Skip to Main content Skip to Navigation
Journal articles

Chitinase genes (CHIAs) provide genomic footprints of a post-Cretaceous dietary radiation in placental mammals

Abstract : The end-Cretaceous extinction led to a massive faunal turnover, with placental mammals radiating in the wake of nonavian dinosaurs. Fossils indicate that Cretaceous stem placentals were generally insectivorous, whereas their earliest Cenozoic descendants occupied a variety of dietary niches. It is hypothesized that this dietary radiation resulted from the opening of niche space, following the extinction of dinosaurian carnivores and herbivores. We provide the first genomic evidence for the occurrence and timing of this dietary radiation in placental mammals. By comparing the genomes of 107 placental mammals, we robustly infer that chitinase genes (CHIAs), encoding enzymes capable of digesting insect exoskeletal chitin, were present as five functional copies in the ancestor of all placental mammals, and the number of functional CHIAs in the genomes of extant species positively correlates with the percentage of invertebrates in their diets. The diverse repertoire of CHIAs in early placental mammals corroborates fossil evidence of insectivory in Cretaceous eutherians, with descendant lineages repeatedly losing CHIAs beginning at the Cretaceous/Paleogene (K/Pg) boundary as they radiated into noninsectivorous niches. Furthermore, the timing of gene loss suggests that interordinal diversification of placental mammals in the Cretaceous predates the dietary radiation in the early Cenozoic, helping to reconcile a long-standing debate between molecular timetrees and the fossil record. Our results demonstrate that placental mammal genomes, including humans, retain a molecular record of the post-K/Pg placental adaptive radiation in the form of numerous chitinase pseudogenes.
Document type :
Journal articles
Complete list of metadata

Cited literature [82 references]  Display  Hide  Download

https://hal-sde.archives-ouvertes.fr/hal-01879154
Contributor : Frederic Delsuc Connect in order to contact the contributor
Submitted on : Saturday, September 22, 2018 - 12:41:57 PM
Last modification on : Thursday, May 19, 2022 - 3:44:13 PM
Long-term archiving on: : Sunday, December 23, 2018 - 1:14:56 PM

File

Emerling-SciAdv-2018.pdf
Publisher files allowed on an open archive

Identifiers

Collections

Citation

Christopher A Emerling, Frédéric Delsuc, Michael W Nachman. Chitinase genes (CHIAs) provide genomic footprints of a post-Cretaceous dietary radiation in placental mammals. Science Advances , American Association for the Advancement of Science (AAAS), 2018, 4 (5), pp.eaar6478. ⟨10.1126/sciadv.aar6478⟩. ⟨hal-01879154⟩

Share

Metrics

Record views

133

Files downloads

150