物种种群存活力分析计算器
使用物种种群存活力分析计算器评估野生物种的灭绝风险。输入种群大小、繁殖率和死亡率，模拟种群动态变化趋势，为濒危物种保护制定科学策略。
Projected Population
1,359
Projected Population vs Projection Period
公式
Population Viability Analysis
Population viability analysis (PVA) projects whether a species can sustain itself over time. The simplest model uses exponential growth.
Formula
N(t) = N0 x e^(r x t)
Where N0 is the current population, r is the net growth rate (birth rate minus death rate), and t is time in years. A positive r indicates growth; negative r indicates decline. The minimum viable population for most mammals is estimated at 500-5,000 individuals.
计算示例
500 individuals with a 12% birth rate and 10% death rate, projected 50 years.
- 01Net growth rate = 0.12 - 0.10 = 0.02 (2%/year)
- 02Projected = 500 x e^(0.02 x 50) = 500 x e^1.0 = 500 x 2.718 = 1,359
- 03Doubling time = ln(2) / 0.02 = 34.7 years
常见问题
What is the minimum viable population?
The minimum viable population (MVP) is the smallest number of individuals needed for a 95% chance of survival over a set period. For most vertebrates, estimates range from 500 to 5,000.
Does this model account for inbreeding?
No. This simple exponential model ignores genetic factors. Small populations face inbreeding depression, which reduces fitness and can accelerate decline.
What is an extinction vortex?
An extinction vortex occurs when declining populations suffer compounding problems: reduced genetic diversity, inability to find mates, and loss of social structure, each accelerating the decline.