Patterning and post-patterning modes of evolutionary digit loss in mammals.
Abstract: A reduction in the number of digits has evolved many times in tetrapods, particularly in cursorial mammals that travel over deserts and plains, yet the underlying developmental mechanisms have remained elusive. Here we show that digit loss can occur both during early limb patterning and at later post-patterning stages of chondrogenesis. In the 'odd-toed' jerboa (Dipus sagitta) and horse and the 'even-toed' camel, extensive cell death sculpts the tissue around the remaining toes. In contrast, digit loss in the pig is orchestrated by earlier limb patterning mechanisms including downregulation of Ptch1 expression but no increase in cell death. Together these data demonstrate remarkable plasticity in the mechanisms of vertebrate limb evolution and shed light on the complexity of morphological convergence, particularly within the artiodactyl lineage.
Publication Date: 2014-06-18 PubMed ID: 24990742PubMed Central: PMC4228958DOI: 10.1038/nature13496Google Scholar: Lookup
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- Journal Article
- Research Support
- N.I.H.
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- Non-P.H.S.
Summary
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The research investigates the evolutionary loss of digits in mammals, studying how these changes occur either in early limb development or later stages. Specific evolutionary adaptations were compared in the jerboa, horse, camel, and pig, demonstrating flexibility in the evolution of vertebrate limbs and providing insight into morphological similarity.
About the Study
- The researchers studied the mechanisms behind the evolutionary reduction in the number of digits (fingers or toes) in certain mammals. This is a common feature in tetrapods, particularly those adapted to desert and plain environments, like horses or camels.
- However, until now, the developmental mechanisms that drove digit loss remained unclear – it was not known whether these changes took place during early sketching of the limb (limb patterning) or at later stages (post-patterning) such as chondrogenesis, the process of cartilage formation.
Findings of the Study
- The study showed that digit loss could occur at both early and late stages of limb development. For some species like the “odd-toed” jerboa (Dipus sagitta), horse, and the “even-toed” camel, considerable cell death helps to mold the tissue around the remaining digits.
- Digit loss in pigs, on the other hand, was directed by early limb patterning processes, which involved the downregulation of Ptch1 expression—a gene involved in developmental processes. In contrast to the other species, there was no significant increase in cell death observed in pigs.
- The findings underscore the plasticity (or flexibility) of limb evolution mechanisms among vertebrates, offering a new perspective on past evolutionary adaptations. Furthermore, the distinct processes of limb development in different species shed light on the complexity of morphological convergence—a concept referring to the tendency for different species to develop similar physical traits, as shared here within the artiodactyl lineage (even-toed ungulates).
Cite This Article
APA
Cooper KL, Sears KE, Uygur A, Maier J, Baczkowski KS, Brosnahan M, Antczak D, Skidmore JA, Tabin CJ.
(2014).
Patterning and post-patterning modes of evolutionary digit loss in mammals.
Nature, 511(7507), 41-45.
https://doi.org/10.1038/nature13496 Publication
Researcher Affiliations
- 1] Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093, USA. [3].
- 1] Department of Animal Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA [2].
- 1] Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA [2].
- Department of Animal Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA.
- cole Normale Supérieure de Lyon, 69007 Lyon, France.
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA.
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA.
- The Camel Reproduction Centre, Dubai, United Arab Emirates.
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
MeSH Terms
- Animals
- Biological Evolution
- Body Patterning / genetics
- Camelus / anatomy & histology
- Camelus / embryology
- Cell Death
- Chondrogenesis / genetics
- Extremities / anatomy & histology
- Extremities / embryology
- Fibroblast Growth Factor 8 / genetics
- Gene Expression Regulation, Developmental
- Hedgehog Proteins / genetics
- Homeodomain Proteins / genetics
- Horses / anatomy & histology
- Horses / embryology
- Mammals / anatomy & histology
- Mammals / embryology
- Mammals / genetics
- Mice
- Oncogene Proteins / genetics
- Patched Receptors
- Patched-1 Receptor
- Phylogeny
- Receptors, Cell Surface / genetics
- Rodentia / anatomy & histology
- Rodentia / embryology
- Swine / anatomy & histology
- Swine / embryology
- Trans-Activators / genetics
- Zinc Finger Protein GLI1
Grant Funding
- R37 HD032443 / NICHD NIH HHS
- R37HD032443 / NICHD NIH HHS
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