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Demographic PVA’s Based on vital rates. Basic types of vital rates Fertility rates Survival rates State transition, or growth rates.

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Presentation on theme: "Demographic PVA’s Based on vital rates. Basic types of vital rates Fertility rates Survival rates State transition, or growth rates."— Presentation transcript:

1 Demographic PVA’s Based on vital rates

2 Basic types of vital rates Fertility rates Survival rates State transition, or growth rates

3 The estimation of Vital rates Accurate estimation of variance and correlation in the demographic rates We need to know: The mean value for each vital rate The variability in each rate The covariance or correlation between each pair of rates

4 Limitations of Matrix selection The assumption that the precise combinations of values that we observed the limited duration of a demographic study will always occur is unlikely to be correct.

5 A more realistic approach Use the means, variances, and correlations between vital rates, and then simulate a broader range of possible values

6 The problem of negative correlations A hypothetical individual is currently in size class 3 and has mean probability s 3 =0.95 of surviving for one year. If it survives it will either stay the same size, or grow to be in size class 4 with mean probability g 4,3 =0.10 a 33 =s 3 (1-g 43 )=(0.95)(1-0.10) and a 43 =s 3 g 43 =(0.95)(0.10)

7 The Desert Tortoise

8 Size classes and definitions of matrix elements for the desert tortoise assuming a prebreeding census Class01234567 Yearling 0f5f5 f6f6 f7f7 Juvenile 1 1 s2s2 s 2 (1-g 2 ) Juvenile 2 2 s2g2s2g2 s 2 (1-g 2 ) Immature 3 s2g2s2g2 s 3 (1-g 3 ) Immature 4 s3g3s3g3 s 4 (1-g 4 ) Subadult 5 s4g4s4g4 s 5 (1-g 5 ) Adult 1 6 s5g5s5g5 s 6 (1-g 6 ) Adult 2 7 s6g6s6g6 s7s7

9 Estimated vital rates GrowthSurvival Class19701980e1980lMeanVar19701980e1980lMeanVar 2.500.50.330.083.631.65.76.044 3.50.180.1770.280.036.911.98.96.002 4.470.06700.180.065.98.59.81.79.039 5.230.2600.160.020.98.921.96.0018 6.0630.0320 0.001.991.68.89.034 7.781.8.86.015

10 Pearson Correlations Growth g2g2 g3g3 g4g4 g5g5 g6g6 g2g2 1 g3g3.4691 g4g4.382.9951 g5g5 -.597.429.5141 g6g6 -0.014.877.919.8111

11 Pearson Correlations Survival s2s2 s3s3 s4s4 s5s5 s6s6 s7s7 s2s2 1 s3s3.7261 s4s4 -.911-.9451 s5s5 -.946-.465.7291 s6s6.487-.247-.083-.7431 s7s7.997.778-.941-.918.4171

12 Pearson Correlations Survival-Growth s2s2 s3s3 s4s4 s5s5 s6s6 s7s7 g2g2 1-.704.898.956-.514-.994 g3g3.496-.957.810.189.516-.563 g4g4 -.41-.925.75.094.597-.481 g5g5.571-.149-.182-.806.995.505 g6g6 -0.017-.7.428-.307.865-.096

13 0.5,0.001 0.5,0.01 0.5,0.2 The beta distribution Key distributions for vital rates

14 The beta distribution

15 Lognormal

16 Stretched Beta

17 Matrix selection Element selection Vital rate selection


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