Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Integr Comp Biol. 2024 Nov 21;64(5):1494-1504. doi: 10.1093/icb/icae008.
Adhesive toe pads have evolved numerous times over lizard evolutionary history, most notably in geckos. Despite significant variation in adult toe pad morphology across independent origins of toe pads, early developmental patterns of toe pad morphogenesis are similar among distantly related species. In these distant phylogenetic comparisons, toe pad variation is achieved during the later stages of development. We aimed to understand how toe pad variation is generated among species sharing a single evolutionary origin of toe pads (house geckos-Hemidactylus). We investigated toe pad functional variation and developmental patterns in three species of Hemidactylus, ranging from highly scansorial (H. platyurus), to less scansorial (H. turcicus), to fully terrestrial (H. imbricatus). We found that H. platyurus generated significantly greater frictional adhesive force and exhibited much larger toe pad area relative to the other two species. Furthermore, differences in the offset of toe pad extension phase during embryonic development results in the variable morphologies seen in adults. Taken together, we demonstrate how morphological variation is generated in a complex structure during development and how that variation relates in important functional outcomes.
黏附足垫在蜥蜴进化史上已经进化了很多次，尤其是在壁虎中。尽管在独立起源的足垫中，成年足垫形态有很大的差异，但在亲缘关系较远的物种中，早期足垫形态发生的发育模式是相似的。在这些遥远的系统发育比较中，足垫的变化是在发育的后期阶段实现的。我们的目的是了解在具有单一足垫进化起源的物种（家壁虎属）之间，如何产生足垫的变异。我们研究了家壁虎属的三个物种的足垫功能变异和发育模式，范围从高度攀附（H. platyurus）到较少攀附（H. turcicus）到完全陆生（H. imbricatus）。我们发现，H. platyurus 产生的摩擦力和黏附力明显更大，相对于其他两个物种，其足垫面积也更大。此外，胚胎发育过程中足垫延伸阶段的偏移差异导致了成年个体中出现的各种形态。总之，我们展示了在发育过程中如何在一个复杂的结构中产生形态变异，以及这种变异如何与重要的功能结果相关。
