Microsatellite genetic diversity and fine-scale spatial genetic structure within a natural stand of Liriodendron chinense (Magnoliaceae) in Lanmushan, Duyun City, Guizhou Province

doi:10.3724/SP.J.1003.2014.14013

Abstract

Abstract:

The Chinese tulip tree (Liriodendron chinense), an endangered species scattered throughout subtropical China and northern Vietnam, suffers from severe habitat fragmentation. Understanding the genetic diversity and fine-scale spatial genetic structure (SGS) of fragmented populations is critical for developing successful conservation strategies for endangered species. In this study, we investigated the population genetic diversity and fine-scale spatial genetic structure in a wild, fragmented population of L. chinense using 13 polymorphic microsatellite loci. No significant differences in genetic diversity were found among habitat fragments or age classes (P > 0.05). Two genetically heterogeneous subpopulations were revealed through Bayesian assignment analysis and Principal Coordinates Analysis (PCoA). Significant SGS was found within the whole population within 200 m, while weak spatial aggregation of related individuals in the two subpopulations was found within 20 m. SGS intensity was weak in this population (Sp = 0.0090), and it was stronger in the village subpopulation (Sp = 0.0067) than in the hill subpopulation (Sp = 0.0053). Liriodendron chinense is a predominantly outcrossing tree and its winged seeds are wind-dispersed, a fact that may reduce SGS intensity in the species. Furthermore, low population density and flat hypsography also likely influence the SGS of L. chinense. The presence of significant heterozygote deficiency in the population (F_IS = 0.099, P < 0.01) suggests a genetic signal of habitat fragmentation. Therefore, measures for promoting pollen flow should be taken for in situ conservation. For ex situ conservation, individuals should be sampled at 20 m apart to efficiently capture genetic diversity of wild populations.

Key words: Liriodendron chinense, habitat fragmentation, genetic diversity, spatial genetic structure, endangered species

Aihong Yang, Jinju Zhang, Hua Tian, Xiaohong Yao, Hongwen Huang. Microsatellite genetic diversity and fine-scale spatial genetic structure within a natural stand of Liriodendron chinense (Magnoliaceae) in Lanmushan, Duyun City, Guizhou Province[J]. Biodiv Sci, 2014, 22(3): 375-384.

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URL: https://www.biodiversity-science.net/EN/10.3724/SP.J.1003.2014.14013

https://www.biodiversity-science.net/EN/Y2014/V22/I3/375

Figures/Tables 7

Fig. 1 Spatial distribution of Liriodendron chinense individu- als in Lanmushan population in Duyun, Guizhou. The five habitat fragments are circled with dash lines. CL, CR, MN, MS and MV refer to habitat fragments of left side of road in village, right side of road in village, north hill, south hill and hill valley, respectively. Different shapes represent two subpopulations, i.e. village subpopulation (●) and hill subpopulation (▲).

Table 1 Summary of genetic diversity and fixation indices for four age-classes and five habitat fragments of Liriodendron chinense in Lanmushan population

遗传参数	N	A	A_E	A_R	Ho	H_E	F_IS
年龄层 Age class
幼树 Seedling	19	3.462	2.492	3.462	0.526	0.582	0.097
小树 Sapling	33	3.462	2.428	3.372	0.491	0.554	0.116
壮树 Adolescent	29	3.615	2.469	3.520	0.502	0.564	0.111
成年树 Adult	39	3.308	2.478	3.273	0.517	0.558	0.075
生境斑块 Habitat fragments
CL	37	3.538	2.559	3.248	0.529	0.590	0.104
CR	26	3.385	2.462	3.255	0.497	0.549	0.097
MN	11	2.462	1.963	2.462	0.483	0.469	-0.0031
MS	35	3.308	2.067	2.788	0.484	0.486	0.004
MV	11	2.846	2.302	2.846	0.559	0.564	0.009
物种水平 Species level	120	4.000	2.508	4.000	0.508	0.563	0.099^**

Table 2 Pairwise genetic differentiation FST (below diagonal) and RST (above diagonal) for habitat fragments of Liriodendron chinense population in Lanmushan. Fragment codes see Fig. 1.

	CL	CR	MN	MS	MV
CL	-	0.007	0.050^*	0.028^*	0.048^*
CR	0.007	-	0.057^*	0.042^*	0.072^*
MN	0.096^*	0.102^*	-	0	0
MS	0.085^*	0.096^*	0	-	0
MV	0.056^*	0.069^*	0	0.011	-

Fig. 2 Results of STRUCTURE analysis based on all the individuals in Lanmushan population using 13 polymorphic microsatellite loci. (a) Plotted the mean likelihood L(K); (b) ∆K value; and (c) Assignments proportion of each individual from all the five habitat fragments. Codes for habitat fragments correspond to those in Fig. 1.

Fig. 3 Principal coordinate plot of genetic distance for the analyzed 120 individuals from five habitat fragments based on 13 SSR markers. The first two principal coordinates account for 13.58% and 9.43% of total genetic variation, respectively. Codes for habitat fragments correspond to those in Fig. 1.

Table 3 Spatial genetic structure statistics for Liriodendron chinense population in Lanmushan

组别 Group	N	P₍_r_{< permuted}_r₎	F₍₁₎	b_F	Sp
整体 Whole population	120	0.001	0.0532	-0.0085^*	0.0090
寨内 Village subpopulation	63	0.001	0.0151	-0.0066	0.0067
山林 Hill subpopulation	57	0.013	0.0147	-0.0052	0.0053

Fig. 4 Correlogram of coefficients for the population Lanmushan, village subpopulation and hill subpopulation. Autocorrelation coefficient (r) (left) and average kinship coefficients Fij (right) between pairs of individuals plotted as the classified geographical distance. Dashed lines represent 95% confidence intervals under the null hypothesis that genotypes are randomly distributed, and error bars delineate standard errors from Jackknife estimates.

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