Michel Eric S, Flinn Emily B, Demarais Stephen, Strickland Bronson K, Wang Guiming, Dacus Chad M
Department of Wildlife, Fisheries and Aquaculture, Mississippi State University; Department of Natural Resource Management, South Dakota State University;
Department of Wildlife, Fisheries and Aquaculture, Mississippi State University.
J Vis Exp. 2017 Aug 8(126):56059. doi: 10.3791/56059.
Cervid phenotype can be placed into one of two categories: efficiency, which promotes survival over extravagant morphometric growth, and luxury, which promotes growth of large weaponry and body size. Populations of the same species display each phenotype depending on environmental conditions. Although antler and body size of male white-tailed deer (Odocoileus virginianus) varies by physiographic region in Mississippi, USA and is strongly correlated with regional variation in nutritional quality, the effects of population-level genetics from native stocks and previous re-stocking efforts cannot be disregarded. This protocol describes how we designed a controlled study, where other factors that influence phenotype, such as age and nutrition, are controlled. We brought wild-caught pregnant females and six-month-old fawns from three distinct physiographic regions in Mississippi, USA to the Mississippi State University Rusty Dawkins Memorial Deer Unit. Deer from the same region were bred to produce a second generation of offspring, allowing us to assess generational responses and maternal effects. All deer ate the same high-quality (20% crude protein deer pellet) diet ad libitum. We uniquely marked each neonate and recorded body mass, hind foot, and total body length. Each subsequent fall, we sedated individuals via remote injection and sampled the same morphometrics plus antlers of adults. We found that all morphometrics increased in size from first to second generation, with full compensation of antler size (regional variation no longer present) and partial compensation of body mass (some evidence of regional variation) evident in the second generation. Second generation males that originated from our poorest quality soil region displayed about a 40% increase in antler size and about a 25% increase in body mass when compared to their wild harvested counterparts. Our results suggest phenotypic variation of wild male white-tailed deer in Mississippi are more related to differences in nutritional quality than population-level genetics.
一类是效率型，其促进生存而非过度的形态计量学生长；另一类是奢侈型，其促进大型武器和体型的生长。同一物种的种群会根据环境条件表现出每种表型。尽管美国密西西比州雄性白尾鹿（Odocoileus virginianus）的鹿角和体型因自然地理区域而异，且与营养质量的区域差异密切相关，但本地种群的种群水平遗传学影响以及先前的重新放养努力也不容忽视。本方案描述了我们如何设计一项对照研究，其中控制了影响表型的其他因素，如年龄和营养。我们从美国密西西比州三个不同的自然地理区域捕获了野生怀孕雌性和6个月大的小鹿，并将它们带到密西西比州立大学拉斯蒂·道金斯纪念鹿场。来自同一区域的鹿进行繁殖以产生第二代后代，这使我们能够评估代际反应和母体效应。所有的鹿都自由采食相同的高质量（粗蛋白含量为20%的鹿颗粒饲料）日粮。我们对每只新生鹿进行独特标记，并记录其体重、后足和全长。随后的每个秋季，我们通过远程注射使个体镇静，并对相同的形态测量指标以及成年鹿的鹿角进行采样。我们发现，从第一代到第二代，所有形态测量指标的大小都有所增加，第二代中鹿角大小完全得到补偿（区域差异不再存在），体重部分得到补偿（仍有一些区域差异的迹象）。与野生捕获的同类相比，来自我们土壤质量最差区域的第二代雄性鹿的鹿角大小增加了约40%，体重增加了约25%。我们的结果表明，密西西比州野生雄性白尾鹿的表型变异与营养质量差异的关系比与种群水平遗传学的关系更大。
