小个体大凉螈增加精子质量投入获得交配后竞争优势  

The smaller Taliang crocodile newt(Liangshantriton taliangensis)invests more in sperm quality to gain advantage in post-copulatory sperm competition

作　　者：程明阳 束潇潇 张勘 朱玉东 龚宇舟[1,2] 肖璐瑶 舒国成 谢锋 CHENG Mingyang;SHU Xiaoxiao;ZHANG Kan;ZHU Yudong;GONG Yuzhou;XIAO Luyao;SHU Guocheng;XIE Feng(CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization&Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province,Chengdu Institute of Biology,Chinese Academy of Sciences,Chengdu 610041,China;University of Chinese Academy of Sciences,Beijing 100049,China;Liziping National Nature Reserve,Ya'an 625400,China;Yibin University,Yibin 644000,China)

机构地区：[1]中国科学院成都生物研究所,中国科学院山地生态恢复与生物资源利用重点实验室,生态保育与生物多样性保护四川重点实验室,成都610041 [2]中国科学院大学,北京100049 [3]栗子坪国家级自然保护区,雅安625400 [4]宜宾学院,宜宾644000

出　　处：《应用与环境生物学报》2021年第4期831-836,共6页Chinese Journal of Applied and Environmental Biology

基　　金：国家重点研发计划重点专项(2017YFC0505202);四川省科技重大专项(2018SZDZX0036);生态环境部生物多样性保护专项(2111101);栗子坪国家级自然保护区物种保护项目(2019)资助。

摘　　要：精子竞争进化稳定策略中"角色模型"预测在交配前竞争中处于不同"角色"地位的雄性在精子竞争中存在不同的精子投资策略,而"稀释假说"提出了在不同空间尺度上对精子投资具有数量或质量的偏向.大多数有尾类两栖动物因体内受精、精子储存和多次交配等特点成为验证上述模型假说的最佳类群.基于雄性大凉螈(Liangshantriton taliangensis)交配前竞争的研究,运用全子集回归分析,探究精子数量和质量的相关特征与身体特征、身体状况之间的关系以及大凉螈交配后精子竞争情况.结果显示头体长(snout-vent length,SVL)更长的雄性倾向于拥有更大的睾丸质量(testis mass,TM)和体积(testis volume,TV),但这种关系并不显著(P_(TM-SVL)=0.095;P_(TV-SVL)=0.058);精子全长(相关系数CC=-0.939,P<0.001)和尾长(CC=-0.865,P<0.001)与雄性头体长存在显著负相关关系,而与雄性比例质量指数(精子全长:CC=1.322,P<0.001;精子尾长:CC=1.745,P<0.001)存在显著正相关关系.该结果说明处于交配前竞争劣势的小个体大凉螈采取补偿策略,产生更大、尾部更长的精子从而增加其在交配后精子竞争中的优势,无论是劣势个体还是身体状况更好的个体,均表现出对增加精子质量的投入偏向,而没有选择增加精子数量.本研究在有尾两栖类中验证了精子竞争的"角色"模型,同时发现在大凉螈的交配系统中对精子质量表现出了相对于精子数量更强的选择性,此发现支持在具有储精腺体结构的小空间交配系统中,精子置换可能在精子竞争中起到更为关键作用的假说.According to evolutionary stable strategy(ESS)theory,the“roles model”in sperm competition predicts that males who occupy different roles during pre-copulatory competition,will adopt different sperm investment strategies during post-copulatory competition.The“sperm dilution”hypothesis suggests that males may invest differently in terms of sperm number or sperm size on different spatial scales.Owing to physiological and behavioral characteristics including internal fertilization,sperm storage,and multiple matings,most urodeles are considered ideal animal models for testing the aforementioned hypotheses.Based on previous research into pre-copulatory competition in male Taliang crocodile newts(Liangshantriton taliangensis),this study aimed to explore post-copulatory competition among L.taliangensis males.Using all-subset regression(ASR)analysis,we tested for relationships between sperm number(testis mass and volume)and size(total sperm length and sperm tail length)and body features(snout-vent length,relative tail length,and relative tail height)and body condition(scaled mass index).Larger males tended to have larger testis mass and testis volume,but the relationship was not found to be statistically significant(P_(TM-SVL)=0.095;P_(TV-SVL)=0.058).A significantly negative correlation was found between sperm size(total sperm length and sperm tail length)and snout-vent length(sperm total length to SVL:coefficient=-0.939,P<0.001;sperm tail length to SVL:coefficient=-0.865,P<0.001).The scaled mass index of males showed a significant positive correlation with sperm size(sperm total length:coefficient=1.322,P<0.001;sperm tail length:coefficient=1.745,P<0.001).This finding indicates that male L.taliangensis with smaller body size experience a pre-copulatory disadvantage,but have adopted compensatory tactics by producing larger-sized,longer-tailed sperm to maximize fertilization success.In addition,both disadvantaged males and males with good body conditions showed a tendency to invest more in sperm quality than in spe

关 键 词：精子竞争 睾丸大小 精子表型 大凉螈 有尾类 两栖动物 

分 类 号：Q958[生物学—动物学]