Ongoing Research Projects

The Dlugosch lab studies the genetics of colonization and its evolutionary and ecological outcomes. Our work draws largely on the natural experiments provided by human-mediated species introductions and we are working to understand how the genetic variation in these populations translates into phenotypic diversity, adaptation, and changes in ecology. 

• Sources of genetic variation & consequences of admixture
  
  
• Evolution of inbreeding depression
  
  
• Evolution of 'invasiveness'
  
  
• The genetic basis of adaptation

Sources of genetic variation and consequences of admixture 

It is a simple truism that evolution requires genetic variation. For colonizing populations, the source(s) of individuals and genes that contribute to a new population will determine its raw material for future evolution. Among introduced species in particular, mixing of material from different source locations and hybridization with related species are both hypothesized to enhance adaptation and establishment success. However, we know little about how often or how much these processes actually contribute to variation in founding populations, and whether such intra- or inter-specific hybridization results in novel traits that are not already found in the initial source of an introduction. Using genomic scans and phenotypic surveys, we are exploring both admixture and inter-specific hybridization in the widespread noxious invader yellow starthistle (Centaurea solstitialis).

Evolutionary loss of inbreeding depression

In plants, the ability to self pollinate would seem to confer a tremendous advantage during colonization, and indeed many studies have found an association between self pollination and colonization success of some kind.  Selfing may be especially beneficial to invading species, because opportunities to establish a new population from a single individual may abound in unoccupied (but suitable) habitat.  Whether inbreeding lineages succeed during colonization should be a function of the need for reproductive assurance and the ability to evolve reduced inbreeding depression.  Invasions provide truly exceptional study systems in which to investigate the adaptive evolution of inbreeding depression and realized rates of inbreeding.  We are exploring these questions in individual, isolated introductions of Canary Island St. Johnswort (Hypericum canariense), which show evidence of dramatic evolutionary losses of inbreeding depression during expansion.

The evolution of 'invasiveness'

There is a growing appreciation that adaptive evolution might contribute directly to invasive behavior in introduced species, allowing them to overcome environmental obstacles and exploit ecological opportunities. Nevertheless, adaptation is a process of relative changes in the fitness of different lineages, and this may have little impact on vital rates in the population overall. We are working to make links between genetic variation, adaptation, and colonization success by following the demographic performance of different genotypes and populations of invading species species.  We are currently planning experiments that will use the contained experimental landscapes (LEO project) inside of Biosphere2 to permit population-level experiments with multiple natural and synthesized invader genotypes.

Genetic basis of adaptation

We have observed evidence of adaptation in recently introduced populations that have experienced strong genetic bottlenecks, highlighting the need to understand how genetic architecture makes such rapid evolution possible. 'Next-generation' sequencing technologies are providing the opportunity to begin making the connection between such rapid phenotypic evolution and its molecular genetic basis in non-model organisms. We are using cutting-edge genomic and bioinformatic approaches to map the genetic basis of evolving traits, and to infer the ecological functions that might be under selection during colonization.