Low genetic diversity and significant structuring in the endangered Mentha cervina populations and its implications for conservation

Abstract

Eighteen populations of the endangered aromatic and medicinal plant Mentha cervina (Lamiaceae) were sampled across its natural range, in the western half of the Iberian Peninsula, and inter-simple sequence repeats (ISSRs) markers were used to assess genetic diversity and population structure. M. cervina populations exhibited a relatively low genetic diversity (percentage of polymorphic loci PPB ¼ 14.2-58.3%, Nei's genetic diversity H e ¼ 0.135-0.205, Shannon's information index I ¼ 0.08 À 0.33). However, the genetic diversity at species level was relatively high (PPB ¼ 98.3%; H e ¼ 0.325; I ¼ 0.23). The results of the analysis of molecular variance indicated very structured populations, with 50% of the variance within populations, 44% among populations and 6% between regions defined by hydrographic basins, in line with the gene differentiation coefficient (G ST ¼ 0.532). A Mantel test did not find significant correlation between genetic and geographic distance matrices (r ¼ 0.064), indicating that isolation by distance is not shaping the present genetic structure. The levels and patterns of genetic diversity in M. cervina populations were assumed to result largely from a combination of evolutionary history and its unique biological traits, such as breeding system, low capacity of dispersion, small effective size and habitat fragmentation. The high genetic differentiation among populations indicates the necessity of conserving the maximum possible number of populations. The results also provide information to select sites for ex situ conservation. Optimal harvesting strategies, cultivation and tissue culture should also be developed as soon as possible to guarantee sustainable use of the species under study.

Genetic diversity of Broussonetia papyrifera populations in southwest China

“…The H E value is lower than the average value of widespread species (H: 0.22) and is close to the average value of endemic species (H: 0.20) according to the Nybom statistic, which calculated the genetic diversity of many plants at the population level [based on random amplified polymorphic DNA (RAPD), AFLP, and ISSR dominant markers] (Nybom, 2004). This suggested that the high overall genetic diversity that was presented by the species itself could be explained mostly by differences among populations that originated from the high genetic structure (Rodrigues et al, 2013).…”

“…Interestingly, the DM, LH, and HQ populations displayed lower genetic diversity (PPB = 31, 48, and 40%, respectively), while the JS, SP, YJ, HH, and YY populations showed higher genetic diversity (PPB = 54,60,61,55,and 61%,respectively). This indicated that populations in fragmented habitats and with a small effective size are sensitive to stochastic events, genetic drift, and inbreeding, leading to a low genetic diversity and the high genetic structure pattern (Hartl and Clark, 1997;Rodrigues et al, 2013).…”

“…Taking into account the observation that B. papyrifera populations are highly structured genetically, outbreeding depression might be a potential genetic threat for already weakened populations (Sagvik et al, 2005). Therefore, it may be wise to protect a network of populations that exchange genetic material and are able to reinforce each other (Rodrigues et al, 2013). For these reasons, we propose that individuals within a cluster can be exchanged.…”

“…The use of molecular markers to evaluate neutral genetic variation is an important tool to study population genetics (Rodrigues et al, 2013). Inter-simple sequence repeat (ISSR) markers permit the detection of polymorphic loci without knowing the DNA sequences of species (Barth et al, 2002).…”

Genetic Variation of Paliurus Ramosissimus (Lour.) Poiret (Rhamnaceae): Implication for Conservation Strategies

“…Therefore, protection of P. ramosissimus on Jeju Island has to firstly begin with protection through in situ conservation, and prevented fragmentation and ruptures. This is because decreases in effective population size lead to stochastic events, genetic drift, and inbreeding, resulting in a decrease of genetic diversity (Hartl and Clark, 1997; Rodrigues et al, 2013). The present habitats of P. ramosissimus need to be protected by conservation areas and there is need to ensure dispersion because of the expected destruction of habitat and decrease of population size.…”