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Terminology??
- Thread starter jeonghun
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Hi all,
There isn't really a precise definition of the terms, they are used because the phylogeny of the Apistogramma and Apistogrammoides species complex is not fully understood, the species are probably still undergoing speciation. Additionally there may still be other scientifically undescribed species ("A." gigas) which belong to this species complex.
From the information in DATZ "S. American Dwarf Cichlids", the molecular phylogeny (based on 2 sets of base sequences from both nuclear and mitochondrial DNA) would suggest that these are a monophyletic group (this just means that they share a single common ancestor).
Taeniacara candidi was the "outgroup", and all species of Apistogramma and Apistogrammoides were more similar to each other, than they were to T. candidi.
In this grouping of the of Apistogramma species there were 4 groups, with A. diplotaenia forming a group on it's own, the fourth "lineage", in this case this indicated that it split from the ancestral species group longest ago. This is a "clade" on its own. The other Apistogramma species, and A. pucallpaensis, form a "clade, supergroup or supercomplex" of species, probably split into 3 lineages (or groups of species that are more closely related to one another than they are to species in other lineages).
Of these groups the A regani lineage contains 3 sub-groups;
a. the grouping of A. eunotus complex, A. regani complex, A. caeti complex, A. resticulosa complex, Xingu-Apistogramma complex, A. commbrae complex and the div /taxa. - regani group (I don't know why some are groups and some complexes), these "a" species are thought to be closely related to one another (this means that speciation has occurred relatively recently), than to the other species in the regani lineage..
b. A borelli on its own, and finally c. A. macmasteri complex & A. hongsloi complex (these are more closely related to one another than they are to the rest of the "c" group), Rotpunk Apistogramma group and Apistogrammoides pucallpaensis (this means that Apistogrammoides is not supported and A. pucallpaensis is an Apistogramma species).
Hope that helps cheers Darrel
There isn't really a precise definition of the terms, they are used because the phylogeny of the Apistogramma and Apistogrammoides species complex is not fully understood, the species are probably still undergoing speciation. Additionally there may still be other scientifically undescribed species ("A." gigas) which belong to this species complex.
From the information in DATZ "S. American Dwarf Cichlids", the molecular phylogeny (based on 2 sets of base sequences from both nuclear and mitochondrial DNA) would suggest that these are a monophyletic group (this just means that they share a single common ancestor).
Taeniacara candidi was the "outgroup", and all species of Apistogramma and Apistogrammoides were more similar to each other, than they were to T. candidi.
In this grouping of the of Apistogramma species there were 4 groups, with A. diplotaenia forming a group on it's own, the fourth "lineage", in this case this indicated that it split from the ancestral species group longest ago. This is a "clade" on its own. The other Apistogramma species, and A. pucallpaensis, form a "clade, supergroup or supercomplex" of species, probably split into 3 lineages (or groups of species that are more closely related to one another than they are to species in other lineages).
Of these groups the A regani lineage contains 3 sub-groups;
a. the grouping of A. eunotus complex, A. regani complex, A. caeti complex, A. resticulosa complex, Xingu-Apistogramma complex, A. commbrae complex and the div /taxa. - regani group (I don't know why some are groups and some complexes), these "a" species are thought to be closely related to one another (this means that speciation has occurred relatively recently), than to the other species in the regani lineage..
b. A borelli on its own, and finally c. A. macmasteri complex & A. hongsloi complex (these are more closely related to one another than they are to the rest of the "c" group), Rotpunk Apistogramma group and Apistogrammoides pucallpaensis (this means that Apistogrammoides is not supported and A. pucallpaensis is an Apistogramma species).
Hope that helps cheers Darrel
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Römer's groupings of species are based on 51 physical features which he considers are the most important for separating species. He used a computer program to break the apisto species into every increasingly smaller groupings - each grouping with more features held in common with other species. Those with the fewest features in common he calls "lineages". He then split each lineage into species-groups with more features in common. Each species-group is then split into super-complexes, which are splint into complexes, which are split into subcomplexes, and finally into individual species.
If you compare Römer's phylogeny with that of Miller & Schleiwen's in the DATZ book, you will see a lot of groupings are the same, but some are quite different. I tend to follow Miller & Schliewen more than Römer in this regard. I believe that Römer didn't use enough physical characteristics in his program to break down the genus properly. Kullander, for example, did a similar computer breakdown of all of the South American cichlids to the genus level. Obviously, a breakdown of cichlids to only the genus level is easier to do. The species of each genus are much more different from those in other genera. This means that fewer features are needed to separate the species to each genus. Kullander needed over 100 features to break cichlids down to the genus level. I imagine that you would need more than 100 to break down a species-rich genus like Apistogramma.
If you compare Römer's phylogeny with that of Miller & Schleiwen's in the DATZ book, you will see a lot of groupings are the same, but some are quite different. I tend to follow Miller & Schliewen more than Römer in this regard. I believe that Römer didn't use enough physical characteristics in his program to break down the genus properly. Kullander, for example, did a similar computer breakdown of all of the South American cichlids to the genus level. Obviously, a breakdown of cichlids to only the genus level is easier to do. The species of each genus are much more different from those in other genera. This means that fewer features are needed to separate the species to each genus. Kullander needed over 100 features to break cichlids down to the genus level. I imagine that you would need more than 100 to break down a species-rich genus like Apistogramma.
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Hi all,
I've got a good range of phylogeny papers covering the cichlids, but concentrating on the Geophagine cichlids. As Mike says the morphometric (basically Romer's measurements) groupings don't always correspond with those from the genetic data (Miller & Schleiwen's).
The problem with morphometrics is that evolutionary pressures may act so strongly on natural selection that species which are not that closely related may come to closely resemble one another via "convergent evolution". A good example would be that most bird pollinated flowers are red, scentless and tubular, whatever plant family the species came from (or closer to home you could think of the similarities between Geophagus/Satanoperca and their Central American Cichlid analogues).
The problem with the strictly genetic approach is that animals that are very similar to one another in appearance may be quite genetically distinct, and vice versa, so it is "pay your money, and take your pick".
Most newer taxonomists favour the DNA approach, and classification by cladistics (they are interested in the order of branching, so for example "fish" would disappear as they are not a monophyletic grouping) but with the current lack of funding for research in taxonomy we are likely to run out of taxonomists long before the question is settled.
cheers Darrel
I've got a good range of phylogeny papers covering the cichlids, but concentrating on the Geophagine cichlids. As Mike says the morphometric (basically Romer's measurements) groupings don't always correspond with those from the genetic data (Miller & Schleiwen's).
The problem with morphometrics is that evolutionary pressures may act so strongly on natural selection that species which are not that closely related may come to closely resemble one another via "convergent evolution". A good example would be that most bird pollinated flowers are red, scentless and tubular, whatever plant family the species came from (or closer to home you could think of the similarities between Geophagus/Satanoperca and their Central American Cichlid analogues).
The problem with the strictly genetic approach is that animals that are very similar to one another in appearance may be quite genetically distinct, and vice versa, so it is "pay your money, and take your pick".
Most newer taxonomists favour the DNA approach, and classification by cladistics (they are interested in the order of branching, so for example "fish" would disappear as they are not a monophyletic grouping) but with the current lack of funding for research in taxonomy we are likely to run out of taxonomists long before the question is settled.
cheers Darrel
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I agree. That is why I tend to go with Miller & Schliewen's genetic studies. They correspond quite closely to Koslowski's groupings based primarily on physical features (morphometrics). When 2 studies from 2 different directions (genetics and morphometrics) result in very similar groupings, there is a much better chance that they are closer to the truth.
