Reduced levels of relatedness indicate that great-tailed grackles disperse further at the edge of their range

  1. Dieter Lukas
  2. Aaron D. Blackwell
  3. Maryam Edrisi
  4. Kristin Hardy
  5. Christa LeGrande
  6. Zara Marfori
  7. Kelsey B. McCune
  8. August Sevchik
  9. Caroline Smith
  10. Corina J. Logan

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Abstract

It is generally thought that behavioral flexibility, the ability to change behavior when circumstances change, plays an important role in the ability of a species to rapidly expand their geographic range. To expand into new areas, individuals might specifically show flexibility in dispersal behavior, their movement away from their parents to where they themselves reproduce. Great-tailed grackles ( Quiscalus mexicanus ) are a bird species that is rapidly expanding its geographic range and are behaviorally flexible. Here, we infer dispersal rates in wild-caught grackles from two populations across their range (an older population in the middle of the northern expansion front in Arizona nearer the core of their original range versus a young population on the northern edge of the expansion front in California) to investigate whether grackles show flexibility in their dispersal behavior between these two populations. Based on genetic relatedness, we observe no closely related pairs of individuals at the edge, suggesting that individuals of both sexes disperse further from their parents and siblings in this population than in the population nearer the core. Our analyses also suggest that, in both populations, females generally move shorter distances from where they hatched than males. These results elucidate that the rapid geographic range expansion of great-tailed grackles is associated with individuals, in particular females, differentially expressing dispersal behaviors.

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  1. Version published to 10.24072/pcjournal.591
  2. Peer Community in Ecology

    Under current global change scenarios, many species may need to shift their current distribution ranges to cope with new environmental and human-related conditions. A species’ ability to do so is closely linked to its dispersal behavior (e.g., Chen et al 2011, Hill et al. 2011), among other factors. Therefore, understanding the factors that influence species dispersal is essential for predicting the future viability of populations.
    One of the factors that may be affecting the dispersal patterns of the species is behavioral flexibility (i.e., the ability of some animal species to adapt their actions to new conditions). In previous studies derived from the same pre-registration as the present work (Logan et al. 2020), the research team of this study has demonstrated that behavioral flexibility in great-tailed grackles (Quiscalus mexicanus) plays a role in shaping their foraging behavior (Logan et al. 2025). More importantly, they have also found differences in the variability of dispersal behavior between populations located at the core versus the edge of the species’ distribution (Logan et al. 2023), suggesting that differential behavioral expression at the range edge may accelerate geographic range expansion.
    In this study, the authors go one step further by comparing the dispersal behavior in wild-caught grackles from the edge and at the core of their distribution range. To do so, they examined average levels of genetic relatedness among individuals within each population.  Overall, they find support for their hypothesis that natal dispersal is greater in those grackle populations located closer to the edge of the expansion front. Additionally, they found sex-related differences in the movement patterns, with females dispersing shorter distances than males. Thus, this study suggests that individual differences in the movement patterns may be behind the rapid geographic range expansion shown by the great-tailed grackles.
    As the authors clearly indicate, the study is limited by the small number of sampled populations (n = 2), and they recommend for future studies including a larger number of populations to better assess other possible factors associated to the genetic differences within the species. Nevertheless, the strength of their conclusions is supported by a large dataset, robust statistical analyses, and a hypothesis-driven approach. In sum, I am pleased to recommend this pre-print (Lukas et al. 2025), as it adds to previous evidence about the drivers of rapid geographic range expansions. I think the study will be of interest of researchers in biogeography, behavior ecology, movement ecology and genetic ecology.
    I would like to emphasize that this manuscript is based on the preregistration by Logan et al. (2020), which already received an In Principle Acceptance (Sebastián-González 2020) in Peer Community in Ecology. Thus, all the objectives, methodology and statistical analyses had already been published and evaluated, and any deviation from the pre-registration has carefully been explained, promoting transparency and reproducibility in science.
     
    References
    Chen, I. C., Hill, J. K., Ohlemüller, R., Roy, D. B., & Thomas, C. D. (2011). Rapid range shifts of species associated with high levels of climate warming. Science, 333(6045), 1024-1026. doi:0.1126/science.120643


    Hill, J. K., Griffiths, H. M., & Thomas, C. D. (2011). Climate change and evolutionary adaptations at species' range margins. Annual review of entomology, 56(1), 143-159. doi:10.1146/annurev-ento-120709-144746


    Logan, C.J., Lukas, D., Geng, X., Hardy, K., LeGrande, C., Marfori, Z., MacPherson, M., Rowney, C., Smith, C., McCune K. B. (2025) Behavioral flexibility is related to foraging, but not social or habitat use behaviors, in a species that is rapidly expanding its range. EcoEvoRxiv, ver.3 peer-reviewed and recommended by PCI Ecology doi:10.32942/X2T036


    Logan, C. J, McCune, K., Bergeron, L., Folsom, M., Lukas, D. (2019). Is behavioral flexibility related to foraging and social behavior in a rapidly expanding species? Recommended by Peer Community In Ecology. http://corinalogan.com/Preregistrations/g_flexforaging.html


    Logan, C.J., McCune, K., LeGrande-Rolls, C., Marfori, Z.; Hubbard, J., Lukas, D. (2023) Implementing a rapid geographic range expansion - the role of behavior changes. Peer Community Journal, 3: e85. https://doi.org/10.24072/pcjournal.320


    Lukas, D., Blackwell, A. D., Edrisi, M., Hardy, K., LeGrande, C., Marfori, Z., McCune, K., Sevchik, A., Smith, C., Logan C. L. (2025) Reduced levels of relatedness indicate that great-tailed grackles disperse further at the edge of their range. EcoEvoRxiv, ver.4 peer-reviewed and recommended by PCI Ecology https://doi.org/10.32942/X2ND0N


    Sebastián González, E. (2020) The role of behavior and habitat availability on species geographic expansion. Peer Community in Ecology. Reviewers: Caroline Nieberding, Tim Parker, and Pizza Ka Yee Chow. https://doi.org/10.24072/pci.ecology.100062

     

     

  3. Version published to 10.32942/x2nd0n