Matzner, Steven

• Postdoctoral Associate, Boyce Thompson Institute, Cornell University, Ithaca, N.Y. 

• Ph.D., Ecology, University of California, Davis 

• B.A., Biology, Augustana College

Range limits for species are "essentially a species ecological niche in space" (Sexton et al. 2009). Key morphological and physiological traits provide species with an advantage in particular environments and these traits or tradeoffs between these key functional traits can determine the distribution of species (Westoby and Wright 2009). For example, the ability of a species to expand its range into a drier environment may come at the expense of its ability to defend itself against herbivory (Siemens et al. 2009). The objective of this research proposal is to understand the mechanism for range limits in two species of milkweeds (Aslelpias) that hybridize along a strong moisture gradient. Our ultimate goal is to determine how key functional traits affect fitness of both the parental species and the hybrids. The specific aims of the proposal are as follows:

Aim 1: Using greenhouse studies, we will identify differences in key seedling drought related traits important for plant establishment in both Aslepias syriaca and A. speciosa and within the hybrids.
Aim 2: We will compare the soil root rhizosphere microbiome using 16S sequencing for Asclepias syriaca and A. speciosa within their home range to determine if there is  a soil microbiome advantage for the home species.
In Aims 1 and 2, we test hypotheses regarding differences in the ability  of the parental species to establish in their home range.
Aim 3:  In common gardens we will identify genotypic, environmental and GXE differences in mortality and herbivory as well as measure  difference in leaf exudates, trichomes, and cardenolides in both species and their hybrids.
In Aim 3, we use the variation in natural hybrids to disentangle whether patterns in herbivory are associated with specific anti-herbivory traits. For example, do differences in aphid infestation between the two species correlate with chemical defenses or morphological traits?