Ecological Niche Overlap and Prediction of the Potential Distribution of Two Sympatric Ficus (Moraceae) Species in the Indo-Burma Region

Abstract

Climate change is a major factor influencing the species distribution and population diversity of living creatures. In this study, the ecological niche model (ENM) MaxEnt was used to evaluate habitat suitability and predict potential habitats of two sympatric fig species, i.e., Ficus squamosa and F. heterostyla, in the Xishuangbanna region of China. Results indicated that mean diurnal range, isothermality, cation exchange capacity (at pH 7), and temperature seasonality were key variables influencing habitat suitability for F. squamosa. However, temperature seasonality and precipitation of the driest quarter showed the greatest contributions to F. heterostyla distribution. During the current period, the habitat suitability distributions of both Ficus species were considerably higher than known occurrences. In the future, potentially suitable distribution areas for both species will reduce overall across the whole study area, although some expansion may occur by 2070. Niche overlap of suitable areas for both species was initially high and then declined in the current period and future epochs in the RCP 2.6 scenario, but increased in the RCP 8.5 scenario. In short, the responses of both Ficus species to climate change differed. Thus, specific actions such as ex situ conservation and assisted migration may be needed to conserve both species.

Enhanced and asymmetric signatures of hybridization at climatic margins: Evidence from closely related dioecious fig species

“…The lower levels of genetic diversity observed in the four southeast F. heterostyla populations included in cluster 1 may result from the more fragmented habitats of Thailand they occupy. Ecological niche modeling of F. heterostyla indicated that habitat loss and fragmentation have been ongoing since the Last Glacial Maximum and are projected to continue into future decades, especially in southeast Thailand ( Fungjanthuek et al., 2022 ). The figs of F. squamosa are close to the ground or at water level (even below water) and restricted to riverine habitats ( Liu et al., 2015a ; Pothasin et al., 2016 ).…”

“…Compared with populations located nearer to equatorial regions, climatically marginal pollinator populations, similar to island populations ( Kusumi et al., 2012 ), are more vulnerable to extinction or temporary absence, and/or a reduction of host availability. Recent evidence indicates that southwest China represents the northern boundary of suitable habitats for the two targeted Ficus species ( Fungjanthuek et al., 2022 ). The present data corroborate these hypothesized predictions evinced by nuclear microsatellite hybridization peaking in northern marginal areas and decreasing towards low latitudes.…”