Question: Looking for suggestions: what is used to mainly place different sub-phyla in the order in which they evolved?
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gravatar for jaqx008
26 days ago by
jaqx00840
jaqx00840 wrote:

Hello all. I have two basal animals belonging to sub-phyla cephalochordate and urochordate (both in the chordate phylum). In different phylogenetic studies, cephalochordates evolved before urochordate, in other studies, urochordate comes before cephalochordates. Its vital for my study to identify which truly evolved first. However, I am trying to figure out a way to go about this and what are the factors to consider or use for building a phylogenetic tree that can help resolve this? thanks

evolution phylogeny • 94 views
ADD COMMENTlink written 26 days ago by jaqx00840

Do you have a molecular clock for any of them?

ADD REPLYlink written 26 days ago by jrj.healey12k

I do not have a molecular clock for them. Is there a place you would suggest I begin? What sort of data can I use as this clock to create a phylogenetic tree?

ADD REPLYlink modified 26 days ago • written 26 days ago by jaqx00840

However, there is a protein they both posses that do not exist along the higher chordate groups.

ADD REPLYlink written 26 days ago by jaqx00840
2

Yeah as the comment below states, its essentially impossible to know for sure unless you have ancient sequencing data to calibrate with.

the best i can think you’d do is Bayesian and maximum likelihood estimation, with something like BEAST perhaps.

The other option might be to test both hypotheses (i.e. with each occurring earlier than the other) and see if there is a more parsimonious/justifiable explanation for your study/data, one way round rather than the other.

ADD REPLYlink modified 25 days ago • written 26 days ago by jrj.healey12k

Its vital for my study to identify which truly evolved first.

I don't think that's possible. Taxonomic hypotheses get updated all the time with improving techniques and newly discovered fossils. Use whichever hypothesis has the broadest consensus and uses the best techniques.

Also, different tree-building methods can give very different results. You'll need to have an idea of the model of evolution.

ADD REPLYlink modified 26 days ago • written 26 days ago by BioinformaticsLad90

Ok, Thank you for your contribution

ADD REPLYlink written 25 days ago by jaqx00840
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