4.2 Distribution changes
According to Figure 1, the reconstructed-suitable distributions for LIG and LGM show that macaques were principally concentrated in the eastern Southwest, Central, and Coastal. Such a distribution pattern corresponded to the dispersal and radiation scenarios of the macaques during the Pliocene and Pleistocene (Li et al., 2020; He et al., 2022; Zhang et al., 2022): Asian macaques migrating from North Africa entered a Convergence-Divergence Center in Southwest China through Europe and Western Asia aforementioned. They then continued the dispersion and radiation along the three major rivers in the East Asian continent (Yangtze, Yellow, and Pearl), reaching far east Asia (Taiwan, Korea, and Japan). Others spread to Southeast Asia, occupying Borneo, Malaysia, and Indonesia (Li et al., 2020). However, as found in this study, most taxa remain in Southwest China (Figure S1), where they initiated dispersion and radiation in East and Southeast Asia (He et al., 2022; Zhang et al., 2022), implying that the Southwest is still their central distribution region.
Compared to the LIG (Figure 1A), some highly suitable areas during the LGM were degraded, especially in Northern China, the Sichuan Basin, and the Qinling-Daba Mountain (Figure 1B). This change must have been associated with the severe monsoon generating the cold and dry climate during the Quaternary (Zhang, 2004), following the rapid uplift of the Himalayan orogeny and the Qinghai-Tibet Plateau. As a result, some animals, including primates, survived the regions with relatively stable environments and ecological niches during the Later Pleistocene (Jablonski, 1993). Macaques (Macaca ) reached Northern China, the northern limit of the subtropic zone, during the Early or Middle Pleistocene (Zhang, 2002). The distribution extended northwards to the Liaodong Peninsula, northeast Beijing, and the northernmost Jinniushan (Jablonski, 1993). What followed up was that tropical and subtropical forests migrated southward from north to south China (Huang et al., 2021), so macaques and other primate species were pushed southern movement (Jablonski, 1998).
Compared to LGM (Figure 1B), the size and regions of suitable distributions of the current macaque distribution have reduced (Figure 2 and 3), so that they were prominently located in high mountainous areas in the Yunnan-Guizhou Plateau in the Southwest, as well as alongside the Qinling Mountains in southeastern Northwest, and southern Coastal and Central (Zhejiang-Fujian). Such modified profiles, as mentioned above, must have been caused by accelerated human-induced activities in China during the Holocene, such as extensive deforestation and cultivation of the lowlands (Olson and James, 1982; Ma et al., 2020), which was accelerated following further exploiting lands and indiscriminate deforestation, particularly after the Qin and Han Dynasties (Ramankutty and Foley, 1999). So after 1,700 BP, 5 million m2 of natural vegetation had been converted into agricultural land and pasture (Pongratz et al., 2008). Further, the two opium wars (1800-1849 and 1850-1899), the Second World War (1939-1945), the Civil War (1900-1949), and the post-war period (1950 ~) aimed at increasing agricultural demands for the rapidly increased human population, have caused a series of waves of significant destroying natural environments and devastating animal distributions (Pan et al., 2016; Huang et al., 2021). Over the last 40 years, the unprecedented social-economic development has led to significantly increasing road construction, cropland, and pasture – which, as indicated in the study, would further push the macaques and other animals to higher mountains.