Week 4: side project

This week, a tangent was added on to my main research project.  The main idea is that closely related milkweed species can and do hybridize with each other.  The two species we are focusing on for this side project are Asclepias syriaca, common milkweed, and Asclepias exaltata, poke milkweed.  These two species prefer different conditions, but often grow close enough together to cross pollinate.  A. exaltata prefers more water and partial sun while A. syriaca is drought tolerant and prefers full sun.  This means that A. exaltata is often found at forest edges and A. syriaca is most common in fields.  You can probably think of many examples of places that these two habitats border each other.  In theory, a hybrid between A. syriaca and A. exaltata would have a blend of traits from each parental species.  In a time of declining forest habitat and changing climate, hybrid species may have the best of both worlds.  Plants may be able to gain favorable characteristics to tolerate changing conditions far more quickly than animals due to their ability to hybridize.

In order to investigate the question of A. syriaca and A. exaltata hybrids, we are measuring leaf characteristics from digitized herbarium specimens.  The two species have distinctly different leaf shapes; A. syriaca leaves are broader and more rounded than A. exaltata leaves.  We are using an image analysis program to measure the pedicel length, midvein length, leaf width, basal angle, and apical angle.  I am then using R to analyze this data.  We expect to see that most leaves cluster with their own species, but hybrids may form a group with intermediate characteristics or cluster with one species or the other.  We may even take a trip to Big Meadows in Shenandoah National Park to take leaf measurements from live plants in the meadow.  I’m excited to take a break from coding and working on the computer to spend time with the live plants.