Background: Global warming caused trophic mismatch has affected the breeding success, and even the survival, of some bird species.The ability of birds to accelerate their reproduction onset in the warmer spring could ...Background: Global warming caused trophic mismatch has affected the breeding success, and even the survival, of some bird species.The ability of birds to accelerate their reproduction onset in the warmer spring could be critical to the survival of some species.The activation of the reproductive endocrine axis in birds is a key physiological process that determines the onset of reproduction.Could birds change the HPG axis endocrine rhythm under the temperature rising condition?Methods: Using plasma LH level as an indicator of initiation of the reproductive endocrine and artificially controlling temperature, we compared variations in the timing of activation of the reproductive endocrine axis in response to temperature in two Chinese bird species, the Eurasian Skylark(Alauda arvensis) and the Great Tit(Parus major) at both the population and individual levels.Results: At the population level, temperature only significantly influenced LH level in the Eurasian Skylark, and had no significant effect on the LH levels in the Great Tit.Mean LH level of Eurasian Skylarks in the 20 ℃ group was higher than that of those in the 15 ℃ group throughout the experiment.Large individual variations in the timing of peak LH levels were observed in the high and the low temperature groups of both Eurasian Skylarks and Great Tits.Conclusions: These results indicate that the effects of temperature differ among species.Meanwhile, there appears to be a degree of within population polymorphism in the timing of reproductive endocrine axis activation in some species.This polymorphism could provide the variation required for bird populations to cope with the possible change of their food peak under the climate warming condition.展开更多
The incubating behavior of the horned lark and small skylark was studied in alpine meadows. The key results are: ① There was no significant difference in the temperature outside the nests of horned larks and small sk...The incubating behavior of the horned lark and small skylark was studied in alpine meadows. The key results are: ① There was no significant difference in the temperature outside the nests of horned larks and small skylarks ( F 1, 87 =3 286,P >0 05). ② If parents were off the nest, the temperature in the nest was not significantly different between the two species( F 1,87 =3 009,P >0 05), however, if parent birds were on the nest, the temperature in horned lark nests was significantly higher than that in small lark nests ( F 1, 210 =7 555,P <0 01). ③ Temperature trends inside and outside the nests of the two species were similar, both following a low high low, pattern and showed a significantly positive correlation(horned lark: r=0 572, n=158, P <0 01;small skylark: r=0 511, n=141, P <0 01). ④ During the hatching period, the temperature in nests was significantly higher than the outside temperature in horned larks( t=7 051, df=157, P <0 01), however, there was no significant difference between the inside and outside in the small skylark( t=-1 558, df=149, P >0 05). ⑤ The attendance time of horned larks and small skylarks showed three peaks; before 09:00 h, between 12:00 and 15:00 and after 19:00 h, respectively. ⑥ The attendance time and incubation behavior of the two species changed with variation in the environmental temperature. ⑦ There was no significant difference in the average attendance time per day between horned larks and small skylarks( P >0 05). ⑧ The attendance frequency of horned larks was high (4 17 times/h), and visit duration short (524 32 s/period), wherase small larks showed the opposite pattern; low attendance frequency(1 79 times/h)with relatively long( 1 510 00 s/ periods)visits. Our results are consistent with the hypothesis that attendance time is a balance between the energy requirements of the parent birds and the temperature requirements of the developing embryos. It follows that a birds choice of nest site should involve a trade off between costs and benefits, e.g. microclimate versus proximity to food resources.展开更多
基金supported by the National Natural Science Foundation of China(No.31372225)Fund of Minzu University of China(No.ydzxxk201619)"111" Project(2008-B0844)
文摘Background: Global warming caused trophic mismatch has affected the breeding success, and even the survival, of some bird species.The ability of birds to accelerate their reproduction onset in the warmer spring could be critical to the survival of some species.The activation of the reproductive endocrine axis in birds is a key physiological process that determines the onset of reproduction.Could birds change the HPG axis endocrine rhythm under the temperature rising condition?Methods: Using plasma LH level as an indicator of initiation of the reproductive endocrine and artificially controlling temperature, we compared variations in the timing of activation of the reproductive endocrine axis in response to temperature in two Chinese bird species, the Eurasian Skylark(Alauda arvensis) and the Great Tit(Parus major) at both the population and individual levels.Results: At the population level, temperature only significantly influenced LH level in the Eurasian Skylark, and had no significant effect on the LH levels in the Great Tit.Mean LH level of Eurasian Skylarks in the 20 ℃ group was higher than that of those in the 15 ℃ group throughout the experiment.Large individual variations in the timing of peak LH levels were observed in the high and the low temperature groups of both Eurasian Skylarks and Great Tits.Conclusions: These results indicate that the effects of temperature differ among species.Meanwhile, there appears to be a degree of within population polymorphism in the timing of reproductive endocrine axis activation in some species.This polymorphism could provide the variation required for bird populations to cope with the possible change of their food peak under the climate warming condition.
文摘The incubating behavior of the horned lark and small skylark was studied in alpine meadows. The key results are: ① There was no significant difference in the temperature outside the nests of horned larks and small skylarks ( F 1, 87 =3 286,P >0 05). ② If parents were off the nest, the temperature in the nest was not significantly different between the two species( F 1,87 =3 009,P >0 05), however, if parent birds were on the nest, the temperature in horned lark nests was significantly higher than that in small lark nests ( F 1, 210 =7 555,P <0 01). ③ Temperature trends inside and outside the nests of the two species were similar, both following a low high low, pattern and showed a significantly positive correlation(horned lark: r=0 572, n=158, P <0 01;small skylark: r=0 511, n=141, P <0 01). ④ During the hatching period, the temperature in nests was significantly higher than the outside temperature in horned larks( t=7 051, df=157, P <0 01), however, there was no significant difference between the inside and outside in the small skylark( t=-1 558, df=149, P >0 05). ⑤ The attendance time of horned larks and small skylarks showed three peaks; before 09:00 h, between 12:00 and 15:00 and after 19:00 h, respectively. ⑥ The attendance time and incubation behavior of the two species changed with variation in the environmental temperature. ⑦ There was no significant difference in the average attendance time per day between horned larks and small skylarks( P >0 05). ⑧ The attendance frequency of horned larks was high (4 17 times/h), and visit duration short (524 32 s/period), wherase small larks showed the opposite pattern; low attendance frequency(1 79 times/h)with relatively long( 1 510 00 s/ periods)visits. Our results are consistent with the hypothesis that attendance time is a balance between the energy requirements of the parent birds and the temperature requirements of the developing embryos. It follows that a birds choice of nest site should involve a trade off between costs and benefits, e.g. microclimate versus proximity to food resources.
