Research interests

I am Julissa Roncal, an associate professor at Memorial University of Newfoundland in Canada. I integrate phylogenetics, biogeography, geology, and ecology to reconstruct the evolutionary origin and assembly of biota with a focus on tropical American environments. To manage the plant natural resources upon which human society so heavily depends, it is important to understand the evolutionary history and processes that led to plant diversity, and incorporate this knowledge within conservation actions. My team and I conduct research in four main areas:

Systematics and Historical Biogeography of Caribbean Plants

The Caribbean is among the top 5 world biodiversity hotspots with significantly less studies than other tropical regions. It has a complex geological history with landmasses fragmentation and rejoining, active volcanisms and sea level changes. Among the hypotheses proposed to explain the origin of Caribbean biota are: in-situ speciation, migration and vicariance. We test these hypotheses using molecular dated phylogenies and biogeographic modelling of Caribbean endemic plants. Main research questions that we have are: How palaeogeographical events influenced the evolution of Caribbean biota? Did the GAARlandia landbridge play a role as colonization facilitator from South America? Does the progression rule (older lineages inhabit older islands and colonize new ones as they emerge) apply to the Caribbean? Relevant papers where the below figures were published: Roncal et al. (2020), Nieto-Blazquez et al. (2021), Nieto-Blazquez et al. (2022)

Evolution of Tropical Plant Species Complexes

Plant species complexes are good systems to study the origin and maintenance of the high species diversity in the tropics because this diversity is due in large part to the presence of many large genera with several recent closely related species. We investigate the genetic, phenotypic, and niche differentiation of  populations or closely related species to provide insight into speciation patterns like sympatric, peripatric, or allopatric speciation. We work with palm (Arecaceae) species complexes of Western Amazonia as case studies (Geonoma macrostachys and Astrocaryum sect Huicungo). Relevant papers where the below figures were published: Roncal et al. (2015) J Biogeogr; Jimenez-Vasquez et al. (2017) Bot J Lin Soc; Bacon et al. (2021) Bot J Lin Soc

Conservation Genomics

Using next generation sequencing data across the entire plant genome, we aim to determine the genetic diversity, structure and evolutionary history of endangered species’ populations. This information permits the delineation of Management and Evolutionary Significant Units for conservation. It also guides the collection of propagules for ex-situ conservation and reintroductions if deemed necessary. Our case studies are in the palm (Parajubaea) and mustard (Braya) families, inhabiting the Andes and limestone barrens of Newfoundland, respectively.

Boreal Phylogenetic Community Ecology

The field of phylogenetic community ecology was born with the suggestion that the phylogenetic distances separating species in a community, i.e. phylogenetic community structure, could indicate whether abiotic, biotic or stochastic factors drive the assembly in a community. However, the ability to infer community assembly processes from phylogenetic distance patterns is challenging because it requires several assumptions. For example: that assembly processes influence all lineages equally within a community. We test this assumption on the boreal biome by investigating changes in phylogenetic structure patterns of clustering versus overdispersion with respect to phylogenetic scale (shallow/deep nodes), and with respect to spatial scale (spatial extent of a boreal habitat versus a plot).

My research program is funded by: