about samantha

Dr. Samantha Kreling is a postdoctoral researcher at Purdue University who studies wildlife biology. Samantha grew up in the San Francisco Bay area of California, and loved reading books (especially about wildlife), doing photography, and hiking in the hills near her house where there were always plenty of interesting animals and plants to observe and learn about. She also grew up playing sports and doing lots of art. She went to college at the University of California, Berkeley, where she studied biology, and after graduating started her PhD at the University of Washington. When she finished her PhD, she went on to become a researcher in another lab at Purdue. In her free time, she loves doing wildlife photography, trying new restaurants and cooking new recipes, and spending time with her needy golden retriever, Sequoia. 

Samantha recently had the results of a study accepted for publication. The goal of her study was to shed some light on differences in coloration between urban and non-urban wildlife. In this study, Samantha read lots of papers published by other scientists to try and develop her own hypothesis about there may be different phenotypes present in urban wildlife. Fur and feather color in mammals and birds is important for several reasons. It may help them blend in and hide from predators, or, for predators, blend in so they can sneak up on prey. Color can also play a role in finding a mate. Fur and feather color is caused by pigments produced by cells called melanocytes. There are two types of this pigment, generally called "melanin": Eumelanin creates black, gray, and dark brown fur and feathers, and phaeomelanin creates red and light brown colors. These are the same pigments that contribute to human hair color! The hair/fur/feather color trait is coded for and controlled by multiple genes, and mutations in these genes can change the color of the hair/fur/feathers. Many of these mutations are single point mutations, meaning that it only takes the addition, removal, or swap of a single base pair to make a difference!

Samantha hypothesized on why there are fur colors in urban environments that aren't often seen in non-urban environments. She came up with several hypotheses for why this might be. Her study includes some helpful diagrams to illustrate these hypotheses.

Some of the reasons these new colors may not exist in non-urban areas are that they may have been eaten by predators before they could breed (A). In urban areas, human presence may protect or shield smaller animals from the predators that do exist, and food from human sources can also help new colors survive (B). Even if there is still a predation risk, urban areas often include a wider variety of color backgrounds like asphalt, brick, cements, and different colors of buildings (as opposed to the largely green and brown backgrounds in the wild). This allows animals of different colors to blend in better in urban areas (C). While human-sources of food can sometimes help urban animals, if those foods are low-nutrition, it could potentially result in non-heritable mutations that affect fur/feather color that wouldn't be seen in non-urban areas where animals are eating their natural diet (D). Similarly, exposure to toxic materials only found in urban areas could increase mutation rates (E). Urban areas tend to be warmer than non-urban, due to the way human made structures reflect and absorb heat differently from soil, grass, and trees. Certain colors may help urban wildlife thermoregulate (control their body temperature) more efficiently (F). Finally, Samantha thinks that "novel" colorations (like a "blonde" raccoon, or albino opossum) may actually protect those individuals because humans are fascinated by them. This fascination may make humans more likely to feed that individual, provide habitat for it, etc (G).

All of these are promising ideas for why urban habitats tend to have different phenotypes present, and in different ratios, than non-urban habitats. The reasons may vary depending on species, and it is very likely a combination of the above hypotheses. More study is required to untangle all the causes and effects of phenotype variation in urban wildlife. Understanding how living in urban environments affects wildlife will be very important as the urbanization of wild places continues and more wildlife moves into our cities and towns.