Repeated evolution of a morphological novelty: a phylogenetic analysis of the inflated fruiting calyx in the Physalideae tribe (Solanaceae)
Repeated evolution of a morphological novelty: a phylogenetic analysis of the inflated fruiting calyx in the Physalideae tribe (Solanaceae)
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DOI：
10.1002/ajb2.1242
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发表时间：
2019-02-01
影响因子：
3
通讯作者：
Smith, Stacey D.
中科院分区：
文献类型：
--
作者：
Deanna, Rocio;Larter, Maximilian D.;Smith, Stacey D.
新果实形态的进化是被子植物成功的关键。膨胀的果萼，其中气球状的花萼膨胀到完全包围果实，在被子植物中反复进化，并被认为有助于保护和传播。我们调查了番茄及其盟友（酸浆科，茄科）这一特点的演变。方法利用ITS、LEAFY、trnL-F、waxy 4个区域，采用最大似然法（ML）和贝叶斯推断法对酸浆科植物的亲缘关系进行估计。在性状进化的最佳拟合ML模型下，利用贝叶斯随机映射估计了祖先状态沿着的结果花萼增大和膨胀的得失数。此外，花萼形态的系统发育信号进行了检查与两个指标（简约得分和弗里茨和Purvis的D）。关键结果基于我们的高分辨率和密集采样的发育，我们推断，花萼进化进行了逐步和定向的方式，从非accident accident膨胀。我们总共推断出24次增大，24次随后过渡到完全膨胀的花萼，只有两次逆转。尽管这种不稳定性，结果花萼accescence和膨胀表现出强烈的系统发育信号。结论本研究的系统发育大大提高了酸浆亚科的分辨率，并强调了分类工作的必要性。比较分析表明，膨胀的果萼已经进化了很多次，这种表型的轨迹一般是逐步的和不可逆的。这些结果为研究这种魅力果实性状重复起源的遗传和发育机制提供了坚实的基础。
Premise of the Study The evolution of novel fruit morphologies has been integral to the success of angiosperms. The inflated fruiting calyx, in which the balloon-like calyx swells to completely surround the fruit, has evolved repeatedly across angiosperms and is postulated to aid in protection and dispersal. We investigated the evolution of this trait in the tomatillos and their allies (Physalideae, Solanaceae). Methods The Physalideae phylogeny was estimated using four regions (ITS, LEAFY, trnL-F, waxy) with maximum likelihood (ML) and Bayesian inference. Under the best-fitting ML model of trait evolution, we estimated ancestral states along with the numbers of gains and losses of fruiting calyx accrescence and inflation with Bayesian stochastic mapping. Also, phylogenetic signal in calyx morphology was examined with two metrics (parsimony score and Fritz and Purvis's D). Key Results Based on our well-resolved and densely sampled phylogeny, we infer that calyx evolution has proceeded in a stepwise and directional fashion, from non-accrescent to accrescent to inflated. In total, we inferred 24 gains of accrescence, 24 subsequent transitions to a fully inflated calyx, and only two reversals. Despite this lability, fruiting calyx accrescence and inflation showed strong phylogenetic signal. Conclusions Our phylogeny greatly improves the resolution of Physalideae and highlights the need for taxonomic work. The comparative analyses reveal that the inflated fruiting calyx has evolved many times and that the trajectory toward this phenotype is generally stepwise and irreversible. These results provide a strong foundation for studying the genetic and developmental mechanisms responsible for the repeated origins of this charismatic fruit trait.