Environmental influences on genetic connectivity and differentiation in Alkanna orientalis populations in the Sinai Mountains, Egypt.

Landscape and environmental features shape gene flow and phenotypic variation among plant ‎populations. Alkanna orientalis (L.) Boiss. is a short-lived perennial medicinal plant in the ‎Boraginaceae that occurs across multiple landforms of the Sinai Mountains at elevations of 1500 m ‎a.s.l. and above. The aim of this study was to infer (1) how genetic diversity is distributed within and ‎among populations of A. orientalis and whether this diversity relates to population size, (2) to what ‎extent landscape features and environmental gradients such as elevation, soil properties and Wadi ‎structure influence gene flow among populations, and (3) whether variation in floral morphometric ‎traits corresponds to underlying genetic structure and reflects local adaptation or is better explained ‎by neutral demographic processes.‎ Samples were collected from 29 populations across the distribution range of the species in St. ‎Katherine Protectorate. Using AFLP markers, we addressed our population genetic questions. As ‎floral traits, we assessed among-population variation in tube and calyx length, limb width, and ‎stamen length.‎ Our results showed that A. orientalis maintains moderate genetic diversity. However, this ‎diversity was not correlated with population size. We found evidence of restricted gene flow, ‎resulting in pronounced genetic differentiation. A Mantel test revealed a significant positive ‎association between genetic and geographic distances, indicating isolation by distance, while ‎additional landscape features also contribute to the genetic structure. Floral traits were related to both ‎environmental gradients and genetic structure.‎ Environmental heterogeneity influences genetic differentiation and floral trait variation, with ‎flash floods promoting gene flow whereas restricted pollinator movement reduces connectivity ‎between populations. The observed patterns suggest adaptive responses to environmental gradients ‎rather than neutral evolutionary processes, indicating natural selection as the primary driver of ‎genetic and morphological variation.‎