Long-Term Evaluation of Breeding Scheme Alternatives for Endangered Honeybee Subspecies

Abstract

Modern breeding structures are emerging for European honeybee populations. However, while genetic evaluations of honeybees are becoming increasingly well understood, little is known about how selection decisions shape the populations’ genetic structures. We performed simulations evaluating 100 different selection schemes, defined by selection rates for dams and sires, in populations of 200, 500, or 1000 colonies per year and considering four different quantitative traits, reflecting different genetic parameters and numbers of influential loci. Focusing on sustainability, we evaluated genetic progress over 100 years and related it to inbreeding developments. While all populations allowed for sustainable breeding with generational inbreeding rates below 1% per generation, optimal selection rates differed and sustainable selection was harder to achieve in smaller populations and for stronger negative correlations of maternal and direct effects in the selection trait. In small populations, a third or a fourth of all candidate queens should be selected as dams, whereas this number declined to a sixth for larger population sizes. Furthermore, our simulations indicated that, particularly in small populations, as many sires as possible should be provided. We conclude that carefully applied breeding provides good prospects for currently endangered honeybee subspecies, since sustainable genetic progress improves their attractiveness to beekeepers.

A theoretical derivation of response to selection with and without controlled mating in honeybees

“…However, they do not account for inbreeding or genetic drift and therefore will always predict a linear genetic gain over time. Long-term simulation studies in honeybees and other species have shown that such a behavior over many generations is unrealistic [ 14 , 28 , 31 – 33 ].…”

Short-term effects of controlled mating and selection on the genetic variance of honeybee populations

“…Besides the Bulmer effect, changes in genetic variance can also be caused by genetic drift, inbreeding, and mutation. The effects of these factors on honeybees have been investigated in various studies (Beye et al 2006 ; Plate et al 2019a , 2020 ; Zayed and Packer 2005 ). However, they will influence the genetic variance only over an extended period of time and not in the short time frame considered in the present study.…”

“…However, they will influence the genetic variance only over an extended period of time and not in the short time frame considered in the present study. The initial gain of genetic variance in the performance and SC after the introduction of controlled mating could therefore become reduced over time as the selection of pseudo sires increases the risks of accumulated inbreeding and genetic drift (Plate et al 2019a , b , 2020 ). Furthermore, we mainly quantified the effects of controlled mating and selection to the immediate next generation.…”

“…Starting from year t cont , mating took place on isolated mating stations. From year t sel on, the reproducing queens were selected after a BLUP breeding value estimation like previously simulated in (Plate et al 2019a , 2020 ). We simulated three different situations regarding the introduction of controlled mating and selection (see Fig.…”

Geometric Morphology and Population Genomics Provide Insights into the Adaptive Evolution of Apis Cerana in Changbai Mountain

“…The declining effective population size and loss of genetic diversity explained the main intrinsic factors for the endangerment of A. cerana in Changbai Mountain, and inbreeding has been shown to negatively affect traits such as nectar production and swarming behaviour [75]. Frequent queen breeding and colony trade activities promote gene flow between native and commercial populations; however, it yet may lead to irreversible loss of local adaptations in native populations, genetic homogenisation, and pose a risk of genetic contamination [76,77].…”