用功能生态学方法揭示峨眉髭蟾蝌蚪和棘腹蛙蟾蝌蚪共存的原因

Functional approach reveals niche differentiation between two coexisting tadpoles: Leptobrachium boringii and Quasipaa boulengeri

采用功能生态学的研究方法,选取了3个指标(功能丰富度、功能定位和功能生态位的重叠程度)对峨眉山清音阁黑龙江中峨眉髭蟾蝌蚪和棘腹蛙蝌蚪共存的原因进行了解析。结果表明,峨眉髭蟾蝌蚪功能丰富度的实测值远远小于棘腹蛙蝌蚪。采用自助法随机抽样15和51个个体时,峨眉髭蟾蝌蚪的功能丰富度值显著小于棘腹蛙蝌蚪。同时,非参数多元方差分析的结果显示二者的功能定位存在显著差异。此外,二者功能生态位重叠程度的实测值与采用自助法计算所得值均极低。以上结果表明二者的功能生态位存在明显分化,表现为峨眉髭蟾蝌蚪个体较大,开口较小,眼间距较大,尾部发达且多采用背腹弯曲的游泳模式;而棘腹蛙蝌蚪开口较大,眼睛间距较小,尾部较为短小且多采用脊椎弯曲的游泳模式。鉴于功能性状可以反映生物体对生长环境的响应,推测两种蝌蚪主要栖息地的微生境也存在分化。

Understanding resource partitioning between species is crucial to describe the coexistence mechanisms between them,and to reveal the ecological functions they serve in ecosystems.Among existing approaches,functional morphology is widely used in aquatic animals,such as phytoplanktons,invertebrates,and fish,by explaining their foraging and swimming characteristics in water bodies.However,little attention has been paid to tadpoles,which may have important functional roles in freshwater ecosystems.Therefore,a functional approach was used,and three indices(i.e.,functional richness,functional identity,and functional overlap)were calculated in the present study to reveal the coexistence mechanism between Leptobrachium boringii and Quasipaa boulengeri tadpoles in Heilongjiang Stream of Qingyinge,Emei Mountain.Our results indicated that the observed functional richness of L.boringii tadpoles(12.59%)was lower than that of Q.boulengeri tadpoles(46.67%).Upon randomly selecting 15 and 51 individuals from the two tadpole populations(L.boringii and Q.boulengeri,respectively),the functional richness of L.boringii was observed to be significantly lower than that of Q.boulengeri.Moreover,functional identity was significantly different between the two tadpole species based on PERMANOVA analyses(P<0.001).In addition,functional overlap between the two tadpole species was extremely low in both observed(1.47%)and bootstrap values(mean=0.06%±0.19%SD when 15 individuals were randomly selected;and mean=0.99%±0.55%SD when 51 individuals were randomly selected).All of these results suggested the existence of niche differentiation between the two tadpole species.Specifically,L.boringii tadpoles displayed larger bodies,smaller mouths,larger interocular distance,stronger tails,and their swimming types were some dorso⁃ventral flexion,with little lateral flexion.In contrast,Q.boulengeri tadpoles can have larger mouths,smaller interocular distances,smaller tails,and swimming behaviour were altered due to greater magnitudes of vertebral curvature.Since functional traits can be correlated with micro⁃environmental factors,habitat differentiation could also be expected between the two tadpole species.