A trade-off between female lifespan and larval diet breadth at the interspecific level in LepidopteraEvol Ecol (2007) 21:307–323
PDF (213.9 KB)Mark A. Jervis AE Peter N. Ferns AE Carol L. Boggs
由幾個食性演化模型中所衍生的預測是：以幼蟲選擇的食草來選擇適合植物的植食性昆蟲成蟲，其雌性成體的壽命或與幼蟲食草寬廣度呈負相關。在其中一類的模型中，雌成蟲壽命驅使幼蟲寄主廣度在上演化的改變；在另一類模型中，是幼蟲食性的廣度驅使雌成蟲壽命在演化上的改變。將此獨立對比的方法運用在一系列在生物學上與親緣關係上具高多樣性的鱗翅目，作者想探討種級程度上不同幼蟲食性廣度(以文獻報導中幼蟲所取食的植物種數來評估)是否與雌成蟲的壽命呈現負相關。作者發現這兩類生活史的差異是完全相反關連的，接下來作者放寬假設，一般對這些模型而言、雌成蟲是負責在不同寄主植物之間散布其子代的生命階段。當作者將不具飛行能力的三種雌成蟲（由於無翅或短翅性，其幼蟲則成為具散布性的階段）加入資料中，以此獨立對比的方法分析，雌成蟲壽命和幼蟲寄主廣度之間的負相關就消失了。作者將此現象詮釋為支持此假設的一般預測。本文是種級程度上不同幼蟲食性廣度是否與雌成蟲的壽命之間取捨的證據，並確認先前節肢動物研究中發現的棲地專一性程度與搜尋時間限制程度呈相反關聯。在作者的“食性寬廣度驅使壽命改變“的模型中，作者預測雌性的卵孵化策略類型(以繁殖率來評估)應該和幼蟲食性廣度呈正相關，並居中銜接幼蟲食性廣度與雌成蟲的壽命之間關係，然而作者對此規則目前並沒有證據。
Abstract
A prediction arising from several evolutionary diet breadth models is that, in insect herbivores whose adults practise adaptive host plant selection based on larval performance, female adult lifespan should be negatively correlated with larval diet breadth. In one category of models, female adult lifespan drives evolutionary changes in larval diet breadth; in the other category, larval diet breadth drives evolutionary changes in female adult lifespan. Applying the method of independent contrasts to a biologically and phylogenetically diverse array of Lepidoptera, we ask whether larval diet breadth—as measured by the number of larval food plant species reported in the literature—is negatively correlated with female adult lifespan at the interspecific level. We show that these two life history variables are indeed inversely related. Next, we relax the assumption, common to all of the models, that the female adult is the life stage responsible for the distribution of progeny among different host plants. By introducing into our data set three species whose females are incapable of flight (due to either aptery or brachyptery), and whose larvae are the dispersive stage, the negative correlation between female adult lifespan and larval diet breadth is lost, when using the independent contrasts method. We interpret this effect as supporting the models’ common prediction. Ours is the first reported evidence of a lifespan/diet breadth trade-off at the interspecific level among insects, and it confirms the findings of a previous study in which the degree of habitat specialisation among arthropods was inversely related to proxy measures of the degree of search time constraint. In one of our ‘‘diet breadth drives changes in lifespan’’ models, the females’ type of egg maturation strategy (as measured by the ovigeny index) is predicted to be positively correlated with larval diet breadth, and it mediates a female adult lifespan/larval diet breadth trade-off; however, we found no convincing support for such a role.
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