It seems to me, from the strange mix of my trained eye for biology (and science in general) and my ignorance for the collection situation of the specimens, that these rays (Potomotrygon leopoldi, P. motoro, etc) are all one species. The only significant difference between the "species" it seems, and I admit I very well might be wrong, is the particular genetic eddies that the isolated geographic locations have developed. In biology, this is known as a subspecies.
"Subspecies A taxonomic subdivision of a species;
a population of a particular region genetically
distinguishable from other such populations and
capable of interbreeding with them." (Farabee, M.)
Species diverge (in general) from geographical separation. This allows both genetic "drift" and beneficial mutations in the different independent breeding groups to produce incompatibilities between the groups; with enough isolation, their anatomies and embryonic "recipes" diverge from each other so far as to render genetic mixing (sexual reproduction) impossible. This prevents any further mixing of the blood lines, further separating the two populations. That is where a species comes from.
These rays (Potamotrygon) are still breeding in the wild, as well as generating fertile offspring. There is enough genetic trickle that it is safe to say that these easily hybridized rays are, in fact, a single species (at least for the commonly kept rays similar to P. motoro and P. leopoldi, although the lifestyle differences and size may not allow this definition to apply to, for instance, P. reticulatus).
If anyone has any experience breeding hybrids, as well as anyone who has contact with the people that collect the specimens from the wild, please either post here or contact me! I'm trying to put a paper together on this, as well as make a modest contribution to the hobby and the scientific understanding of these beautiful creatures.
Farabee, M. "Online Biology Book." Glossary.
1994-2000. Bradley University. 12 Nov. 2008
<http://www.estrellamountain.edu/faculty/farabee/BIOBK/BioBookglossS.htm[FONT=Arial, Helvetica, sans-serif]l>[/FONT]
"Subspecies A taxonomic subdivision of a species;
a population of a particular region genetically
distinguishable from other such populations and
capable of interbreeding with them." (Farabee, M.)
Species diverge (in general) from geographical separation. This allows both genetic "drift" and beneficial mutations in the different independent breeding groups to produce incompatibilities between the groups; with enough isolation, their anatomies and embryonic "recipes" diverge from each other so far as to render genetic mixing (sexual reproduction) impossible. This prevents any further mixing of the blood lines, further separating the two populations. That is where a species comes from.
These rays (Potamotrygon) are still breeding in the wild, as well as generating fertile offspring. There is enough genetic trickle that it is safe to say that these easily hybridized rays are, in fact, a single species (at least for the commonly kept rays similar to P. motoro and P. leopoldi, although the lifestyle differences and size may not allow this definition to apply to, for instance, P. reticulatus).
If anyone has any experience breeding hybrids, as well as anyone who has contact with the people that collect the specimens from the wild, please either post here or contact me! I'm trying to put a paper together on this, as well as make a modest contribution to the hobby and the scientific understanding of these beautiful creatures.
Farabee, M. "Online Biology Book." Glossary.
1994-2000. Bradley University. 12 Nov. 2008
<http://www.estrellamountain.edu/faculty/farabee/BIOBK/BioBookglossS.htm[FONT=Arial, Helvetica, sans-serif]l>[/FONT]
