Eco-Geography and Phenology Are the Major Drivers of Reproductive Isolation in the Royal Irises, a Species Complex in the Course of Speciation

Inna Osmolovsky, Mariana Shifrin, Inbal Gamliel, Jonathan Belmaker, Yuval Sapir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The continuous nature of speciation implies that different species are found at different stages of divergence, from no- to complete reproductive isolation. This process and its underlying mechanisms are best viewed in incipient species. Moreover, the species complex can offer unique insight into how reproductive isolation (RI) has evolved. The royal irises (Iris section Oncocyclus) are a young group of species in the course of speciation, providing an ideal system for speciation study. We quantified pre- and post-zygotic reproductive barriers between the eight Israeli species of this complex and estimated the total RI among them. We tested for both pre-pollination and post-pollination reproductive barriers. Pre-pollination barriers, i.e., eco-geographic divergence and phenological differentiation were the major contributors to RI among the Iris species. On the other hand, post-pollination barriers, namely pollen–stigma interactions, fruit set, and seed viability had negligible contributions to total RI. The strength of RI was not uniform across the species complex, suggesting that species may have diverged at different rates. Overall, this study in a young, recently diverged group of species provides insight into the first steps of speciation, suggesting a crucial role of the pre-zygotic barriers.

Original languageEnglish
Article number3306
JournalPlants
Volume11
Issue number23
DOIs
StatePublished - Dec 2022

Funding

FundersFunder number
American Iris Society Foundation
Manna Centre for Food Security
Tel Aviv University

    Keywords

    • ecological speciation
    • reproductive isolation
    • speciation continuum
    • species complex

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