Date of Award
Animals dynamically invest their acquired energetic resources into fitness-related traits, and life-history trade-offs occur when limited resources are invested in a given trait at the expense of another. The phenotypic effects of life history trade-offs are well documented, but the mechanisms facilitating these trade-offs are poorly understood. One such mechanism is the insulin/insulin-like signaling (IIS) network, and specifically its two primary hormones: insulin-like growth factor 1 (IGF1) and insulin-like growth factor 2 (IGF2). IGF1 is well-characterized but IGF2 is severely understudied, though it is present in nearly all amniotes and sometimes expressed at higher levels than IGF1 in adulthood. I tested how different environmental pressures affect expression of these hormones in adult female green anoles (Anolis carolinensis). Because maternal effects, which are transgenerational effects whereby the mother’s environment influences offspring phenotype, can also promote life-history trade-offs, I also tested how these same environmental manipulations affect egg and offspring phenotypes. IGFs are affected by diet restriction and sprint training in females, albeit in different ways that are also dependent on mass and energetic history of the individual in question. IGF1 and IGF2 are therefore implicated in the response to variation in environment and the manner in which energetic environment is manipulated matters. Similarly, manipulating diet and locomotor investment also had distinct effects on both egg and offspring phenotypes, again in a manner that depended on the mass of the mother. These results implicate both the IIS and related pathways in life-history trade-offs involving the maternal and offspring phenotypes in green anoles.
Marks, Jamie, "Environmental Sensitivity of Maternal and Offspring Phenotype in the Green Anole (Anolis carolinensis) Lizard" (2022). University of New Orleans Theses and Dissertations. 3032.