Data from: Seasonal variation in male alternative reproductive tactics

Genetic parentage analyses reveal considerable diversity in alternative reproductive behaviours (e.g. sneaking) in many taxa. However, little is known about whether these behaviours vary seasonally and between populations. Here, we investigate seasonal variation in male reproductive behaviours in a population of two-spotted gobies (Gobiusculus flavescens) in Norway. Male two-spotted gobies guard nests, attract females and care for fertilized eggs. We collected clutches and nest-guarding males early and late in the breeding season in artificial nests and used microsatellite markers to reconstruct parentage from a subset of offspring from each nest. We hypothesized that mating, reproductive success and sneaking should be more prevalent early in the breeding season when competition for mates among males is predicted to be higher. However, parentage analyses revealed similar values of mating, reproductive success and high frequencies of successful sneaking early (30% of nests) and late (27% of nests) in the season. We also found that multiple females with eggs in the same nest were fertilized by one or more sneaker males, indicating that some males in this population engage in a satellite strategy. We contrast our results to previous work that demonstrates low levels of cuckoldry in a population in Sweden. Our results demonstrate marked stability in both the genetic mating system and male alternative reproductive tactics over the breeding season. However, sneaking rates may vary geographically within a species, likely due to local selection influencing ecological factors encountered at different locations.

遗传亲权分析（genetic parentage analyses）揭示，诸多分类单元中存在丰富多样的替代性繁殖行为，例如偷配（sneaking）。然而，学界对这类行为是否存在季节变化以及种群间差异尚不清楚。本研究以挪威海域的双斑虾虎鱼（Gobiusculus flavescens）种群为研究对象，探究雄性繁殖行为的季节变化规律。雄性双斑虾虎鱼会守卫巢穴、吸引雌性并照料受精鱼卵。本研究于繁殖季的早期与晚期，通过人工巢穴采集了鱼卵集群与守巢雄性个体，并利用微卫星标记（microsatellite markers）对每个巢穴中的部分子代开展亲权重建分析。我们提出如下研究假设：繁殖季早期雄性间的配偶竞争更为激烈，因此交配行为、繁殖成功率以及偷配行为的发生频率应更高。但亲权分析结果显示，繁殖季早期与晚期的交配频次、繁殖成功率数值相近，且成功偷配的发生频率均处于较高水平：早期偷配出现于30%的巢穴中，晚期则为27%。研究同时发现，同一巢穴内的多尾雌性所产鱼卵可被一头或多头偷配雄性（sneaker males）受精，表明该种群中的部分雄性会采取卫星繁殖策略。我们将本次研究结果与此前针对瑞典某双斑虾虎鱼种群的相关研究进行对比，后者报道了较低的偷配发生水平。本研究结果表明，在整个繁殖季中，该种群的遗传婚配系统与雄性替代性繁殖策略均保持显著稳定。不过，同一物种的偷配率可能存在地理差异，这大概率是由不同生境下的局部选择作用对所遭遇的生态因子的影响所导致的。