Undergraduate Projects

The Pygmy rabbit (Brachylagus idahoensis) is a sagebrush obligate, which lives in small, fragmented populations.  Because many of the persisting populations are isolated, understanding dispersal can be crucial for the continued success of the species.  Pygmy rabbits disperse relatively long distances for their size and not much is known about what geographic features might serve as barriers.  To understand what serves as a barrier to dispersal by pygmy rabbits, Wendy Estes-Zumpf and Janet Rachlow at the University of Idaho (UI) are studying rabbits at several field sites in Idaho, Montana and Utah.  During June-July of 2006, I worked as a summer intern on this project through the Center for Research on Invasive Species and Small Populations (CRISSP) at UI.  The field sites were selected on the basis of proximity to a geographic feature, such as sites on either side of a mountain range or river.  We trapped rabbits and gathered measurements on weight, foot size, ear size, ectoparasite load, and sex.  We also obtained a DNA sample for genetic analyses.  Wendy Estes-Zumpf is using 19 microsatellites to analyze how closely related populations are and what geographic features the rabbits cross while dispersing.  This research will help us understand what geographic features are acceptable and which might further divide already fragmented populations.

Invasiveness may be the result of ‘novel weapons’ that aid an introduced plant to outcompete evolutionarily naïve neighbours in its new range.  Roots of Eurasian species of Centaurea are thought to produce allelochemicals that function as novel weapons in North America.  However, a series of three experiments suggested that fungal endophytes that naturally established in seedling roots could have been confounded with novel weapons.  In the first two experiments, endophtyes in roots of C. stoebe significantly reduced the biomass of naïve neighbours (i.e., Festuca idahoensis plants), compared to the effect of endophyte-free C. stoebe on F. idahoensis.  For the third experiment, relative abundances of endophytes of C. stoebe in both its native and invaded ranges were determined so that representatives of the six most common haplotypes, three from each range, could be employed as root inoculants.  In general, each of these endophytes again reduced the growth of naïve neighbours (i.e., Festuca idahoensis); remarkably, each also increased the growth of adapted neighbours (i.e., Festuca ovina) that were tested for the first time.  Four of the six endophytes caused C. stoebe to gain a competitive advantage over its naïve neighbour  that was significantly greater than the competitive advantage of endophyte-free C. stoebe over that same neighbour. Endophyte-free C. stoebe had no greater competitive advantage over F. idahoensis than it had over F. ovina.  By aiding an invasive plant against F. idahoensis in a cryptic manner, endophytes could be confounded with novel weapons.  However, without evidence that these endophytes are themselves native to Eurasia, it is premature to assert that they are themselves novel weapons.