温度对乌龟孵育和性比的影响

Temperature Effects on Sex Determination in Chinemys reevesii

研究不同孵育温度对乌龟(Chinemys reevesii)孵育和性比的影响.在(25±0.5)℃,(29±0.5)℃和(33±0.5)℃等3个孵化温度下,分别放置90枚受精卵.在一定温度范围内,胚胎的发育速度随着孵化温度的升高而加快,孵育时间随着孵化温度的升高而变短.孵化累积温度在29℃时最低,25℃时最高,33℃时则居中.在25℃和29℃时,孵化成活率较高,达到80%以上.在33℃时孵化成活率仅为58.89%,说明33℃的孵育温度对胚胎发育有不利影响.在25℃时,雄性子代占优势,雌性率为5.33%;在33℃时,雌性子代占绝对优势,雌性率为95.74%;在29℃时,性比达到平衡,雌性率接近50%,说明乌龟的性别决定属TSD机制.

In order to understand the sex determination pattern in Chinemys reevesii, the sex phenotypes on different incubation temperature were observed and the mechanism of sex determination was analyzed firstly by using rearing propagate population in this paper. Eggs were divided into three groups （90 eggs per group） and incubated under three different temperatures, such as （25 ± 0.5）℃ , （29 ± 0.5 ） ℃ and （ 33 ± 0.5 ） ℃. The embryonic developmental rates increase as the incubation temperatures rise at the three different temperatures. Cumulative temperature units （degree · hours） was highest at （ 25 -± 0.5 ） ℃, lowest at （ 29 ± 0.5 ） ℃, and middle at （ 33 ± 0.5 ） ℃, At （ 25 ± 0.5 ） ~ and （29 ±0.5）℃, embryonic survival rate was 80%, but only 58.89% at （33 ± 0.5）℃. The data indicated that higher temperature at （ 33 ± 0.5 ） ℃ could affect embryonic development, because the survival rate was lower than that at （29 ± 0.5 ） ℃ and at （25 _± 0.5） ℃. The resulted females increase as the incubation temperatures rise. The percentage of females was 5.33% at （25 ± 0.5 ）℃ and 45.56% at （29 ± 0.5 ）℃, whereas the ratio moved up to 95.74% at （33 ± 0. 5 ）℃ , and suggested that Chinemys reevesii should be temperature dependent sex determination （TSD） mechanism, and belong to the TSD I pattern in which females are produced at high temperatures and males at low ones.