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Birth-Death & Coalescent Theory
Mode
Coalescent Tree
Birth-Death Process
Both (side-by-side)
Regenerate
Parameters
Sample size n
12
Pop size N_e
100
Birth rate λ
0.15
Death rate μ
0.08
Statistics
TMRCA (expect)
—
Net diversif.
—
Total branches
—
Tree height
—
Theory
Kingman Coalescent (1982):
P(k→k-1 in dt) = C(k,2)/N_e dt
E[T_k] = N_e / C(k,2)
E[TMRCA] = 2N_e(1−1/n)
Birth-Death (Yule process):
dP_n/dt = λ(n−1)P_{n-1} − λnP_n
Diversification rate r = λ − μ
Expected clades: ~e^{rt}
Net: N(t) = N_0·e^{(λ−μ)t}