Classic Mendelian inheritance is the bedrock of population genetics and underpins pedigree-based management of animal populations. However, assumptions of Mendelian inheritance might not be upheld in conservation breeding programmes if early viability selection occurs, even when efforts are made to equalise genetic contributions of breeders. To test this possibility, we investigated deviations from Mendelian proportions in a captive metapopulation of the endangered Tasmanian devil. This marsupial population is ideal for addressing evolutionary questions in conservation due to its large size, range of enclosure types (varying in environmental conditions), good genomic resources (which aid interpretation), and the species’ biology. Devil mothers give birth to more offspring than they can nurse in the pouch, providing the potential for intense viability selection amongst embryos. We used data from 140 known sire-dam-offspring triads to isolate within-family selection from population-level mechanisms (such as mate choice or inbreeding), and compared observed offspring genotypes at 123 targeted SNPs to neutral (i.e., Mendelian) expectations. We found lower offspring heterozygosity than expected, and subtle patterns that varied across a gradient of management intensity from zoo-like enclosures to semi-wild environments for some loci. Meiotic drive or maternal-foetal incompatibilities are consistent with our results, although we cannot statistically confirm these mechanisms. We found some evidence that maternal genotype affects annual litter size, suggesting that family-level patterns are driven by differential offspring mortality before birth or during early development. Our results show that deviations from Mendelian inheritance can occur in conservation programmes, despite best-practice management to prevent selection.

中文翻译：

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在保护计划中偏离孟德尔比例的第一个证据

经典的孟德尔遗传是种群遗传学的基石，也是基于谱系的动物种群管理的基础。然而，如果早期生存力选择发生，即使在努力平衡育种者的遗传贡献时，孟德尔遗传的假设可能不会在保护育种计划中得到支持。为了测试这种可能性，我们调查了濒临灭绝的袋獾的圈养种群中孟德尔比例的偏差。由于其体型大、围栏类型多样（环境条件不同）、良好的基因组资源（有助于解释）和物种生物学，这种有袋动物种群非常适合解决保护中的进化问题。恶魔母亲生下的后代比它们在育儿袋中所能哺育的还多，提供在胚胎之间进行强烈活力选择的潜力。我们使用来自 140 个已知的父系 - 母系 - 后代三合会的数据将家族内选择与种群水平机制（例如配偶选择或近亲繁殖）分离，并将观察到的 123 个靶向 SNP 的后代基因型与中性（即孟德尔）预期进行比较。我们发现后代杂合度低于预期，并且在从类似动物园的围栏到一些位点的半野生环境的管理强度梯度中存在微妙的模式。减数分裂驱动或母胎不相容性与我们的结果一致，尽管我们无法从统计上证实这些机制。我们发现了一些证据表明母体基因型会影响每年的产仔数，表明家庭层面的模式是由出生前或早期发育过程中不同的后代死亡率驱动的。我们的结果表明，尽管有防止选择的最佳实践管理，但保护计划中仍可能发生与孟德尔遗传的偏差。