Inoue Yoshihiro, Okamiya Hisanori, Aota Takayuki, Crossland Michael R, Kishida Osamu
Graduate School of Environmental Sciences, Hokkaido University, Takaoka, Tomakomai, Hokkaido, 053-0035, Japan.
Kamakura Jogakuin Junior and Senior High School, Yuigahama, Kamakura, Kanagawa, 248-0014, Japan.
Oecologia. 2025 Jan 30;207(1):27. doi: 10.1007/s00442-024-05658-0.
Alien species can influence populations of native species through individual-level effects such as predation, competition, and poisoning. For alien species that possess strong defensive chemicals, poisoning is one of the most powerful mechanisms of individual-level effects on native biota. Although toxic alien species could potentially negatively affect survival (lethal effects) or life history traits (sub-lethal effects) of native predators via poisoning, previous studies have mainly focused on acute lethal effects. Thus, delayed effects on predator life history traits have been largely overlooked. To fill this knowledge gap, we conducted laboratory and field experiments to investigate whether toxic alien prey (hatchlings and tadpoles of an invasive toad, Bufo formosus) affect the survival and/or growth and development of a native predatory salamander (larvae of Hynobius retardatus) on Hokkaido, Japan. The laboratory experiment revealed that consumption of a single toad hatchling exerted non-lethal effects on salamanders, but suppressed both salamander growth and development of an ecological phenotype (broad-gape) normally induced by environmental conditions. Furthermore, the field experiment in a natural pond showed that the presence of toad hatchlings and tadpoles resulted in reduced salamander growth (smaller body size) and lower survival of salamanders in the later larval period. The results of the laboratory and field experiments are complementary evidence of the life history impacts of the toxic alien toad on native salamanders. Thus, the poisoning effects of toxic alien species can affect the life history of native predators even if they do not exert acute lethality.
外来物种可以通过捕食、竞争和中毒等个体层面的影响来影响本地物种的数量。对于拥有强大防御性化学物质的外来物种来说，中毒是对本地生物群产生个体层面影响的最有力机制之一。尽管有毒外来物种可能通过中毒对本地捕食者的生存（致死效应）或生活史特征（亚致死效应）产生负面影响，但以往的研究主要集中在急性致死效应上。因此，对捕食者生活史特征延迟效应的研究在很大程度上被忽视了。为了填补这一知识空白，我们进行了实验室和野外实验，以调查有毒外来猎物（一种入侵蟾蜍，黑眶蟾蜍的幼体和蝌蚪）是否会影响日本北海道本地捕食性蝾螈（极北鲵的幼体）的生存和/或生长发育。实验室实验表明，食用一只蟾蜍幼体对蝾螈产生了非致死效应，但抑制了蝾螈的生长以及通常由环境条件诱导的一种生态表型（大口型）的发育。此外，在天然池塘进行的野外实验表明，蟾蜍幼体和蝌蚪的存在导致蝾螈生长减缓（体型变小），并且在幼体后期蝾螈的存活率降低。实验室和野外实验的结果是有毒外来蟾蜍对本地蝾螈生活史影响的补充证据。因此，有毒外来物种的中毒效应即使不产生急性致死性，也会影响本地捕食者的生活史。
