Lineage‐level distribution models lead to more realistic climate change predictions for a threatened crayfish

Zhixin Zhang,Jamie M Kass,Stefano Mammola,Kousuke Ikeda,Itsuro Koizumi,Toru Suzuki,Kazunori Tanaka,Masashi Yokota,Xuecao Li,Nisikawa Usio,Raimundo Real

doi:10.1111/ddi.13225

Abstract

AbstractAimAs climate change presents a major threat to biodiversity in the next decades, it is critical to assess its impact on species habitat suitability to inform biodiversity conservation. Species distribution models (SDMs) are a widely used tool to assess climate change impacts on species’ geographical distributions. As the name of these models suggests, the species level is the most commonly used taxonomic unit in SDMs. However, recently it has been demonstrated that SDMs considering taxonomic resolution below (or above) the species level can make more reliable predictions of biodiversity change when different populations exhibit local adaptation. Here, we tested this idea using the Japanese crayfish (Cambaroides japonicus), a threatened species encompassing two geographically structured and phylogenetically distinct genetic lineages.LocationNorthern Japan.MethodsWe first estimated niche differentiation between the two lineages of C. japonicus using n‐dimensional hypervolumes and then made climate change predictions of habitat suitability using SDMs constructed at two phylogenetic levels: species and intraspecific lineage.ResultsOur results showed only intermediate niche overlap, demonstrating measurable niche differences between the two lineages. The species‐level SDM made future predictions that predicted much broader and severe impacts of climate change. However, the lineage‐level SDMs led to reduced climate change impacts overall and also suggested that the eastern lineage may be more resilient to climate change than the western one.Main conclusionsThe two lineages of C. japonicus occupy different niche spaces. Compared with lineage‐level models, species‐level models can overestimate climate change impacts. These results not only have important implications for designing future conservation strategies for this threatened species, but also highlight the need for incorporating genetic information into SDMs to obtain realistic predictions of biodiversity change.

Highlights

We quantified realized niches for two genetic lineages of C. japonicus and used Species distribution models (SDMs) calibrated at species and lineage levels to investigate potential impacts of climate change on the species’ range
Our results showed that species- and lineage-level SDMs projected largely different impacts of climate change: the species-level model predicted widespread range reductions, while the lineage-level models predicted contraction or little change for the western lineage but expansion for the eastern lineage
If there is local adaptation in these two distinct lineages, which is probable given the known phylogenetic history and our niche overlap results, the lineage-level models are likely to make more realistic future predictions of habitat suitability than the species-level models, and our results show that the eastern lineage may be more resilient to climate change and may experience range expansion

Summary

Introduction

We quantified realized niches (i.e. the portion of the fundamental niche currently used by the species; Guisan et al, 2017; Soberón & Nakamura, 2009), developed SDMs and made future predictions to examine how climate change might influence C. japonicus by constructing species-level versus genetic lineage-level models. We sought to address the following hypotheses: (1) there will be divergence in realized niches between the eastern and western lineages of C. japonicus, and (2) there will be considerable differences between the future projections of the SDMs at the species and lineage levels.

Objectives

Results

Conclusion