Sex in the city: sexual selection and urban colonization in passerines

Abstract

Urbanization leads to a rapid and drastic transformation of habitats, forcing native fauna to manage novel ecological challenges or to move. Sexual selection is a powerful evolutionary force, which is sometimes predicted to enhance the ability of species to adapt to novel environments because it allows females to choose high-quality males, but other times is predicted to reduce the viability of populations because it pushes males beyond naturally selected optima. However, we do not know whether or how sexual selection contributes to the likelihood that animals will establish in urban areas. We use a comparative analysis of passerine birds to test whether traits associated with pre- and post-mating sexual selection predict successful colonization of urban areas. We found that plumage dichromatism was negatively associated with urban tolerance, but found no relationship with sexual size dimorphism or testes mass relative to body mass. While we cannot determine the exact reason why species with high plumage dichromatism occur less in cities, it is likely that urban areas increase the costs of expressing bright coloration due, for instance, to dietary constraints, limited male parental care or increased predation.

United colours of the city: A review about urbanisation impact on animal colours

“…Sexual dimorphism may be favourable to urban birds because it allows them to maintain high population fitness and population persistence through female mate choice and male–male competition (Candolin & Heuschele 2008; Iglesias‐Carrasco et al . 2019). On the other hand, sexual dimorphism can constrain species presence in urban areas due to sexual selection costs related to increased predation or infections (Iglesias‐Carrasco et al .…”

“…On the other hand, sexual dimorphism can constrain species presence in urban areas due to sexual selection costs related to increased predation or infections (Iglesias‐Carrasco et al . 2019). However, urban areas are characterised by lower predation pressure than non‐urban areas (Vincze et al .…”

“…2008; Iglesias‐Carrasco et al . 2019). The most striking difference between these studies may be attributed to methodological factors, since Leveau (2019) considered the relative abundance of the species, whereas Croci et al .…”

“…(2008) and Iglesias‐Carrasco et al . (2019) analysed species presence/absence in urban and non‐urban areas at global and regional scales, respectively; Iglesias‐Carrasco et al . (2019) analysed only passerine birds.…”

Socioeconomic variation across multiple cities predicts avian life-history strategies

“…There is now considerable evidence from both birds and mammals suggesting that cities filter for subsets of local species that have traits suited to population persistence in urban environments (Chace & Walsh 2006; Kark et al 2007; Croci et al 2008; Leveau 2013; Meffert & Dziock 2013; Meillère et al 2015; Aronson et al 2016; Silva et al 2016; Jokimäki et al 2016; Alberti et al 2017; Leveau et al 2017; Sepp et al 2018; Santini et al 2019; Hensley et al 2019). Relative to non-urban species, successful urban colonizers tend to have larger body masses, bigger brains and be tolerant of a broad range of environments (Bonier et al 2007; Croci et al 2008; Maklakova et al 2011; Lowry et al 2013; Iglesias-Carrasco et al 2019). The use of cities by migratory species is relatively unexplored, but there is some evidence that migratory birds may be underrepresented in urban ecosystems (Allen & O’Connor 2000; Kluza et al 2000; Poague et al 2000).…”