The Novel Weapons Hypothesis (NWH)

The Novel Weapons Hypothesis (NWH) suggests that invasive plant species can potentially out-compete native species due to their allelopathic (phototoxic and/or antimicrobial) chemicals. This use of “novel weapons” is usually thought of as a form of competition due to its potential to degrade the metabolism of neighboring plant species. Because native plants have not previously encountered the toxins released from the invasive allelopathic species, they have no evolved defences. The Novel Weapons Hypothesis has been observed and tested within a plethora of plant species. Tangential to the Novel Weapons Hypothesis, is the Biochemical Recognition Hypothesis (BRH), which suggests that seeds can detect potential competitors and can subsequently induce dormancy until
study, they compared twelve different species (six native and six nonnative) with varying seed sizes between each. Testing both nonnative and native species was important to the understanding of the impact that leachates from species that historically share and area, and species that have had no history of interaction, had on germination. The differing seed sizes allowed for a better understanding of the Biochemical Recognition Hypothesis, due to the known differences between small and large seeds. Small seeds are typically less provisioned than larger seeds, have a longer soil seed bank life span, and are less prone to predation. On the contrary, larger seeds are often more provisioned, have shorter soil seed bank life spans, and are more prone to predation. The selective pressures on larger seeds, enforce quick germination rather than induced dormancy. Smaller seeds, however, are typically less prone to predations and subsequently have less pressure to germinate quickly. Also, their small size allows them to “sink” into the soil easier than larger seeds. Because the soil seed banks of smaller seeds are longer lived than larger seeds, dormancy is in many cases an adaptive