Is there a loophole in Dollo's law? A DevoEvo perspective on irreversibility (of felid dentition)

• Published in: Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
• Main Author: Lynch, Vincent J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Lynx; Lynx lynx lynx
• Online Access: http://dx.doi.org/10.1002/jez.b.23163; https://onlinelibrary.wiley.com/doi/pdf/10.1002/jez.b.23163; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/jez.b.23163

Abstract There is a longstanding interest in whether the loss of complex characters is reversible (so‐called “Dollo's law”). Reevolution has been suggested for numerous traits but among the first was Kurtén, who proposed that the presence of the second lower molar (M 2 ) of the Eurasian lynx ( Lynx lynx ) was a violation of Dollo's law because all other Felids lack M 2 . While an early and often cited example for the reevolution of a complex trait, Kurtén and Werdelin used an ad hoc parsimony argument to support their. Here I revisit the evidence that M 2 reevolved lynx using explicit parsimony and maximum likelihood models of character evolution and find strong evidence that Kurtén and Werdelin were correct—M 2 reevolved in E. lynx . Next, I explore the developmental mechanisms which may explain this violation of Dollo's law and suggest that the reevolution of lost complex traits may arise from the reevolution of cis‐regulatory elements and protein−protein interactions, which have a longer half‐life after silencing that protein coding genes. Finally, I present a developmental model to explain the reevolution M 2 in E. lynx , which suggest that the developmental programs required for the establishment of serially homologous characters may never really be lost so long as a single instance of the character remains—thus the gain and loss and regain of serially homologous characters, such mammalian molars, may be developmentally and evolutionarily “simple.”