牛耳朵和马坝报春苣苔同域种群授粉后的生殖隔离

doi:10.17520/biods.2017029

摘要/Abstract

摘要：

生殖隔离是物种形成的关键, 也是物种保持完整性和独立性的基础。报春苣苔属(Primulina)是我国苦苣苔科中最大的属, 具有极为丰富的物种多样性。大部分报春苣苔属植物为喀斯特地区特有植物, 近缘种的同域分布也相当普遍。为更好地理解该属植物的物种多样性形成及维持机制, 我们选取了牛耳朵(P. eburnea)和马坝报春苣苔(P. mabaensis)的同域种群, 分析了授粉后的多种隔离机制强度, 主要包括花粉竞争、坐果率、种子重量、种子萌发率、花粉活力。结果显示, 牛耳朵和马坝报春苣苔的授粉后总隔离强度都较弱(0.09 vs. 0.13), 其中花粉竞争及种子萌发率的隔离强度为负值, 对物种间基因流发生起促进作用; 而坐果率、种子重量以及花粉活力的隔离强度均为正值, 表现为对种间基因流起阻止作用。牛耳朵和马坝报春苣苔较弱的授粉后隔离机制不足以完全阻止物种间杂交、保持物种独立性, 但野外较少存在自然杂交个体暗示着两者可能存在较强的授粉前隔离机制。

关键词: 喀斯特植物, 报春苣苔属, 同域种群, 生殖隔离, 杂交, 花粉竞争

Abstract

Reproductive isolation is essential for sympatric populations of closely related species to maintain species integrity and to prevent genetic introgression caused by hybridization. Primulina is the largest genus of Gesneriaceae in China, with a high degree of species diversity and endemism. Most species of the genus are karst habitat specialists (i.e. calciphiles), and many closely related species show a sympatric distribution in karst landscapes. To better understand the mechanism of sympatry in Primulina, post-pollination reproductive isolation, including pollen competition, fruit set, seed mass, seed germination, and pollen viability, was investigated in two closely related species, P. eburnea and P. mabaensis. Results indicated that the total post-pollination isolation strength for P. eburnea and P. mabaensis was 0.09 and 0.13, respectively, which were not strong enough to prevent hybridization completely. The strength of reproductive isolation from pollen competition and seed germination of P. eburnea and P. mabaensis was negative, suggesting facilitation for gene flow between species; while the strength of the fruit set, seed mass, and pollen viability showed a weak role in preventing interspecies hybridization. However, the two species are able to maintain their integrity well, as rare hybrid individuals are found in nature, suggesting that the existence of pre-pollination isolation mechanisms may play a more important role in maintaining species boundaries in these two species.

Key words: karst plant, Primulina, sympatric populations, reproductive isolation, hybridization, pollen competition

张小龙, 杨丽华, 康明 (2017) 牛耳朵和马坝报春苣苔同域种群授粉后的生殖隔离. 生物多样性, 25, 615-620. DOI: 10.17520/biods.2017029.

Xiaolong Zhang, Lihua Yang, Ming Kang (2017) Post-pollination reproductive isolation of sympatric populations of Primulina eburnea and P. mabaensis (Gesneriaceae). Biodiversity Science, 25, 615-620. DOI: 10.17520/biods.2017029.

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https://www.biodiversity-science.net/CN/Y2017/V25/I6/615

