Ecological genetics of the wind-pollinated, tetraploid, Allocasuarina emuina L. Johnson (Casuarinaceae) from southeast Queensland reveals montane refugia for coastal heath during the last interglacial

2012 ◽  
Vol 60 (8) ◽  
pp. 718 ◽  
Author(s):  
R. W. Lamont ◽  
R. L. Stokoe ◽  
A. Shapcott
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Population Genetic ◽  
Genetic Material ◽  
Natural Populations ◽  
Seed Viability ◽  
Ecological Genetics ◽  
Last Interglacial ◽  
Study Results ◽  
Southeast Queensland

The subtropical coastal heathlands of southeast Queensland contain many rare and threatened species and have undergone considerable habitat loss in recent years due to high levels of urbanisation. We used morphological and microsatellite markers to investigate the reproductive ecology, in relation to fire, and population genetic structure of the endangered shrub Allocasuarina emuina. Highly significant differences (P < 0.001) were detected among populations for all cone- and seed-related morphological traits, which revealed distinct northern and southern groups of populations, a pattern repeated in the genetic component of the study. Results also indicated that the reproductive viability of A. emuina is more related to fire interval than population size and confirmed that seed viability declines with time since fire. The highest level of genetic diversity for the species was observed in the population on Mt Emu (AE4A; HE = 0.688). Contrary to the expectations of population genetic theory, no relationship was found between the level of genetic variation and population size, density or degree of isolation, hinting that genetic diversity is being conserved as a result of polyploidy and apomixis. However, genetic signatures in the northern populations indicated that unidirectional dispersal of genetic material from the putatively refugial population on Mt Emu to the surrounding coastal plain has been occurring with recession of sea levels following the last interglacial. The findings of the study will aid in both the conservation of natural populations and translocations of A. emuina and have significant implications relating to the biogeographical history of a considerable number of co-occurring heathland taxa.

scholarly journals Alive and kicking, or, living on borrowed time? – Microsatellite diversity in natural populations of the endangered Ulmus minor Mill. sensu latissimo from Croatia

2016 ◽  
Vol 75 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Marko Zebec ◽  
Marilena Idžojtić ◽  
Zlatko Šatović ◽  
Igor Poljak ◽  
Zlatko Liber
Keyword(s):  
Genetic Diversity ◽  
Natural Populations ◽  
Genetic Bottleneck ◽  
Dutch Elm Disease ◽  
Significant Excess ◽  
Mediterranean Populations ◽  
Ulmus Minor ◽  
Study Results ◽  
The Impact ◽  
Microsatellite Diversity

AbstractThe main objective of this research was to assess the genetic diversity of 5 natural field elm populations in Croatia. The study results suggest that the observed populations are characterized by a satisfactory amount of heterozygosity, and that the impact of the Dutch elm disease on the amount of genetic diversity in the sampled populations is currently negligible. However, one population displayed a significant excess of heterozygosity, implying a genetic bottleneck. The existence of a very clear genetic differentiation between the continental and the Mediterranean populations of Ulmus minor in Croatia was noticed.

High seed viability recorded in an endangered endemic species, 'Isoplexis isabelliana' (Scrophulariaceae), after more than 30 years of storage in a conservation seed bank

2021 ◽  
Vol 42 ◽  
pp. e69341
Author(s):  
Miguel Ángel González Pérez ◽  
Nereida Cabrera-García ◽  
Isabel Cayon-Fernández
Keyword(s):  
Seed Bank ◽  
Germination Rate ◽  
Genetic Material ◽  
Natural Populations ◽  
Seed Viability ◽  
Seed Storage ◽  
Botanical Garden ◽  
Storage Conditions ◽  
Seed Banks ◽  
Ex Situ

Conservation seed banks are essential for ex-situ conservation of genetic biodiversity. These institutions are especially relevant for threatened species and play a vital role in their conservation by preserving genetic material. However, samples deposited in the seed banks must germinate when necessary to use them (i.e., recovery plans, etc.). This study uses four accessions of the endemic endangered species from Gran Canaria Island (Canary Islands), Isoplexis isabelliana (Webb & Berthel.) Masf. (Scrophulariaceae). Germination tests were carried out to measure seed viability through time and the possible impact of seed storage on their viability. These accessions have been kept in the seed bank for four months to thirty years under different storage conditions. Germination results differed for seeds after 45 days of exposition using 16 hours light and 8 hours darkness at 17 °C. Accessions kept in the seed bank, independently of storage, showed a high germination percentage (89%). Whereas the accessions with rough storage conditions showed a 0% germination rate. The results highlighted the good state of conservation of the material deposited in the Seed Bank of the Botanical Garden "Viera y Clavijo" and the reliability of the temperature and humidity conditions in which the seeds of I. isabelliana have been stored. We consider these results as momentous since several natural populations of I. isabelliana has been affected by the last forest fire on the island.

scholarly journals The Sensitiveness of Expected Heterozygosity and Allelic Richness Estimates for Analyzing Population Genetic Diversity

2021 ◽  
Author(s):  
María Eugenia Barrandeguy ◽  
María Victoria García
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Variability ◽  
Population Size ◽  
Genetic Drift ◽  
Population Genetic ◽  
Allelic Richness ◽  
Theoretical Background ◽  
Computational Simulations ◽  
Expected Heterozygosity

Genetic diversity comprises the total of genetic variability contained in a population and it represents the fundamental component of changes since it determines the microevolutionary potential of populations. There are several measures for quantifying the genetic diversity, most notably measures based on heterozygosity and measures based on allelic richness, i.e. the expected number of alleles in populations of same size. These measures differ in their theoretical background and, in consequence, they differ in their ecological and evolutionary interpretations. Therefore, in the present chapter these measures of genetic diversity were jointly analyzed, highlighting the changes expected as consequence of gene flow and genetic drift. To develop this analysis, computational simulations of extreme scenarios combining changes in the levels of gene flow and population size were performed.

