then staining the tissue, examining the skeletal shape, and then dissolving the skeleton under a microscope as part of the initial evaluation. I've been curious enough to look for studies on whole genome sequencing of coral but have not been able to find much.

 

[Jason Truong]

At first, they were cataloged according to their skeleton and other physical appearances. Now, I'm sure DNA technology is being used to diversify each species and be able to tell the differences between very similar corals. DNA technology is relatively new so going back and doing the whole identification and categorization process can be a pain

 

[Spare time]

My guess is that they use DNA for phylogeny rather than morphology. Morphology is good for categories similar organisms by appearance but since DNA tech is in a sort of boom right now a lot of fields of evolutionary studies have been re-evaluating species taxonomy.

 

[Jason Truong]

My guess is that they use DNA for phylogeny rather than morphology. Morphology is good for categories similar organisms by appearance but since DNA tech is in a sort of boom right now a lot of fields of evolutionary studies have been re-evaluating species taxonomy.

Yeah they've just recently started using DNA for identification though. Process is pretty expensive to do but worth it in my opinion.

 

[duberii]

How would the skeleton or even DNA be enough to determine if they could reproduce though? Perhaps it's a case of the definition of a word changing over time, but I feel like it would be extremely difficult to determine something like breeding capabilities from DNA or morphological differences.

 

[EMeyer]

Always a fun discussion. Put three biologists together in a room and ask them the definition of species, and you'll probably get at least 4 different definitions.

The OP is proposing the biological species concept focusing on reproductive viability. Most modern systematics (the classification of living things) follows the phyogenetic species concept instead - a species is a collection of living things sharing a set of derived traits that distinguish that group from their other close relatives.

The characters (traits) used to classify corals (like everything else in the modern era) are DNA sequences rather than morphological traits. Which is GREAT, because trying to decipher anything from skeletal morphology was probably as reliable as tea leaves, and was a giant pain. DNA is easy, relatively speaking.

 

[duberii]

Always a fun discussion. Put three biologists together in a room and ask them the definition of species, and you'll probably get at least 4 different definitions.

The OP is proposing the biological species concept focusing on reproductive viability. Most modern systematics (the classification of living things) follows the phyogenetic species concept instead - a species is a collection of living things sharing a set of derived traits that distinguish that group from their other close relatives.

The characters (traits) used to classify corals (like everything else in the modern era) are DNA sequences rather than morphological traits. Which is GREAT, because trying to decipher anything from skeletal morphology was probably as reliable as tea leaves, and was a giant pain. DNA is easy, relatively speaking.

Interesting... I had no idea that there are different definitions of species- add this to the proof that high school biology curriculums need to be updated That raises another question for me though- if we are now basing it on DNA, and all corals probably have 99% DNA overlap, where do you draw the line between a new species and individual variation? I guess every individual could be its own species but at that point it's pretty arbitrary.

 

[EMeyer]

Because when biologists sequence DNA to compare species, they don't just sequence the whole genome (for a lot of reasons). They sequence a specific set of markers that are known to differ among corals in informative ways.

For most corals, a single marker (a few hundred base pairs, or "letters" long) is enough to classify the species. But the relationships remained unresolved for large groups of corals.

More recently, we've started sequencing sets of several hundred markers at once ("phylogenomics") which provides much better resolution.

You are right that each coral is genetically identical, but DNA sequencing reveals that there are groups of corals that share a characteristic set of variations. These groups are designated as species.

And biologists debate this stuff as much as zoa hobbyists debate zoa IDs

 

[Jason Truong]

My major is Biochemistry, and my answer to that is we know if two individuals are the same species if they are able to sexually reproduce viable, fertile offspring. Hybridism allows for the reproduction of offspring, however, most cases of hybridization causes at least one sex to be infertile. Has lots to due with the number of chromosomes and how each chromosome is able to mix with the other.

 

[Spare time]

How would the skeleton or even DNA be enough to determine if they could reproduce though? Perhaps it's a case of the definition of a word changing over time, but I feel like it would be extremely difficult to determine something like breeding capabilities from DNA or morphological differences.

What defines a species is hotly debated. The idea of the biological species concept is, at least in my opinion, outdated. Organisms and nature are not in categories, but rather we try to do this. This works to a certain degree, but since life is ever evolving and changing, these boxes begin to warp and bend overtime.

 

[EMeyer]

What defines a species is hotly debated. The idea of the biological species concept is, at least in my opinion, outdated. Organisms and nature are not in categories, but rather we try to do this. This works to a certain degree, but since life is ever evolving and changing, these boxes begin to warp and bend overtime.

Yeah, the biological species concept has some pretty serious flaws. Its the most widely discussed in popular writing but few if any biologists really work with that concept any more.

There's no perfect species concept, because as you pointed out, 'species' is not a category imposed by Nature but a desire by humans to draw sharp lines within a continuum.

The biological species concept is attractive for its simplicity but it only really works if we're willing to either lump together things that are clearly different species, or designate lots of "species complexes" (groups of closely related and interbreeding organisms).