图/表 4

参考文献 24

[1]	Ai B, Gao Y, Zhong XL, Tao JJ, Kang M, Huang HW (2015) Comparative transcriptome resources of eleven Primulina species, a group of ‘stone plants’ from a biodiversity hot spot. Molecular Ecology Resources, 15, 619-632.
[2]	Baack E, Melo MC, Rieseberg LH, Ortiz-Barrientos D (2015) The origins of reproductive isolation in plants. New Phytologist, 207, 968-984.
[3]	Brys R, Vanden Broeck A, Mergeay J, Jacquemyn H (2014) The contribution of mating system variation to reproductive isolation in two closely related Centaurium species (Gentianaceae) with a generalized ?ower morphology. Evolution, 68, 1281-1293.
[4]	Brys R, Cauwenberghe JV, Jacquemyn H (2016) The importance of autonomous selﬁng in preventing hybridization in three closely related plant species. Journal of Ecology, 104, 601-610.
[5]	Chung KF, Huang HY, Peng JI, Xu WB (2013) Primulina mabaensis (Gesneriaceae), a new species from a limestone cave of northern Guangdong, China. Phytotaxa, 92, 40-48.
[6]	Coyne JA, Orr HA (2004) Speciation. Sinauer Associates, Sunderland, MA.
[7]	Dafni A (1992) Pollination Biology. Oxford University Press New York.
[8]	Gao Y, Ai B, Kong HH, Kang M, Huang HW (2015) Geographical pattern of isolation and diversification in karst habitat islands: a case study in the Primulina eburnea complex. Journal of Biogeography, 42, 2131-2144.
[9]	Huang SQ, Shi XQ (2013) Floral isolation in Pedicularis: how do congeners with shared pollinators minimize reproductive interference? New Phytologist, 199, 858-865.
[10]	Husband BC, Schemske DW, Burton TL, Goodwillie C (2002) Pollen competition as a unilateral reproductive barrier between sympatric diploid and tetraploid Chamerion angustifolium. Proceedings of the Royal Society B, 269, 2565-2571.
[11]	Kang M, Tao JJ, Wang J, Ren C, Qi QW, Xiang QY, Huang HW (2014) Adaptive and nonadaptive genome size evolution in karst endemic flora of China. New Phytologist, 202, 1371-1381.
[12]	Kay KM (2006) Reproductive isolation between two closely related humming bird pollinated neotropical gingers. Evolution, 60, 538-552.
[13]	Klips RA (1999) Pollen competition as a reproductive isolation mechanism between two sympatric Hibiscus species (Malvaceae). American Journal of Botany, 86, 269-272.
[14]	Liu RR, Pan B, Zhou TJ, Liao JP (2012) Cytological studies on Primulina taxa (Gesneriaceae) from limestone karsts in Guangxi Province, China. Caryologia, 65, 295-303.
[15]	Luo ZL, Duan TT, Yuan S, Chen S, Bai XF, Zhang DX (2015) Reproductive isolation between sympatric sister species, Mussaenda kwangtungensis and M. pubescens var. alba. Journal of Integrative Plant Biology, 57, 859-870.
[16]	Martin NH, Willis JH (2007) Ecological divergence associated with mating system causes nearly complete reproductive isolation between sympatric Mimulus species. Evolution, 61, 68-82.
[17]	Möller M, Wei YG, Wen F, Clark JL, Weber A (2016) You win some you lose some: updated generic delineations and classification of Gesneriaceae—implications for the family in China.Guihaia, 36, 44-60.
[18]	Rhymer JM, Simberloff D (1996) Extinction by hybridization and introgression. Annual Review of Ecology, Evolution and Systematics, 27, 83-109.
[19]	Snow AA, Spira TP (1996) Pollen-tube competition and male ﬁtness in Hibiscus moscheutos. Evolution, 50, 1866-1870.
[20]	Sobel JM, Chen GF (2014) Unification of methods for estimating the strength of reproductive isolation. Evolution, 68, 1511-1522.
[21]	Soltis PS, Soltis DE (2009) The role of hybridization in plant speciation. Annual Review of Plant Biology, 60, 561-588.
[22]	Wang WT, Pan KY, Li ZY, Weitzman AL, Skog LE (1998) Gesneriaceae. In: Flora of China (eds Wu ZY, Raven PH), pp. 244-401. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis.
[23]	Wolf DE, Takebayashi N, Riesebrg LH (2001) Predicting the risk of extinction through hybridization. Conservation Biology, 15, 1039-1053.
[24]	Xu SQ, Schlüter PM, Scopece G, Breitkopf H, Gross K, Cozzolino S, Schiestl FP (2011) Floral isolation is the main reproductive barrier among closely related sexually deceptive orchids. Evolution, 65, 2606-2620.

