Inheritance of somatic mutations can affect fitness in monkeyflowers.

The article investigates the evolutionary significance of inherited somatic mutations in the bush monkeyflower (Mimulus aurantiacus), a perennial plant capable of transmitting mutations arising during both mitotic (somatic) and meiotic cell divisions. By comparing progeny from autogamous (within-flower self-pollination) and geitonogamous (between-flowers on different stems of the same plant) crosses, the study assessed how somatic mutations affect offspring fitness, particularly under drought conditions that mimic the plant's native environment. Results showed variable fitness effects among different stems ("units"), with some autogamous progeny exhibiting increased seed production and enhanced drought tolerance, while others showed no significant differences or slight deleterious effects. The findings suggest that somatic mutations can contribute to genetic variation influencing plant fitness and evolution, although their impact may be subtle in well-adapted environments.