摘要
检测了卵胎生入侵种食蚊鱼(Gambusia affinis)繁殖期个体大小和形态特征的两性异形以及雌性繁殖输出。结果表明,繁殖期,雌性个体的数量显著大于雄性个体,雌性个体的体长显著大于雄性个体,食蚊鱼属于偏向雌性的两性异形。以体长为协变量的One-way ANCOVA及后续的Tukey's检验显示,特定体长食蚊鱼的雌性个体的头宽、眼间距、体宽和体重均显著大于雄性个体;头长和尾鳍长的两性间差异不显著。6个形态特征变量的主成分分析(Eigenvalue≥1)发现,前2个主成分共解释65.1%的变异。头宽、眼间距、体宽和体重在第一主成分有较高的正负载系数(解释45.4%变异),头长在第二主成分有较高的负负载系数(解释19.7%变异)。食蚊鱼的繁殖输出与母体个体大小的线性回归显示,窝仔数和窝仔重均与母体体长、体重呈显著的正相关;食蚊鱼的繁殖输出与母体局部特征的线性回归显示,窝仔数和窝仔重均与母体头宽、眼间距和体宽呈显著的正相关。窝仔数与后代个体的平均体长呈显著的正相关、与后代个体的平均体重相关不显著,后代个体大小与数量不发生权衡。食蚊鱼繁殖期的性别比例、个体大小和局部形态特征的两性异形受生育力选择、性选择、生态位分化、食物竞争等多种选择压力的作用,也有利于该物种种群扩张和快速入侵。
In this study, we measured the sexual dimorphism in body size and six other mophometrical variables along with the individual fecundity in females of ovoviviparous and invasive mosquitofish Gambusia affinis, collected in Lishui （Zhejiang, eastern China）, during the reproductive season. The results showed that the number of adult females was more than that of the males during the breeding season, and the body length of adult females was significantly longer than that of adult males. Therefore, G. affinis is a species with highly female-biased sexual size dimorphism. One-way analysis of variance with body length as a covariate showed significantly higher （P〈0.0001） head width, interorbital width, body width, and body mass for G. affinis females than males, while no significant sexual differences were identified based on the head length or caudal fin length. A principal component analysis resolved two components （with Eigenvalues 〉~ 1 ） from six morphometrical variables, accounting for 65.1% of variation in the original data. The first component （45.4% variance explained） had high positive loading for size-free values of head width, interorbital width, body width, and body mass ; and the second component （19.7% variance explained） had of unary linear regression showed that the reproductive high negative loading for the size-free value of head length. Analysis outputs （including brood size and mass） of G. affinis positively correlated with the female body length, body mass, head width, interorbital width, and body width. Brood size positively correlated with the average body length of offspring, but there was no correlation between the brood size and the average body mass. No trade-off Was identified between the size and number of offspring. Sexual dimorphism in sex ratio, body size, and local characteristics of G. affinis was influenced by a variety of selection pressure parameters, including fecundity selection, sexual selection, niche differentiation, and food competition during the breeding season. Sexual dimorphism also contributed to population expansion and rapid invasion of the species. Our results have provided some basic data for further studies on the evolution mechanisms of fish sexual dimorphism.
出处
《生态学报》
CAS
CSCD
北大核心
2016年第9期2497-2504,共8页
Acta Ecologica Sinica
基金
国家自然科学基金项目(31270443)
浙江省大学生科技创新活动计划(2013R429025)
关键词
食蚊鱼
卵胎生
两性异形
性别比例
繁殖输出
Gambusia affinis
ovoviviparity
sexual dimorphism
sex ratio
reproductive outputs
