Research in my lab generally falls within three main foci, 1) mammary physiology, metabolic adaptations to support lactation, and milk synthesis, 2) Programming of offspring physiology and performance through early life experiences, including the intrauterine environment experienced during fetal development and the bioactive and nutritive factors consumed through colostrum and milk, and 3) Causes and consequences of variation in maternal investment, particularly with respect to offspring growth and performance and life history tradeoffs. These topics are studied across multiple levels of biological organization (molecular and cellular to organismal) and both within an evolutionary framework and from an animal production standpoint. My research approach is integrative, employing a variety of methods including field studies, traditional laboratory assays, and high throughput sequencing technologies, and involving a range of mammalian species, from small rodents to dairy cattle.
Maternal effects, life history, & offspring outcomes
As part of my graduate research, I investigated maternal effects on offspring body mass and growth rate, two fitness-related traits, in Columbian ground squirrels. This species is an obligate hibernator that fasts during the 8-9 month hibernation period. For adult females, the short active season is characterized by a reproductive period involving breeding, gestation, and lactation, and a period of hyperphagia prior to immergence into the hibernacula. Consequently, body mass at immergence is a strong predictor of survival through hibernation, for both adults and juveniles. I examined the influence of maternal size, condition, and reproductive timing as well as the nutritive composition of mother’s milk on juvenile body mass, pre-weaning growth rate, and survival through the first hibernation (Skibiel et al. 2009; Skibiel and Hood 2015).
Besides providing the nutritional building blocks necessary for neonatal tissue accretion and organ development and the energy for activity and growth, milk contains bioactive factors, such as hormones, that can function as signals of the maternal environment and modify offspring phenotype in the short and long term (i.e. lactocrine programming). Through a postdoctoral fellowship at Harvard University, I examined the interaction between maternal life history, milk-borne hormones, and neonatal behavior and growth (Hinde et al. 2015).
Evolution of lactation strategies
Milk composition is a critical component of a species’ lactation strategy, yet we know relatively little about the factors driving variation in milk composition within and among species. I compiled data on 130 species and conducted a phylogenetically informed comparative analysis to test hypotheses regarding the contribution of a number of life history traits and ecological variables to the evolution of the diverse nutritional profiles of milks observed in the class Mammalia. I also examined milk composition of the Columbian ground squirrel with respect to the species’ unique reproductive ecology (Skibiel et al. 2013a; Skibiel and Hood 2013).
Maternal investment & life history tradeoffs
Maternal care is an integral part of reproduction in many animals, particularly mammals, given their extended periods of gestation and lactation. Importantly, maternal care constitutes behaviors that impart fitness benefits, but entail a cost to the mother. These costs in conjunction with the finite resources available to allocate among various physiological processes give rise to life history tradeoffs, such as between growth and maintenance or current and future reproduction. As part of my dissertation research, I compared maternal investment in gestation versus lactation and examined fitness consequences of variation in maternal investment in Columbian ground squirrels. Through litter size manipulations, I also tested fundamental hypotheses regarding energy allocation as a causal factor in reproductive tradeoffs (Skibiel et al. 2009; Skibiel et al. 2013b).
Environmental stressors & physiology
Climate change is occurring at an unprecedented rate in Earth’s recent history, requiring rapid adaptive responses. Rising temperatures and redistribution of precipitation threaten global food security through reduced crop and livestock productivity and health, and adversely impact wild species, from shifting phenology and distribution to causing loss of habitat and biodiversity. Studying the physiological responses to environmental stressors, such as high ambient temperature, can assist in developing strategies to mitigate effects of climate change on agricultural enterprises and can provide insight into how populations adapt to changing environmental conditions. Through my postdoctoral fellowship at the University of Florida, I currently investigated the cellular and molecular pathways through which heat stress reduces milk production in mature dairy cows. Exposure to heat stress during late pregnancy also has long-term effects on the developing fetus, from depressed postnatal immune function to reduced milk production in the first lactation. Utilizing transcriptomics, proteomics, and epigenetics methods, I sought to understand how the intrauterine environment modulates offspring physiology and behavior (Laporta et al. 2017; Skibiel et al. 2017; Skibiel et al. 2018a; Skibiel et al. 2018b; Skibiel et al. 2018c).
Amy L. Skibiel
University of Idaho
Department of Animal and Veterinary Science
Moscow, ID 83844
© 2018 by Amy L. Skibiel. All Rights Reserved.