Coyote crossroads: LA coyotes differ genetically from nearby forest coyotes
Adducci II A, Jasperse J, Riley S, Brown J, Honeycutt R, Monzón J. 2020. Urban coyotes are genetically distinct from coyotes in natural habitats. J Urban Ecol. 6(1). doi:10.1093/JUE/JUAA010.
Header image: Coyote crossing the road; photo by Tom Shockey
Coyotes in the city
All throughout North America and Central America you may spot a Coyote shuffling nearby. This is because Coyotes (Canis latrans) use nearly all habitats and can eat a variety of foods. The flexibility to live in many habitats helps them thrive even in highly urbanized cities. In fact, researchers studying Coyotes in the city have found that they often are less wary of humans, readily exploit human food and are more active at night relative to their forest counterparts.
Figure 1: Coyote in road: picture by Raquel Baranow
Is living in the city inherently bad?
As scientists study how urbanization and human development affect species, they are finding that some animals, like coyotes, seem to be able to adjust to city life. Many rodents, lizards, birds and coyotes seem to exploit access to human food (https://link.springer.com/article/10.1007/s13280-014-0547-2). However, a long term consequence of living in the city could be a loss of genetic diversity.
Genetic diversity and why does it matter
Genetic diversity is a measure of distinct breeding groups in a population. Populations with more distinct breeders will be more diverse and thus less susceptible to the negative effects that can result from inbreeding. One concern with living in the city is that animals may not be able to navigate throughout highly developed areas (like major highways) and thus populations will be smaller and less connected to other populations. For example, coyotes live in many areas throughout North and Central America. Nearly 30 years ago, studies found very little genetic differentiation in coyotes across the American Continent. This means that populations have high genetic diversity because of the species ability to live in many habitats and to travel great distances. This resulted in a large genetic diversity and there were no detectable subgroups with distance across the continent. However, recently it was found that urban features in New York were associated with genetic subgroups in coyotes. Because of this, the author of the study Anthony Anduci II (Genetic Researcher at University of Ljubljana) and his colleagues, explored whether development in the city of Los Angeles also result in a decrease of genetic diversity in Coyotes.
Escape from LA: does city life affect genetic diversity?
To study whether urbanization in LA affected genetic diversity of coyotes, researchers first identified populations across LA that were distributed along a gradient of development (Figure 2). The team obtained a total of 134 genetic samples across the city of LA. They found that populations could be genetically separated into four subgroups and a fifth highly mixed genetic group. Groups 1,2 and 4 are associated with increased urbanization. Coyotes from the genetic population 3 mostly lived in forest habitats and in the outskirts of the metropolitan area.
Figure 2: Sites where coyotes were sampled in and around the metropolitan area of Los Angeles, California USA. Figure from article(open access).
The researchers also tested for associations with road density and genetic diversity. They found that population 3 (forest and city outskirt coyotes) had the highest genetic diversity and that genetic diversity decreased with urbanization (figure 3). Interestingly, this forest population had similar genetic diversity in contrast to the admixture population. Furthermore, forest sites are far more distant to each other than the city sites. This finding might be explained by the fact that coyotes in highly urbanized areas might not be able to move out of these areas to breed with other coyotes. In contrast, forest coyotes might be more readily breeding between subgroups regardless of the greater distance between them. In fact, populations with the lowest genetic diversity (1 and 4) also had the greatest density of roads per kilometer squared.
Figure 3: Comparison of genetic diversity (number of alleles) against urbanization. Forest coyotes (population 3) had a higher genetic diversity than genetic population in more urbanized areas (populations 1,2 & 4). Figure from article (open access).
The findings of this study are an important evidence to show how features of urbanization can impact species that appear to thrive in these habitats. In other words, even though we have evidence of coyotes adjusting to life in the city, they are still affected by features of the city. This can be used to advocate for more natural corridors to allow animals to cross the road safely and travel beyond the highly urbanized areas.