Garcia Tiffany Sacra, Sih Andrew
Department of Biology, University of Kentucky, Lexington, KY 40506, USA.
Oecologia. 2003 Sep;137(1):131-9. doi: 10.1007/s00442-003-1314-4. Epub 2003 Jun 28.
Although many organisms show multiple types of trait responses to predation risk (e.g., shifts in behavior, morphology, color, chemistry or life history), relatively few studies have examined how prey integrate these multiple responses. We studied the joint expression of color and behavioral responses to predation risk in two sister species of salamander larvae that live in habitats with different selection pressures. We examined responses to predation risk in three situations that differed in availability of refuge and substrate color heterogeneity, and thus availability of behavioral options for reducing risk. Relative to Ambystoma texanum, A. barbouri larvae were darker in color and showed a greater range of color change. With no variation in background color or refuge available, both species exhibited color change to better match the available background. The degree of color change showed by both species, however, did not depend on predation risk. Given the option to choose between light and dark substrates, A. texanum exhibited behavioral background matching (i.e., they preferred substrates that matched their own body color), while A. barbouri's substrate preferences did not depend on their initial body color. Instead, A. barbouri responded to risk by showing a strong preference for dark substrates, followed by a change to a darker body color. With refuge available, A. texanum's refuge use was color-dependent; larvae that were well camouflaged spent less time in refuge. In contrast, A. barbouri showed strong refuge use in response to risk, regardless of their body color. Overall, these results reflect how conflicting selection pressures (predation risk, habitat ephemerality, risk of UV damage) and species differences in mean color and ability to change color can govern the interplay of complementary and compensatory behavioral and color responses to predation risk.
尽管许多生物对捕食风险表现出多种类型的性状反应（例如，行为、形态、颜色、化学或生活史的变化），但相对较少的研究考察了猎物如何整合这些多种反应。我们研究了生活在具有不同选择压力栖息地的两种蝾螈幼虫姐妹种对捕食风险的颜色和行为反应的联合表达。我们在三种避难所可用性和底物颜色异质性不同的情况下研究了对捕食风险的反应，因此也研究了降低风险的行为选择的可用性。相对于德克萨斯钝口螈，巴氏钝口螈幼虫颜色更深，颜色变化范围更大。在背景颜色或避难所没有变化的情况下，两个物种都表现出颜色变化以更好地匹配可用背景。然而，两个物种表现出的颜色变化程度并不取决于捕食风险。当可以在浅色和深色底物之间进行选择时，德克萨斯钝口螈表现出行为背景匹配（即，它们更喜欢与自己体色匹配的底物），而巴氏钝口螈的底物偏好并不取决于它们的初始体色。相反，巴氏钝口螈通过对深色底物表现出强烈偏好，然后体色变深来应对风险。有避难所时，德克萨斯钝口螈对避难所的使用取决于颜色；伪装良好的幼虫在避难所花费的时间较少。相比之下，巴氏钝口螈无论体色如何，对风险都表现出强烈的避难所使用行为。总体而言，这些结果反映了相互冲突的选择压力（捕食风险、栖息地短暂性、紫外线损伤风险）以及平均颜色和变色能力的物种差异如何支配对捕食风险的互补和补偿性行为及颜色反应的相互作用。
