Royal Botanic Gardens, Kew, Richmond, UK.
Grupo de Investigación en Biodiversidad, Medio Ambiente y Salud - BIOMAS, Universidad de las Américas, Quito, Ecuador.
Ann Bot. 2023 Oct 18;132(2):255-267. doi: 10.1093/aob/mcad099.
Understanding diaspore morphology and how much a species invests on dispersal appendages is key for improving our knowledge of dispersal in fragmented habitats. We investigate diaspore morphological traits in high-Andean Compositae and their main abiotic and biotic drivers and test whether they play a role in species distribution patterns across the naturally fragmented high-Andean grasslands.
We collected diaspore trait data for 125 Compositae species across 47 tropical high-Andean summits, focusing on achene length and pappus-to-achene length ratio, with the latter as a proxy of dispersal investment. We analysed the role of abiotic (temperature, elevation and latitude) and biotic factors (phylogenetic signal and differences between tribes) on diaspore traits and whether they are related to distribution patterns across the Andes, using phylogenomics, distribution modelling and community ecology analyses.
Seventy-five percent of the studied species show small achenes (length <3.3 mm) and 67% have high dispersal investment (pappus length at least two times the achene length). Dispersal investment increases with elevation, possibly to compensate for lower air density, and achene length increases towards the equator, where non-seasonal climate prevails. Diaspore traits show significant phylogenetic signal, and higher dispersal investment is observed in Gnaphalieae, Astereae and Senecioneae, which together represent 72% of our species. High-Andean-restricted species found across the tropical Andes have, on average, the pappus four times longer than the achene, a significantly higher dispersal investment than species present only in the northern Andes or only in the central Andes.
Small achenes and high diaspore dispersal investment dominate among high-Andean Compositae, traits typical of mostly three tribes of African origin; but traits are also correlated with the environmental gradients within the high-Andean grasslands. Our results also suggest that diaspore dispersal investment is likely to shape species distribution patterns in naturally fragmented habitats.
了解传播体的形态以及物种在传播附属物上的投入程度，对于提高我们对破碎生境中传播的认识至关重要。我们研究了高海拔安第斯山脉的菊科植物的传播体形态特征及其主要的非生物和生物驱动因素，并测试了它们是否在物种分布模式中发挥作用 across 自然破碎的高海拔草原。
我们收集了 125 种菊科植物的传播体性状数据 across 47 个热带高海拔山顶，重点关注瘦果长度和冠毛到瘦果长度的比值，后者作为传播投入的代理。我们分析了非生物因素（温度、海拔和纬度）和生物因素（系统发育信号和部落差异）对传播体性状的影响，以及它们是否与安第斯山脉 across 的分布模式有关，使用系统基因组学、分布模型和群落生态学分析。
研究的 75%的物种显示出小瘦果（长度<3.3 毫米）和 67%的物种具有高传播投入（冠毛长度至少是瘦果长度的两倍）。传播投入随海拔升高而增加，可能是为了补偿较低的空气密度，而瘦果长度则向赤道方向增加，那里盛行非季节性气候。传播体性状显示出显著的系统发育信号，并且在 Gnaphalieae、Astereae 和 Senecioneae 中观察到更高的传播投入，这三个部落 together 代表了我们 72%的物种。 across 热带安第斯山脉发现的高海拔特有种，平均而言，冠毛是瘦果的四倍长，具有显著高于仅在北安第斯或中安第斯出现的物种的传播投入。
小瘦果和高传播体传播投入在高海拔安第斯山脉的菊科植物中占主导地位，这些特征typical of 起源于非洲的三个部落；但这些特征也与高海拔草原内的环境梯度有关。我们的研究结果还表明，传播体传播投入可能会影响自然破碎生境中的物种分布模式。
