Intraspecific variation of Pterocarpus erinaceus Poir. along an aridity gradient: Insights into its response to drier conditions

Description of the studyIntraspecific phenotypic variation is widespread in nature, and understanding its causes and consequences is key to predict the evolutionary trajectories of plant populations and their adaptive responses to environmental stressors. Widely distributed species often encounter broad environmental gradients, imposing differential selective pressures across populations. If there is sufficient genetic variation and the effects of natural selection are stronger than those from neutral evolutionary processes, differences in patterns of selection may lead to adaptive population differentiation. Thus, understanding how species adapt to environmental changes is crucial for effective conservation and habitat restoration. In this regard, our study examines morphological and functional trait variability in Pterocarpus erinaceus Poir., a species with a wide distribution range along the South-North aridity gradient prevailing in Benin.This study was conducted in the Republic of Benin, West Africa, and covered the entire environmental gradient from south to north. Benin is located in the intertropical zone, between latitude 6°30' and 12°30' North and longitude 1° and 3°40' East (Figure 1). The country includes three climate zones, defined based on phytogeographic data and climatic gradient: (i) the Sudanian zone (SZ) in the north (semi-) arid zone (9°45'-12°25'N and 0°45’-3°50’E), (ii) the Sudano-Guinean zone (SGZ) in the sub-humid zone (7°30'-9°45'N and 1°30’ – 3°50’E), and (iii) the Guinean zone (GZ) in the south humid zone (6°25'-7°30'N and 1°45’-2°50’E). Annual rainfall ranges from 800 to 1400 mm from north to south (Adomou, 2005). This rainfall gradient has resulted in the presence of dense deciduous forests in the south and woodlands and savannas in the north (Table 1).We included the data file and the r script.Variables Id : Plot identification codeClimate_Zone : Climate ZonePopulation : Population selection by climate zoneTLL: Total Leaf length (cm)PEL: Petiole Length (cm)LEL: Leaflet lengthLW: Leaflet width (cm)PeL: Petiolule lengthNL: Number of LeafletLRCC: Chlorophyll content (%)LM: Leaflet mass (g)LA: Leaflet area (cm2)SLA: Specific leaf area (m2/g)LMA: Leaf mass per area (g/m2)DBH: Diameter at breast height (cm)TH: Total height (m)NB: Number of branchesbio_1: Annual mean temperaturebio_11: Mean Temperature of Coldest Quarterbio_16: Precipitation of Wettest Quarterbio_2: Mean Diurnal Range (Mean of monthly (max temp - min temp))bio_3: Isothermalitybio_12: Annual PrecipitationIndex_of_Aridity: Aridity IndexeEle : AltitudeGZ : Guinean ZoneSGZ : Sudano-Guinean ZoneSZ : Sudanian Zone