Depatie Trinity H, Wessinger Carolyn A
Department of Biological Sciences, University of South Carolina, 715 Sumter St. Columbia, SC 29208 USA.
bioRxiv. 2024 Dec 5:2024.12.02.626427. doi: 10.1101/2024.12.02.626427.
Adaptive radiation in ecologically and morphologically diverse plant lineages presents an opportunity to investigate the rapid evolution of novel floral traits. While some types of floral traits, such as flower color, are well-characterized, other types of complex morphologies remain understudied. One example is occluded personate flowers, dorso-ventrally compressed flowers with obstructed floral passageways, which have evolved in multiple genera, but have only been characterized from snapdragon.
Our study examined the morphological basis and evolutionary history of personate flowers in a clade of species that includes three personate-flowered species. We characterized floral morphology and inferred phylogenomic relationships for 13 species in this group in order to examine the evolutionary history of personate flowers. We used phylogenomic tests for introgression to examine whether personate-flowered lineages have a history of introgression.
Unlike the personate flowers of snapdragon, personate flowers in are produced by deep pleats in the ventral petal tissue that curve the ventral petal surface upwards, obstructing the floral tube opening. Our phylogenetic tree suggests that personate flowers evolved in two separate lineages. Phylogenomic analyses indicate incomplete lineage sorting and introgression between certain taxa have contributed to phylogenomic discordance, however we found little evidence of recent introgression between the two personate-flowered lineages.
The evolution of personate flowers in involves a distinct morphological basis than snapdragon. Personate flowers have evolved multiple times in on a rapid evolutionary timescale. The source of genetic variation for repeated shifts may be de novo mutations or pre-existing variants.
生态和形态多样的植物谱系中的适应性辐射为研究新的花部性状的快速进化提供了契机。虽然某些类型的花部性状，如花色，已得到充分表征，但其他类型的复杂形态仍未得到充分研究。一个例子是闭合假面状花，即背腹扁平且花管通道受阻的花，这种花在多个属中都有进化，但仅在金鱼草中有过特征描述。
我们的研究考察了一个包含三个具假面状花物种的类群中假面状花的形态学基础和进化历史。我们对该类群中的13个物种的花形态进行了表征，并推断了系统发育关系，以研究假面状花的进化历史。我们使用系统发育基因组渗入测试来检验具假面状花的谱系是否有渗入历史。
与金鱼草的假面状花不同，[该类群中]的假面状花是由腹瓣组织中的深褶形成的，这些深褶使腹瓣表面向上弯曲，从而阻塞了花管开口。我们的系统发育树表明，假面状花在两个独立的谱系中进化。系统发育基因组分析表明，不完全谱系分选以及某些分类群之间的渗入导致了系统发育不一致，然而我们几乎没有发现两个具假面状花的谱系之间近期有渗入的证据。
[该类群中]假面状花的进化涉及与金鱼草不同的形态学基础。假面状花在[该类群中]在快速的进化时间尺度上多次进化。重复转变的遗传变异来源可能是从头突变或预先存在的变异。
