# Plastic Germination, Temporal Niche Partitioning and Emergent Assortative Mating in Annual Plants

## TL;DR

The paper shows how plants can evolve to germinate at different times, which helps them coexist and diversify into new species.

## Contribution

The study reveals that plastic germination can drive genetic diversification and ecological speciation through temporal niche partitioning and assortative mating.

## Key findings

- Adaptive plasticity in germination evolves via genetic associations with fecundity traits.
- Plastic germination enhances temporal niche partitioning and promotes divergence into specialized morphs.
- Plasticity generates temporal assortative mating, maintaining trait associations without genetic linkage.

## Abstract

Temporal fluctuations in the environment can promote coexistence via the storage effect, where competing variants are buffered during unfavourable years. In annual plants, this can arise from seed dormancy: seeds remain in the seed bank across years and germinate under suitable conditions. Here, we investigate how plasticity in germination timing (where seeds use environmental cues to adjust when they germinate) affects genetic diversification and ecological speciation. Using eco‐evolutionary models, we show that adaptive plasticity readily evolves via genetic associations between germination and fecundity traits, allowing seeds to germinate preferentially in years favourable for reproduction. This enhances temporal niche partitioning and promotes divergence into specialised morphs. Because these morphs germinate in different years, plasticity generates temporal assortative mating and maintains trait associations even without genetic linkage. Our results show that adaptive plasticity and genetic diversification can interact synergistically: predictive germination not only buffers fluctuations but also drives the evolution of biodiversity.

Temporal environmental fluctuations can drive genetic diversity and species coexistence via the storage effect. Using eco‐evolutionary models of annual plants, we show that adaptive plasticity in seed germination readily evolves and promotes genetic diversification by facilitating temporal niche partitioning, and in sexual populations can initiate ecological speciation by generating temporal assortative mating. These results highlight how adaptive plasticity and genetic diversification can interact synergistically to enhance biodiversity.