Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Núcleo Milenio de Ecología y Manejo Sustentable de Islas Oceánicas (ESMOI), Departamento de Biología Marina, Universidad Católica del Norte, Coquimbo, Chile.
J Anim Ecol. 2022 Jun;91(6):1148-1162. doi: 10.1111/1365-2656.13546. Epub 2021 Jun 16.
Integration of multiple approaches is key to understand the evolutionary processes of local adaptation and speciation. Reptiles have successfully colonized desert environments, that is, extreme and arid conditions that constitute a strong selective pressure on organisms. Here, we studied genomic, physiological and morphological variations of the lizard Liolaemus fuscus to detect adaptations to the Atacama Desert. By comparing populations of L. fuscus inhabiting the Atacama Desert with populations from the Mediterranean forests from central Chile, we aimed at characterizing features related to desert adaptation. We combined ddRAD sequencing with physiological (evaporative water loss, metabolic rate and selected temperature) and morphological (linear and geometric morphometrics) measurements. We integrated the genomic and phenotypic data using redundancy analyses. Results showed strong genetic divergence, along with a high number of fixed loci between desert and forest populations. Analyses detected 110 fixed and 30 outlier loci located within genes, from which 43 were in coding regions, and 12 presented non-synonymous mutations. The candidate genes were associated with cellular membrane and development. Desert lizards presented lower evaporative water loss than those from the forest. Morphological data showed that desert lizards had smaller body size, different allometry, larger eyeballs and more dorsoventrally compressed heads. Our results suggest incipient speciation between desert and forest populations. The adaptive signal must be cautiously interpreted since genetic drift could also contribute to the divergence pattern. Nonetheless, we propose water and resource availability, and changes in habitat structure, as the most relevant challenges for desert reptiles. This study provides insights of the mechanisms that allow speciation as well as desert adaptation in reptiles at multiple levels, and highlights the benefit of integrating independent evidence.
整合多种方法是理解局部适应和物种形成进化过程的关键。爬行动物已经成功地在沙漠环境中殖民，即极端干旱的条件，这对生物构成了强烈的选择压力。在这里，我们研究了蜥蜴 Liolaemus fuscus 的基因组、生理和形态变化，以检测其对阿塔卡马沙漠的适应。通过比较栖息在阿塔卡马沙漠的 L. fuscus 种群和来自智利中部地中海森林的种群，我们旨在描述与沙漠适应相关的特征。我们将 ddRAD 测序与生理（蒸发水损失、代谢率和选择温度）和形态（线性和几何形态测量）测量相结合。我们使用冗余分析整合了基因组和表型数据。结果显示，沙漠和森林种群之间存在强烈的遗传分歧，以及大量固定的基因座。分析检测到 110 个固定和 30 个外显子基因座位于基因内，其中 43 个位于编码区，12 个具有非同义突变。候选基因与细胞膜和发育有关。沙漠蜥蜴的蒸发水损失低于森林蜥蜴。形态学数据显示，沙漠蜥蜴的体型较小，体轴比例不同，眼球较大，头部更加背腹扁平。我们的研究结果表明，沙漠和森林种群之间存在物种形成的初期迹象。适应性信号必须谨慎解释，因为遗传漂变也可能导致这种分歧模式。尽管如此，我们提出了水和资源的可用性以及栖息地结构的变化，作为沙漠爬行动物面临的最相关挑战。本研究提供了在多个层面上理解允许物种形成和爬行动物适应沙漠的机制的见解，并强调了整合独立证据的好处。
