  I describe an analytical approximation for calculating the short-term
probability of loss of a chromosome under the neutral Wright-Fisher model with
recombination. I also present an upper and lower bound for this probability.
Exact analytical calculation of this quantity is difficult and computationally
expensive because the number of different ways in which a chromosome can be
lost, grows very large in the presence of recombination. Simulations indicate
that the probabilities obtained using my approximate formula are always
comparable to the true expectations provided that the number of generations
remains small. These results are useful in the context of an algorithm that we
recently developed for simulating Wright-Fisher populations forward in time.
C++ programs that can efficiently calculate these formulas are available on
request.
