Maternal effects and urbanization: Variation of yolk androgens and immunoglobulin in city and forest blackbirds

Abstract

Wildlife inhabiting urban environments exhibit drastic changes in morphology, physiology, and behavior. It has often been argued that these phenotypic responses could be the result of micro‐evolutionary changes following the urbanization process. However, other mechanisms such as phenotypic plasticity, maternal effects, and developmental plasticity could be involved as well. To address maternal effects as potential mechanisms, we compared maternal hormone and antibody concentrations in eggs between city and forest populations of European blackbirds (Turdus merula), a widely distributed species for which previous research demonstrated differences in behavioral and physiological traits. We measured egg and yolk mass, yolk concentrations of androgens (androstenedione [A4], testosterone [T], 5α‐dihydrotestosterone [5α‐DHT], and immunoglobulins [IgY]) and related them to population, clutch size, laying order, embryo sex, and progress of breeding season. We show (a) earlier onset of laying in the city than forest population, but similar egg and clutch size; (b) higher overall yolk androgen concentrations in the forest than the city population (sex‐dependent for T); (c) greater among‐female variation of yolk T and 5α‐DHT concentrations in the forest than city population, but similar within‐clutch variation; (d) similar IgY concentrations with a seasonal decline in both populations; and (e) population‐specific positive (city) or negative (forest) association of yolk A4 and T with IgY concentrations. Our results are consistent with the hypotheses that hormone‐mediated maternal effects contribute to differences in behavioral and physiological traits between city and forest individuals and that yolk androgen and immunoglobulin levels can exhibit population‐specific relationships rather than trade‐off against each other.

A global meta‐analysis reveals higher variation in breeding phenology in urban birds than in their non‐urban neighbours

“…Our final dataset included 399 comparisons between paired urban–non‐urban populations from 35 bird species and 68 studies (Figure 1; refs. : Antonov & Atanasova, 2003; Bailly et al, 2016; Baldan & Ouyang, 2020; Beck & Heinsohn, 2006; Berardelli et al, 2010; Biard et al, 2017; Boal & Mannan, 1999; Bobek et al, 2018; Brahmia et al, 2013; Caizergues et al, 2018; Capilla‐Lasheras et al, 2017; Cardilini et al, 2013; Charter et al, 2007; Conway et al, 2006; de Satgé et al, 2019; Dhondt et al, 1984; Eden, 1985; Evans & Gawlik, 2020; Gahbauer et al, 2015; Glądalski, Bańbura, Kaliński, Markowski, Skwarska, Wawrzyniak, Zieliński, & Bańbura, 2016; Glądalski, Bańbura, Kaliński, Markowski, Skwarska, Wawrzyniak, Zieliński, Cyżewska, & Bańbura, 2016; Glądalski et al, 2015, 2017, 2018; Gryz & Krauze‐Gryz, 2018; Hajdasz et al, 2019; Hinsley et al, 2008; Ibáñez‐Álamo & Soler, 2010; Isaksson et al, 2008; Isaksson & Andersson, 2007; Jarrett et al, 2020; Kelleher & O'Halloran, 2007; Kettel et al, 2019; Kopij, 2017; Lee et al, 2017; Lin et al, 2015; Liven‐Schulman et al, 2004; Luna et al, 2020; Mcgowan, 2001; Mennechez & Clergeau, 2006; Middleton, 1979; Millsap et al, 2004; Minias, 2016; Morrissey et al, 2014; Newhouse et al, 2008; Partecke et al, 2020; Perlut et al, 2016; Pollock et al, 2017; Preiszner et al, 2017; Rollinson & Jones, 2003; Rosenfield et al, 2019; Schmidt & Steinba...…”

Cities as parasitic amplifiers? Malaria prevalence and diversity in great tits along an urbanization gradient

“…Urbanization not only impacts individual species but also species interactions (Faeth et al, 2011), which can affect species evolution (Ots & Hõrak, 1998;Marzal et al, 2005;Dyrcz et al, 2005). In particular, host-parasite interactions can be altered in urban habitats (Martin & Boruta, 2013;Becker et al, 2015) because of variations in both the occurrence and abundance of species enabling the spread and transmission of the parasite (i.e., the vector species) (Reyes et al, 2013;Giraudeau et al, 2014;Neiderud, 2015), changes in vectors' feeding preferences in urban areas (Santiago-Alarcon et al, 2012;Abella-Medrano et al, 2018) and shifts in body condition and immune system efficiency of host species (Bailly et al, 2016;Capilla-Lasheras et al, 2017;Partecke et al, 2020). Depending on the positive and/or negative impact on the vector and host species, the effect of urbanization on disease prevalence can be twofold.…”

Cities as parasitic amplifiers? Malaria prevalence and diversity in great tits along an urbanization gradient

“…If urbanization affects species singularly, it also affects the way species interact with each other (Faeth et al 2011) ultimately impacting species evolution (Ots and Hõrak 1998;Marzal et al 2005;Dyrcz et al 2005). In particular, host-parasite interactions can be altered in urban habitats (Martin and Boruta 2013;Becker et al 2015) for several reasons including (1) variation in both the occurrence and density of vector species (Reyes et al 2013;Giraudeau et al 2014;Neiderud 2015), (2) changes in vectors' feeding preferences in urban areas (Santiago-Alarcon et al 2012;Abella-Medrano et al 2018) and (3) shifts in body condition and immune system efficiency of host species in link with urban environmental conditions (Bailly et al 2016;Capilla-Lasheras et al 2017;Partecke et al 2020). As such, depending on the positive and/or negative impact on the vector and host species, the effect of urbanization on disease prevalence can be twofold.…”