Kistler Tristan, Brascamp Evert W, Basso Benjamin, Phocas Florence, Bijma Piter
Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350, Jouy-en-Josas, France.
UMT PrADE, 84914, Avignon, France.
Heredity (Edinb). 2025 May 22. doi: 10.1038/s41437-025-00768-8.
Honeybee breeding is organized around annual cycles, following seasonal change. Generation intervals are thus commonly multiples of whole years. Most queens are generally raised during spring or early summer in temperate climates. A generation interval of 1 year limits phenotyping to early recordable traits, before the spring following queens' births. Some traits, however, can only be recorded later, as is typically the case for total honey yield. Their recording on selection candidates thus increases the generation interval to at least 2 years, a common interval on the dam path. Using stochastic simulation, we investigated the impact of halving the dam generation interval and therefore recording only early traits on candidate dams. The generation interval on the sire path remained at 2 years with complete phenotyping. Breeding goals with varying weights on early and late traits were considered, as well as negative to positive genetic correlations between traits. The acceleration of the breeding scheme generally increased genetic gain for two-trait breeding goals, from 0% up to +47% after 20 years of selection. Although inbreeding rates per generation were slightly lower in the accelerated breeding scheme, inbreeding rates per year were significantly higher. This was due to the faster generation turnover (+33%) leading to 20-30% higher inbreeding coefficients (+0.04 to +0.07) after 20 years of selection. To avoid too high inbreeding, shortening the generation interval should be accompanied by strategies to limit inbreeding while still retaining most of the genetic gain, such as increasing the breeding nucleus size by relaxing selection intensity.
蜜蜂育种是围绕年度周期进行组织的，遵循季节变化。因此，世代间隔通常是整年的倍数。在温带气候下，大多数蜂王一般在春季或初夏培育。1年的世代间隔将表型分析限制在蜂王出生后的次年春季之前可早期记录的性状上。然而，有些性状只能在之后记录，蜂蜜总产量通常就是这种情况。因此，在选择候选蜂时对这些性状进行记录会使世代间隔增加到至少2年，这在母系路径上是常见的间隔。我们通过随机模拟研究了将母系世代间隔减半，从而仅对候选母蜂记录早期性状的影响。父系路径上的世代间隔在进行完整表型分析时保持为2年。我们考虑了对早期和晚期性状赋予不同权重的育种目标，以及性状之间从负到正的遗传相关性。育种方案的加速通常会增加两性状育种目标的遗传增益，在选择20年后，遗传增益从0%提高到了 +47%。虽然加速育种方案中每代的近亲繁殖率略低，但每年的近亲繁殖率显著更高。这是由于世代更替更快（+33%），导致在选择20年后近亲繁殖系数提高了20 - 30%（从 +0.04提高到 +0.07）。为避免过高的近亲繁殖，缩短世代间隔应同时采取限制近亲繁殖的策略，同时仍保留大部分遗传增益，例如通过放宽选择强度来增加育种核心群规模。
