Morranlab
Contact Info
- Levi T. Morran
- lmorran@indiana.edu
Indiana University Jordan Hall room 117 1001 E. 3rd St. Bloomington, IN, USA
I am currently a postdoc in the Lively lab at Indiana University.
Email me if you would like a full version of my CV.
Education
- 2009, PhD, University of Oregon
- 2004, BS, Indiana University
Research interests
I am broadly interested in factors that either facilitate or constrain adaptive evolution. Currently I am exploring the roles that mating systems and coevolutionary dynamics play in adaptive evolution.
I utilize experimental evolution to directly test hypotheses and determine the manner in which evolution proceeds by characterizing both the phenotypic and genetic changes that occur in evolving populations.
- MATING SYSTEM EVOLUTION
Mating systems dictate the manner in which genes are transmitted from parent to offspring, and therefore determine the level of genetic variation within and between lineages of a population. Mating systems are a key component of reproduction and reproduction is a basic requirement in biology. Despite this ubiquitous importance, many different mating systems exist in nature. I am interested in the selective pressures that favor specific mating systems, the genetic consequences of different mating systems, and their overall role in shaping the evolutionary trajectory of a population and/or lineage over time.
I primarily work with the nematode Caenorhabditis elegans because this species utilizes two different mating strategies, outcrossing and self-fertilization. C. elegans hermaphrodites can either self-fertilize or outcross with male individuals.
Current Projects:
- Genetics of Parallel Evolution in Experimentally Evolved Outcrossing Populations: In a previous experimental evolution project, I exposed several obligate outcrossing C. elegans populations to Serratia marcescens. Each population evolved the same defensive response to Serratia marcescens despite the fact that each population started the experiment with a different genetic background. I am currently working to determine the genetic basis of adaptation and parallel evolution of the behavioral response that arose in each population.
- Maintenance of Male-Specific Genes and Phenotypes in Selfing and Outcrossing Populations: C. elegans maintains males at very low frequencies in most strains (an indicator that outcrossing is rare in these strains). Theoretical work suggests that C. elegans naturally maintains males at frequencies sufficient to maintain male-specific genes through selection, and therefore preserve the male phenotype from mutation accumulation. I am using long-term experimental evolution to determine the consequences of maintaining males at low frequencies. I will measure the rate and magnitude of molecular and phenotypic change in male-specific genes and traits within populations that maintain males at different frequencies (ranging from obligate selfing to obligate outcrossing).
- COEVOLUTIONARY DYNAMICS
Coevolution accounts for a significant proportion of the evolutionary change that occurs in nature. This is quite reasonable because most, if not all, species live as members of communities composed of many species. As a result of interactions between members in a community, many species utilize not only their own genome, but also the genome of other species to facilitate survival and reproduction in context of mutualistic interactions. Conversely, antagonistic interactions between species are capable of driving rapid evolutionary change between interacting species. Thus intergenomic interactions, resulting from both mutualistic and antagonistic coevolution, play a major role in shaping the evolutionary trajectory of many species.
Current Projects:
-Antagonistic coevolution - Experimental Coevolution Test of the Red Queen: This project combines my interests in both mating system evolution and coevolutionary dynamics! The Red Queen Hypothesis predicts that selective pressure from coevolving parasites can select for increased sexual reproduction (or outcrossing) in host populations because sex (or outcrossing) can produce offspring with rare genotypes that may avoid infection. I am using the nematode C. elegans, along with several components of the C. elegans genetic tool-kit, to experimentally test Red Queen Hypothesis predictions, as they pertain to outcrossing and self-fertilization, via experimental coevolution with the virulent bacterial pathogen Serratia marcescens.
-Mutualistic coevolution - Empirical Tests and Genomic Analysis of the Constraints Imposed by Coevolution Within a Mutualism: The mutualistic relationship between the nematode, Steinernema carpocapsae, and its symbiotic bacteria, Xenorhabdus nematophila, provides a rich experimental context for testing coevolutionary hypotheses. The two symbiotic partners operate in conjunction to infect a wide range of insect hosts. Although the nematode and bacterium share a very close mutualistic relationship, each can be maintained separately in the laboratory. This aspect of the system permits the deconstruction of the relationship and the opportunity to study the evolutionary constraints of an intimate mutualistic relationship. In this system suites of genes in both mutualist species facilitate interactions between both species and can ultimately determine the collective fitness of the pair. Thus, the genetic basis of these crucial emergent traits exhibited by the species pair is partitioned across the species barrier. This distribution of correlated genes between separate species may limit the adaptive potential and alter the evolutionary trajectory of the symbiotic relationship and/or each species separately. I am using experimental evolution in this system to determine the effect of coevolution within a mutualism on adaptation rates in X. nematophila either maintained within or independent of its nematode symbiont.
