Sex chromosomes can differ between species as a result of evolutionary turnover, a process that can be driven by evolution of the sex determination pathway. Canonical models of sex chromosome turnover hypothesize that a new master sex determining gene causes an autosome to become a sex chromosome or an XY chromosome pair to switch to a ZW pair (or vice versa). Here, a novel paradigm for the evolution of sex determination and sex chromosomes is presented, in which there is an evolutionary transition in the master sex determiner, but the X chromosome remains unchanged. There are three documented examples of the novel paradigm, and it is hypothesized that a similar process could happen in a ZW sex chromosome system. Three other taxa are also identified where the novel paradigm may have occurred, and how it could be distinguished from canonical trajectories in these and additional taxa is also described.

中文翻译：

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性别决定和性染色体的进化：一种新的替代范式。

由于进化周转，性染色体在物种之间可能有所不同，这一过程可以由性别决定途径的进化驱动。性染色体转换的典型模型假设新的主要性别决定基因导致常染色体变成性染色体或 XY 染色体对转换为 ZW 对（反之亦然）。在这里，提出了一种性别决定和性染色体进化的新范式，其中主性别决定因素存在进化转变，但 X 染色体保持不变。新范式有三个记录在案的例子，并且假设在 ZW 性染色体系统中可能发生类似的过程。还确定了可能发生新范式的其他三个分类群，