Transcriptional heterochrony in talpid mole autopods
1 Paläontologisches Institut und Museum, Universität Zürich, Karl-Schmid-Strasse 4, Zürich 8006, Switzerland
2 RIKEN Center for Developmental Biology, Laboratory for Evolutionary Morphology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
3 Institute of Biology, University of Leiden, Sylviusweg 72, Leiden, BE 2333, The Netherlands
4 Departamento de Genética, Universidad de Granada, Avenida del Conocimiento, Granada, Armilla 18100, Spain
EvoDevo 2012, 3:16 doi:10.1186/2041-9139-3-16Published: 9 August 2012
Talpid moles show many specializations in their adult skeleton linked to fossoriality, including enlarged hands when compared to the feet. Heterochrony in developmental mechanisms is hypothesized to account for morphological evolution in skeletal elements.
The temporal and spatial distribution of SOX9 expression, which is an early marker of chondrification, is analyzed in autopods of the fossorial Iberian mole Talpa occidentalis, as well as in shrew (Cryptotis parva) and mouse (Mus musculus) for comparison.
Results and discussion
SOX9 expression is advanced in the forelimb compared to the hind limb in the talpid mole. In contrast, in the shrew and the mouse, which do not show fossorial specializations in their autopods, it is synchronous. We provide evidence that transcriptional heterochrony affects the development of talpid autopods, an example of developmental penetrance. We discuss our data in the light of earlier reported pattern heterochrony and later morphological variation in talpid limbs.
Transcriptional heterochrony in SOX9 expression is found in talpid autopods, which is likely to account for pattern heterochrony in chondral limb development as well as size variation in adult fore- and hind limbs.