One is genetic relation, another morphological. Can they be discussed as equals?
Dear George,
my view is this: there is no simple parallelism.
- Monophyly is recognized by shared synapomorphies;
- Paraphyly also needs synapomorphies to be recognized at all, but often involves homoplasies (in the form of reversals), and of course plesiomorphies;
- Polyphyly is likely when synapomorphies are absent and homoplasies dominate, but plesiomorphies are abundant as well.
- Monophyly is a hypothesis of relationship, synapomorphy is a character-state indicating potential relationship between taxa.
Cheers
Rainer
I was wondering about that question because there appeared to be not much correspondence between monophyly, paraphyly, polyphyly as (hypotheses for) types of taxa groupings and (syn)apomorphy, (sym)plesiomorphy, homoplasy as characterizations of a (morphological) similarity shared by some taxa under consideration of a certain hypothesis of relationship.
On second thought it is not so far-fetched:
Monophyletic groupings are based on the correct interpretation of synapomorphies. Paraphyletic groupings are based on the wrong interpretation of symplesiomorphies as synapomorphies.
Polyphyletic groupings are based on the wrong interpretation of homoplasies as synapomorphies.
Monophyly, paraphyly and polyphyly are applied only fot taxa: a taxon created by scientist can be either natural, or artificial, that is either monophyletic in strict sense (i.e., holophyletic) (natural), or polyphyletic (artificial), or paraphyletic (natural in some respect). Apomorphies, plesiomorphies and homoplasies belong to characters, which are natural objects themselves, so cannot be artificial. The taxon is (or regarded to be) holopyletic if, besides other characters, its diagnosis includes autapomorphies. The taxon is plesiomorphon (and possibly can be paraphyletic), if its diagnosis includes plesiomorphies only. The taxon is possibly polyphyletic, if its diagnosis consists of homoplasy only. For details - see www.insecta.bio.spbu.ru
Dear George,
Please clarify for yourself first what you want to know:
1) if you speak about taxa and their groupings then the terms monophyly, paraphyly and polyphyly are applicable;
2) if you speak about the characters then apply the terms apomorphy, plesiomorphy, homoplasy.
Dear Jurate, Both these categories apply the taxa, so I just wonder to make a parallel between these two categories 1) genetic and 2) morphological. Both can serve to make an phylogenetic analyses and discussion about taxa. Could you comment? Michael and Rainer gave interesting comments.
Dear George,
Yes, Rainer and Michael commented very well. There is no simple parallelism. The greatest problem is the correct recognition of the characters and the right fnterpretation of them while building your phylogenetic hypothesis. My only advice is to methodically and consequently register the characters first and take a broad scale (morphology, molecular, ecology, behaviour etc) while creating your contextual analysis and a framework of phylogenetic hypothesis.
- Badges
- Science topic
- Similar topics
- Data Mining
- Classification