1 Introduction
The geographical distribution of plant populations is influenced by both the biological characteristics of the plant species and their environment (Thuiller et al., 2005; Ge et al., 2012). Primarily, the climate within large-scale regions serves as the principal determinant affecting species distribution. Changes in climate consequently alter species’ responses and selection to climate and habitat (Ma et al., 2022). In recent times, exacerbated by climate change and human interference, species habitats have suffered severe degradation. This degradation is particularly notable in the significant reduction of suitable growth areas for endangered plants, leading to diminished resources for wild species (Lenoir et al., 2008; Liu et al., 2015). Consequently, investigating the impacts of changing climates on species distribution patterns is crucial for understanding historical and future changes in species range and can furnish a scientific foundation for conserving germplasm resources in endangered plants (Li et al., 2021).
Species distribution models (SDMs) rely on various environmental variables such as climate and soil, closely related to the real growth and distribution of species. These models can predict potential suitable distribution areas of species using specific algorithms, thereby elucidating the predominant environmental factors influencing their distribution and exploring the ecological requirements of species (Araújo et al., 2012). Among the myriad of models, SDMs encompass 19 different methodologies, including the rule-set genetic algorithm model (GARP), maximum entropy model (MaxEnt), and ecological factor analysis models (ENFA) (Phillips et al., 2008). The MaxEnt model stands out due to its relative maturity, ease of operation, and high prediction accuracy (Hao et al., 2020). It can infer and predict from incomplete known information, making it widely applicable in studying the introduction and cultivation of relict plants, horticultural tree species, and invasive plants (Elith et al., 2006).
Tetracentron sinense Oliv., a Tertiary relict plant, represents the sole surviving species in the Tetracentron genus of the Trochodendraceae family (Fan et al., 2021). This species holds significant importance in the discussion of the systematic evolution of angiosperm plants. Unfortunately, due to its ornamental, furniture, and medicinal value, T. sinense has been subjected to extensive exploitation by humans, resulting in poor regeneration of its natural populations (Pang et al., 2018; Lu et al., 2020; Wang et al., 2023). Consequently, it has been designated as a national secondary protection plant in China and listed in Appendix III of the Convention on International Trade of Endangered Species (Fu, 1992). The preservation of germplasm resources has garnered considerable attention from researchers (Duan et al., 2019; Zhang et al., 2019).
Fossil records indicate that Tetracentron Oliv. was once widely distributed across Europe, North America, and East Asia during the Pleistocene era (Rix, 2007). A phylogeographical analysis based on the chloroplast genome suggests that the current geographical distribution pattern of T. sinense may have been shaped by Quaternary climate oscillations, with Southwest China potentially serving as a biological refuge during glacial periods (Sun et al., 2014). Li et al. (2018) observed a correlation between the phenotypic variation of T. sinense and environmental factors such as mean annual sunshine duration, mean temperature in July, and annual mean precipitation. However, the specific influence of these environmental factors on the geographic distribution of T. sinense remains ambiguous. Additionally, how will the distribution pattern of T. sinense evolve in the context of past and future climate changes? What are the primary environmental factors constraining its geographical distribution? And how do these factors influence its distribution? These questions remain unanswered, impeding the effective protection and management of T. sinense germplasm resources.
Utilizing the MaxEnt model and ArcGIS spatial analysis technology, this study examines potentially suitable areas for T. sinense across historical periods (the last interglacial period, the last glacial maximum, and the Middle Holocene) as well as current and future periods (2050s and 2070s). The objectives of this study are to (1) analyze the dynamic changes in potentially suitable areas, (2) investigate the main environmental factors driving changes in the distribution pattern ofT. sinense , and (3) furnish a scientific basis for the effective protection and management of T. sinense .