Tommy Herrera

he/him

Education: Majoring in fishery, wildlife, and conservation biology

McNair Project: Where west meets east: A mid-continental transition zone and spatial congruence of North American boreal small mammal diversification (2020)

Mentor: Andrew Hope, Ph.D.

Anthropogenic environmental changes are altering biodiversity’s distribution and ecological interactions with rising temperatures driving populations poleward and fragmenting high latitude communities. Comparative phylogeographic assessments are a powerful tool for quantifying and interpreting regional biodiversity dynamics and taxonomic groups with shared ecology and evolutionary history offer an opportunity for assessing evolutionary and ecological processes. Here, we resolve the intra-specific phylogeographic structure of 8 small mammal species associated with North America’s boreal forest and belonging to the Boreo-Cordilleran faunal community to resolve infraspecific phylogeographic structure, establish regional transition zones, and lay a preliminary framework for assessing changing biodiversity dynamics through time. We then assess lineage divergence and geographic structure using geodata processing and Bayesian computation methods to test the hypotheses of spatial congruence and temporal incongruence of species diversification across a mid-continental ecotone in Manitoba, Canada separating eastern and western lineage differentiation. Our results affirm spatial congruence and temporal incongruence of regional divergence across North America’s high latitude taxon groups, suggesting repeated episodes of diversification through time with climactic and geographic drivers. They also indicate spatial and temporal incongruence among other taxonomic groups, suggesting alternative drivers for diversification. Our results highlight the need for further investigation into the ecological factors that shape communities’ evolutionary histories and continued assessment of biodiversity by building on North America’s phylogeographic structure and establishing a geographically and evolutionarily significant region for studying future regional biodiversity dynamics that could aid conservation in predicting, assessing, and mitigating the disturbances of anthropogenic environmental change.

McNair Project: Comparative phylogeography and distribution modeling for Great Plains mammals (2021)

Mentor: Andrew Hope, Ph.D.

The Great Plains is the interface between North America’s major biomes and faunal communities. Much of the Great Plains’ faunal community persist on the peripheral of adjacent regional distributions, however, little has been invested into understanding the region’s community assemblage. Here we evaluate phylogeographic literature from the past decade to construct a comparative phylogeography of vertebrate species co-distributed across the Great Plains of North America to establish regional clusters of phylogeographic breaks, challenge classical approaches of assessing phylogeographic concordance, and explore the mechanisms structuring genetic diversity in biodiversity of the Great Plains. Assessment of six phylogeographic studies of species associated with the Great Plains showed four of the six species expressed phylogeographic breaks through the southern Great Plains. The phylogeographic breaks assessed varied throughout tier precise geographic orientation, however, this is expected as the Great Plains lack physical landscape features to uphold highly localized phylogeographic breaks. The observed breaks possessed varying levels of divergence times linked to vicariance (geographic separation) via Pliocene and Pleistocene glacial cycles as the driving mechanism. Our observations highlight the need for increased investigation of species throughout the Great Plains, including both evolutionary and ecological, and increased sampling altogether throughout North America.