Clock gene variation in Tachycineta swallows.

Area of Science:

• Animal behavior
• Evolutionary biology
• Genetics

Background:

• Animals use photoperiod cues for reproduction, regulated by the circadian clock.
• Clock gene poly-Q length polymorphism has been linked to latitude and breeding timing in some species.
• Clutch initiation timing significantly impacts fitness in Tachycineta swallows.

Purpose of the Study:

• To investigate the association between Clock poly-Q length polymorphism and latitude in five Tachycineta species.
• To determine if Clock poly-Q variation relates to breeding phenology, including clutch initiation and incubation duration.
• To explore the link between Clock poly-Q allele diversity and clutch size decline within breeding seasons.

Main Methods:

• Compared Clock poly-Q region length polymorphism across five Tachycineta species with varying latitudes.
• Analyzed associations between Clock genotype and latitude, clutch initiation date, and incubation period.
• Examined the relationship between Clock poly-Q allele diversity and within-season clutch size decline.

Main Results:

• Clock poly-Q variation was not associated with latitude across the studied species.
• An association was found between Clock poly-Q allele diversity and the degree of clutch size decline.
• No evidence supported a link between Clock poly-Q variation and clutch initiation date or incubation duration.

Conclusions:

• There is no general association between latitude, breeding phenology, and Clock polymorphism in Tachycineta swallows.
• Clock poly-Q allele diversity, rather than latitude, may influence reproductive strategies like clutch size adjustment.