短命植物异喙菊异形果实的两头下注策略

doi:10.3773/j.issn.1005-264x.2009.05.009

摘要/Abstract

摘要：

异喙菊(Heteracia szovitsii)是准噶尔荒漠中常见的一种具异形果实的菊科一年生早春短命植物。该文对其同一果序中3种果实的形态结构与扩散特征进行了比较研究, 并对其生态学意义进行了探讨。结果表明: 1)异喙菊3种果实的形态特征存在明显差异, 导致其扩散特性明显不同, 避免了同胞子代在生态位上的竞争。其中, 中央果具冠毛, 成熟后以果实为散布单元借风力扩散到较大范围; 外围果与过渡果均无冠毛, 分别以果序和果实为单元扩散至母株附近。2) 3种果实胚大小的差异导致其幼苗大小和竞争能力不同。外围果与过渡果的胚比中央果的大, 萌发后可产生较大和竞争力较强的幼苗。3)与中央果相比, 外围果和过渡果果皮颜色较深, 所含酚类物质较多, 厚度较大且厚壁组织较多, 对胚的保护能力强, 且种子休眠程度深。4)异形痩果在数量上的差异, 分摊了扩散和定居中的风险。数量较多的中央果增加了随机散布的机会, 可为其扩大种群开拓更大的范围, 而数量较少的外围果和过渡果可有效地减少近距离扩散所造成的同胞子代间竞争。异喙菊异形果实的产生及其生态学行为属于典型的两头下注策略: 外围果和过渡果代表了“谨慎”或“低风险”策略, 中央果则代表了“冒险”或“高风险”策略。通过这些策略, 异喙菊可将其在准噶尔荒漠极端环境中的生存风险进行有效地分摊, 以保障其繁衍成功。

关键词: 短命植物, 异喙菊, 异形果实, 形态结构, 扩散, 两头下注策略

Abstract:

Aims Heteracia szovitsii is a common ephemeral Asteraceae species that germinates in early spring in the Junggar Desert of China and produces three types of achenes with different morphologies in one infructescence. To better understand how this species is adapted to its desert habitat, we studied 1) the morphological, structural and dispersal characteristics of the three types of achenes and 2) according to the bet-hedging strategy, how heterocarpy spreads the risk of survival in the desert environment.
Methods For the three types of achenes, we recorded number, mass, morphology, surface ornamentation (via scanning electron micrographs), pericarp structure, dispersal distance and landing time in the laboratory and mode of dispersal and its duration in the field.
Important findings Compared with central achenes, the pericarps of peripheral and intermediate achenes were thicker, darker in color, and contained a higher amount of phenolic compounds and more sclerenchyma, which could protect the embryo better and cause the seeds to be more dormant. Embryo mass of peripheral and intermediate achenes was greater than that of central achenes, and thus could produce larger and more competitive seedlings. After maturation, central achenes with pappus dispersed over a wide range, while peripheral and intermediate achenes with no pappus usually dispersed near the mother plant. The different number of heteromorphic achenes could spread the risk of dispersal and settlement for this species. The larger number of central achenes increases chance for their random dispersal, and this is favorable for exploiting a larger geographical range for the population. The lower number of peripheral and intermediate achenes could decrease sibling competition due to dispersal near the mother plant. Formation of heteromorphic achenes is a form of bet hedging that could spread the risk of mortality in the extreme environment of the Junggar Desert. The peripheral and intermediate achenes presumably represent a “low-risk” strategy and the central achenes a “high-risk” strategy in one capitulum. Based on these strategies, H. szovitsii can spread the risk of survival and ensure its reproductive success.

Key words: ephemerals, Heteracia szovitsii, heteromorphic achenes, achene morphology and structure, dispersal, bet hedging

成小军, 谭敦炎. 短命植物异喙菊异形果实的两头下注策略. 植物生态学报, 2009, 33(5): 901-910. DOI: 10.3773/j.issn.1005-264x.2009.05.009

CHENG Xiao-Jun, TAN Dun-Yan. BET HEDGING IN HETEROMORPHIC ACHENES OF HETERACIA SZOVITSII (ASTERACEAE), A DESERT EPHEMERAL. Chinese Journal of Plant Ecology, 2009, 33(5): 901-910. DOI: 10.3773/j.issn.1005-264x.2009.05.009

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https://www.plant-ecology.com/CN/Y2009/V33/I5/901

