Small mammals play important roles in ecosystems, but are often overlooked due to their small size and plentiful abundance. Two studies evaluated the morphological differences and diversity of small mammal species based on how they react to different environmental conditions. The first study analyzed the morphological differences of skulls between and within two species of Peromyscus species due to differences in shape, size, and geographic position. This study also determined if landmark-based geometric morphometrics could reliably discriminate between the two species. The second study analyzed small mammal diversity and abundance due to differences in microhabitat conditions in an endangered ecosystem: tallgrass prairie. Small mammals are an important food source to other vertebrate and also help regulate vegetation composition in the tallgrass prairie ecosystem. Results of both studies could help future studies identify how different variables affect small mammal morphology and diversity.