Evidence of natural hybridization and introgression between Medicago ciliaris and Medicago intertexta

TL;DR

This study provides evidence of natural hybridization and gene flow between Medicago ciliaris and Medicago intertexta in Tunisia, based on reproductive traits and genetic markers, indicating ongoing introgression between these species.

Contribution

It is the first to document natural hybridization and introgression between M. ciliaris and M. intertexta using reproductive and genetic data.

Findings

Significant decrease in pollen fertility and seed production in hybrid populations

Biometrical traits and isozyme patterns show intermediacy between species

Evidence supports natural hybridization and introgression in wild populations

Abstract

The present study, investigated some reproductive and fertility parameters in some wild populations, originating from the North Tunisia (4 populations of Medicago ciliaris and 3 populations of Medicago intertexta). Previous finding revealed that these species are genetically distinct and easily recognized by the number of flowers per inflorescence and pod dimensions. However, biometrical traits and isozyme patterns intermediacy between these two species had detected the existence of a potential spontaneous interspecific hybrid originating from Sedjnane locality in Tunisia. Indeed, the present work has shown significant decrease of pollen fertility and seed production for this population when compared to the others(pollen viability 75%, pollen germinability 8% and pod production=9%). These results suggested a possible natural interspecific hybrid and confirming introgressive hybridization possibility between M. intertexta and M. ciliaris.