Recent and widespread rapid morphological change in rodents

Area of Science:

• Evolutionary biology
• Mammalogy
• Ecology

Background:

• Rapid morphological change in mammals is rarely documented, typically observed in island rodents due to isolation.
• Island populations often exhibit such changes attributed to selective pressures or founder effects.

Purpose of the Study:

• To investigate the frequency and drivers of rapid morphological change in rodents across diverse geographic locations.
• To determine if mainland rodent populations exhibit similar rapid morphological changes as island populations.

Main Methods:

• Analysis of approximately 17,000 measurements from 1302 rodents across 28 museum series on four continents.
• Utilized generalized linear models and principal component analysis to assess morphological trait changes.
• Correlated morphological trends with environmental factors like human population density and climate data.

Main Results:

• Documented rapid morphological changes in rodents at 20 of 28 museum sites, including 15 mainland locations.
• Observed trends in 15 morphological traits, with a slight overall increase in body size.
• Found associations between morphological changes in several traits and human population density, temperature gradients, and precipitation trends.

Conclusions:

• Rapid morphological change in rodents is frequent and occurs on both mainland and island environments.
• Human population growth and climate change are suggested as significant drivers of these observed rodent morphological shifts.
• Morphological changes are not solely confined to isolated island ecosystems.