title: Replaying evolutionary transitions from the dental fossil record.
abstract: The evolutionary relationships of extinct species are ascertained primarily through the analysis of morphological characters. Character inter-dependencies can have a substantial effect on evolutionary interpretations, but the developmental underpinnings of character inter-dependence remain obscure because experiments frequently do not provide detailed resolution of morphological characters. Here we show experimentally and computationally how gradual modification of development differentially affects characters in the mouse dentition. We found that intermediate phenotypes could be produced by gradually adding ectodysplasin A (EDA) protein in culture to tooth explants carrying a null mutation in the tooth-patterning gene Eda. By identifying development-based character inter-dependencies, we show how to predict morphological patterns of teeth among mammalian species. Finally, in vivo inhibition of sonic hedgehog signalling in Eda null teeth enabled us to reproduce characters deep in the rodent ancestry. Taken together, evolutionarily informative transitions can be experimentally reproduced, thereby providing development-based expectations for character-state transitions used in evolutionary studies.
authors: Developmental Biology Program, Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland.
authors: Enni
authors: E
authors: Harjunmaa
authors: 1] Program in Craniofacial and Mesenchymal Biology, University of California, San Francisco, San Francisco, California 94114, USA [2] Department of Orofacial Sciences, University of California, San Francisco, San Francisco, California 94114, USA.
authors: Kerstin
authors: K
authors: Seidel
authors: Developmental Biology Program, Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland.
authors: Teemu
authors: T
authors: Häkkinen
authors: Developmental Biology Program, Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland.
authors: Elodie
authors: E
authors: Renvoisé
authors: Developmental Biology Program, Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland.
authors: Ian J
authors: IJ
authors: Corfe
authors: Division of Materials Physics, Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki, Finland.
authors: Aki
authors: A
authors: Kallonen
authors: Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
authors: Zhao-Qun
authors: ZQ
authors: Zhang
authors: 1] School of Biological Sciences, Monash University, Victoria 3800, Australia [2] Geosciences, Museum Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia.
authors: Alistair R
authors: AR
authors: Evans
authors: Developmental Biology Program, Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland.
authors: Marja L
authors: ML
authors: Mikkola
authors: 1] Developmental Biology Program, Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland [2] Genomics, Bioinformatics and Evolution Group. Department de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Spain.
authors: Isaac
authors: I
authors: Salazar-Ciudad
authors: 1] Program in Craniofacial and Mesenchymal Biology, University of California, San Francisco, San Francisco, California 94114, USA [2] Department of Orofacial Sciences, University of California, San Francisco, San Francisco, California 94114, USA [3] Department of Pediatrics, University of California, San Francisco, San Francisco, California 94114, USA [4] Institute for Human Genetics, University of California, San Francisco, San Francisco, California 94114, USA.
authors: Ophir D
authors: OD
authors: Klein
authors: Developmental Biology Program, Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland.
authors: Jukka
authors: J
authors: Jernvall
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003198:Computer Simulation; D053331:Ectodysplasins / Q000172:deficiency / Q000235:genetics / Q000494:pharmacology; D005260:Female; D005580:Fossils; D017353:Gene Deletion; D053823:Hedgehog Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008963:Molar / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development; D010641:Phenotype; D015398:Signal Transduction / Q000187:drug effects; D014070:Tooth / Q000033:anatomy & histology* / Q000187:drug effects / Q000254:growth & development*
chemical_list: D053331:Ectodysplasins; D053823:Hedgehog Proteins; C465570:Shh protein, mouse