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观测指标 Observation index	外围果 Peripheral achene	过渡果 Intermediate achene	中央果 Central achene	F	p
形状 Shape	倒四棱锥形, 背腹扁压Obpyramidal, back and front compressed	倒四棱锥形, 背腹微扁压 Obpyramidal, back and front compressed slightly	倒圆锥形, 不扁压 Turbinate, not compressed	-	-
颜色 Color	暗红色 Dark-wine	紫红色 Purple-red	灰褐色 Gray-brown	-	-
附属结构 Additional structure	两侧有较宽的翅, 腹面及背面有较宽的棱, 果喙短, 不具冠毛 Wide bilateral wings, front and back have wide ribs, fruit beak short, no pappus	两侧有较窄的翅, 腹面及背面有较窄的棱, 果喙较长, 不具冠毛 Narrow bilateral wings, front and back have narrow ribs, fruit beak elongated, no pappus	具细长的果喙, 在喙顶部有1~3轮污白色冠毛 1-3 whorls of well developed white pappus at top of elongated fruit beak	-	-
果体长 Length of achenes (mm)	3.54±0.05^Aa	3.20±0.03^Bb	3.07±0.03^Bc	43.19	＜ 0.01
两侧宽 Width from side to side (mm)	3.27±0.05^Aa	1.70±0.05^Bb	1.03±0.02^Cc	732.54	＜ 0.01
背腹宽 Width from back to front (mm)	2.25±0.05^Aa	1.42±0.04^Bb	1.00±0.03^Cc	260.37	＜ 0.01
侧翅宽 Width of lateral wing (cm)	1.21±0.03^Aa	0.71±0.03^Bb	-	148.70	＜ 0.01
腹棱宽 Width of front ribs (cm)	0.79±0.17^a	0.42±0.02^b	-	4.63	＜ 0.05
果喙长 Length of beaks (mm)	1.05±0.03^Cc	2.21±0.10^Bb	9.22±0.37^Aa	396.24	＜ 0.01
果体长/果喙长 The ratio of length of fruit body to beak	3.47±0.09^Aa	1.60±0.07^Bb	0.42±0.07^Cc	398.32	＜ 0.01
冠毛数量 No. of pappi	-	-	40.32±1.02	-	-
冠毛长 Length of pappi (mm)	-	-	3.00±0.03	-	-

观测指标 Observation index	外围果 Peripheral achene	过渡果 Intermediate achene	中央果 Central achene	F	p
形状 Shape	倒四棱锥形, 背腹扁压Obpyramidal, back and front compressed	倒四棱锥形, 背腹微扁压 Obpyramidal, back and front compressed slightly	倒圆锥形, 不扁压 Turbinate, not compressed	-	-
颜色 Color	暗红色 Dark-wine	紫红色 Purple-red	灰褐色 Gray-brown	-	-
附属结构 Additional structure	两侧有较宽的翅, 腹面及背面有较宽的棱, 果喙短, 不具冠毛 Wide bilateral wings, front and back have wide ribs, fruit beak short, no pappus	两侧有较窄的翅, 腹面及背面有较窄的棱, 果喙较长, 不具冠毛 Narrow bilateral wings, front and back have narrow ribs, fruit beak elongated, no pappus	具细长的果喙, 在喙顶部有1~3轮污白色冠毛 1-3 whorls of well developed white pappus at top of elongated fruit beak	-	-
果体长 Length of achenes (mm)	3.54±0.05^Aa	3.20±0.03^Bb	3.07±0.03^Bc	43.19	＜ 0.01
两侧宽 Width from side to side (mm)	3.27±0.05^Aa	1.70±0.05^Bb	1.03±0.02^Cc	732.54	＜ 0.01
背腹宽 Width from back to front (mm)	2.25±0.05^Aa	1.42±0.04^Bb	1.00±0.03^Cc	260.37	＜ 0.01
侧翅宽 Width of lateral wing (cm)	1.21±0.03^Aa	0.71±0.03^Bb	-	148.70	＜ 0.01
腹棱宽 Width of front ribs (cm)	0.79±0.17^a	0.42±0.02^b	-	4.63	＜ 0.05
果喙长 Length of beaks (mm)	1.05±0.03^Cc	2.21±0.10^Bb	9.22±0.37^Aa	396.24	＜ 0.01
果体长/果喙长 The ratio of length of fruit body to beak	3.47±0.09^Aa	1.60±0.07^Bb	0.42±0.07^Cc	398.32	＜ 0.01
冠毛数量 No. of pappi	-	-	40.32±1.02	-	-
冠毛长 Length of pappi (mm)	-	-	3.00±0.03	-	-

测量指标 Measurement index	外围果 Peripheral achene	过渡果 Intermediate achene	中央果 Central achene	F	p
每果序中果实数(个) No. of achenes per infructescence	7.87±0.11^Aa	10.50±0.39^Bb	14.20±0.58^Cc	60.35	＜ 0.01
果实百粒重 Mass per 100 achenes (mg)	355.07±4.01^Aa	146.05±1.10^Bb	73.06±0.84^Cc	3 566.84	＜ 0.01
胚百粒重 Mass per 100 dispersal units (mg)	54.27±0.38^Aa	43.56±0.22^Bb	37.02±0.14^Cc	1 065.67	＜ 0.01
果皮/果实质量比 Mass ratio of pericarp to achene (％)	84.79±0.18^Aa	70.16±0.18^Bb	49.27±0.60^Cc	2 269.01	＜ 0.01

测量指标 Measurement index	外围果 Peripheral achene	过渡果 Intermediate achene	中央果 Central achene	F	p
每果序中果实数(个) No. of achenes per infructescence	7.87±0.11^Aa	10.50±0.39^Bb	14.20±0.58^Cc	60.35	＜ 0.01
果实百粒重 Mass per 100 achenes (mg)	355.07±4.01^Aa	146.05±1.10^Bb	73.06±0.84^Cc	3 566.84	＜ 0.01
胚百粒重 Mass per 100 dispersal units (mg)	54.27±0.38^Aa	43.56±0.22^Bb	37.02±0.14^Cc	1 065.67	＜ 0.01
果皮/果实质量比 Mass ratio of pericarp to achene (％)	84.79±0.18^Aa	70.16±0.18^Bb	49.27±0.60^Cc	2 269.01	＜ 0.01