Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-27T11:48:56.324Z Has data issue: false hasContentIssue false

Speed of coming down from infinity for birth-and-death processes

Published online by Cambridge University Press:  11 January 2017

Vincent Bansaye*
Affiliation:
École Polytechnique
Sylvie Méléard*
Affiliation:
École Polytechnique
Mathieu Richard*
Affiliation:
École Polytechnique
*
* Postal address: CMAP, École Polytechnique, CNRS, route de Saclay, 91128 Palaiseau Cedex, France.
* Postal address: CMAP, École Polytechnique, CNRS, route de Saclay, 91128 Palaiseau Cedex, France.
* Postal address: CMAP, École Polytechnique, CNRS, route de Saclay, 91128 Palaiseau Cedex, France.

Abstract

We describe in detail the speed of `coming down from infinity' for birth-and-death processes which eventually become extinct. Under general assumptions on the birth-and-death rates, we firstly determine the behavior of the successive hitting times of large integers. We identify two different regimes depending on whether the mean time for the process to go from n+1 to n is negligible or not compared to the mean time to reach n from ∞. In the first regime, the coming down from infinity is very fast and the convergence is weak. In the second regime, the coming down from infinity is gradual and a law of large numbers and a central limit theorem for the hitting times sequence hold. By an inversion procedure, we deduce that the process is almost surely equivalent to a nonincreasing function when the time goes to 0. Our results are illustrated by several examples including applications to population dynamics and population genetics. The particular case where the death rate varies regularly is studied in detail.

Type
Research Article
Copyright
Copyright © Applied Probability Trust 2017 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

[1] Aldous, D. J. (1999). Deterministic and stochastic models for coalescence (aggregation and coagulation): a review of the mean-field theory for probabilists. Bernoulli 5, 348.Google Scholar
[2] Allen, L. J. S. (2011). An Introduction to Stochastic Processes with Applications to Biology, 2nd edn. CRC Press, Boca Raton, FL.Google Scholar
[3] Anderson, W. J. (1991). Continuous-Time Markov Chains: An Applications-Oriented Approach. Springer, New York.Google Scholar
[4] Berestycki, J., Berestycki, N. and Limic, V. (2010). The λ-coalescent speed of coming down from infinity. Ann. Prob. 38, 207233.Google Scholar
[5] Billingsley, P. (1986). Probability and Measure, 2nd edn. John Wiley, New York.Google Scholar
[6] Bingham, N. H., Goldie, C. M. and Teugels, J. L. (1989). Regular Variation (Encyclopedia Math. Appl. 27). Cambridge University Press.Google Scholar
[7] Cattiaux, P. et al. (2009). Quasi-stationary distributions and diffusion models in population dynamics. Ann. Prob. 37, 19261969. Google Scholar
[8] Donnelly, P. (1991). Weak convergence to a Markov chain with an entrance boundary: ancestral processes in population genetics. Ann. Prob. 19, 11021117.Google Scholar
[9] Karlin, S. and McGregor, J. L. (1957). The differential equations of birth-and-death processes, and the Stieltjes moment problem. Trans. Amer. Math. Soc. 85, 489546.Google Scholar
[10] Karlin, S. and Taylor, H. M. (1975). A First Course in Stochastic Processes, 2nd edn. Academic Press, New York.Google Scholar
[11] Klesov, O. I. (1983). The rate of convergence of series of random variables. Ukrain. Mat. Zh. 35, 309314.Google Scholar
[12] Kot, M. (2001). Elements of Mathematical Ecology. Cambridge University Press.Google Scholar
[13] Lambert, A. (2005). The branching process with logistic growth. Ann. Appl. Prob. 15, 15061535.Google Scholar
[14] Limic, V. and Talarczyk, A. (2010). Diffusion limits for mixed with Kingman coalescents at small times. Preprint. Available at http://arxiv.org/abs/1409.6200v1.Google Scholar
[15] Slade, P. F. and Wakeley, J. (2005). The structured ancestral selection graph and the many-demes limit. Genetics 169, 11171131.Google Scholar
[16] Sibly, R. M. et al. (2005). On the regulation of populations of mammals, birds, fish, and insects. Science 309, 607610.Google Scholar
[17] Taylor, H. M. and Karlin, S. (1998). An Introduction to Stochastic Modeling, 3rd edn. Academic Press, San Diego, CA.Google Scholar
[18] Van Doorn, E. A. (1991). Quasi-stationary distributions and convergence to quasi-stationarity of birth–death processes. Adv. Appl. Prob. 23, 683700.CrossRefGoogle Scholar