Collaborators
- Jennifer Anderson, University of Oregon, Phillips Lab
- Farrah Bashey-Visser, Indiana University
- Heidi Goodrich-Blair, University of Wisconsin-Madison
- Curt Lively, Indiana University
- Michelle Parmenter, University of Oregon, Phillips Lab
- Patrick Phillips, University of Oregon
Publications
-
Bashey, F., L.T. Morran, and C.M. Lively. 2007. Coinfection, kin selection, and the rate of host exploitation by a parasitic nematode. Evolutionary Ecology Research 9: 947-958.
- Morran LT, Cappy BJ, Anderson JL, and Phillips PC. Sexual partners for the stressed: facultative outcrossing in the self-fertilizing nematode Caenorhabditis elegans. Evolution. 2009 Jun;63(6):1473-82. DOI:10.1111/j.1558-5646.2009.00652.x |
- Morran LT, Parmenter MD, and Phillips PC. Mutation load and rapid adaptation favour outcrossing over self-fertilization. Nature. 2009 Nov 19;462(7271):350-2. DOI:10.1038/nature08496 |
- Anderson JL, Morran LT, and Phillips PC. Outcrossing and the maintenance of males within C. elegans populations. J Hered. 2010 Mar-Apr;101 Suppl 1(Suppl 1):S62-74. DOI:10.1093/jhered/esq003 |
Research in News and Media Coverage
Mutation load and rapid adaptation favour outcrossing over self-fertilization:
News and Views, Agrawal, AF. 2009 Evolutionary biology: Why reproduction often takes two.
University of Oregon news release
The following two links include sexual content that may not be suitable for all individuals:
Science and Faith
I am an evolutionary biologist and a follower of Jesus. I chose evolutionary biology (and specifically experimental evolution) as a field of study to get a firsthand look at the process of evolution as part of a personal search for truth. After almost 10 years of research, I am continually fascinated by, and an ardent proponent of, evolution and its comprehensive ability to explain the diversity of life on Earth. My quest for truth through the study of evolution has only served to strengthen my faith and allowed me to experience intellectual and spiritual freedom by embracing both faith and science as integral components in my life.
Given my faith and my love of science, it is no surprise that I have a keen interest in the creation/evolution debate currently ongoing in the United States. I believe that Intelligent Design and certain forms of Creationism threaten to undermine the scientific integrity of science classrooms across the country, while also marginalizing and sabotaging religious faith. I am particularly interested in making science and the scientific method accessible, comprehensible, and nonthreatening to faith-based groups in an effort to preserve scientific integrity and reconcile the fact of evolution with the choice to have faith in the supernatural.
I am profoundly interested in the relationship between science and faith. It is one of my favorite discussion points, so please feel free to email me with your thoughts or comments. I truly enjoy civil discussion and hearing different points of view.
Ken Miller and Francis Collins are excellent scientists and scholars that present compelling cases regarding the compatibility of science and faith. I highly recommend their work to anyone exploring this topic.
Organizations I Support
- Team Zachary raises funds for Lymphoma research through the University of Nebraska Medical Center in memory of my best friend Zach May.
- Smoky Mountain Great Dane Rescue, run by my brother and his wife, fosters, adopts, and advocates for Great Danes in the Southeastern US.
- National Center for Science Education is an organization that advocates for the inclusion of evolution and exclusion of nonscientific "origins" theories in public school science curricula.
Lifetime Collaborators
Fun Stuff
Sports
- Indianapolis Colts I love football!
- Oakland Athletics I like baseball.
- Columbia City High School Football My good friend is the varsity coach, this team is steadily improving and fun to follow.
- Eugene Marathon I'm not a runner, but I enjoy running (I've run the half, not the full).
Music
- WTTS Fm 92.3 From Dylan to Marley to Dave, they play great music.
- Carbon Leaf Great band everyone should check out!
- Mat Kearney Excellent musician and great performer!
- I've been known to listen to some George Strait every now and then too.
Movies
- Star Wars Uncut The rumors that I own a jedi robe are in fact true.
Food
I like cheeseburgers, burritos, and subs more than anyone really should. Here are a few of my favorites:
- Cornucopia- Best burgers in Eugene, OR!
- Opie Taylor's- Best burgers in Bloomington, IN! I attempted the Double Tank Burger Challenge and failed miserably. If you are up for a challenge, go for it! I hope you have better luck than me!
- Laughing Planet Cafe - Great burritos in Eugene and Bloomington!
- Dagwood's- Awesome subs in B-Town! I highly recommend the Dagwood Supreme.
