The role of menopause and reproductive senescence in a long-lived social mammal

Table 2 GLM models illustrating how other hypotheses about killer whale reproduction were evaluated.

Comparison	Error	Model	n	n_A	BIC	Pr [M\|Y]
Repro. lifespan	Gaussian	Null	21		751.2	0.824
Repro. lifespan	Gaussian	mom's survival status	21	11	754.3	0.176
IBI	Poisson	Null	62		107.1	0.645
IBI	Poisson	mom's survival status	62	28	108.4	0.345
juvenile φ(1–5)	Binomial	Null	890		419.4	0.963
juvenile φ(1–5)	Binomial	grandma's survival status	890	674	426.6	0.027
juvenile φ(1–5)	Binomial	grandma's survival status + maternal age	890		432.9	0.001

This table includes comparisons for reproductive lifespan, females' interbirth intervals, and survival of grandoffspring (φ). In each case, the null model is the simplest possible (grandmothers have no effect). The sample size for each comparison (n) represents the number of whales, except in the case of juvenile survival, where it represents whale-years (an individual may be recorded for several years). The subset of sample size with grandmothers alive is also included (n_A).

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