要 sex 不要命的雄性劍紋帶蛇

瘋狂的交配導致雄性劍紋帶蛇（Thamnophissirtalis parietalis）老化更快，死亡更早。比起雌將維持身體優先於短期生殖的成功的雌性，它們的身體維護要差一些。

來源 悉尼大學

編譯 紫蘇

在北美地區的劍紋帶蛇種群中：雄性每年進行 2-4 周的代價昂貴的交配，在這段時間它們不進食，與成千上萬的其他雄性競爭。雌性僅在「狂歡地」停留一天，雄性則可能停留長達21天。

這篇論文發表在Royal Society journal Proceedings B(論文信息見文末）。

這些蛇在他們的公共巢穴冬眠了八個月，在春天大批醒來，他們聚集在一起，雄性們為著雌性的交配權展開激烈的競爭。

研究人員測定了兩個性別的蛇的端粒長度（衰老的生物標誌物）。他們發現雄性不能保持較好的身體狀態，老化速度快於女性。這可能是因為雄性選擇將能力花費在交配上，而沒有用於防止和修復與衰老相關的 DNA 和細胞損傷。相比之下，女性優先維持身體狀況，並可以更好地修復細胞損傷，讓她們有更長的生命和未來的繁殖機會。

悉尼大學的作者 Christopher R Friesen 博士解釋說，這些蛇每年只有四個月用於覓食和繁殖，利用這麼短時間完成繁殖，它們可算是相當成功。

「雖然我們相信所有的雌性每年都會交配，但他們僅在交配地停留一個小時內1到3天。而雄性要長得多，少則7天，長的可達21天，這似乎導致雄性老化速度更快。「弗里森博士說。

「女性每隔一年繁殖一次，繁殖成功要依賴它們的脂肪/能量儲備。我們以前的研究表明，女性真正完成受精之前，可以將精子存儲長達15個月或更長時間！」

加拿大馬尼托巴省的劍紋帶蛇種群。（Christopher R Friesen）

除了優先保護自己的身體以外，在加拿大馬尼托巴省研究的雌性劍紋帶蛇不會浪費能量照顧他們的後代，與大多數的蛇類是一致的。

相關論文信息

題目Age-related sex differences in body condition and telomere dynamics of red-sided garter snakes

作者Nicky Rollings, Emily J. Uhrig, Randolph W. Krohmer, Heather L. Waye, Robert T. Mason, Mats Olsson, Camilla M. Whittington, Christopher R. Friesen

發表時間5 April 2017

DOI10.1098/rspb.2016.2146

摘要Life-history strategies vary dramatically between the sexes, which may drive divergence in sex-specific senescence and mortality rates. Telomeres are tandem nucleotide repeats that protect the ends of chromosomes from erosion during cell division. Telomeres have been implicated in senescence and mortality because they tend to shorten with stress, growth and age. We investigated age-specific telomere length in female and male red-sided garter snakes, Thamnophis sirtalis parietalis. We hypothesized that age-specific telomere length would differ between males and females given their divergent reproductive strategies. Male garter snakes emerge from hibernation with high levels of corticosterone, which facilitates energy mobilization to fuel mate-searching, courtship and mating behaviours during a two to four week aphagous breeding period at the den site. Conversely, females remain at the dens for only about 4 days and seem to invest more energy in growth and cellular maintenance, as they usually reproduce biennially. As male investment in reproduction involves a yearly bout of physiologically stressful activities, while females prioritize self-maintenance, we predicted male snakes would experience more age-specific telomere loss than females. We investigated this prediction using skeletochronology to determine the ages of individuals and qPCR to determine telomere length in a cross-sectional study. For both sexes, telomere length was positively related to body condition. Telomere length decreased with age in male garter snakes, but remained stable in female snakes. There was no correlation between telomere length and growth in either sex, suggesting that our results are a consequence of divergent selection on life histories of males and females. Different selection on the sexes may be the physiological consequence of the sexual dimorphism and mating system dynamics displayed by this species.

摘要http://rspb.royalsocietypublishing.org/content/284/1852/20162146

喜歡這篇文章嗎？立刻分享出去讓更多人知道吧！