Genetic structure across urban and agricultural landscapes reveals evidence of resource specialization and philopatry in the Eastern carpenter bee, Xylocopa virginica L.

Abstract

Human activity continues to impact global ecosystems, often by altering the habitat suitability, persistence, and movement of native species. It is thus critical to examine the population genetic structure of key ecosystemservice providers across human‐altered landscapes to provide insight into the forces that limit wildlife persistence and movement across multiple spatial scales. While some studies have documented declines of bee pollinators as a result of human‐mediated habitat alteration, others suggest that some bee species may benefit from altered land use due to increased food or nesting resource availability; however, detailed population and dispersal studies have been lacking. We investigated the population genetic structure of the Eastern carpenter bee, Xylocopa virginica, across 14 sites spanning more than 450 km, including dense urban areas and intensive agricultural habitat. X. virginica is a large bee which constructs nests in natural and human‐associated wooden substrates, and is hypothesized to disperse broadly across urbanizing areas. Using 10 microsatellite loci, we detected significant genetic isolation by geographic distance and significant isolation by land use, where urban and cultivated landscapes were most conducive to gene flow. This is one of the first population genetic analyses to provide evidence of enhanced insect dispersal in human‐altered areas as compared to semi‐natural landscapes. We found moderate levels of regional‐scale population structure across the study system (GʹST = 0.146) and substantial co‐ancestry between the sampling regions, where co‐ancestry patterns align with major human transportation corridors, suggesting that human‐mediated movement may be influencing regional dispersal processes. Additionally, we found a signature of strong site‐level philopatry where our analyses revealed significant levels of high genetic relatedness at very fine scales (<1 km), surprising given X. virginica's large body size. These results provide unique genetic evidence that insects can simultaneously exhibit substantial regional dispersal as well as high local nesting fidelity in landscapes dominated by human activity.

Population genomics and phylogeography of Colletes gigas, a wild bee specialized on winter flowering plants

“…Their genetic characteristics are quite different, especially at the genomic level (Grozinger & Zayed, 2020 ; Zayed, 2009 ). Given that the current mainstream methods for population genome analysis are performed on diploid data (see Ballare & Jha, 2020 ; Ji et al, 2020 ), female specimens were used to ensure data consistency. Female adults of C .…”

“…Their genetic characteristics are quite | 3 of 12 different, especially at the genomic level (Grozinger & Zayed, 2020;Zayed, 2009). Given that the current mainstream methods for population genome analysis are performed on diploid data (see Ballare & Jha, 2020;Ji et al, 2020), female specimens were used to ensure data consistency. Female adults of C. gigas (N = 55) were collected between October and December in 2019 and October in 2020, using a systematic sampling strategy to ensure the uniformity of spatial distribution (Table 1, Figure 1).…”

“…Some species adapt to and even thrive in human‐dominated habitats. For example, habitat restoration promotes the rapid colonization of new habitats in cities and suburbs (Matteson et al, 2008 ; Theodorou et al, 2018 ), increasing the genetic diversity of bees (Ballare & Jha, 2020 ; Theodorou et al, 2020 ; Vickruck & Richards, 2017 ). In addition, the natural abundance and distribution of host plants (Dellicour et al, 2014 , 2015 ) and the human‐mediated domestication of crops (López‐Uribe et al, 2016 ) can promote the rapid expansion of obligate bees with respect to population size and geographic distribution.…”

Expanding insect pollinators in the Anthropocene

“…This ability, combined with increased forest coverage after 1945 and the urbanization of Europe after 1900, has probably allowed it drastically to increase its abundance, range, and density, including in new countries where it can be the most common species in urban areas (Prŷs‐Jones et al ., 2016 ; BWARS, 2017 ; Prŷs‐Jones, 2019 ). In North America, the carpenter bee Xylocopa virginica also benefits from anthropogenic modifications of habitats, this large bee nesting almost exclusively in structures built from milled lumber such as spruce and pine (Ballare & Jha, 2020 ). In cities, the increasing popularity of bee hotels in public parks also provides new nesting opportunities for bees.…”

Natural and anthropogenic landscape factors shape functional connectivity of an ecological specialist in urban Southern California

“…Anthropogenic disturbances have direct and indirect effects on connectivity through habitat fragmentation and degradation (e.g., vegetation community conversion and introduction of invasive species). Urban development and land use change can act as a barrier or a conduit to gene flow, depending on the species and the composition of the urban landscape (Ballare & Jha, 2020 ; Miles et al, 2019 ). Species with limited dispersal abilities, as well as those incapable of occupying the urban matrix, exhibit higher levels of genetic divergence in response to anthropogenic factors including habitat fragmentation and habitat loss (Delaney et al, 2010 ; Epps & Keyghobadi, 2015 ; Miles et al, 2019 ; Richmond et al, 2009 ).…”