研究发现狼更愿意吃鱼
每年关注大麻哈鱼动向的可不仅仅只有渔夫。
据美国《科学》杂志在线新闻报道,一项持续4年的对加拿大不列颠哥伦比亚省沿岸的狼毛和狼粪进行的研究显示,在整个秋季,这种食肉动物的食谱有70%是由大麻哈鱼构成的。通常认为,鹿肉是狼最爱吃的食物,因此当发现它们也对河中的大麻哈鱼感兴趣时,研究人员无不感到非常惊讶。不过有人就指出,与鹿相比,大麻哈鱼有一个重要的优势——被鱼鳍在脸上扇一下比叫鹿蹄子在肋骨上踹一脚轻得多。研究人员在9月2日的《BMC生态学》(BMC Ecology)上报告了这一发现。
推荐原始出处:
BMC Ecology,2008, 8:14,Chris T Darimont, Paul C Paquet and Thomas E Reimchen
Spawning salmon disrupt trophic coupling between wolves and ungulate prey in coastal British Columbia
Chris T Darimont , Paul C Paquet and Thomas E Reimchen
Background
As a cross-boundary resource subsidy, spawning salmon can strongly affect consumer and ecosystem ecology. Here we examine whether this marine resource can influence a terrestrial wolf-deer (Canis lupus-Odocoileus hemionus) predator-prey system in coastal British Columbia, Canada. Data on resource availability and resource use among eight wolf groups for three seasons over four years allow us to evaluate competing hypotheses that describe salmon as either an alternate resource, consumed in areas where deer are scarce, or as a targeted resource, consumed as a positive function of its availability. Faecal (n = 2203 wolf scats) and isotopic analyses (n = 60 wolf hair samples) provide independent data sets, also allowing us to examine how consistent these common techniques are in estimating foraging behaviour.
Results
At the population level during spring and summer, deer remains occurred in roughly 90 and 95% of faeces respectively. When salmon become available in autumn, however, the population showed a pronounced dietary shift in which deer consumption among groups was negatively correlated (r = -0.77, P <0.001) with consumption of salmon, which occurred in 40% of all faeces and up to 70% of faeces for some groups. This dietary shift as detected by faecal analysis was correlated with seasonal shifts in d13C isotopic signatures (r = 0.78; P = 0.008), which were calculated by intra-hair comparisons between segments grown during summer and fall. The magnitude of this seasonal isotopic shift, our proxy for salmon use, was related primarily to estimates of salmon availability, not deer availability, among wolf groups.
Conclusions
Concordance of faecal and isotopic data suggests our intra-hair isotopic methodology provides an accurate proxy for salmon consumption, and might reliably track seasonal dietary shifts in other consumer-resource systems. Use of salmon by wolves as a function of its abundance and the adaptive explanations we provide suggest a long-term and widespread association between wolves and salmon. Seasonally, this system departs from the common wolf-ungulate model. Broad ecological implications include the potential transmission of marine-based disease into terrestrial systems, the effects of marine subsidy on wolf-deer population dynamics, and the distribution of salmon nutrients by wolves into coastal ecosystems.
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