Question
Why do cicadas only come out for 17 years? Is there some biological reason that they have evolved to live this way?
Answer
Cicadas, particularly those with 13- and 17-year life cycles, exhibit an evolutionary advantage through their prime-numbered emergence intervals. This strategy minimizes predator encounters and enhances survival.
Evolutionary Advantages of Prime-Numbered Life Cycles
Predator Avoidance: Cicadas with prime-numbered life cycles (13 or 17 years) reduce the likelihood of synchronizing with predator population cycles, which typically have shorter, non-prime intervals. This minimizes predation risk during their mass emergence [1] [2].
Hybridization Avoidance: Prime-numbered cycles help avoid hybridization between cicada populations with different life cycles. Hybrid offspring, which emerge in non-prime years, face higher predation due to lower population densities, thus selecting against non-prime cycles [2].
Mechanisms and Implications
Synchronized Emergence: The synchronization of cicada emergence is controlled by genetic and environmental factors, allowing them to emerge en masse, which overwhelms predators and increases individual survival chances [3] [4].
Ecological and Evolutionary Impact: The mass emergence of cicadas contributes significantly to nutrient flow in ecosystems and influences the evolutionary dynamics of their predators and symbionts [4] [5].
The prime-numbered life cycles of cicadas provide a significant evolutionary advantage by reducing predation and hybridization risks. This strategy ensures their survival and successful reproduction, contributing to their ecological role and evolutionary success.
References
- D’agostino, S. Mix up your routine, as cicadas with prime number cycles. . 2020 https://doi.org/10.1093/oso/9780198843597.003.0002
- Toivonen, J., & Fromhage, L. Hybridization selects for prime‐numbered life cycles in Magicicada: An individual‐based simulation model of a structured periodical cicada population. Ecology and Evolution. 2020; 10. https://doi.org/10.1002/ece3.6270
- Sota, T. Life‐cycle control of 13‐ and 17‐year periodical cicadas: A hypothesis and its implication in the evolutionary process. Ecological Research. 2022 https://doi.org/10.1111/1440-1703.12354
- Simon, C., Cooley, J., Karban, R., & Sota, T. Advances in the Evolution and Ecology of 13- and 17-Year Periodical Cicadas.. Annual review of entomology. 2021 https://doi.org/10.1146/annurev-ento-072121-061108
- Wang, D., Huang, Z., Billen, J., Zhang, G., He, H., & Wei, C. Complex co-evolutionary relationships between cicadas and their symbionts.. Environmental microbiology. 2021 https://doi.org/10.1111/1462-2920.15829
