Data from: Intermittent breeding and constraints on litter size: consequences for effective population size per generation (Ne) and per reproductive cycle (Nb)

In iteroparous species, it is easier to estimate Nb = effective number of breeders in one reproductive cycle than Ne = effective population size per generation. Nb can be used as a proxy for Ne and also can provide crucial insights into eco-evolutionary processes that occur during reproduction. We used analytical and numerical methods to evaluate effects of intermittent breeding and litter/clutch size on inbreeding Nb and Ne. Fixed or random litter sizes ≥ 3 have little effect on either effective-size parameter; however, in species (e.g., many large mammals) in which females can produce only one offspring per cycle, female Nb = ∞ and overall Nb = 4Nb(male). Intermittent breeding reduces the pool of female breeders, which reduces both female and overall Nb; reductions are larger in high-fecundity species with high juvenile mortality and increase when multiple reproductive cycles are skipped. Simulated data for six model species showed that both intermittent breeding and litter-size constraints increase Ne, but only slightly. We show how to quantitatively account for these effects, which are important to consider when a) using Nb to estimate Ne, or b) drawing inferences about male reproductive success based on estimates of female Nb.对于多次繁殖物种（iteroparous species）而言，估算单次繁殖周期内的繁殖有效数量（Nb, effective number of breeders）要比估算每一代的有效种群大小（Ne, effective population size per generation）更为容易。Nb既可以作为Ne的替代指标，也能为繁殖过程中发生的生态进化过程提供关键洞见。我们采用解析法与数值模拟方法，评估了间歇繁殖与窝仔/产卵量对近交繁殖有效数量（inbreeding Nb）以及Ne的影响。当窝仔数固定或随机且≥3时，二者几乎不受影响；但在雌性单周期仅能繁育1只后代的物种（如多数大型哺乳动物）中，雌性Nb为无穷大，整体Nb=4Nb(雄性)。间歇繁殖会缩减雌性繁殖者种群规模，进而降低雌性与整体Nb；在繁殖力高且幼体死亡率高的物种中，这种缩减效应更为显著，且跳过多次繁殖周期时缩减程度会进一步加大。针对6个模式物种的模拟数据显示，间歇繁殖与窝仔数限制均会小幅提升Ne。我们还给出了如何量化表征上述效应的方法，这些效应在以下两种场景中尤为值得考量：a) 利用Nb估算Ne时，或b) 基于雌性Nb的估算结果推断雄性繁殖成功率时。