Plasticity of reproduction in insects

NSF Cross-Disciplinary Research at Undergraduate Institutions

Physiology and fitness consequences of life-history phenotypes in insects

David W. Borst, Steven A. Juliano, Douglas W. Whitman, Olcay Akman, PIs
Jason Jannot, Post doctoral researcher
Last update: 20 Aug. 2008

Data Analysis Resource With Interactive Navigation -
A useful tool for statistical modeling. Click to explore this resource (Prepared by Olcay Akman)

Abstract
The phenotypes of organisms (i,e., their morphological, physiological, and behavioral traits) vary enormously. A central goal of biology is to understand how these different traits are produced (i.e., what physiological mechanisms produce them) and why these traits exist (i.e., what is their adaptive significance or why did they evolve). Because physiological mechanisms translate environmental and genetic effects into traits, these mechanisms may place limits on the traits that can be expressed. Thus, the relationship between the mechanisms that produce phenotypic traits and the adaptive significance of these traits are complex. Two important traits of any species are its adult body size and the time required to reach adulthood. Both traits have enormous functional significance for an organism, and strongly affect their survival and reproduction. In this CRUI program, we will study these two traits in several neighboring Florida populations of lubber grasshoppers (Romalea microptera). In previous studies, we found that the average sizes of females in separate populations consistently differ by as much as 2-fold. We will use laboratory studies to determine how an individual’s adult body size is determined by the rearing environment (i.e., phenotypic plasticity, or more simplistically “nurture”), and by inherent differences among individuals (i.e., genetic differentiation, or more simplistically “nature”). We also determine how these differences affect the time to become an adult. We will use field studies to determine the effects of these traits on survival and reproductive success of individuals to the local environment. An understanding of how these traits are produced and why they are adaptive requires a cross-disciplinary approach from the fields of evolutionary biology, ecology, physiology, and biochemistry. These fields will be integrated using novel mathematical modeling methods (e.g., Artificial Neural Networks, Life Table Models). These methods will be used to develop predictive models for the effects of environmental and genetic factors on adult body size and the time to adulthood and will enable us to evaluate the adaptive significance of these traits in the field. Thus, this cross-disciplinary program will merge math, biochemistry, physiology, and ecology to address issues of considerable biological importance. The undergraduate CRUI participants will discover the power that such collaborative projects bring to the investigation of complex biological processes.

David Borst, Steve Juliano, Douglas Whitman, and Olcay Akman direct a project funded by the National Science Foundation’s Cross-disciplinary Research at Undergraduate Institutions program for undergraduate research on plasticity of reproduction in insects. Undergraduate research fellows pursue research on the physiological mechanisms and fitness consequences of life history phenotypes in insects. This work is a continuation of our past work on phenotypic plasticity of reproduction in our model species, Romalea microptera.

Publications resulting from past CRUI grants to this research group:

David W. Borst

Steven A. Juliano

Douglas W. Whitman (coming soon)

June 2005: Group trip to the Everglades

We went to the Everglades to gather data on geographic variation in body size of adult grasshoppers. We visited 7 sites [Anhinga Trail, Paurotis Pond, Shark Valley North, Shark Valley South, Panther Campground (=Trail Lakes), Copeland (=Auto Alley), and Fakahatchee Strand; See map above] and made measurements of grasshoppers at each site. Data from this trip will be used to test for geographic variation in body size, and in conjunction with data from past years, to test for inter-year varitiation among the sites. Below are some pictures from the trip.