BRC-BIO: Investigating Color and Pattern Diversity in Painted Turtles

Northeastern Illinois University, Chicago IL

Investigators

Abstract

This research explores the function of variation in shell color and pattern in painted turtles. The work involves experiments and field work focused on understanding the antioxidant function of pigments in turtle tissues. In doing so, the work will explore how antioxidants impact survival, and the natural variation in shell colors and patterns. Understanding the antioxidant function and survival impacts of pigments is essential for making predictions about how turtles may respond to environmental change. This research will also provide students at a Hispanic-serving institution in Chicago the opportunity to conduct field work and research. Students will be trained in science communication and will co-author research papers. Students will also be able to participate in a paid internship with a software company who will develop an open-source platform for extracting color and pattern data from images. Understanding biological diversity requires both identifying the mechanisms and functions that underlie it, and understanding the fitness consequences of variation. Animal coloration and patterning are great traits with which to study functions and consequences of variation because these highly visible phenotypes can impact every aspect of an individual’s life. Painted turtles are so named because of their yellow skin stripes and their bright orange ventral shells. Despite their name and widespread range, little is known about their color or patterns. This research addresses these gaps in knowledge in three ways. First, by identifying the function of shell coloration (Objective 1). Second, by assessing how shell coloration impacts fitness (Objective 2). Third, by characterizing the variation in the shell patterns (Objective 3). Objective 1 will be investigated by manipulating the pigment content of turtle eggs in the nest and assessing the impact on antioxidant capacity. The researchers hypothesize that the carotenoids that are responsible for the bright orange shell color have a role in mitigating oxidative stress during recovery from overwintering. This hypothesis and the associated methods are built on previous work and pilot data. Objective 2 will be investigated by taking advantage of a natural experiment, by comparing both the population-level survival trajectories and the individual-level survival of two populations of painted turtles with similar pigment concentrations but different colorations. Lastly, Objective 3 will be studied by assessing intra-clutch, intrapopulation, and interpopulation variance in shell pattern using geometric morphometrics and neural networks. This latter objective will be done in collaboration with a software firm that can provide training and internships to students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.