Nielsen Danny P, Matocq Marjorie D
Department of Natural Resources and Environmental Science University of Nevada Reno NV USA.
Graduate Program in EECB University of Nevada Reno NV USA.
Ecol Evol. 2021 Mar 17;11(9):4909-4919. doi: 10.1002/ece3.7399. eCollection 2021 May.
Ecotones, characterized by adjacent yet distinct biotic communities, provide natural laboratories in which to investigate how environmental selection influences the ecology and evolution of organisms. For wild herbivores, differential plant availability across sharp ecotones may be an important source of dietary-based selection.We studied small herbivore diet composition across a sharp ecotone where two species of woodrat, and . , come into secondary contact with one another and hybridize. We quantified woodrat dietary preference through trn metabarcoding of field-collected fecal pellets and experimental choice trials. Despite gene flow, parental and maintain distinct diets across this fine spatial scale, and across temporal scales that span both wet and dry conditions. maintained a more diverse diet, with (California coffeeberry) making up a large portion of its diet. maintains a less diverse diet, with (desert almond) comprising more than half of its diet. Both and are known to produce potentially toxic plant secondary compounds (PSCs), which should deter herbivory, yet these plants have relatively high nutritional value as measured by crude protein content. and consumed and , respectively, in greater abundance than these plants are available on the landscape-indicating dietary selection. Finally, experimental preference trials revealed that exhibited a preference for , while exhibited a relatively stronger preference for . We find that exhibit a generalist herbivore strategy relative to , which exhibit a more specialized feeding strategy in this study system.Our results suggest that woodrats respond to fine-scale environmental differences in plant availability that may require different metabolic strategies in order to balance nutrient acquisition while minimizing exposure to potentially toxic PSCs.
生态交错带以相邻但不同的生物群落为特征，为研究环境选择如何影响生物的生态和进化提供了天然实验室。对于野生食草动物来说，跨越明显生态交错带的不同植物可利用性可能是基于饮食选择的一个重要来源。我们研究了小型食草动物在一个明显的生态交错带中的饮食组成，在这个交错带中，两种林鼠，即[具体林鼠名称1]和[具体林鼠名称2]，再次相互接触并杂交。我们通过对野外收集的粪便颗粒进行trn宏条形码分析和实验选择试验来量化林鼠的饮食偏好。尽管存在基因流动，但亲本[具体林鼠名称1]和[具体林鼠名称2]在这个精细的空间尺度以及跨越干湿条件的时间尺度上都保持着不同的饮食。[具体林鼠名称1]的饮食更为多样，[加州咖啡莓]占其饮食的很大一部分。[具体林鼠名称2]的饮食多样性较低，[沙漠杏仁]占其饮食的一半以上。已知[具体林鼠名称1]和[具体林鼠名称2]所食用的植物都会产生潜在有毒的植物次生化合物（PSC），这应该会抑制食草行为，但这些植物按粗蛋白含量衡量具有相对较高的营养价值。[具体林鼠名称1]和[具体林鼠名称2]分别比这些植物在景观中的可利用量更大量地食用了[具体植物名称1]和[具体植物名称2]，这表明存在饮食选择。最后，实验偏好试验表明[具体林鼠名称1]对[具体植物名称1]表现出偏好，而[具体林鼠名称2]对[具体植物名称2]表现出相对更强的偏好。我们发现相对于[具体林鼠名称2]，[具体林鼠名称1]表现出一种广食性食草动物策略，而[具体林鼠名称2]在本研究系统中表现出更专业化的取食策略。我们的结果表明，林鼠对植物可利用性的精细尺度环境差异做出反应，这可能需要不同的代谢策略来平衡营养获取，同时尽量减少接触潜在有毒的PSC。
