Project Description
Latex, a suspension of particles in sap, often including rubber and various toxic chemicals, is a particularly important plant chemical defense against insect herbivores. Insects have developed a number of sophisticated behaviors to attempt to sabotage latex defense systems. The current ecological interactions between latex-producing plants and latex-sabotaging insect herbivores is most likely due to an escalating arms race resulting in increasingly deadly latex in plants and increasingly complex sabotaging behaviors in insects. However, the evolution of this system is complex and difficult to understand by studying modern plants due to rampant evolutionary convergence and extensive phenotypic plasticity. Fossil evidence could directly show the evolutionary patterns, but, despite a number of reports of fossil latex, there has been little investigation of how latex changes through time. There is as of yet no reports of fossil evidence of latex-sabotaging behavior. The objective of this research is to review and synthesize the literature on fossil latex, to determine how this key plant defense against insect herbivores has changed since its origin in the Eocene (~45 million years ago).
Tasks and Responsibilites
The student will be responsible for searching the literature on fossil latex, obtaining papers as necessary through google scholar interlibrary loans, and reading the papers. For each reported occurrence of fossil latex, the student will note the location and age of the fossil site, the museum the houses the specimens, and what if any analyses were done on the latex. If any analyses were carried out, the student will note the conclusions, specifically latex canal morphology (unbranched, branched, articulated, unarticulated), latex canal architecture (how the latex canals are arranged in the leaf), and latex chemistry. Finally, the student will work with me to develop a hypothesis about the evolution of latex and latex canals from the Eocene to the present, and also assess which sites need to be studied in more detail to fully test this hypothesis. Moreover, although the literature review will not reveal direct information about the behavior of insect herbivores, today insect behavior is very closely correlated to features of the latex system in the plant. So, we will also make some tentative hypotheses about when specific latex-sabotaging behaviors developed in insects.
Desired Qualifications
None.