Department of Ecology & Evolution

Kronforst Lab

We have a variety of on-going research projects in the lab, some of which are briefly described here:

Genetics of mimicry in Heliconius

Neotropical butterflies in the genus Heliconius are unpalatable, aposematic, and they have undergone a recent adaptive radiation in wing color patterns as a consequence of natural selection for Müllerian mimicry. We are working to identify the molecular basis of the genes that control wing pattern diversity in Heliconius using a combination of high-resolution genetic mapping, fine-scale linkage disequilibrium mapping, and comparative analyses of gene expression. Currently, much of our work is focused on association mapping the color patterning loci K, Yb, and B/D in Heliconius cydno.

association figure

Mate choice and speciation

The white vs. yellow color difference that mediates premating reproductive isolation between sister species H. cydno and H. pachinus in Costa Rica also segregates in a polymorphic population of H. cydno alithea in western Ecuador. Using a combination of genetic mapping and mate choice experiments we are comparing the genetic basis of mimicry between the systems in Costa Rica and Ecuador and determining whether color-based mate preference also segregates with color in a polymorphic setting.

Heliconius butterflies

Genetics of mate preference in Heliconius

In addition to warning predators, the color patterns of Heliconius butterflies are used as conspecific recognition cues during mating. Previously, we have shown that the white vs. yellow wing color difference between H. cydno and H. pachinus (the K locus) is a critical recognition cue and a major QTL for male color preference is tightly linked to color itself. We are currently applying genetic and association mapping approaches to identify the genetic basis of assortative color preference in Heliconius and characterize the association between color and preference.

genetics Heliconius

Speciation and mimicry in tiger swallowtail butterflies

The recently described North American Papilio appalachiensis is suspected to be a hybrid species between Papilio glaucus and P. canadensis. It has a mix of morphological and phenological traits derived from its putative parental species. It shares its mimetic female form and some wing pattern elements with P. glaucus but most other traits with P. canadensis. We are using a variety of molecular genetic approaches to investigate the evolutionary history of P. appalachiensis and its relationships with P. glaucus and P. canadensis to determine whether it is a product of historical hybridization between the latter two species.

Tiger Swallowtail butterfly

Genetics of mimicry in Papilio polytes

Papilio polytes, a widely ranging Asian swallowtail, has a single male form and several female forms, most of which mimic locally abundant and toxic Pachliopta butterflies. There is a dominance hierarchy between female forms, the non-mimetic female form being recessive to all others. We are studying the genetic basis of the female-limited mimetic polymorphism in P. polytes with the goal of identifying the molecular basis of this mimicry supergene. Furthermore, in collaboration with Sean Mullen, we are comparing the genetic basis of mimicry among Heliconius, Papilio, and Limenitis butterflies.

Comparative phylogeography of Heliconius co-mimics

H. erato and H. melpomene mimic one another throughout their shared range of Central and South America but their color patterns change, in tandem, from location to location. The evolutionary processes responsible for this geographic variation in mimicry remain unclear. We are estimating racial-level phylogenies for the two species using both AFLPs and mtDNA sequences and testing whether the two species radiated in parallel across time and space. Our results are showing that the two species arrived in this diverse mimetic relationship starting at very different times, places, and phenotypes.

Heliconius image

Phylogeography of Heliconius across Central America

Research on phylogeography in Heliconius has largely focused on South America, with only Costa Rica and Panama sampled from Central America. Thus the biogeography of Heliconius in Mesoamerica has not been investigated. We are sampling Heliconius species across Central America to examine biogeographic patterns. In particular we are focusing on comparing pairs of mimetic species such as H. erato and H. melpomene.


Hybridization & introgression among Heliconius

Hybridization is widespread among closely-related Heliconius species and we are using molecular genetics to quantify the extent and timing of interspecific gene flow among sympatric species. Our work in Costa Rica has shown appreciable introgression among the closely-related species H. cydno, H. pachinus, and H. melpomene. Furthermore, we have found evidence for on-going gene flow between the melpomene/cydno clade and H. hecale, a member of the silvaniform clade, groups that diverged almost 2.5 million years ago. Currently, we are following up on this work by examining hybridization and gene flow among melpomene/cydno/silvaniform species in west Ecuador.

Genetics of migration in monarch butterflies

Monarch butterflies (Danaus plexippus) are famous principally for their spectacular annual migration up through North America. However, the subspecies D. plexippus megalippe, which resides mostly in Central and South America, does not show migratory behavior. We are interested in comparing these migratory and non-migratory relatives to determine the extent of their genetic divergence, and to identify genes which may be involved in the evolution of migratory behavior.


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