Historical data reveals rapid phenotypic change in a polymorphic salamander

Nicholas Federico

Authors:  Maggie M. Hantak, Nicholas A. Federico, David C. Blackburn, Robert Guralnick

Faculty Mentor: Robert Guralnick

College: Florida Museum of Natural History


Color polymorphism is the presence of multiple color phenotypes (i.e., morphs) that co-exist within populations. The Eastern Red-Backed Salamander, Plethodon cinereus, has two common color morphs, a ‘striped’ morph exhibiting a red stripe on a black back, and an ‘unstriped’ morph that is completely black. Previous studies on P. cinereus detected a correlation between temperature and morph frequencies, along with other physiological and behavioral differences. However, previous studies have largely focused on a single population at a single time point, and therefore, spatiotemporal patterns of this polymorphism remain unknown. We examine whether morphs respond to changes in climate through differential alterations in body size and/or changes in morph frequency ratios across multiple populations and decades. We collected data from the Smithsonian National Museum of Natural History by taking digital photographs of 2,902 salamanders from five populations. Salamander length was measured, and citizen scientists identified color morph from photographs. Mixed-models show that smaller individuals are found in warmer temperatures and seasons, and salamander body size is decreasing over time. Models also show that the proportion of striped morphs has increased over time, and that striped morphs are more associated with warmer temperatures, while unstriped morphs are more associated with higher precipitation.

Poster Pitch

Click the video below to view the student's poster pitch.


Click the image to enlarge.
11 Responses
  1. Nice poster and some interesting results! So what would happen with increased temperature & humidity together (shift towards a wetter & warmer climate)?

    I particularly like the use of citizen science for the project. Any idea how many folks helped on Notes from Nature? Do you report your results back to them at some point?

    1. Nicholas Federico

      Based on these results I can’t definitively say what the exact results would be as we are unsure which variable would have the larger impact on frequencies.

      Regarding notes from nature, we had 279 participants over the course of the project. On the site, there is a blog post for each project and that post will be updated with the results for participants to see.

  2. Ajay Patel

    Great Poster dude! Do you think the correlation between temperature and striped morph frequency is a byproduct of the increase over time, or the other way around?

    1. Nicholas Federico

      I think it is likely that striped morphs increase over time is a byproduct of the correlation between striped morphs and temperature, yes.

  3. Mark

    Very interesting. Do you have any idea why the striped and solid morphs might be correlated with different temperature and precipitation levels? Might these traits increase fitness in their respective conditions, and if so, why?

    1. Nicholas Federico

      My theory is that it is based on each morphs ability to thermoregulate. It would seem that something in the striped morph’s biology, whether it be the coloration itself or another mechanism, allows it to maintain homeostasis in warmer and dryer conditions. The unstriped morph seems that it may not be able to maintain homeostasis as easily, and as such only thrives in cooler conditions, and also wetter conditions where it is easier to stay cool. However, more studies would be needed to be confident about this.

  4. Dave Blackburn

    Nice poster! I think that your figure showing morph frequencies through time would benefit from noting the specific years sampled.

  5. Nik Mirsaderov

    Very cool project! This is very relevant considering the climate change that is currently taking place. This study could have some major impacts on the world regarding evolution of organisms due to temperature, weather, and climate.

  6. Nik Mirsaderov

    Very cool project! This study is definitely relevant to the changing climate that we see today. I believe that this is very important regarding the theory of evolution, especially due to aspects of temperature, biome, weather, and climate.