Graduate Student
Department of Zoology
University of Hawaii, Manoa
Honolulu, HI, 96822

vanderga@hawaii.edu
 
 

Research Interests

I am interested in the effects of habitat fragmentation on the distributions and population structures of the Hawaiian Tetragnatha spiders.

Kipukas:

I work in a forest kipuka system on the Big Island of Hawaii.  The Hawaiian word "Kipuka" means a variation or a change in form.  Kipukas are formed when a continuous forested habitat on the slope of an active volcano is covered by a newer lava flow.  Small remnant islands of forest are left behind in a sea of new lava. Over time, the plants and animals remaining in these patches can recolonize the new lava flow, generating a mosaic of successional habitats.  This is a continuous process spanning the life of the volcano. The kipuka system offers a unique opportunity to study the effects of natural fragmentation on a native ecosystem over known periods of time.

Consequences of Habitat Fragmentation:

Populations of species that are limited to the interior forest habitat in different kipukas may be isolated from one another, despite the relatively short geographic distances between these patches.  Isolation can then lead to genetic divergence among populations and ultimately, speciation. Alternatively, the dispersal capabilities of organisms between kipukas may be maintaining populations in fragments, as well as maintaining gene flow between these populations.

I am investigating the genetic isolation of populations of native spiders in the genus Tetragnatha using molecular methods.
 

Some Tetragnatha Spiders:

Tetragnatha spiders have undergone an emmense radiation in the Hawaiian islands.  In the forest kipukas on the big island, I have found 9 species.  Some are restricted to the interior forest habitat, while others prefer the edges of patches and others are found throughout the forest, edge and lava habitats.