Natural intraspecific trait variation patterns of the wild soursop annona senegalensis (Annonaceae) along a climatic gradient in Benin, West Africa

Abstract

Background and aims – Geographic patterns of phenotypic variability can inform understanding of the resilience potential of plant species to environmental hazards such as climate change. Such understanding provides support for conservation and domestication efforts. Here, we investigated natural morphological variation of the individuals, fruits, seeds, and leaves of the tropical shrub Annona senegalensis Pers. along a climatic gradient. Methods – Morphological data were collected on shrubs, fruits, seeds, and leaves of 150 shrubs from five populations in the three climatic zones of Benin. Linear mixed effects models were used to test the variability of the morphological traits of the species and also to estimate the variance components in order to tease apart the importance of each source of variation. The most important morphological descriptors discriminating climatic zones were identified using a stepwise discriminant analysis. Redundancy analysis was then used to determine the relationships between discriminant morphological traits and bioclimatic variables. Key results – Morphological traits of A. senegalensis varied greatly both within and among climatic zones. A substantial part (42%) of the among-climatic zones phenotypic variability in the species was attributable to climate, mainly rainfall and temperature. Morphological traits such as big shrubs, big fruits, and high number of seeds per fruit were associated with high mean annual rainfall and low mean temperature of the warmest quarter. Conclusions – The findings suggest an important zonal adaptation of the species to climate variability. The phenotypic diversity pattern that we highlighted can be useful when designing conservation policies for the species. However, quantitative genetics through common garden or reciprocal transplantation experiments related to the species’ populations would enable to explore the heritable part of the observed variability to support effective conservation and domestication efforts.