Fišer Žiga, Prevorčnik Simona, Lozej Nina, Trontelj Peter
Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
Zoology (Jena). 2019 Jun;134:58-65. doi: 10.1016/j.zool.2019.03.001. Epub 2019 Mar 8.
Shelter-seeking is a vital behavior for stress reduction and survival in a range of animals. It comes at the cost of reduced foraging, mate finding, dispersal and territoriality, and is expected to reflect the trade-off between fitness costs and benefits. One way to test this hypothesis is to compare shelter-seeking behavior in surface habitats and in caves where external threat factors are largely reduced. We did so using the freshwater isopod Asellus aquaticus from the Postojna-Planina Cave System and surrounding surface waters. Animals from two distinct, replicated pairs of surface and cave populations were individually offered a choice between shelter and open area. The thigmotatic sensation of a transparent plastic plate was the only stimulus that could trigger the sheltering behavior. Video recordings showed a clear reduction of shelter-seeking behavior in the cave ecomorph in one population pair (Pivka). There were no changes in the other population pair (Rak), where the behavioral response had a much higher variance. Our results were partly in agreement with the hypothesis that shelter-seeking behavior should be selected against in an environment with reduced external threats. It is nevertheless too early for generalizations as the results in the second population pair were inconclusive. Additionally, we showed that for benthic walkers like A. aquaticus the use of rough substrate is crucial to obtain unbiased behavioral responses. Results of some previous studies using smooth glass or plastic substratum could be affected by unnatural behavior of animals constantly trying to find firm contact with the ground.
寻求庇护是一系列动物减轻压力和生存的重要行为。它是以减少觅食、寻找配偶、扩散和领地行为为代价的，并且预计反映了适应性成本和收益之间的权衡。检验这一假设的一种方法是比较地表栖息地和洞穴中的寻求庇护行为，在洞穴中外部威胁因素会大幅减少。我们使用来自波斯托伊纳-普拉尼纳洞穴系统及周边地表水的淡水等足类动物水虱（Asellus aquaticus）进行了此项研究。分别向来自两对不同的、重复的地表和洞穴种群的动物提供在庇护所和开阔区域之间的选择。透明塑料板的趋触感觉是唯一能触发庇护行为的刺激因素。视频记录显示，在一对种群（皮夫卡）中，洞穴生态型的寻求庇护行为明显减少。在另一对种群（拉克）中没有变化，其行为反应的方差要高得多。我们的结果部分支持了这样的假设，即在外部威胁减少的环境中，寻求庇护行为应被淘汰。然而，由于第二对种群的结果尚无定论，现在进行概括还为时过早。此外，我们表明，对于像水虱这样的底栖步行者来说，使用粗糙的基质对于获得无偏差的行为反应至关重要。一些先前使用光滑玻璃或塑料基质的研究结果可能会受到动物不断试图与地面建立牢固接触的不自然行为的影响。
