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INTERMITTENT BREEDING AND CONSTRAINTS ON LITTER SIZE: CONSEQUENCES FOR EFFECTIVE POPULATION SIZE PER GENERATION ( N e ) AND PER REPRODUCTIVE CYCLE ( N b )
Author(s) -
Waples Robin S.,
Antao Tiago
Publication year - 2014
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12384
Subject(s) - biology , fecundity , semelparity and iteroparity , litter , inbreeding , effective population size , avian clutch size , population , reproduction , population size , zoology , offspring , ecology , juvenile , demography , genetic variation , pregnancy , genetics , sociology , gene
In iteroparous species, it is easier to estimate N b (effective number of breeders in one reproductive cycle) than N e (effective population size per generation). N b can be used as a proxy for N e 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 N b and N e . 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 N b = ∞ and overall N b = 4 N b ( male ) . Intermittent breeding reduces the pool of female breeders, which reduces both female and overall N b ; 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 N e , but only slightly. We show how to quantitatively account for these effects, which are important to consider when (1) using N b to estimate N e , or (2) drawing inferences about male reproductive success based on estimates of female N b .