Department of Biology, University of Saskatchewan, 112 Science Place, S7N 5E2 Saskatoon, SK Canada.
Department of Biomedical Sciences WCVM, University of Saskatchewan, 52 Campus Dr., S7N 5B4 Saskatoon, SK Canada.
Front Zool. 2014 Oct 14;11(1):76. doi: 10.1186/s12983-014-0076-7. eCollection 2014.
Many species of ambystomatid salamanders are dependent upon highly variable temporary wetlands for larval development. High larval densities may prompt the expression of a distinct head morphology that may facilitate cannibalism. However, few studies have characterized structural cannibalism within natural populations of larval salamanders. In this study we used two species of larval salamanders, long-toed (Ambystoma macrodactylum) and ringed salamanders (A. annulatum). Head morphometrics and stable isotopic values of carbon (δ(13)C) and nitrogen (δ(15)N) were used to identify the presence or absence of structural cannibalism. Weather conditions were also analyzed as a potential factor associated with the expression of cannibalistic morphology.
Populations of salamander larvae did not consistently exhibit cannibalistic morphologies throughout collection periods. Larval long-toed salamanders exhibited trophic polymorphisms when relatively lower precipitation amounts were observed. Larval ringed salamanders were observed to be cannibalistic but did not exhibit polymorphisms in this study.
Structural cannibalism may be transient in both species; however in long-toed salamanders this morphology is necessary for cannibalism. Ringed salamanders can be cannibalistic without morphological adaptations; however the cannibal morph may prolong the viable time period for cannibalism. Additionally, weather conditions may alter pond hydroperiod, subsequently influencing head morphology and cannibalism.
许多蝾螈物种依赖高度可变的临时湿地来进行幼体发育。高幼体密度可能会促使形成一种独特的头部形态，从而促进同类相食。然而，很少有研究描述过自然种群中幼体蝾螈的结构性同类相食。在这项研究中，我们使用了两种幼体蝾螈，长趾（Ambystoma macrodactylum）和环纹（A. annulatum）。头部形态计量学和碳（δ¹³C）和氮（δ¹⁵N）的稳定同位素值用于识别结构性同类相食的存在与否。天气条件也被分析为与同类相食形态表达相关的潜在因素。
在收集期间，蝾螈幼虫种群并没有一致地表现出同类相食的形态。当观察到相对较少的降水量时，长趾蝾螈幼体表现出营养多态性。本研究中观察到环纹蝾螈具有同类相食行为，但没有表现出形态多态性。
结构性同类相食在这两个物种中可能是短暂的；然而，在长趾蝾螈中，这种形态是同类相食所必需的。环纹蝾螈可以进行同类相食而无需形态适应；然而，同类相食形态可能会延长同类相食的可行时间。此外，天气条件可能会改变池塘的水期，从而影响头部形态和同类相食。
