Environmental virus communities are highly diverse. However, the infection physiology underlying the evolution of diverse phage lineages and their ecological consequences are largely unknown. T7-like cyanophages are abundant in nature and infect the marine unicellular cyanobacteria, Synechococcus and Prochlorococcus, important primary producers in the oceans. Viruses belonging to this genus are divided into two distinct phylogenetic clades: clade A and clade B. These viruses have narrow host-ranges with clade A phages primarily infecting Synechococcus genotypes, while clade B phages are more diverse and can infect either Synechococcus or Prochlorococcus genotypes. Here we investigated infection properties (life history traits) and environmental abundances of these two clades of T7-like cyanophages. We show that clade A cyanophages have more rapid infection dynamics, larger burst sizes and greater virulence than clade B cyanophages. However, clade B cyanophages were at least 10-fold more abundant in all seasons, and infected more cyanobacteria, than clade A cyanophages in the Red Sea. Models predicted that steady-state cyanophage abundances, infection frequency, and virus-induced mortality, peak at intermediate virulence values. Our findings indicate that differences in infection properties are reflected in virus phylogeny at the clade level. They further indicate that infection properties, together with differences in subclade diversity and host repertoire, have important ecological consequences with the less aggressive, more diverse virus clade having greater ecological impacts.

环境病毒群落高度多样化。然而，不同噬菌体谱系进化背后的感染生理学及其生态后果在很大程度上尚不清楚。 T7 样噬藻体在自然界中大量存在，并感染海洋单细胞蓝细菌、聚球藻属和原绿球藻属，它们是海洋中重要的初级生产者。属于该属的病毒分为两个不同的系统发育分支：分支 A 和分支 B。这些病毒的宿主范围较窄，分支 A 噬菌体主要感染聚球藻基因型，而分支 B 噬菌体更加多样化，可以感染聚球藻或原绿球藻基因型。在这里，我们研究了这两个 T7 类噬藻体分支的感染特性（生活史特征）和环境丰度。我们发现，与进化枝 B 噬藻体相比，进化枝 A 噬藻体具有更快的感染动态、更大的爆发大小和更强的毒力。然而，与红海中的 A 进化枝噬藻体相比，B 进化枝噬藻体在所有季节的数量至少高出 10 倍，并且感染的蓝藻数量也更多。模型预测稳态噬藻体丰度、感染频率和病毒引起的死亡率在中等毒力值时达到峰值。我们的研究结果表明，感染特性的差异反映在进化枝水平的病毒系统发育中。他们进一步表明，感染特性以及分支多样性和宿主库的差异具有重要的生态后果，攻击性较小、更加多样化的病毒分支具有更大的生态影响。