Adaptive Sex Ratio Variation in Lampreys: Implications for Ecosystem Dynamics and Species Interactions

Lampreys can alter the sex ratio of their population in response to resource availability in the environment, which has significant implications for the ecosystem. This paper built a population growth model based on the Malthusian Model to describe the relationship between the natural growth rate of lamprey populations and resource availability. It highlights how variations in the sex ratio contribute to changes in birth rates while also considering the influence of resource availability on mortality rates. This model incorporates a specific coefficient to measure the rate of resource consumption, underlining the adaptability of lampreys in various ecological contexts. Then, to explore the interaction between lamprey and other species, this paper devised a simplified food web reflecting real-world conditions and established an ecological interaction model based on the Lotka-Volterra equations. This model employs a simplified food web that mirrors real-life ecosystems, categorizing related species into predators, competitors, and prey/hosts, thus offering a comprehensive view of lampreys' ecological relationships. Simulation results indicate that lampreys' strategy of sex ratio adaptation significantly bolsters their survival and reproductive success across both resource-depleted and resource-rich environments. This adaptive mechanism underscores their competitive edge in diverse ecological settings, confirming the critical influence of lampreys on ecosystem balance and biodiversity.