Establishment probability in newly founded populations.

Area of Science:

• Ecology
• Conservation Biology
• Population Dynamics

Background:

• Population establishment is crucial for species survival and relies on reaching a stable, established phase.
• Quantifying establishment probability in newly founded populations has lacked simple, robust methods.
• Stochastic population models are valuable but require effective tools for probability assessment.

Purpose of the Study:

• To develop a novel, simple, and robust method for quantifying the establishment probability of newly founded populations.
• To determine the critical initial number of individuals required for a population to reach the established phase.
• To provide a transferable method applicable across various conservation biology systems.

Main Methods:

• Utilized a novel application of the "Wissel plot" by plotting -ln(1 - P0(t)) against time t.
• The method is based on the equation P(0)t=1-c(1)e(-ω(1t)), relating extinction probability to population constants.
• Applied the method to a stochastic population model of the African wild dog (Lycaon pictus) for illustration.

Main Results:

• A newly founded population reaches the established phase if the y-axis intercept of the "Wissel plot" (-ln(c(1))) is negative.
• For the African wild dog model, establishment requires an initial release of four packs (32 individuals).
• The method successfully determined a critical initial population size for successful establishment.

Conclusions:

• The presented "Wissel plot" method offers a generic and transferable approach to quantify establishment probability.
• This method disaggregates population viability components, distinguishing establishment from persistence.
• The findings have broad implications for conservation biology and species reintroduction strategies.