Evolution of Anisogamy in Organisms with Parthenogenetic Gametes
Evolution of Anisogamy in Organisms with Parthenogenetic Gametes
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DOI：
10.1086/715185
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发表时间：
2021-09-01
影响因子：
2.9
通讯作者：
Parker, Geoff A.
中科院分区：
文献类型：
--
作者：
Lehtonen, Jussi;Horinouchi, Yusuke;Parker, Geoff A.
两性是由它们产生的配子的大小来定义的，异配生殖是两种不同配子大小的状态（因此，雌性和雄性）。这种分歧的起源已经收到了很多研究兴趣，无论是理论上还是实证上。配子动力学（GD）理论是一种被广泛接受的异配生殖的理论解释，而绿色藻类一直是该理论的重要实验检验场。然而，一些绿色和褐藻产生单性生殖配子（配子可以不与另一配子融合而发育），与GD理论中未融合配子不发育的假设相反。在这里，我们构建了一个GD模型占孤雌配子。我们发现，在全混合和高效施肥的条件下（即，从1972年起的经典GD模型的条件），结果基本上保持不变的孤雌配子。然而，在配子限制条件下，异配生殖在新模型中不太容易进化，并且出现了一个新的结果：而以前的模型通常预测异配生殖或小同配生殖的进化，当前的模型表明，当孤雌生殖配子在低效受精的条件下进化时，大同配生殖可以进化。我们的分析揭示了在这个相对未知的配子系统下与性别比例有关的未探索的并发症。我们讨论了这些并发症对我们的模型施加的限制，并为未来的研究提出了建议。我们比较模型的结果与藻类在自然界中的孤雌生殖配子。
The two sexes are defined by the sizes of the gametes they produce, anisogamy being the state with two differing gamete sizes (hence, females and males). The origin of this divergence has received much research interest, both theoretically and empirically. The gamete dynamics (GD) theory is a widely accepted theoretical explanation for anisogamy, and green algae have been an important empirical testing ground for the theory. However, some green and brown algae produce parthenogenetic gametes (gametes that can develop without fusing with another gamete), in contrast to an assumption in GD theory that unfused gametes do not develop. Here, we construct a GD model accounting for parthenogenetic gametes. We find that under conditions of panmixia and highly efficient fertilization (i.e., conditions of classical GD models from 1972 onward), the results remain largely unaltered by parthenogametes. However, under gamete-limited conditions anisogamy evolves less easily in the new model, and a novel result emerges: whereas previous models typically predict the evolution of either anisogamy or small isogamy, the current model shows that large isogamy can evolve when parthenogenetic gametes evolve under conditions of inefficient fertilization. Our analyses uncover unexplored complications relating to sex ratios under this relatively uncharted gametic system. We discuss limitations these complications impose on our models and suggest avenues for future research. We compare model results to algae with parthenogenetic gametes in nature.