Sniegula Szymon, Golab Maria J, Johansson Frank
Department of Ecosystem Conservation, Institute of Nature Conservation, Polish Academy of Sciences, al. Mickiewicza 33, 31-120, Krakow, Poland.
Department of Ecology and Genetics, Uppsala University, SE-751 05, Uppsala, Sweden.
BMC Evol Biol. 2017 Jul 14;17(1):167. doi: 10.1186/s12862-017-1010-3.
Predation is ubiquitous in nature. One form of predation is cannibalism, which is affected by many factors such as size structure and resource density. However, cannibalism may also be influenced by abiotic factors such as seasonal time constraints. Since time constraints are greater at high latitudes, cannibalism could be stronger at such latitudes, but we know next to nothing about latitudinal variation in cannibalism. In this study, we examined cannibalism and activity in larvae of the damselfly Lestes sponsa along a latitudinal gradient across Europe. We did this by raising larvae from the egg stage at different temperatures and photoperiods corresponding to different latitudes.
We found that the more seasonally time-constrained populations in northern latitudes and individuals subjected to greater seasonal time constraints exhibited a higher level of cannibalism. We also found that activity was higher at north latitude conditions, and thus correlated with cannibalism, suggesting that this behaviour mediates higher levels of cannibalism in time-constrained animals.
Our results go counter to the classical latitude-predation pattern which predicts higher predation at lower latitudes, since we found that predation was stronger at higher latitudes. The differences in cannibalism might have implications for population dynamics along the latitudinal gradients, but further experiments are needed to explore this.
捕食现象在自然界中普遍存在。捕食的一种形式是同类相食，它受到许多因素的影响，如体型结构和资源密度。然而，同类相食也可能受到非生物因素的影响，如季节性时间限制。由于高纬度地区的时间限制更大，同类相食在这些纬度地区可能更强，但我们对同类相食的纬度变化几乎一无所知。在本研究中，我们沿着欧洲的纬度梯度研究了豆娘Lestes sponsa幼虫的同类相食和活动情况。我们通过在对应于不同纬度的不同温度和光周期下将幼虫从卵期饲养至成虫期来进行此项研究。
我们发现，纬度较高地区受季节性时间限制更强的种群以及受季节性时间限制更大的个体表现出更高水平的同类相食现象。我们还发现，在北纬条件下活动更为频繁，且与同类相食现象相关，这表明这种行为在受时间限制的动物中促成了更高水平的同类相食。
我们的结果与经典的纬度 - 捕食模式相反，该模式预测低纬度地区的捕食率更高，因为我们发现高纬度地区的捕食现象更强。同类相食现象的差异可能对沿纬度梯度的种群动态产生影响，但需要进一步的实验来探索这一点。
