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General Note: |
Faculty of the division of the biological sciences and the Pritzker School of Medicine. |
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Dissertation Note: |
Doctor of Philosophy (Ph. D.) University of Chicago 2015 |
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Summary, Etc. Note: |
Summary: In response to unpredictable or stochastic environmental fluctuations, parents may alter their behavior, morphology, and physiology to cope with such changes. Consequently, these sudden changes can impact their offspring by shaping their phenotypic development beyond the influence exerted from inherited genes. This facet of parental effects theory--deemed parental programming--contributes to phenotypic variation within a population, as parents "prepare" their offspring for success by tailoring their phenotypes toward future environmental conditions. Thus, parental effects are partially responsible for generating the raw material by which natural selection operates. For mammalian and avian species in particular, endocrine factors are likely key components driving parental programming, as hormonal changes often precede or accompany phenotypic change (e.g. morphology, behavior, etc.). However, few studies have addressed this mechanism in biparental care systems, or determined whether offspring traits modified by parental effects are consistent into later life stages. In this dissertation, pre-partum hormones of captive coyote (Canis latrans) breeding pairs were assessed in response to environmental cues (i.e. novel conspecific odors) and prior breeding experiences (i.e. first-time versus experienced breeders). Resultant parenting behaviors, pup personality traits (i.e. boldness, activity, aggression), and pup hormonal outcomes (i.e. cortisol, testosterone) were examined to determine if pre-partum hormones of parents were associated with phenotypic outcomes of their offspring across multiple life stages |
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Summary: First, I exposed captive coyote pairs to novel conspecific odors (i.e. mixture of fermented glandular oils, urine, etc.) mid-gestation as a proxy for increased conspecific density (Chapter 2). Additionally, breeding pairs were observed as first-time and experienced parents. Coyote pairs provided with odors had higher fecal androgen metabolites compared with those that received water as a control, implying coyote androgens were sensitive to social olfactory cues. Meanwhile, both males and females had lower pre-partum fecal androgen metabolites as experienced versus first-time breeders. |
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Summary: Second, parenting behaviors of coyote pairs were observed from 5 to 15 weeks of offspring age to assess whether pre-partum hormonal outcomes were associated with subsequent parenting behaviors (Chapter 3). Maternal (but not paternal) fecal androgen metabolites observed mid-gestation were negatively associated with contact and aggression, suggesting that mothers with higher androgen metabolites over gestation contacted and aggressed their pups less than other moms. Further, experienced parents contacted and aggressed their pups more frequently. |
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Summary: Third, I addressed whether pre-partum odor cues and breeding experience of parents affected boldness and hormonal physiology of pups (Chapter 4). Pup boldness was assessed using feeding and novel object tests with a predator stimulus (i.e. human observer) present for both tests. Cortisol and testosterone concentrations were analyzed using hair shaved from pups at 5, 10, and 15 weeks of age. Pups born to experienced parents re-emerged from their dens more during behavioral tests, and had lower hair testosterone at 5 weeks of age. Pre-partum fecal androgen metabolites of parents were negatively associated with how frequently pups ate during feeding tests, suggesting that decreased parental androgens are associated with increased pup boldness. |
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Summary: Finally, feeding and novel object tests were repeated on a subset of coyote pups during the yearling stage to determine if phenotypes were consistent over developmental time (Chapter 5). A set of 13 behaviors were analyzed using a principal components analysis to identify personality components. Further, I collected fecal samples over a 7-week period to quantify fecal glucocorticoid and androgen metabolites of coyote yearlings. Individuals that were more willing to eat when exposed to predator cues (i.e. humans) as pups were also more likely to be more active and exploratory. Yearling fecal androgen metabolites were also positively associated with pre-partum fecal androgen metabolites of their parents when those yearlings were developing neonates. |
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Summary: Taken together, these results suggest coyote parents were able to transduce their environmental (i.e. odor) and breeding experiences via androgens into meaningful phenotypic outcomes for pups. Specifically, decreased pre-partum androgens of parents were associated with increased boldness behaviors in their offspring. Boldness and other personality traits of pups were associated with the behaviors of those individuals as yearlings, highlighting the pervasive and long-term nature of parental effects in this system. In addition, fecal androgen metabolites of yearlings and their parents were positively associated, indicating that parental physiology over gestation affected the subsequent physiology of their offspring long-term. Parental effects in coyotes therefore may be implicated in affecting traits (i.e. boldness, behavioral plasticity) that have previously been considered integral in coyote colonization of nonnative habitats such as urbanized ecosystems. |