The relative frequency of sexual versus asexual reproduction governs the distribution of genetic diversity within and among populations. Most studies on the consequences of reproductive variation focus on the mating system (i.e., selfing vs. outcrossing) of diploid-dominant taxa (e.g., angiosperms), often ignoring asexual reproduction. Although reproductive systems are hypothesized to be correlated with life-cycle types, variation in the relative rates of sexual and asexual reproduction remains poorly characterized across eukaryotes. This is particularly true among the three major lineages of macroalgae (green, brown, and red). The Rhodophyta are particularly interesting, as many taxa have complex haploid–diploid life cycles that influence genetic structure. Though most marine reds have separate sexes, we show that freshwater red macroalgae exhibit patterns of switching between monoicy and dioicy in sister taxa that rival those recently shown in brown macroalgae and in angiosperms. We advocate for the investigation of reproductive system evolution using freshwater reds, as this will expand the life-cycle types for which these data exist, enabling comparative analyses broadly across eukaryotes. Unlike their marine cousins, species in the Batrachospermales have macroscopic gametophytes attached to filamentous, often microscopic sporophytes. While asexual reproduction through monospores may occur in all freshwater reds, the Compsopogonales are thought to be exclusively asexual. Understanding the evolutionary consequences of selfing and asexual reproduction will aid in our understanding of the evolutionary ecology of all algae and of eukaryotic evolution generally.

中文翻译：

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大型藻类生殖系统变异的生态进化重要性：以淡水红藻为例

有性生殖与无性生殖的相对频率决定了种群内部和种群之间遗传多样性的分布。大多数关于生殖变异后果的研究都集中在二倍体优势类群（例如被子植物）的交配系统（即自交与异交）上，常常忽略无性繁殖。尽管假设生殖系统与生命周期类型相关，但真核生物有性生殖和无性生殖相对速率的变化仍然很少被描述。在大型藻类的三大谱系（绿藻、棕藻和红藻）中尤其如此。红藻门特别有趣，因为许多类群具有影响遗传结构的复杂单倍体-二倍体生命周期。尽管大多数海洋红藻具有不同的性别，但我们发现淡水红藻在姐妹类群中表现出单性和双性之间的转换模式，这与最近在褐藻和被子植物中显示的模式相媲美。我们主张使用淡水红细胞研究生殖系统进化，因为这将扩大这些数据存在的生命周期类型，从而能够在真核生物中进行广泛的比较分析。与它们的海洋近亲不同，Batrachospermales 中的物种具有附着在丝状（通常是微观孢子体）上的宏观配子体。虽然所有淡水红藻都可能通过单孢子进行无性繁殖，但 Compsopogonales 被认为是完全无性繁殖的。了解自交和无性繁殖的进化后果将有助于我们理解所有藻类的进化生态学和一般的真核进化。