Hi Joe,

The fossil version of BAMM can handle extinct clades and shifts in rate regime 
on branches, but I am not sure if the developers have implemented 
trait-dependent speciation and extinction.  You can check out this paper and 
maybe follow-up with the developers:

https://academic.oup.com/sysbio/article-abstract/68/1/1/4999317?redirectedFrom=fulltext

Pyrate may be able to do all you need.  There are a lot of papers that use this 
tool, and I don’t have the details at hand, but check out the Google Scholar 
page of its developer, Daniele Silvestro:

https://scholar.google.com/citations?user=X1jlzMoAAAAJ&hl=en&oi=ao

Pyrate is a python program (no R interface), but Daniele is known to be helpful 
to users if they have questions.

If the taxa have stratigraphic ranges (rather than all being restricted to a 
single interval), you can use non-phylogenetic approaches to look for an 
association between stratigraphic range and body size. If your hypothesis about 
extinction is correct, large-bodied taxa should have longer stratigraphic 
ranges.  The simplest approach would be correlation or regression but you can 
switch to Pyrate (which also run on strat range data, rather than a phylogeny) 
or Capture-Mark-Recapture if you want to have a more flexible modeling 
framework. Those latter approaches can handle, for example, temporal or 
taxonomic variation in preservation and/or extinction. I can send references 
for these approaches to you separately if you’d like.

The non-phylogenetic approaches are less suitable for trait-dependent 
speciation, however, because you have to make assumptions about transitions 
between traits (e.g., that small bodied taxa always arise from other 
small-bodied taxa).

Best,
Gene

Gene Hunt  (he/him)
Curator
Department of Paleobiology
w 202.633.1331  [email protected]<mailto:[email protected]>  
web<https://naturalhistory.si.edu/staff/gene-hunt>

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From: R-sig-phylo <[email protected]> on behalf of Joseph 
Keating via R-sig-phylo <[email protected]>
Date: Tuesday, December 3, 2024 at 3:21 AM
To: [email protected] <[email protected]>
Subject: [R-sig-phylo] Trait-dependence for an extinct clade
External Email - Exercise Caution

Dear All

I�m hoping you can advise me on an appropriate test of trait-dependence for an 
entirely extinct clade.

I want to look at the evolution of body size in ostracoderms - the palaeozoic 
armoured jawless fish. A number of ostracoderm clades show an apparent increase 
in body size through the Devonian. This is taken as a classic example of 
'Cope's Rule' and has also been linked to competition with / predation by jawed 
vertebrates.

I have some dated trees for a couple of the most diverse ostracoderm clades. 
Each tree consists of around 100 taxa (this might not sound like a lot, but is 
actually around 25% of the total known diversity). I've also got a keen MSc 
student ready to collect body sizes for these groups, potentially using some 
nice 3D models to get volume estimates.

I had initially thought to use  �quasse� to model body-size dependent 
speciation and extinction rates, but after some digging it seems like this only 
works for ultrametric trees. Is there a nice statical way of testing whether 
bodysize is correlated with extinction or speciation given a tree comprising 
100% fossils? My hypothesis is that extinction is more likely in ostracoderms 
with small body sizes.

Any help you can provide would be hugely appreciated!

All the best

Joe Keating



Dr Joseph Keating
Palaeobiology Research Group
University of Bristol
Bristol Life Sciences Building
24 Tyndall Avenue
Bristol
BS8 1TQ

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