Clock gene is associated with individual variation in the activation of reproductive endocrine and behavior of Asian short toed lark

Abstract

Within year individual variation in the timing of seasonal reproduction within wild bird populations in highly seasonal environments can be pronounced, but the molecular and physiological mechanisms responsible for this variation are unclear. We investigated the relationship between Clock gene poly-Q length, activation of the HPG endocrine axis, and the timing of breeding behavior, in a wild population of the Asian short-toed lark (Calandrella cheleensis) in Inner Mongolia, China. Six variants of Clock gene poly-Q alleles were identified in this population. Clock poly-Q mean allele length was positively correlated with the mean peak date deviation of individual birds. The shorter an individual’s Clock poly-Q mean allele length, the earlier its plasma LH, T and E2 values peaked. Mean Clock poly-Q allele length of nestlings in the same nest were positively correlated with the standardized laying date of the first egg in that nest. These results suggest that the Clock gene influences the reproductive timing of birds through its effect on the HPG endocrine axis, and that individual variation in the timing of reproduction may have a genetic basis.

No evidence for an association between Clock gene allelic variation and migration timing in a long-distance migratory shorebird (Limosa lapponica baueri)

“…Analogous studies in fish and flies support the idea that Clock allelic variation is associated with latitudinal adaptations (Costa et al 1992;Leder et al 2006;O'Malley and Banks 2008). It has been suggested that the effect of Clock on breeding timing may be via its effect on the hypothalamus-pituitary-gonad (HPG) endocrine axis (Zhang et al 2017). Clock has also been suggested to relate to migration timing or distance in birds, but results have been variable.…”

“…Variation in ClockpolyQ in birds has been mostly studied in relation to latitudinal clines across populations or breeding phenology traits (e.g., laying date) (Johnsen et al 2007;Liedvogel et al 2009;Bourret and Garant 2015;Zhang et al 2017). Analogous studies in fish and flies support the idea that Clock allelic variation is associated with latitudinal adaptations (Costa et al 1992;Leder et al 2006;O'Malley and Banks 2008).…”

“…The functional significance of variation in ClkpolyQ length is thought to lie in responses to photoperiod, with a tendency toward longer alleles in more northern populations reflecting selection pressures from longer daylengths at higher latitudes (Johnsen et al 2007;Bazzi et al 2016a). There is some evidence for ClkpolyQ length of individual birds relating to laying date in passerines (Liedvogel et al 2009;Caprioli et al 2012;Bourret and Garant 2015;Zhang et al 2017). Zhang et al (2017) proposed, based on rat (Rattus rattus) studies by Resuehr et al (2007), that CLOCK/BMAL1 binds to E-box elements in the gonadotropin releasing hormone receptor (GnRH-R) gene promoter region.…”

Unraveling the Big Sleep: Molecular Aspects of Stem Cell Dormancy and Hibernation

“…Studies conducted in hibernators have shown that torpor limits radiation-induced DNA damage in squirrels, hamsters, and mice ( Ghosh et al, 2017 ; Tinganelli et al, 2019 ), which has awakened the interest of its utility in cancer therapies and long-haul space missions. The mechanisms that mediate radioprotection during torpor are not known.…”

Fitness consequences of fish circadian behavioural variation in exploited marine environments

“…In addition, we should explore the plasticity and additive genetic variation (including its heritability) of fish chronotypes to evaluate the potential for evolution in circadian behavioural traits. In a quantitative genetic way, one potential route would be the exploration of candidate genes and polymorphisms linked to chronotypes, such as the CLOCK or the NPAS2 genes ( Stuber et al, 2016 ), and how they are translated across generations ( Helm & Visser, 2010 ; Zhang et al, 2017 ).…”