Niche explosion

Area of Science:

• Ecology
• Evolutionary Biology
• Entomology

Background:

• Several phytophagous insect groups exhibit a syndrome including wingless females, larval dispersal, woody hosts, extreme polyphagy, high abundance, invasiveness, and parthenogenesis.
• Extreme polyphagy, defined as feeding on ≥20 hostplant families, is observed convergently in diverse insect taxa like bagworm moths, tussock moths, root weevils, and scale insects.

Purpose of the Study:

• To hypothesize and explore the ecological and evolutionary drivers behind extreme polyphagy in phytophagous insects.
• To propose the "niche explosion" hypothesis as a unifying explanation for the observed syndrome.

Main Methods:

• The study employs a hypothesis-driven approach, integrating ecological observations with population genetics and evolutionary theory.
• It examines the interplay between population size, host range, natural selection, and reproductive strategies (parthenogenesis).

Main Results:

• The "niche explosion" hypothesis posits a positive feedback loop where large population size facilitates a broad host range.
• This feedback loop has demographic (amplification effect) and population-genetic components, enhancing natural selection effectiveness.
• Increased selection effectiveness in large populations may explain the frequent origins of obligate parthenogenesis in extreme polyphages.

Conclusions:

• The niche explosion hypothesis offers a framework for understanding the evolution of generalist feeding strategies and pest status in insects.
• It predicts specific patterns in comparative genomics and population genetics, and has implications for trade-offs, parthenogenesis, and population dynamics.