科學家手把手教你區分野生三文魚與養殖三文魚

論文題目：Judging a salmon by its spots: environmental variation is the primary determinant of spot patterns in Salmo salar

期刊：BMC Ecology

作者：Katarina M. J?rgensen et al.

數字識別碼：10.1186/s12898-018-0170-3

你知道三文魚身上的斑點數可以用於區分野生三文魚和養殖三文魚嗎？最近一項發表於BMC Ecology的研究表明，相較於基因的微小作用，環境更大程度上決定了養殖三文魚有更多斑點。

我們已了解到是養殖環境中的某些因素使養殖三文魚有很多斑點，但引起斑點的準確原因尚不明確，可能是光照、溫度、餌料到魚群密度或增長率中的任何一個因素。

我們研究了特定品種的養殖三文魚是否具有不同數量的斑點，基於其是在河中孵化還是一直生活在三文魚養殖場中。

我們將養殖的三文魚種投放到挪威的Guddal河中，它們孵化並逗留了2-4年。然後我們將這些小三文魚帶出河，轉移到位於Matre的研究站，隨後在陸上的池塘中養殖兩年。然而，這些三文魚的斑點仍然比一直在Matre標準養殖條件下養殖的三文魚少了七倍，儘管這些三文魚來自同一品種。

圖片來源：Monica F Solberg，編輯：Katarina J?rgensen

養殖三文魚和在養殖環境下生長的野生三文魚都會有很多斑點，而在河中生長的所有養殖和野生三文魚的斑點較少。這意味著我們可以確定是環境決定了三文魚有多少斑點。

然而，我們還在三文魚染色體上發現了一個數量性狀基因座（QTL）的區域，其中含有與斑點數量相關的基因。所以，基因的確起到了一定的作用，但與環境的影響相比，基因的影響微乎其微。

這些來自Guddal河的野生三文魚和養殖三文魚都只有少量斑點，儘管這些三文魚在位於Matre的研究站的池塘中生活了兩年。這說明三文魚在幼鮭時期從河流中轉移前就已長出斑點。三文魚離開河流環境前就長出了不同的斑點，這一現象非常重要。

目前，清理河流里逃走的養殖三文魚都是通過一些明顯的特徵如身體形狀、鰭的磨損和斑點。如果養殖三文魚在自然中長期生存，就會變得像野生三文魚。

幾項研究表明，三文魚上的斑點隨著時間的推移仍保持穩定，所以它們在逃走後可能不會消失，儘管我們並未對此進行驗證。但是對於在河裡捕捉到的三文魚，其身上斑點較多仍可作為它是逃走的養殖三文魚的可靠標識。

最近，在斑馬魚中進行的實驗表明，當其條紋在實驗中被破壞後，重新長出條紋的方式符合艾倫圖靈的生物模式形成理論。圖靈模式認為環境可以影響生物模式，併產生個體特徵，例如人類指紋。在大西洋三文魚等被充分研究的物種中發現環境決定模式，為研究生物模式形成提供了新的契機。

模式的個性特徵和斑點長期的穩定性也表明斑點模式可以用於通過視頻監控來識別魚類個體，而這可以用於監測養殖場和河流中的環境。

摘要：

Background

In fish, morphological colour changes occur from variations in pigment concentrations and in the morphology, density, and distribution of chromatophores in the skin. However, the underlying mechanisms remain unresolved in most species. Here, we describe the first investigation into the genetic and environmental basis of spot pattern development in one of the world』s most studied fishes, the Atlantic salmon. We reared 920 salmon from 64 families of domesticated, F1-hybrid and wild origin in two contrasting environments (Hatchery; tanks for the freshwater stage and sea cages for the marine stage, and River; a natural river for the freshwater stage and tanks for the marine stage). Fish were measured, photographed and spot patterns evaluated.

Results

In the Hatchery experiment, significant but modest differences in spot density were observed among domesticated, F1-hybrid (1.4-fold spottier than domesticated) and wild salmon (1.7-fold spottier than domesticated). A heritability of 6% was calculated for spot density, and a significant QTL on linkage group SSA014 was detected. In the River experiment, significant but modest differences in spot density were also observed among domesticated, F1-hybrid (1.2-fold spottier than domesticated) and wild salmon (1.8-fold spottier than domesticated). Domesticated salmon were sevenfold spottier in the Hatchery vs. River experiment. While different wild populations were used for the two experiments, on average, these were 6.2-fold spottier in the Hatchery vs. River experiment. Fish in the Hatchery experiment displayed scattered to random spot patterns while fish in the River experiment displayed clustered spot patterns.

Conclusions

These data demonstrate that while genetics plays an underlying role, environmental variation represents the primary determinant of spot pattern development in Atlantic salmon.

期刊介紹：BMC Ecologyis an open access, peer-reviewed journal that considers articles on environmental, behavioral and population ecology as well as biodiversity of plants, animals and microbes.

2016 Journal Metrics

Citation Impact

2.896 - 2-year Impact Factor

NA - 5-year Impact Factor

1.148 - Source Normalized Impact per Paper (SNIP)

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