Admixture of hybrid swarms of native and introduced lizards in cities is determined by the cityscape structure and invasion history

Abstract

Introductions of non-native lineages increase opportunities for hybridization. Non-native lineages of the common wall lizard, , are frequently introduced in cities where they hybridize with native populations. We aimed at unravelling the invasion history and admixture of native and non-native wall lizards in four German cities using citywide, comprehensive sampling. We barcoded and genotyped 826 lizards and tested if gene flow in populations composed of admixed native and introduced lineages is facilitated by similar environmental factors to those in native populations by comparing fine-scale landscape genetic patterns. In cities with non-native lineages, lizards commonly occurred in numerous clusters of hybrid swarms, which showed variable lineage composition, consisting of up to four distinct evolutionary lineages. Hybrid swarms held vast genetic diversity and showed recent admixture with other hybrid swarms. Landscape genetic analyses showed differential effects of cityscape structures across cities, but identified water bodies as strong barriers to gene flow in both native and admixed populations. By contrast, railway tracks facilitated gene flow of admixed populations only. Our study shows that cities represent unique settings for hybridization, caused by multiple introductions of non-native taxa. Cityscape structure and invasion histories of cities will determine future evolutionary pathways at these novel hybrid zones.

Gene flow and genetic drift in urban environments

“…(2), to determine which variables best predicted the response to urbanization, we used a multi-model averaging approach. This approach identifies the best fitting model implemented, using the dredge function in the r package mumin (Barton & Barton, 2013; Methods in Appendix S1). In addition to using model averaging, we also performed a more conventional single ANOVA on each response variable.…”

“…To test whether the urban landscape is indeed the main factor driving these differences in genetic drift and gene flow between urban and nonurban populations, many studies have used a landscape genetics approach (Beninde, Feldmeier, Veith, & Hochkirch, ; Delgado‐Ratto et al, ; Thomassen et al, ; Wood et al, ; Yakub & Tiffin, ). This approach allows researchers to identify potential barriers or conduits to gene flow between populations and make inferences about the effects of the landscape on evolutionary processes.…”

Beyond the landscape: Resistance modelling infers physical and behavioural gene flow barriers to a mobile carnivore across a metropolitan area

“…Molecular genetic methods permit inferences about wildlife dispersal without the need to collect extensive field data on individual movements (Frantz, Do Linh San, Pope, & Burke, 2010;Guillot, Leblois, Coulon, & Frantz, 2009). Recently, numerous studies of gene flow in urban areas have been published, but many of those focus on smaller and less mobile species that are thought to face major barriers in urban areas (Beninde, Feldmeier, Veith, & Hochkirch, 2018;Combs, Puckett, Richardson, Mims, & Munshi-South, 2018;Munshi-South, 2012). Studies on larger and more vagile species, in contrast, analysed the population genetic structure of animals from peripheral suburban populations or from isolated sampling sites within urban and rural areas (Blanchong, Sorin, & Scribner, 2013;Santonastaso, Dubach, Hauver, Graser, & Gehrt, 2012;Stillfried, Fickel, et al, 2017;Wandeler, Funk, Largiadèr, Gloor, & Breitenmoser, 2003).…”

Metropolitan lizards? Urbanization gradient and the density of lagartixas (Tropidurus hispidus) in a tropical city

“…This understanding, however, is limited as most studies have focused almost completely on birds and mammals (e.g., Chiari, Dinetti, Licciardello, Licitra, & Pautasso, ; Sol et al, ; Santini et al, ; but see Walsh, Goulet, Wong, & Chapple, and Winchell, Carlen, et al, ). Moreover, most studies are restricted to temperate regions (e.g., Beninde, Feldmeier, Veith, & Hochkirch, ; Møller et al, ), while the impact on most of the species of vertebrates that live in tropical cities is practically unknown; we have only a vague idea of how urbanization affects their ecology, morphology, and genetics.…”

“…Moreover, most studies are restricted to temperate regions (e.g., Beninde, Feldmeier, Veith, & Hochkirch, 2018;Møller et al, 2012), while the impact on most of the species of vertebrates that live in tropical cities is practically unknown; we have only a vague idea of how urbanization affects their ecology, morphology, and genetics.…”