College of Animal Science, Xinjiang Agricultural University, Urumqi, 830052, China.
Wildlife Conservation and Utilization, Nanjing Forestry University, Nanjing, 210037, Jiangsu, China.
Sci Rep. 2020 Dec 16;10(1):22068. doi: 10.1038/s41598-020-79113-4.
Toe fringe is the most typical morphological feature of lizards adapted to sandy environments, and it is simple in shape, can evolve repeatedly, and has a high degree of repetition; therefore, this feature is suitable for testing the adaptive convergence suggested by form-environment correlations. Phrynocephalus mystaceus mainly lives in dune habitats, has a developed bilateral toe fringe, and exhibits fast sand-burying behavior for predator avoidance. We tested the effects of resecting the medial and bilateral toe fringes on the locomotor performance and sand-burying performance of P. mystaceus. The results showed that the maximum sprint speed and acceleration on sand substrate did not significantly differ under different conditions (P > 0.05). Sand-burying performance scores of the unresected individuals were significantly greater than those of the resected individuals (P < 0.05). A partial least squares (PLS) regression analysis showed that the relative area of toe fringe was the main factor affecting the sand-burying performance of unresected P. mystaceus. For lizards without fringe, the PLS regression showed that the swinging index of the hind-limb was the main factor affecting the sand-burying performance of the lizard. A comparison of the swinging indexes of the hind-limb of the lizard under three states revealed that under the unresected states, the frequency of the swinging of the hind-limb was significantly higher than those of lizards with resected bilateral fringes, further indicating that the lizards compensated for the loss of fringe by increasing the time and frequency of swinging of the hind-limb. A path analysis also showed that the fringe affected the sand-burying performance of P. mystaceus not only directly but also indirectly by affecting the frequency of the swinging of the hind-limb. After the bilateral toe fringe was removed, a significant negative correlation between locomotor and sand-burying performance was observed (P < 0.05). Taken together, these results provide experimental evidence that toe fringe is positively associated with the sand-burying performance of P. mystaceus.
趾缘是适应沙环境的蜥蜴最典型的形态特征，其形态简单，可重复进化，重复性高；因此，该特征适合测试形态-环境相关性所提出的适应趋同。密点麻蜥主要生活在沙丘栖息地，具有发达的双侧趾缘，并表现出快速的沙埋行为以躲避捕食者。我们测试了切除内侧和双侧趾缘对密点麻蜥运动性能和沙埋性能的影响。结果表明，在不同条件下，沙上最大冲刺速度和加速度没有显著差异（P>0.05）。未切除个体的沙埋性能得分显著大于切除个体（P<0.05）。偏最小二乘（PLS）回归分析表明，趾缘相对面积是影响未切除密点麻蜥沙埋性能的主要因素。对于没有缘的蜥蜴，PLS 回归表明后肢摆动指数是影响蜥蜴沙埋性能的主要因素。对三种状态下蜥蜴后肢摆动指数的比较表明，在未切除状态下，后肢摆动的频率显著高于切除双侧缘的蜥蜴，进一步表明蜥蜴通过增加后肢摆动的时间和频率来补偿缘的损失。路径分析还表明，缘不仅直接影响密点麻蜥的沙埋性能，还通过影响后肢摆动的频率间接影响其沙埋性能。双侧趾缘切除后，运动性能和沙埋性能之间呈显著负相关（P<0.05）。综上所述，这些结果为趾缘与密点麻蜥沙埋性能呈正相关提供了实验证据。
