Learning from failures: testing broad taxonomic hypotheses about plant naturalization.

Area of Science:

• Ecology
• Botany
• Invasive Species Biology

Background:

• Current understanding of plant naturalization patterns relies solely on successful introductions, potentially introducing bias.
• Excluding failed naturalizations conflates introduction probability with naturalization success, skewing ecological interpretations.

Purpose of the Study:

• To conduct a flora-wide comparative test of major invasion hypotheses using comprehensive datasets of both successful and failed plant naturalizations.
• To investigate taxonomic patterns of plant naturalizations across New Zealand and Australia, accounting for introduction failures.

Main Methods:

• Utilized two extensive datasets encompassing both successful and failed plant naturalizations in New Zealand and Australia.
• Performed comparative analyses to test established invasion hypotheses, including Darwin's naturalization hypothesis.
• Examined the influence of climatic origins and the presence of native relatives on naturalization success rates.

Main Results:

• Identified consistently successful naturalizing taxa across New Zealand and Australia, irrespective of environmental differences.
• Demonstrated that broad climatic origins partially explain variations in naturalization success between the two countries.
• Found that species with native relatives were generally more successful, contradicting Darwin's hypothesis, with family-specific inconsistencies observed.
• Showed that islands are not inherently more susceptible to invasion than continents when failed introductions are considered.

Conclusions:

• Accounting for failed naturalizations provides a more accurate assessment of invasion dynamics and taxonomic patterns.
• Climatic origins and native relatives are significant factors in plant naturalization, though their effects vary.
• The 'island invisibility' hypothesis is challenged by evidence that includes failed introductions.