Agenda

Samantha S. Hopkins, University of Oregon - Earth Science Department

Title: Rodent Ecology and Evolution in the Neogene: Holarctic Perspectives on the Consequences of Habitat Change

Abstract:
Dramatic changes in terrestrial ecosystems through the Neogene have had a significant effect on the evolution of mammals. Major changes in body size, in diets, in locomotor habits, and in social behavior have been demonstrated by numerous past studies. The increasing dominance of open habitats and cool, seasonal climates have driven greater hypsodonty in ungulate herbivores with an increasingly grassy diet, as well as larger body mass and more frequent cursoriality. Large carnivores likewise see increases in cursoriality and body size to keep pace with their prey. Predatory clades also see new hunting strategies to account for changes in both the prey species themselves and the characteristics of the environments, with longer sight lines and less opportunity for concealment and ambush. Lagging behind our understanding of the larger mammals is our understanding of changes in small mammal ecology. A recent synthesis of North American data using the NOW database revealed that the ecomorphology of small mammals changed much earlier than their larger relatives, with increases in both hypsodonty and open-habitat locomotor adaptations such as digging and hopping. We have added to this dataset to ask how small mammals in Asia and Europe responded to similar changes, given that the timing of the spread of open habitats was similar throughout the Holarctic. Small mammals show some similar changes, but the degree of community change is less dramatic in Europe than it is in North America, with more of the continent still forested even into the Pleistocene. This apparently smaller change is likely exacerbated by the underrepresentation of the more forested eastern half of the North American continent in published Neogene fossil occurrences. Asia’s rodent diversity bears more resemblance to that of North America, with greater diversity of open-habitat-adapted small mammal taxa through much of the Neogene, before ungulates and large carnivores become well-adapted to open ec osystems. This finding shows the importance of small mammals, which respond more rapidly to environmental change than their larger cousins, to detecting the timing of ecosystem changes. The distinct responses in Europe and Asia also highlight global differences in patterns of ecological change, making it all the more important to add data from South America, Australia, and Africa to these databases in order to get a clear sense of the relationship between mammals and ecosystem change.

You can attend the seminar online, zoom link: https://unive.zoom.us/j/87474284419
Meeting ID: 874 7428 4419

Bio Sketch
Samantha Hopkins studies the evolution of ecology in fossil mammals, particularly rodents and other small mammals. She uses a wide range of methods from phylogenetic comparative methods and systematics to field techniques such as biostratigraphy and paleomagnetics. Her interests are particularly focused on the spread of open habitats in the late Paleogene and early Neogene, and she has worked on the evolution of burrowing habits and hypsodonty in a wide range of small mammal groups. She has also studied the systematics and evolutionary history of the Aplodontiidae, a group of rodents that once ranged over Eurasia and North America, but are now limited to a much narrower range in the Northwest U.S. She’s currently focused on understanding the processes that shape evolutionary change in ecology both within small mammal lineages and within communities of small mammals.
https://earthsciences.uoregon.edu/profile/shopkins/