Abstract
Condamine et al. (2019; 22: 1900–1912) fitted linear and exponential functions of time‐dependent, diversity‐dependent and temperature‐dependent diversification to investigate diversification dynamics of tetrapod families. Here I highlight potential misinterpretations when using linear diversification dependencies and provide some clarifications.
Highlights
Condamine et al (2019) investigated diversity-dependent and temperature-dependent phylogenetic models of diversification across 218 tetrapod families, along with constant-rate and time-dependent models. This technical comment pertains to the linear time-dependent model, which can lead to unintended model fits under certain circumstances and may only used with caution in model testing
A positive a (b) reflects a slowdown of speciation towards the present, whereas a negative a (b) reflects a speed-up of speciation towards the present. . ..’. This is problematic because, under the linear function k(t) = k0 + a*t, a negative change factor (a) leads to negative speciation rates once a*t is more negative than k0 is positive or T> abs(k0/a)
Even if the user specifies a linear time dependency of k(t) = k0 + a*t, it is the equation k(t) = abs(k0 + a*t) that is effectively used during computation
Summary
Condamine et al (2019) investigated diversity-dependent and temperature-dependent phylogenetic models of diversification across 218 tetrapod families, along with constant-rate and time-dependent models. This technical comment pertains to the linear time-dependent model, which can lead to unintended model fits under certain circumstances and may only used with caution in model testing.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
