Invasive plants optimize leaf nitrogen allocation in photosynthesis

Area of Science:

• Ecology
• Plant Biology
• Evolutionary Biology

Background:

• Invasive plants often possess acquisitive functional traits that enhance photosynthetic capacity, allowing them to outcompete native species.
• A key question is whether these superior traits are newly evolved in the invasive range or pre-adapted from the native range.

Purpose of the Study:

• To investigate the origins of enhanced photosynthetic capacity in invasive plants.
• To determine if invasive species evolve superior traits in their introduced range or arrive pre-adapted.
• To understand the mechanisms behind photosynthetic shifts, specifically leaf nitrogen allocation.

Main Methods:

• Measured photosynthetic performance of 27 invasive and 17 native species across 414 populations in temperate forest and field habitats.
• Quantified leaf nitrogen allocation among photosynthetic, structural, and defensive functions.
• Compared home and away range populations of invasive species.

Main Results:

• Invasive species exhibited higher photosynthetic capacity and photosynthetic nitrogen allocation than native species in both habitats, despite similar total leaf nitrogen.
• In fields, invasive species increased Rubisco investment in the away range, boosting carboxylation rates.
• In forests, invasive species showed greater chlorophyll allocation and quantum yield, advantages already present in their home range.

Conclusions:

• Enhanced nitrogen investment in photosynthesis is a common competitive advantage for invasive species.
• This advantage arises from a combination of pre-adaptation and evolution in the introduced range.
• Invasive species' success is not due to trade-offs with structural or defensive functions.