Evolutionary dynamics of ecological niche in three Rhinogobio fishes from the upper Yangtze River inferred from morphological traits.

Meirong Wang,Huanzhang Liu,Shaorong Yang,Fei Liu,Pengcheng Lin

doi:10.1002/ece3.1386

Abstract

In the past decades, it has been debated whether ecological niche should be conserved among closely related species (phylogenetic niche conservatism, PNC) or largely divergent (traditional ecological niche theory and ecological speciation) and whether niche specialist and generalist might remain in equilibrium or niche generalist could not appear. In this study, we employed morphological traits to describe ecological niche and test whether different niche dimensions exhibit disparate evolutionary patterns. We conducted our analysis on three Rhinogobio fish species (R. typus,R. cylindricus, and R. ventralis) from the upper Yangtze River, China. Among the 32 measured morphological traits except body length, PCA extracted the first four principal components with their loading scores >1.000. To find the PNC among species, Mantel tests were conducted with the Euclidean distances calculated from the four principal components (representing different niche dimensions) against the pairwise distances calculated from mitochondrial cytochrome b sequence variations. The results showed that the second and the third niche dimension, both related to swimming ability and behavior, exhibited phylogenetic conservatism. Further comparison on niche breadth among these three species revealed that the fourth dimension of R. typus showed the greatest width, indicating that this dimension exhibited niche generalism. In conclusion, our results suggested that different niche dimensions could show different evolutionary dynamic patterns: they may exhibit PNC or not, and some dimensions may evolve generalism.

Highlights

Ecological niche describes a part of the ecological space available in the environment, which is occupied by a species (Ricklefs 2010)
Principal component analysis produced four factors describing 83.237% of the total variance in the transformed morphological variables surveyed in this study (Table 2); the first dimension (PC1) explained 42.012%; the second dimension (PC2) explained 31.686%; the third dimension (PC3) explained 5.137%; the fourth dimension (PC4) explained 4.401%
The Mantel tests between Euclidean distances and pairwise distances showed that phylogenetic relatedness and morphological niche similarity were significantly correlated for the dimensions 2 and 3 (Table 3; dimension 2: P = 0.001; dimension 3: P = 0.001), which indicated that the niche dimensions 2 and 3 exhibited phylogenetic conservatism among these three Rhinogobio species (Table 3)

Summary

Introduction

Ecological niche describes a part of the ecological space available in the environment, which is occupied by a species (Ricklefs 2010). Ecological niche is suggested to be crucial for our understanding of the mechanism driving speciation and biological diversification, and the niche concept has become a central component in ecological research (Futuyma and Mitter 1996; Kozak and Wiens 2006; Violle et al 2011; Gabaldon et al 2013). There have been increasing interests in analyses of how ecological niche evolves. The classical niche theory proposes that there should be distinct niche differences among species during evolution Closely related species should be morphologically and ecologically different

Objectives

Methods

Results

Conclusion