Boecklen William J, Hoffman M Timm
Department of Biology, New Mexico State University, Box 30001, Las Cruces, New Mexico, USA.
Stress Ecology Research Unit, National Botanical Institute, Private Bag X16, Rondebosch, 7700, Cape Town, South Africa.
Oecologia. 1993 Oct;96(1):49-55. doi: 10.1007/BF00318030.
We examined patterns of herbivory in the dioecious desert shrub, Ephedra trifurca (Ephedraceae), along a small watershed in the northern Chihuahuan Desert. We documented significant (p=0.002) sexual dimorphism in densities of Lasioptera ephedrae and L. ephedricola (Diptera: Cecidomyiidae), with male E. trifurca supporting higher densities than did females. Densities of gall midges varied significantly (p<0.001) among four sample populations of E. trifurca arrayed along the watershed and exhibited an inverse gradient with elevation. There was also a significant (p=0.006) sex-by-site interaction such that the degree of intersexual variation in gall densities decreased down the watershed. Variation in gall densities and intersexual variation in gall densities exhibited inverse trends with variation in soil water and inorganic nitrogen concentrations along the watershed.
我们在奇瓦瓦沙漠北部的一个小流域，对雌雄异株的沙漠灌木三裂麻黄（麻黄科）的食草模式进行了研究。我们记录到，麻黄木虱和麻黄食木虱（双翅目：瘿蚊科）的密度存在显著的（p = 0.002）性别二态性，雄性三裂麻黄上的密度高于雌性。在沿流域分布的四个三裂麻黄样本种群中，瘿蚊的密度差异显著（p < 0.001），且随海拔呈现反向梯度变化。此外，还存在显著的（p = 0.006）性别×地点交互作用，即瘿蚊密度的两性间变异程度沿流域向下递减。瘿蚊密度的变异以及瘿蚊密度的两性间变异，与沿流域土壤水分和无机氮浓度的变异呈现相反趋势。
