Heat altered scent-marks of amphisbaenians

The efficacy of sexual signals in communication is often maximized under specific environmental conditions. Anthropic alterations of these conditions might, thus, negatively affect communication during reproductive behavior. In fossorial animals, inhabiting visually restricted environments, chemical senses are very important. We examined whether climatic episodes of heat-waves with unusual high temperatures may affect the information provided to females by the sexual chemical signals of males of a fossorial reptile, the amphisbaenian <i>Blanus cinereus</i>. The results showed that experimentally heat-altered substrate scent marks of males can still provide information to females about the presence of a male. Females spent more time on males' scent marks, irrespective of the temperature treatment, than on control clean ones. However, heat-altered scent marks did not seem to convey information about the health state of the producer. Females spent more time on unaltered scent marks of healthier males (probably indicating mating preferences for these males), while female preferences for some heat-altered scent marks were not related to size or health of the same individual males. Chemical analyses indicated that the overall chemical profile of precloacal secretions (used for scent marking) did not change with increased temperatures. However, the relationship between proportions of some compounds in secretions and males' health state found in unaltered secretions was lost in heat-altered ones. We conclude that unusual increased environmental temperatures may decrease the efficacy of underground sexual chemical signals in this amphisbaenian (i.e., a loss of information on male quality), and consequently, may negatively affect sexual selection and reproduction.

性信号在通讯中的效能通常在特定环境条件下达到峰值。人为改变这些环境条件，可能会对繁殖行为中的通讯过程产生负面影响。对于栖息于视觉受限环境的穴居动物（fossorial animals）而言，化学感官至关重要。我们以一种穴居爬行动物——蚓蜥类（amphisbaenian）的灰蓝蚓蜥<i>Blanus cinereus</i>为研究对象，探究异常高温的热浪气候事件是否会影响雄性个体通过性化学信号向雌性传递的信息。实验结果显示，经高温处理的雄性底物气味标记，仍能向雌性传递雄性存在的相关信息；无论是否经过高温处理，雌性在雄性气味标记区域停留的时长均显著长于空白清洁底物对照组。但经高温处理的气味标记，似乎无法传递信号个体的健康状态信息：雌性会在健康雄性的未处理气味标记区域停留更久——这或许暗示雌性对这类雄性存在交配偏好；而雌性对部分经高温处理的气味标记的偏好，与对应雄性的体型或健康状态并无关联。化学分析结果表明，用于气味标记的肛前分泌物（precloacal secretions）的整体化学组成并未随温度升高发生改变，但在未处理的分泌物中，部分化合物占比与雄性健康状态之间的关联，在经高温处理的分泌物中不复存在。综上，异常升高的环境温度可能会降低该蚓蜥类物种地下性化学信号的通讯效能，即雄性质量相关信息的传递出现损失，进而可能对性选择与繁殖过程产生负面影响。