ABSTRACT
Leaves play a central role in plant fitness, allowing efficient light capture, gas exchange and thermoregulation, ensuring optimal growing conditions for the plant. Phenotypic variability in leaf shape and size has been linked to environmental heterogeneity and habitat characteristics. Therefore, the study of foliar morphology in plant populations can help us to identify the environmental factors that may have influenced the process of species diversification. In this study, we used European wild pear (Pyrus pyraster (L.) Burgsd., Rosaceae) as a model species to investigate the phenotypic variability of leaves under different environmental conditions. Using leaf morphometric data from 19 natural populations from the north-western part of the Balkan Peninsula, a high level of variability among and within populations were found. Leaf traits related to leaf size were more variable compared to leaf shape traits, with both influenced by geographic and environmental factors. Consequently, patterns of isolation by environment (IBE) and distance (IBD) were identified, with IBE showing a stronger influence on leaf variability. Multivariate statistical analysis revealed that European wild pear populations from the north-western part of the Balkan Peninsula can be divided into two morphological clusters, consistent with their geographical distance and environmental conditions. Our results confirm a high level of phenotypic variability in European wild pear populations, providing additional data on this poorly studied species, emphasizing phenotypic plasticity as a major driver in the adaptation of this noble hardwood species to rapid climate change.
ABSTRACT
Service tree, Sorbus domestica L., is a rare and neglected wild fruit tree species of southern and central Europe. Being distributed in different eco-geographical regions, with fragmented and low-density populations, S. domestica represents an interesting model case for investigating patterns of within- and between-population diversity at geographical and environmental scales. This study aimed to analyze the proximate composition, antioxidant activity, and morphometric fruit characteristics. We examined the diversity and population divergences of 49 S. domestica individuals originating from seven populations across continental and Mediterranean eco-geographical regions. In addition, tests of isolation by distance and environment were performed to detect the magnitude of divergence explained by geographic and environmental variables. Significant differences between the studied populations were found in almost all of the studied morphometric and chemical fruit characteristics. The studied service tree populations were characterized by high phenotypic variation despite the low number of trees per population. Model-based population structure analysis using morphometric and chemical fruit characteristics revealed three groups of service tree populations. We concluded that non-effective pollen and seed dispersal along with genetic drift and specific environmental factors resulted in a distinct phenotype with a specific chemical composition in the isolated island population. In addition, a pattern of isolation by the environment was revealed. We infer that morphological and chemical differences between the studied populations in the true service tree from different eco-geographical regions were mediated by adaptation to the specific environmental conditions.