Data from: Contrasting effects of landscape features on genetic structure in different geographical regions in the ornate dragon lizard, Ctenophorus ornatus

Habitat fragmentation can have profound effects on the distribution of genetic variation within and between populations. Previously, we showed that in the ornate dragon lizard, Ctenophorus ornatus, lizards residing on outcrops that are separated by cleared agricultural land are significantly more isolated and hold less genetic variation than lizards residing on neighbouring outcrops connected by undisturbed native vegetation. Here, we extend that fine-scale study to examine the pattern of genetic variation and population structure across the species’ range. Using a landscape genetics approach, we test whether land clearing for agricultural purposes has affected the population structure of the ornate dragon lizard. We found significant genetic differentiation between outcrop populations (FST = 0.12), as well as isolation-by-distance within each geographic region. In support of our previous study, land clearing was associated with higher genetic divergences between outcrops and lower genetic variation within outcrops, but only in the region that had been exposed to intense agriculture for the longest period of time. No other landscape features influenced population structure in any geographic region. These results show that the effects of landscape features can vary across species’ ranges and suggest there may be a temporal-lag in the response to contemporary changes in land use. These findings therefore highlight the need for caution when assessing the impact of contemporary land use practices on genetic variation and population structure.生境破碎化（habitat fragmentation）对种群内部及种群间的遗传变异分布具有深远影响。此前我们的研究表明，在饰纹龙蜥（Ctenophorus ornatus）中，栖息于被开垦农田分隔的岩露头的个体，相较于栖息于由未受干扰原生植被相连的相邻岩露头的个体，其种群隔离程度显著更高，且种群内遗传变异水平更低。本研究将该精细尺度研究拓展至该物种种群分布的全域范围，以探究其遗传变异模式与种群结构。本研究采用景观遗传学（landscape genetics）方法，探究农业开垦活动是否对饰纹龙蜥的种群结构产生了影响。研究结果显示，岩露头种群间存在显著的遗传分化（遗传分化系数FST=0.12），且各地理区域内均存在距离隔离效应。与此前研究结果一致，农业开垦活动与岩露头种群间更高的遗传分化及岩露头种群内更低的遗传变异显著相关，但该效应仅出现在农业开发历史最悠久的区域。其余景观特征未对任意地理区域的种群结构产生影响。上述结果表明，景观特征的影响效应可随物种种群分布范围的不同而发生变化，同时提示当代土地利用变化的生态响应可能存在时间滞后性。因此，本研究结果提醒我们，在评估当代土地利用活动对遗传变异与种群结构的影响时需保持谨慎。