scholarly journals Genetic Diversity, Structure and Effective Population Size of Old-Growth vs. Second-Growth Populations of Keystone and Long-Lived Conifer, Eastern White Pine (Pinus strobus): Conservation Value and Climate Adaptation Potential

2021 ◽  
Vol 12 ◽  
Author(s):  
Om P. Rajora ◽  
John W. R. Zinck
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Effective Population Size ◽  
Population Genetic ◽  
Conservation Value ◽  
Adaptive Potential ◽  
Effective Population ◽  
White Pine ◽  
Old Growth ◽  
Second Growth

Whether old-growth (OG) forests have higher genetic diversity and effective population size, consequently higher conservation value and climate adaptive potential than second-growth (SG) forests, remain an unresolved issue. We have tested the hypothesis that old-growth forest tree populations have higher genetic diversity, effective population size (NE), climate adaptive potential and conservation value and lower genetic differentiation than second-growth forest tree populations, employing a keystone and long-lived conifer, eastern white pine (EWP; Pinus strobus). Genetic diversity and population structure of old-growth and second-growth populations of eastern white pine (EWP) were examined using microsatellites of the nuclear and chloroplast genomes and single nucleotide polymorphisms (SNPs) in candidate nuclear genes putatively involved in adaptive responses to climate and underlying multilocus genetic architecture of local adaptation to climate in EWP. Old-growth and second-growth EWP populations had statistically similar genetic diversity, inbreeding coefficient and inter-population genetic differentiation based on nuclear microsatellites (nSSRs) and SNPs. However, old-growth populations had significantly higher chloroplast microsatellites (cpSSRs) haploid diversity than second-growth populations. Old-growth EWP populations had significantly higher coalescence-based historical long-term NE than second-growth EWP populations, but the linkage disequilibrium (LD)-based contemporary NE estimates were statistically similar between the old-growth and second-growth EWP populations. Analyses of population genetic structure and inter-population genetic relationships revealed some genetic constitution differences between the old-growth and second-growth EWP populations. Overall, our results suggest that old-growth and second-growth EWP populations have similar genetic resource conservation value. Because old-growth and second-growth EWP populations have similar levels of genetic diversity in genes putatively involved in adaptive responses to climate, old-growth, and second-growth populations may have similar adaptive potential under climate change. Our results could potentially be generalized across most of the boreal and temperate conifer forest trees. Our study contributes to address a long-standing issue, advances research field and knowledge about conservation and ecological and climate adaptation of forest trees.

scholarly journals Reconstructing hotspots of genetic diversity from glacial refugia and subsequent dispersal in Italian common toads (Bufo bufo)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrea Chiocchio ◽  
Jan. W. Arntzen ◽  
Iñigo Martínez-Solano ◽  
Wouter de Vries ◽  
Roberta Bisconti ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Genetic ◽  
Environmental Changes ◽  
Glacial Refugia ◽  
Bufo Bufo ◽  
Genetic Admixture ◽  
Secondary Contact ◽  
Last Interglacial ◽  
Contact Zones ◽  
Genetic Lineages

AbstractGenetic diversity feeds the evolutionary process and allows populations to adapt to environmental changes. However, we still lack a thorough understanding of why hotspots of genetic diversity are so 'hot'. Here, we analysed the relative contribution of bioclimatic stability and genetic admixture between divergent lineages in shaping spatial patterns of genetic diversity in the common toad Bufo bufo along the Italian peninsula. We combined population genetic, phylogeographic and species distribution modelling (SDM) approaches to map ancestral areas, glacial refugia, and secondary contact zones. We consistently identified three phylogeographic lineages, distributed in northern, central and southern Italy. These lineages expanded from their ancestral areas and established secondary contact zones, before the last interglacial. SDM identified widespread glacial refugia in peninsular Italy, sometimes located under the present-day sea-level. Generalized linear models indicated genetic admixture as the only significant predictor of the levels of population genetic diversity. Our results show that glacial refugia contributed to preserving both levels and patterns of genetic diversity across glacial-interglacial cycles, but not to their formation, and highlight a general principle emerging in Mediterranean species: higher levels of genetic diversity mark populations with substantial contributions from multiple genetic lineages, irrespective of the location of glacial refugia.

scholarly journals Variable opportunities for outcrossing result in hotspots of novel genetic variation in a pathogen metapopulation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Anna-Liisa Laine ◽  
Benoit Barrès ◽  
Elina Numminen ◽  
Jukka P Siren
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Structure ◽  
Fungal Pathogen ◽  
Population Genetic ◽  
Reproductive Strategies ◽  
Natural Populations ◽  
Pathogen Population ◽  
To Come ◽  
Pathogen Populations

Many pathogens possess the capacity for sex through outcrossing, despite being able to reproduce also asexually and/or via selfing. Given that sex is assumed to come at a cost, these mixed reproductive strategies typical of pathogens have remained puzzling. While the ecological and evolutionary benefits of outcrossing are theoretically well-supported, support for such benefits in pathogen populations are still scarce. Here, we analyze the epidemiology and genetic structure of natural populations of an obligate fungal pathogen, Podosphaera plantaginis. We find that the opportunities for outcrossing vary spatially. Populations supporting high levels of coinfection –a prerequisite of sex – result in hotspots of novel genetic diversity. Pathogen populations supporting coinfection also have a higher probability of surviving winter. Jointly our results show that outcrossing has direct epidemiological consequences as well as a major impact on pathogen population genetic diversity, thereby providing evidence of ecological and evolutionary benefits of outcrossing in pathogens.

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