BACKGROUND Recent human transcriptomic analyses revealed a very large number of testis-enriched genes, many of which are involved in spermatogenesis. This comprehensive transcriptomic data lead us to the question whether positive selection was a decisive force influencing the evolution and variability of testis-enriched genes in humans. We used two methodological approaches to detect different levels of positive selection, namely episodic positive diversifying selection (i.e., past selection) in the human lineage within primate phylogeny, potentially driven by sperm competition, and recent positive directional selection in contemporary human populations, which would indicate adaptation to different environments. RESULTS In the human lineage (after correction for multiple testing) we found that only the gene TULP2, for which no functional data are yet available, is subject to episodic positive diversifying selection. Using less stringent statistical criteria (uncorrected p-values), also the gene SPATA16, which has a pivotal role in male fertility and for which episodes of adaptive evolution have been suggested, also displays a putative signal of diversifying selection in the human branch. At the same time, we found evidence for recent positive directional selection acting on several human testis-enriched genes (MORC1, SLC9B1, ROPN1L, DMRT1, PLCZ1, RNF17, FAM71D and WBP2NL) that play important roles in human spermatogenesis and fertilization. Most of these genes are population-specifically under positive selection. CONCLUSION Episodic diversifying selection, possibly driven by sperm competition, was not an important force driving the evolution of testis-enriched genes in the human lineage. Population-specific, recent positive directional selection suggests an adaptation of male reproductive genes to different environmental conditions. Positive selection acts on eQTLS and sQTLs, indicating selective effects on important gene regulatory functions. In particular, the transcriptional diversity regulated by sQTLs in testis-enriched genes may be important for spermatocytes to respond to environmental and physiological stress.

中文翻译：

---

特定于人群的近期积极的定向选择表明，人类雄性生殖基因适应不同的环境条件。

背景技术最近的人类转录组分析揭示了大量的睾丸富集基因，其中许多与精子发生有关。这些全面的转录组数据导致我们质疑阳性选择是否是影响人类睾丸富集基因进化和变异的决定性力量。我们使用了两种方法学方法来检测不同水平的阳性选择，即灵长类动物系统发生中人类谱系中可能由精子竞争驱动的情景性阳性多样化选择（即过去的选择），以及当代人群中最近的阳性定向选择。表示适应不同的环境。结果在人类谱系中（经过多次测试校正后），我们发现只有TULP2基因，对于尚无可用功能数据的情况，需要进行情节积极的多元化选择。使用不太严格的统计标准（未校正的p值），SPATA16基因在雄性育性中也起着关键作用，并且已经提出了适应进化的观点，该基因也显示了人类分支中多样化选择的推定信号。同时，我们发现证据表明，最近的正向方向选择作用于几个富含人类睾丸的基因（MORC1，SLC9B1，ROPN1L，DMRT1，PLCZ1，RNF17，FAM71D和WBP2NL），这些基因在人类精子发生和受精中起着重要作用。这些基因中的大多数在正选择下是群体特异性的。结论可能由精子竞争推动的情景多样化选择，它不是驱动人类谱系中富含睾丸的基因进化的重要力量。特定于人群的近期积极的定向选择表明，雄性生殖基因适应不同的环境条件。正选择作用于eQTLS和sQTL，表明对重要基因调控功能的选择性作用。特别是，受精子丰富的基因中的sQTL调节的转录多样性对于精子细胞对环境和生理压力的响应可能很重要。