Research

I am broadly interested in how ecological selection generates and maintains population-level genetic and phenotypic diversity. As an outgrowth my main research interests and in an effort to work collaboratively with local communities at my field sites, I have become increasingly interested in research related to the conservation of intraspecific diversity. I approach my research questions using an integrative approach spanning morphological, ecological, and genomic techniques and leveraging museum collections in addition to field and molecular work. Below, I describe my major ongoing projects.

Local Adaptation in Generalists: Species whose ranges encompass substantial environmental variation should experience heterogeneous selection, potentially resulting in local adaptation. Repeated covariation between phenotype and environment across ecologically similar species that inhabit similar environmental gradients provides strong evidence for adaptation. Caribbean anoles provide an excellent system in which to study repeated local adaptation because many species are widespread generalists occurring throughout environmentally heterogenous island landscapes that typically range from xeric coastal scrub to montane rainforests. My research in this area has utilized Lesser Antillean anoles as evolutionary replicates to show parallel patterns phenotype-environment covariation. Current projects include investigating if phenotypic parallelism is underlain by parallelism in lower levels of biological organization and identifying the precise selective forces that shape patterns of phenotypic variation across the landscape.

Example publications:

  • Yuan ML, Jung C, Frederick JH, Fenton C, de Queiroz K, Cassius J, Williams R, Wang IJ, Bell RC (2023) Parallel and non-parallel phenotypic responses to environmental variation across Lesser Antillean anoles. Evolution. DOI: 10.1093/evolut/qpad018
  • Wogan GOU, Yuan ML, Mahler DL, Wang IJ (2020) Genome-wide epigenetic isolation by environment in a widespread Anolis lizard. Molecular Ecology 29:40–55. DOI:10.1111/mec.15301

Diversification through Niche Partitioning: Niche differentiation as an outcome of competition has long been posited as a major driver of diversification. A central theme of my research is understanding the contexts in which competition can act as the dominant driver of divergence. Research in this area spans several systems including the repeated adaptive radiations of the Greater Antilles, novel communities of introduced anoles, and the depauperate Lesser Antillean anole fauna. By exploring competition in related species under various context, I aim to build a multifaceted understanding of when competition does and does not lead to diversification. Projects in this area include demonstrating correlative selection of traits associated with microhabitat partitioning, showing that phylogenetic contingency plays an important role in how species respond to competition, and an ongoing effort to characterize the genomics of character displacement.

Example publications:

  • Wogan GOU, Yuan ML, Mahler DL, Wang IJ (2023) Hybridization and transgressive evolution as drivers of adaptive radiations: reticulate evolution generates diversity in the Puerto Rican Anolis Lizards. Systematic Biology. syad026. DOI: https://doi.org/10.1093/sysbio/syad026
  • Yuan ML, Jung C, Wake MH, Wang IJ (2020) Habitat use, competition, and phylogenetic history shape the evolution of claw and toepad morphology in Lesser Antillean anoles. Biological Journal of the Linnean Society 129:630–643. DOI: 10.1093/biolinnean/blz203
  • Yuan ML, Wake MH, Wang IJ (2019) Phenotypic integration between claw and toepad traits promotes microhabitat specialization in the Anolis adaptive radiation. Evolution 73:231-244. DOI: 10.1111/evo.13673

Island Conservation Biology: The Caribbean forms one of the world’s biodiversity hotspots and has been a foundational system for our understanding of island biogeography. My research in this area strives to contribute to capacity building in local communities and to provide information of applied value to stakeholders. Major projects in this are aimed at understanding how land use change disrupts local adaptation, understanding how historical processes such as volcanism and sea level change have shaped population structure, and resolving the cryptogenic species problem (species are those whose native and non-native ranges are unknown). The Caribbean poses a particular challenge to accurate assessments of species distributions due to the network of anthropogenically-interconnected insular systems in close geographic proximity whose human influence dates to prehistory. In the absence of high quality historical data, phylogeographic and population genetic analyses can provide useful tools for differentiating native and introduced ranges.

Example publications:

  • Yuan ML, Frederick JH, McGuire JA, Bell RC, Smith SR, Fenton C, Cassius J, Williams R, Wang IJ, Powell R, Hedges SB (2022) Endemism, invasion, and overseas dispersal: the phylogeographic history of the Lesser Antillean frog, Eleutherodactylus johnstonei. Biological Invasions 24:2707–2722. DOI: 10.1007/s10530-022-02803-9

Natural History: Evolutionary biology and ecology are deeply rooted in the tradition of natural history. Therefore, I believe that an understanding of the natural history of my study systems are important for building a more fully formed understanding of basic questions in evolutionary and ecology. I am continuing to contribute basic natural history information on Caribbean herpetofauna.