Adcyap1 polymorphism covaries with breeding latitude in a Nearctic migratory songbird, the Wilson's warbler (Cardellina pusilla)

Abstract

Understanding the genetic background of complex behavioral traits, showing multigenic control and extensive environmental effects, is a challenging task. Among such traits, migration is known to show a large additive genetic component. Yet, the identification of specific genes or gene regions explaining phenotypic variance in migratory behavior has received less attention. Migration ultimately depends on seasonal cycles, and polymorphism at phenological candidate genes may underlie variation in timing of migration or other aspects of migratory behavior. In this study of a Nearctic-Neotropical migratory songbird, the Wilson's warbler (Cardellina pusilla), we investigated the association between polymorphism at two phenological candidate genes, Clock and Adcyap1, and two aspects of the migratory phenotype, timing of spring migration through a stopover site and inferred latitude of the breeding destination. The breeding destination of migrating individuals was identified using feather deuterium ratio (d 2 H), which reliably reflects breeding latitude throughout the species' western breeding range. Ninety-eight percent of the individuals were homozygous at Clock, and the rare heterozygotes did not deviate from homozygous migration phenology. Adcyap1 was highly polymorphic, and allele size was not significantly associated with migration date. However, Adcyap1 allele size significantly positively predicted the inferred breeding latitude of males but not of females. Moreover, we found a strong positive association between inferred breeding latitude and Adcyap1 allele size in long-distance migrating birds from the northern sector of the breeding range (western Canada), while this was not the case in short-distance migrating birds from the southern sector of the breeding range (coastal California). Our findings support previous evidence for a role of Adcyap1 in shaping the avian migratory phenotype, while highlighting that patterns of phenological candidate gene-phenotype associations may be complex, significantly varying between geographically distinct populations and even between the sexes.

Clockgene polymorphism, migratory behaviour and geographic distribution: a comparative study of trans‐Saharan migratory birds

“…; Bazzi et al . ), suggesting that differences among species could be due to any type of nucleotide variation. Hence, Adcyap1 allele size variation among species could not be attributed to short tandem repeats only, nor the type of mutation might be easily correlated with specific functional changes, implying that allele size variation at the promoter region of this candidate gene is not useful for comparative purposes.…”

“…, ; Bazzi et al . , ; Bourret & Garant ). Such an among‐species variability in candidate gene diversity could be associated with migratory behaviour and/or geographic distribution.…”

Length polymorphisms at two candidate genes explain variation of migratory behaviors in blackpoll warblers (Setophaga striata)

“…For Adcyap1 , longer alleles have been shown to be associated with greater migratory restlessness (Mueller et al, ; Peterson et al, ), earlier spring arrival dates (Mettler, Segelbacher, & Schaefer, ), and earlier postnatal dispersal (Chakarov, Jonker, Boerner, Hoffman, & Krüger, ). Additionally, in one species, more northerly breeding populations had longer Adcyap1 alleles on average than southerly populations (Bazzi et al, ), which may reflect geographic variation in migratory strategies or phenological schedules resulting from local adaptation to environmental cues (Johnsen et al, ). However, the relationships between candidate genes and migratory phenotypes may also be influenced by local environmental factors such as temperature, photoperiod, and breeding density (Bourret & Garant, ), potentially complicating interpretations of geographic patterns within species.…”

Circadian genes polymorphism and breeding phenology in a resident bird, the yellow‐legged gull

“…These findings are in line with an increasing body of evidence showing that differences in polymorphism in photoperiodic genes, especially Clock r1 and Adcyap1 , often occur among geographically distinct populations (Johnsen et al ., ; O'Malley & Banks, ; O'Malley et al ., ; Kuhn et al ., ; Bazzi et al ., ). Comparisons of latitudinal clines in allele frequency and in the gene‐phenotype associations depending on the breeding latitude in the yellow‐legged gull would help to establish whether variation at these genes may have played a role in adaptation to local environments, like in other vertebrates (Johnsen et al ., ; O'Malley & Banks, ; O'Malley et al ., ).…”

“…To date, only one study (Bourret & Garant, ) disclosed a complex genotype by environment interaction on breeding date: in female tree swallows ( Tachycineta bicolor ), Adcyap1 length polymorphism did not predict laying dates per se (see also Chakarov et al ., ), but depending on the breeding latitude (Bourret & Garant, ). We note that a lack of the association between length polymorphism in the Adcyap1 gene and breeding phenology can be explained by the observed genetic variability of this gene, which is markedly lower than that disclosed in other species (Chakarov et al ., ; Bourret & Garant, ; Bazzi et al ., , b).…”