Research themes

Effects of gene flow on adaptation & fitness

Predicting the fitness effects of gene flow is a notorious challenge in evolutionary and conservation biology. Gene flow among populations in different environments can introduce maladaptive alleles and reduce population fitness, but on the other hand, gene flow can increase fitness by increasing additive genetic variation in small, inbred populations and masking deleterious alleles. 

We use the model Trinidadian guppy system to study the complex role of gene flow on adaptation and fitness. A series of introduction experiments in Trinidad set up a great opportunity to study how gene flow affects locally adapted traits, fitness, and population dynamics in a well-characterized system. 

We are expanding on work with this system through individual-based pedigree reconstruction in wild populations in Trinidad, mesocosm experiments, and by gaining an understanding of the genomic architecture of hybrid fitness.

We collaborate with Funk , Angeloni , Hoke , and Ghalambor labs at Colorado State University on much of this work.

Genetic rescue in small populations

Genetic rescue is an increase in population growth caused by the introduction of new genetic variation. This could be caused by a recovery from inbreeding depression or increased potential for adaptive evolution.

We are interested in accurately predicting the conditions that lead to genetic rescue such as level of inbreeding depression, amount of gene flow, and level of divergence between recipient and source populations. We are also interested in determining the underlying genomic architecture. For example, is genetic rescue caused by a genome-wide increase in heterozygosity or by the masking of deleterious recessive alleles?

We are working towards a better understanding of genetic rescue through experiments, genomic data, meta-analyses, and theory and aim to apply what we've learned to species of conservation concern. 

Genetic variation in wild populations and landscapes 

We believe that molecular tools are transforming what we can learn about the ecology of organisms and will play an increasingly important role in ‘next generation natural history’. Genomic advances and increasingly sophisticated analyses are now able to provide extremely precise estimates of demographic parameters (i.e., effective population size, and gene flow), inbreeding, and the exciting possibility of characterizing adaptive genetic variation across landscapes, a previously unrealistic pursuit for non-model organisms.    

We use genomic tools such as RADseq, whole-genome-sequencing, and exon capture to answer questions about the ecology and evolution of natural populations as well as to inform conservation and management of imperiled species.

Current Fitz Lab research in this area includes characterizing 'streamscape' genomic patterns across the range of Arkansas darters (Etheostoma cragini; candidate for listing under the U.S. Endangered Species Act) and comparative genomics of desert extremist sand-diving lizards in the Namib Sand Sea (Meroles anchietae and M. cuneirostris) . 

Other Collaborations

Red-backed salamander population dynamics 

We have joined on as collaborators to SPARCnet : the salamander population adaptation reseach collaboration network. In December 2016 we established a red-backed salamander monitoring site (6 plots of 50 cover boards each) at KBS. Through linking individual based mark-recapture data at our site to other sites across the range we will help determine local and regional population dynamic patterns and test how land use change and climate affects salamander fitness. Local MSU collaborators include BEACON postdoc  Dr. Alexa Warwick and IBIO professor Dr. Elise Zipkin .  

Guppy gut microbiome

Microbes are increasingly realized to be an important component determining host fitness. In collaboration with KBS microbial ecologist  Dr. Sarah Evans we are examining how host-associated microbes are dually influenced by the genetic background and phenotypic traits of their host and environmental factors. 

Population genomics and assisted gene flow in declining Florida Scrub Jay populations