引物名称 Primer	正向引物 Forward primer	反向引物 Reverse primer	扩增片段长度多态性 Amplified fragment length polymorphism (bp)
引物名称 Primer	正向引物 Forward primer	反向引物 Reverse primer	牛耳朵 Primulina eburnea	马坝报春苣苔 P. mabaensis
325	AACGGAGAACACCCCATTTA	TCGCCTTATGAAGGTTTTGG	249	246
415	AACCCATCGTTTCACTCCAC	CTCGGAATCAACTCCTAGCG	289	299
1143	CGGAGTCAGCTTTGCACATA	CTCTCTCCTACACACGAGCG	222	219

引物名称 Primer	正向引物 Forward primer	反向引物 Reverse primer	扩增片段长度多态性 Amplified fragment length polymorphism (bp)
引物名称 Primer	正向引物 Forward primer	反向引物 Reverse primer	牛耳朵 Primulina eburnea	马坝报春苣苔 P. mabaensis
325	AACGGAGAACACCCCATTTA	TCGCCTTATGAAGGTTTTGG	249	246
415	AACCCATCGTTTCACTCCAC	CTCGGAATCAACTCCTAGCG	289	299
1143	CGGAGTCAGCTTTGCACATA	CTCTCTCCTACACACGAGCG	222	219

隔离机制 Isolation barriers	计算方程 Equation for calculating reproductive isolation (RI)
花粉竞争	1-2×[异源花粉授粉率/(异源花粉授粉率+同源花粉授粉率)]
Pollen competition	1-2×[interspecific pollination ratio/(interspecific pollination rate + intraspecific pollination rate)]
坐果率	1-2×[杂交坐果率/(杂交坐果率+自交坐果率)]
Fruit set	1-2×[interspecific fruit set/(interspecific fruit set + selfing fruit set)]
种子重量	1-2×[杂交种子重量/(杂交种子重量+自交种子重量)]
Seed mass	1-2×[interspecific seed mass of per fruit /(interspecific seed mass of per fruit + selfing seed mass of per fruit) ]
种子萌发率	1-2×[杂交种子萌发率/(杂交种子萌发率+自交种子萌发率)]
Seed germination rate	1-2×[interspecific seed germination/(interspecific seed germination + selfing seed germination)]
花粉活力	1-2×[杂交F₁代花粉活力/(杂交F₁代花粉活力+亲本花粉活力)]
Pollen viability	1-2×[interspecific F₁ pollen viability/(interspecific F₁ pollen viability + parent pollen viability)]

隔离机制 Isolation barriers	计算方程 Equation for calculating reproductive isolation (RI)
花粉竞争	1-2×[异源花粉授粉率/(异源花粉授粉率+同源花粉授粉率)]
Pollen competition	1-2×[interspecific pollination ratio/(interspecific pollination rate + intraspecific pollination rate)]
坐果率	1-2×[杂交坐果率/(杂交坐果率+自交坐果率)]
Fruit set	1-2×[interspecific fruit set/(interspecific fruit set + selfing fruit set)]
种子重量	1-2×[杂交种子重量/(杂交种子重量+自交种子重量)]
Seed mass	1-2×[interspecific seed mass of per fruit /(interspecific seed mass of per fruit + selfing seed mass of per fruit) ]
种子萌发率	1-2×[杂交种子萌发率/(杂交种子萌发率+自交种子萌发率)]
Seed germination rate	1-2×[interspecific seed germination/(interspecific seed germination + selfing seed germination)]
花粉活力	1-2×[杂交F₁代花粉活力/(杂交F₁代花粉活力+亲本花粉活力)]
Pollen viability	1-2×[interspecific F₁ pollen viability/(interspecific F₁ pollen viability + parent pollen viability)]

隔离机制 Isolation barriers	牛耳朵 P. eburnea	马坝报春苣苔 P. mabaensis
花粉竞争 Pollen competition	-0.321	-0.026
坐果率 Fruit set	0.058	0.003
种子重量 Seed mass	0.157	0.019
种子萌发率 Seed germination rate	-0.068	-0.199
花粉活力 Pollen viability	0.264	0.333
授粉后隔离总强度 RI	0.090	0.130