Articles by Chad M. Dacus in JoVE
Protocol for Assessing the Relative Effects of Environment and Genetics on Antler and Body Growth for a Long-lived Cervid Eric S. Michel1,2, Emily B. Flinn1, Stephen Demarais1, Bronson K. Strickland1, Guiming Wang1, Chad M. Dacus3 1Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, 2Department of Natural Resource Management, South Dakota State University, 3Mississippi Department of Wildlife, Fisheries and Parks Phenotypic differences among cervid populations may be related to population-level genetics or nutrition; discerning which is difficult in the wild. This protocol describes how we designed a controlled study where nutritional variation was eliminated. We found that phenotypic variation of male white-tailed deer was more limited by nutrition than genetics.
Other articles by Chad M. Dacus on PubMed
Soil Resources Area Affects Herbivore Health International Journal of Environmental Research and Public Health. 06, 2011 | Pubmed ID: 21776246 Soil productivity effects nutritive quality of food plants, growth of humans and animals, and reproductive health of domestic animals. Game-range surveys sometimes poorly explained variations in wildlife populations, but classification of survey data by major soil types improved effectiveness. Our study evaluates possible health effects of lower condition and reproductive rates for wild populations of Odocoileus virginianus Zimmerman (white-tailed deer) in some physiographic regions of Mississippi. We analyzed condition and reproductive data for 2400 female deer from the Mississippi Department of Wildlife, Fisheries, and Parks herd health evaluations from 1991-1998. We evaluated age, body mass (Mass), kidney mass, kidney fat mass, number of corpora lutea (CL) and fetuses, as well as fetal ages. Region affected kidney fat index (KFI), which is a body condition index, and numbers of fetuses of adults (P≤0.001). Region affected numbers of CL of adults (P≤0.002). Mass and conception date (CD) were affected (P≤0.001) by region which interacted significantly with age for Mass (P≤0.001) and CD (P
Improved Nutrition Cues Switch from Efficiency to Luxury Phenotypes for a Long-lived Ungulate Ecology and Evolution. Oct, 2016 | Pubmed ID: 27942376 Cervid phenotype can be categorized as efficiency, which promotes survival but not extravagant growth, or luxury which promotes growth of large weaponry and body size. Although nutritional variation greatly influences these phenotypic forms, the potential for subspecies-linked genetic or founder effects from restocking efforts of harvested species has not been eliminated. We measured intergenerational phenotypic change of males in response to improved nutrition in three captive-reared populations of white-tailed deer. Study animals were offspring of females captured from three regions displaying variation in antler and body size as well as nutritional variation. We fed all animals a high-quality diet and measured antler and body size for two generations. We predicted that improved long-term nutrition would cue a switch from efficiency to luxury phenotype for all populations and that regional compensation of antler and body size would occur. Improved nutrition positively influenced all measures of antler and body size; however, changes varied in magnitude. Antler size was more responsive than body size. Improved nutrition also facilitated regional compensation of antler size and partial compensation of body size. Our results show that improved long-term nutrition cues a shift from efficiency to luxury phenotype in a long-lived cervid with weaponry being more responsive than body size. Compensation of antler size suggests that weaponry is greatly influenced by nutrition and is not restricted by subspecies-linked genetic or founder effects from restocking efforts related to our regional populations. Therefore, strategies to improve cervid antler and body size should include habitat management that elevates long-term diet quality.