Latitudinal variation in nematode diversity and ecological roles along the Chinese coast.

Jihua Wu,Youzheng Zhang,Huili Chen,K.C Burns

doi:10.1002/ece3.2538

Abstract

AimTo test changes in the phylogenetic relatedness, niche breadth, and life‐history strategies of nematodes along a latitudinal gradient.LocationSixteen wetland locations along the Pacific coast of China, from 20°N to 40°N.MethodsLinear regression was used to relate nematode phylogenetic relatedness (average taxonomic distinctness (AvTD) and average phylogenetic diversity [AvPD]), life‐history group (based on “c‐p” colonizer–persister group classification), and dietary specificity (based on guild classification of feeding selectivity) to latitude.ResultsWetland nematode taxonomic diversity (richness and Shannon diversity indices) decreased with increasing latitude along the Chinese coast. Phylogenetic diversity indices (AvTD and AvPD) significantly increased with increasing latitude. This indicates that at lower latitudes, species within the nematode community were more closely related. With increasing latitude, the nematode relative richness and abundance decreased for selective deposit feeders but increased for nonselective deposit feeders. The proportion of general opportunists decreased with increasing latitude, but persisters showed the opposite trend. The annual temperature range and the pH of sediments were more important than vegetation type in structuring nematode communities.Main conclusionNematode niche breadth was narrower at lower latitudes with respect to dietary specificity. Higher latitudes with a more variable climate favor r over K life‐history strategists. Nematode communities at lower latitudes contained more closely related species.

Highlights

Latitudinal gradients in diversity are observed for a wide range of biological groups including plants and animals (Willig, Kaufman, & Stevens, 2003)
Based on BIO-ENV analyses, our study showed that climate variables, such as annual temperature range (ATR) and sediment properties such as pH, were more important than the dominant vegetation type
In addition to the variables including annual temperature, annual temperature range, and soil pH which were significantly associated with nematode diversity, annual precipitation and total soil nitrogen were found relating to the relative abundance and species richness of nematode ecological groups

Summary

| INTRODUCTION

Latitudinal gradients in diversity are observed for a wide range of biological groups including plants and animals (Willig, Kaufman, & Stevens, 2003). Some of the most frequently proposed mechanisms include geographic area, net productivity, species interaction strength, and environmental stability These mechanisms were used to explain changes in species diversity with latitudinal gradient, but. Despite exceptions in polar regions (Adams et al, 2006), coexisting species in a community are often found to be more phylogenetically related at high latitudes where the environment is more dynamic (Qian, Zhang, Zhang, & Wang, 2013) These patterns are mostly proposed for several taxa including plant, bird, and mammal species (Cardillo, Orme, & Owens, 2005; Qian et al, 2013; Safi et al, 2011), and it is still unclear for most taxonomic groups and studies on changes in phylogenetics are far behind those on changes in species richness with latitudinal gradients. Based on the literature describing these relationships for aboveground taxa, we tested the following hypotheses: (1) nematode taxonomic richness and diversity (a)

| MATERIALS AND METHODS

| DISCUSSION

Findings

| CONCLUSION