4.1 Ecological niche differentiation in SDMs
The use of species distribution models (SDMs) in biodiversity assessments primarily focuses on estimating habitat suitability at the species level (Collart et al., 2021; Elith et al., 2010; Elith & Leathwick, 2009). These species-level SDMs assume ”ecological niche conservatism” and overlook within-species phylogenetic or functional heterogeneity. However, recent studies have highlighted the importance of considering population-level differences in sustainable management systems, as they reveal variations in climate predictor responses within species (Benito Garzón et al., 2019; Collart et al., 2021; Nielsen et al., 2021; Song & Li, 2023). Using the Japanese crayfish (Cambaroides japonicus ) as an example, researchers demonstrated that by accounting for local adaptations in distinct populations, SDMs with resolutions below the species level can more reliably forecast changes in biodiversity (Zhang et al., 2021).
Our findings indicate intermediate niche differences (0.465) between the EIOS and WPI lineages of T. maxima , suggesting the need for population-level SDMs for this species (Fig. 1-2). While all our models exhibited strong predictive performance and good model transferability (Table 2), the species-level model projected larger range contractions due to climate change compared to the lineage-level models (Table 3). Incorporating possible local adaptations, population-level SDMs yield different predictions regarding the effects of climate change. Therefore, our distribution predictions were less pessimistic when using lineage-level models, aligning with earlier research suggesting that intraspecific variation may mitigate the impact of climate change on species distribution (Chardon et al., 2020; Razgour et al., 2019).