Research Spotlight: September 2020

Contributed by: Kayce C. Bell, Assistant Curator of Terrestrial Mammals at the Natural History Museum of Los Angeles County
Urban evolutionary research has accelerated in recent years as we recognize the value of understanding how evolution is occurring in these human-made landscapes. Research has revealed that urban-living populations have not just ecological, but also evolutionary responses to inhabiting an urban environment. In a recent paper, Natural history collections are critical resources for contemporary and future studies of urban evolution, my colleagues at the Natural History Museum of Los Angeles County and I investigated the role of natural history collections in urban evolutionary studies and wrote guidelines for increasing support and use of collections. There are numerous examples of evolutionary studies that take advantage of the time-series nature of natural history collections, from shifting distributions to morphological adaptations. It is indisputable that natural history collections are valuable for documenting change through time and urbanization is a prime example of the change that natural history collections record. 

In addition to summarizing the potential contributions of collections to urban evolutionary research, we investigated urban evolution studies that have used or contributed to natural history collections. A survey of 18 broad and taxon-specific journals over 11 years found 84 papers relevant to urban evolution that potentially could have used museum specimens and/or contributed specimens to natural history collections. We found that 10 urban evolution studies indicated they used natural history collections. We also recorded if a study collected a resource (e.g. specimen, tissue, photo, bird song) that could have been deposited in a natural history collection and only 10 (of 81 that collected a resource) indicated contributing specimens and data to collections. This latter finding suggests that researchers are not archiving material that would allow their results to be confirmed, nor are these projects producing specimens and other collections for future urban evolutionary research. 
We suspected that a major limitation to using natural history collections in urban evolution research was a lack of specimens. To test this hypothesis, we used percent impervious surface data as a proxy for urbanization in counties in the contiguous U.S. and plotted that against the number of amphibian, reptile, bird, and mammal specimens recorded in VertNet for that county over one decade (2000–2009). There was no discernible trend for reptiles, a moderately positive correlation for amphibians, birds had a strong positive correlation with urbanization, and mammals had a significantly negative correlation. These trends are likely explained by the different ways specimens are acquired. For example museums in urban areas often have active salvage programs for birds (e.g. collecting bird strikes against buildings), whereas mammal specimens are generally collected from less developed, more rural environments.

Urban evolutionary studies cannot use specimens that don’t exist. Our finding that few studies deposited specimens or specimen resources in an accessible archive suggests that there is work to be done to build this resource. The low levels of urban specimen deposition may be due to the inability of a museum to take in such specimens and data, a lack of investigator awareness of museums, or, likely, some combination of these, and perhaps other, factors. With this in mind, we have outlined a set of recommendations for various stakeholders to increase the number of urban specimens in museums. These recommendations include encouraging museum staff to advertise their collections policies to biologists and agencies, funding agencies requiring specimen deposition in funded proposals, and increasing institutional support for collections, among other actions. As museum scientists, we hope that an awareness of avenues for building urban specimen resources and their value for future research will encourage support for, contributions to, and use of urban natural history specimens in scientific research.

Photo Credit: 
Photo 1: taken by Hark and released under license from Adobe Stock
Photo 2 - 4: Allison Shultz