Roughly halfway embryonic development, half of Triturus embryos die inside their egg. In a new paper in Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, we follow embryonic development and show that during one specific developmental stage, unimaginatively named “stage 23”, morphological variation in embryos becomes elevated. This reflects the onset of the developmental arrest, caused by the balanced lethal system, in those unfortunate embryos that are doomed to die. To understand how these embryos die exactly, we need to get a more detailed picture of embryonic development in Triturus.

Reference: Bugarčić, M., Ivanović, A., Cvijanović, M., Ajduković, M., Drobnjaković, M., Wielstra, B., Vučić, T. (2026). Dynamics of size and shape variation during embryonic development in the Balkan crested newt. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution TBA.