Climatic differentiation of the invasive alien plant Senecio inaequidens (Asteraceae) during invasion

Despite the problems they cause, biological invasions represent a great opportunity to study large-scale plant evolution, e.g. in response to changing climate. Senecio inaequidens DC. is an herbaceous perennial originating from South Africa. It was introduced as a wool alien in a few precise locations about one century ago and after a lag phase of several decades, started to spread rapidly throughout Europe and its contrasted climate. Our study uses common garden experiments to assess the differentiation of the species along both altitudinal and climatic gradients. Life history traits are measured and linked to climatic conditions of source populations. Results show that the species evolved along a climatic gradient from the Mediterranean to the high Pyrenean. This along-invasion differentiation can be linked to mean temperature evolution along the gradient and shows how an introduced species can potentially develop adaptations to new encountered thermic conditions in a length of time of several decades. How understanding the adaptive response of a plant to new climatic conditions will help anticipating the potential response of the flora to climate change is discussed.FRFC 2.4605.0