Submission Date

5-4-2026

Document Type

Paper- Restricted to Campus Access

Department

Biology

Adviser

Cory Straub

Second Adviser

Tristan Ashcroft

Committee Member

Colleen Bove

Department Chair

Denise Finney

Project Description

Red-backed salamanders (Plethodon cinereus) are a terrestrial salamander serving as a potential model organism for amphibian ecology, evolution, and behavior. This species exhibits a genetically based color polymorphism. The two morphs, unstriped and striped, have shown to occupy different environmental niches, with the unstriped morph associated with warmer temperatures and dryer conditions while the striped are associated with cooler temperatures and wetter conditions. We studied a P. cinereus population located in Collegeville, Pennsylvania to explore these niche differences and further investigate the environmental variables that underly the color morphs’ niche differences. We explored the influence of moisture and temperature on microhabitat selection in the field and laboratory and created statistical models exploring the relationship between temperature, precipitation, and color morph frequencies among populations in Northeast USA. In the field study, we found that unstriped color morphs were associated with cooler and wetter microhabitats, while striped morphs showed little response to moisture but were associated with warmer microhabitats. These results are consistent with previous findings for this population but are inconsistent with the more common geographical findings that unstriped morphs are associated with warmer and drier conditions than striped morphs.  Soil temperature and moisture were highly correlated in the field, so we attempted to disentangle these factors in the laboratory study. We found no evidence that the color morphs differ in their thermal preferences when moisture is not a limiting resource. Finally, our field results indicated that striped morphs can tolerate a broader range of temperature and moisture than unstriped morphs, so we hypothesized that geographic locations with greater variation in these conditions would support populations with a higher frequency of striped morphs. Our analyses show that mean temperature and temperature variation are valid predictors of striped morph frequency, but precipitation mean and variation are not significant predictors. We conclude that, in our study population, the striped morph tolerates a broader range of soil temperature and moisture than the unstriped morph, including warmer and drier conditions, but more studies are needed to confirm if this niche difference exists across populations. Future inter-population studies with better data on surface microclimates are needed to better test the hypothesis that striped morphs tolerate greater climate variation.

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