Data from: Evolution and reciprocal origins in Mediterranean ferns: the Asplenium obovatum and A. adiantum-nigrum complexes

Asplenium is estimated to be the largest fern genus, and is very prone to polyploidy and hybridization. We investigated the phylogenetic relationships of two geographically-restricted complexes in the Mediterranean Basin, and searched for evidence of multiple and/or reciprocal origins of the allopolyploids. The Asplenium obovatum and A. adiantum-nigrum complexes include a total of five diploid and four polyploid taxa, and are linked by the tetraploid A. balearicum. We collected 36 new samples representing all nine taxa, from which we amplified 5 chloroplast regions. We also included sequences from GenBank and performed ML and BI analyses to identify multiple and reciprocal origins. We conducted a larger molecular dating analysis to assess relationships with the rest of Asplenium and estimate divergence times. This matrix included 137 species of Asplenium and three outgroups, including sequences previously published. All sequences of allotetraploids A. adiantum-nigrum and A. balearicum grouped with A. onopteris, with no sign of reciprocal parentage, but possible evidence of multiple origins. The tetraploids A. foreziense and A. billotii grouped with both respective parents, indicating probable multiple and reciprocal origins. The best supported case of reciprocal parentage is A. foreziense. In the larger analysis, the species studied resolve in two different clades that correspond to the two complexes, and the groups are not closely related, with a conservative estimate of 45.43 Mya for their divergence. There is evidence of multiple origins of all four allopolyploids, though only with strong support for one, and of reciprocal origins for two of the four allopolyploids, though again only one is well supported. A. balearicum represents a hybridization event between members of clades whose ancestors diverged roughly 45 million years ago, making this divergence one of the oldest to have descendants later produce hybrid offspring.

铁角蕨属（Asplenium）被认为是现存最大的蕨类植物属，该类群极易发生多倍化与杂交事件。本研究针对地中海盆地两个地理限定的类群复合体开展系统发育关系探究，并搜寻异源多倍体多次起源及/或双向起源的相关证据。倒卵叶铁角蕨（Asplenium obovatum）复合体与黑柄铁角蕨（Asplenium adiantum-nigrum）复合体共计包含5个二倍体类群与4个多倍体类群，四倍体巴利阿里铁角蕨（Asplenium balearicum）为二者的联系类群。我们采集了覆盖全部9个类群的36份全新样本，对其中5个叶绿体区域进行扩增；同时纳入GenBank数据库中的序列数据，开展最大似然法（ML）与贝叶斯推断（BI）分析，以验证多次及双向起源现象。我们还开展了更大规模的分子定年分析，以评估该类群与铁角蕨属其余类群的系统发育关系并估算分化时间。该分析矩阵涵盖137种铁角蕨属物种与3个外类群，包含已发表的序列数据。所有异源四倍体黑柄铁角蕨与巴利阿里铁角蕨的序列均与欧洲蕨叶铁角蕨（Asplenium onopteris）聚为一支，未发现双向亲本的信号，但存在多次起源的潜在证据。四倍体福齐耶铁角蕨（Asplenium foreziense）与比洛蒂铁角蕨（Asplenium billotii）的序列分别与其各自的亲本类群聚类，表明二者可能存在多次且双向的起源事件，其中双向起源支持度最高的类群为福齐耶铁角蕨。在更大规模的分析中，本研究涉及的物种被划分至两个对应各自复合体的不同演化支，二者亲缘关系并不紧密，保守估算其分化时间为4543万年前。本研究结果表明，4种异源多倍体均存在多次起源的证据，仅其中1类群得到较强的统计支持；同时4类异源多倍体中有2类存在双向起源的迹象，但同样仅1类群获得了较好的支持。巴利阿里铁角蕨源自两个分化时间约为4500万年前的演化支类群间的杂交事件，这一分化事件是现存后代产生杂交后代的最古老分化事件之一。