Broadly, my research interest is in avian speciation and diversification. I approach this question from multiple angles and time-scales, with analyses spanning the whole population genetic-phyogeographic-phylogenetic continuum. My major geographic focus is on islands of the South Pacific, which act as a natural laboratory for studying the speciation process.
Gene Flow in Islands
One aspect of insular speciation that has received little attention in the past is how much gene flow occurs between populations once they are isolated. As others are finding in mainland systems, the more taxa we examine, the more cases of post-divergence gene flow we find. This occurs at a range of taxonomic levels (species to populations), and across hundreds of kilometers of open ocean. There is also ample opportunity to integrate estimates of gene flow into classic island biogeographic theory, to find potential factors that reduce gene flow between islands (e.g. trade winds, reproductive isolation, reduced dispersal ability). We have also found that such gene flow can bias phylogeographic inference within groups of islands, such that the most isolated island may be inferred as sister to all others, even when that conflicts with colonization history. Finally, this line of research provides an interesting possibility to explain the maintenance of populations on small, isolated islands via genetic rescue from rare migrants. I am integrating all of this into population genetic simulations, including spatially explicit ones using SLiM.
Systems: Symposiachrus barbatus complex and 16 other Solomon Island taxa, Pachycephala vitiensis complex, simulations
Systems: Symposiachrus barbatus complex and 16 other Solomon Island taxa, Pachycephala vitiensis complex, simulations
Diversification of Insular Clades
I am interested in all aspects of diversification, phylogenetics, biogeography, and systematics of island taxa. I find that each presents an interesting problem that is oftentimes met with an additional level of complexity relative to mainland taxa. One major question I am interested in is the impact of dispersal ability on diversification in taxa. I am also interested in better understanding the relationship between morphometric, plumage, and genetic differentiation in island taxa. This often includes subspecies-level phylogenetics, especially due to the inconsistent taxonomic treatment of phenotypically divergent island taxa (see all subspecies of Aplonis tabuensis to the right).
Systems: Aplonis starlings
Systems: Aplonis starlings
Introgression and Hybrid Populations
In both islands and mainland populations, genomic methods have enabled us to find more and more examples of adaptive introgression and hybrid populations. I am broadly interested in researching the importance of adaptive introgression in insular and continental populations, and determining how widespread a phenomenon it is. This comes with a focus on uncovering the "diversification stories" of challenging clade. This often manifests in determining instances of hybrid populations (including hybrid species and subspecies) in the wild, a phenomenon of potentially underappreciated frequency, especially in insular species.
Systems: Vireo bellii, Symposiachrus trivirgatus complex, Pachycephala vitiensis complex
Systems: Vireo bellii, Symposiachrus trivirgatus complex, Pachycephala vitiensis complex
Odds and Ends
I've got a few other projects less concordant with my other research themes. This includes everything from evolutionary morphology of crane claws to assessing the potential hybrid nature of vagrant wrens in New Mexico. I'm always interested in taking casual field and literature observations to the next level, and love to discussing that with others! I also seek to be collaborative, and am a collaborator on several exciting projects and have provided bioinformatic support for many others.
Publications
*dENOTES Co-first authors
Skeen H, Willard DE, Jones AW, Winger BM, Gyllenhaal EF, Tsuru BR, Hackett SJ, Novembre J (2023). Intestinal microbiota of Nearctic-Neotropical migratory birds more variable over seasons and years than between host species. Molecular Ecology, 32, 3290–3307. (Link)
Tan DJX, Gyllenhaal EF, Andersen MJ (2022). PleistoDist: A toolbox for visualising and quantifying the effects of Pleistocene sea-level change on island archipelagos. Methods in Ecology and Evolution, 14(2), 496-504. (Link)
McCullough JM, Gyllenhaal EF, Mapel XM, Andersen MJ, & Joseph L (2021). Taxonomic implications of recent molecular analyses of Spectacled (Symposiachrus trivirgatus) and Spot-winged (S. guttula) Monarchs (Passeriformes: Monarchidae). Emu, 121(4), 365–371. (Link)
Williamson JL*, Gyllenhaal EF*, Oliver KD, Brady SS, Johnson AB, Michelsohn MJ, & Andersen MJ (2021). Predictable outcomes of warbler hybridization: Synthesis and an exceptional Yellow × Black-throated Blue Warbler (Setophaga petechia × S. caerulescens) pairing. The Wilson Journal of Ornithology, 133(1), 82–102. (Link)
Andersen MJ, McCullough JM, Gyllenhaal EF, Mapel XM, Haryoko T, Jønsson KA, & Joseph L (2021). Complex histories of gene flow and a mitochondrial capture event in a nonsister pair of birds. Molecular Ecology, 30(9), 2087–2103. (Link)
Mapel XM*, Gyllenhaal EF*, Modak TH, DeCicco LH, Naikatini A, Utzurrum RB, Seamon JO, Cibois A, Thibault J, Sorenson MD, Moyle RG, Barrow LN, Andersen MJ (2020). Inter- and intra-archipelago dynamics of population structure and gene flow in a Polynesian bird. Molecular Phylogenetics and Evolution, 156, 107034. (Link)
Gyllenhaal EF, Mapel XM, Naikatini A, Moyle RG, & Andersen MJ (2020). A test of island biogeographic theory applied to estimates of gene flow in a Fijian bird is largely consistent with neutral expectations. Molecular Ecology, 29(21), 4059-4073. (Link)
Tan DJX, Gyllenhaal EF, Andersen MJ (2022). PleistoDist: A toolbox for visualising and quantifying the effects of Pleistocene sea-level change on island archipelagos. Methods in Ecology and Evolution, 14(2), 496-504. (Link)
McCullough JM, Gyllenhaal EF, Mapel XM, Andersen MJ, & Joseph L (2021). Taxonomic implications of recent molecular analyses of Spectacled (Symposiachrus trivirgatus) and Spot-winged (S. guttula) Monarchs (Passeriformes: Monarchidae). Emu, 121(4), 365–371. (Link)
Williamson JL*, Gyllenhaal EF*, Oliver KD, Brady SS, Johnson AB, Michelsohn MJ, & Andersen MJ (2021). Predictable outcomes of warbler hybridization: Synthesis and an exceptional Yellow × Black-throated Blue Warbler (Setophaga petechia × S. caerulescens) pairing. The Wilson Journal of Ornithology, 133(1), 82–102. (Link)
Andersen MJ, McCullough JM, Gyllenhaal EF, Mapel XM, Haryoko T, Jønsson KA, & Joseph L (2021). Complex histories of gene flow and a mitochondrial capture event in a nonsister pair of birds. Molecular Ecology, 30(9), 2087–2103. (Link)
Mapel XM*, Gyllenhaal EF*, Modak TH, DeCicco LH, Naikatini A, Utzurrum RB, Seamon JO, Cibois A, Thibault J, Sorenson MD, Moyle RG, Barrow LN, Andersen MJ (2020). Inter- and intra-archipelago dynamics of population structure and gene flow in a Polynesian bird. Molecular Phylogenetics and Evolution, 156, 107034. (Link)
Gyllenhaal EF, Mapel XM, Naikatini A, Moyle RG, & Andersen MJ (2020). A test of island biogeographic theory applied to estimates of gene flow in a Fijian bird is largely consistent with neutral expectations. Molecular Ecology, 29(21), 4059-4073. (Link)