Effects Of Ambient Temperature And Clock Gene On The Reproductive Endocrine And Reproductive Behavioral Rhythm Of Short-toed Bailing

Proper timing of seasonal breeding is a key component of fitness because birds must synchronize hatching with the narrow time window of maximal food abundance to enhance their reproductive success.The birds have formed a biological mechanism of photoperiod induced reproductive endocrine and reproductive behavior in the long-term evolution at mid to high latitude areas.However,many studies have shown the breeding timing of birds is related to spring temperature.How temperature affects breeding timing of birds?This physiological mechanism is still unclear.Meanwhile,in a same year,there is variation in onset of reproduction within populations,whether this difference is generated by the genetic control of the reproductive endocrine process?We take the Asian short-toe lark in Mongolia as the research object,we Study the differences in eproductive endocrine of Asian short-toed lark from 2014 to 2016 years,meanwhile,we explore the effect of temperature on the genes expression of reproductive signal pathway by qRT-PCR approach for the first time.This study also discuss the relationship between the breeding behavior of the Asian short-toe lark and the mean length of Poly-Q fragment.The main results are as follows:1.The Asian short-toe lark's LH,T and E2 peak levels in 2014 were significantly higher than those in 2015 and 2016,and the peaks of LH,T and E2 levels in 2014 advanced than 2015 and 2016,because of higher temperatures in the spring of 2014.These conclusions indicate that the temperature have an impact on the reproductive endocrine of the Asian short-toe lark.2.The temperature can affect the expression of TSH?,DIO2,DIO3,GnRH,GnRHR,LHGCR and FSHR genes on the hypothalamus and pituitary reproductive endocrine pathway in Asian short-toe lark.Stimulation of high tempreature results in up-regulation of TSH?,DIO2 and down-regulation of DIO3.Indeed,GnRH,LHGCR and FSHR was up-regulated by DIO2 under high tempreature,which results in the peak of reproductive hormones in advance.These results suggest that temperature regulates the expression of key genes in the hypothalamus,then affects the reproductive endocrine of birds.3.In this study,we detected associations between Poly-Q mean length and reproductive timing within a free-living Asian short toe lark population.In females,but not males,with a higher number of poly-Q repeats at the Clock locus have later hatch and lay dates,and with a shorter number of poly-Q repeats at the Clock locus have early hatch and lay dates.The length of the poly-Q fragment has a significant effect on the date of laying and hatching in Asian short-toe lark population.The polymorphism of the Clock gene is the genetic basis of individual differences in the reproductive rhythm of the Asian short toe lark.4.In the context of global climate change,the reproductive rhythm of Asian short toe lark can respond to annual spring temperature changes.At the same time,there are genetic reproductive rhythm differences within the population.Our study shows that the Asian short toe lark has a micro-evolution potential to cope with the phenological changes caused by climate change.