一項研究報告說，與海蟾蜍種群在同一塊土地上定居下來相比,，當它們?nèi)肭忠粔K土地的時候,，它們的種群有不同的分散和移動的模式,。Tom Lindström及其同事分析了關(guān)于入侵性海蟾蜍到達澳大利亞熱帶地區(qū)的一個研究地點并在之后8年的時間里定居下來的一個廣泛的無線電追蹤數(shù)據(jù)集。這組科研人員發(fā)現(xiàn)作為入侵先鋒的蟾蜍和入侵后的幾年在同一地點的蟾蜍之間的運動模式的差別,。這組科研人員的模型區(qū)分了海蟾蜍運動的兩個階段,，它們分別是轉(zhuǎn)彎角度尖銳、步長較短的安營扎寨階段和一個一直朝著一個方向長距離運動的分散階段,。先導蟾蜍把他們的時間的更大一部分用在了分散模式上,，并且當它們處于分散模式的時候，它們顯示出了比入侵后到來的蟾蜍更長的每日位移和更高的方向性,。這些變化的一個結(jié)果是,，在入侵前沿的海蟾蜍的總年位移是同一地點數(shù)年后跟蹤的海蟾蜍總年位移的2倍以上。這組作者說,，這些結(jié)果提示僅僅追蹤定居下來的種群的研究可能低估了生物在新的土地上的散播,。（生物谷 Bioon.com）
生物谷推薦的英文摘要
PNAS doi: 10.1073/pnas.1303157110
Rapid shifts in dispersal behavior on an expanding range edge
Tom Lindströma,1,2, Gregory P. Browna, Scott A. Sissonb, Benjamin L. Phillipsc, and Richard Shinea
Dispersal biology at an invasion front differs from that of populations within the range core, because novel evolutionary and ecological processes come into play in the nonequilibrium conditions at expanding range edges. In a world where species’ range limits are changing rapidly, we need to understand how individuals disperse at an invasion front. We analyzed an extensive dataset from radio-tracking invasive cane toads (Rhinella marina) over the first 8 y since they arrived at a site in tropical Australia. Movement patterns of toads in the invasion vanguard differed from those of individuals in the same area postcolonization. Our model discriminated encamped versus dispersive phases within each toad’s movements and demonstrated that pioneer toads spent longer periods in dispersive mode and displayed longer, more directed movements while they were in dispersive mode. These analyses predict that overall displacement per year is more than twice as far for toads at the invasion front compared with those tracked a few years later at the same site. Studies on established populations (or even those a few years postestablishment) thus may massively underestimate dispersal rates at the leading edge of an expanding population. This, in turn, will cause us to underpredict the rates at which invasive organisms move into new territory and at which native taxa can expand into newly available habitat under climate change.
