Estimating the number of sexual events per generation in a facultatively sexual haploid population.

In populations of facultatively sexual organisms, the proportion of sexually produced offspring contributed to each generation is a critical determinant of their evolutionary potential. However, estimating this parameter in natural populations has proved difficult. Here we develop a population genetic model for estimating the number of sexual events occurring per generation for facultatively sexual haploids possessing a biallelic mating-type locus (e.

Cryptic genetic variation and adaptation to waterlogging in Caledonian Scots pine, L.

Local adaptation occurs as the result of differential selection among populations. Observations made under common environmental conditions may reveal phenotypic differences between populations with an underlying genetic basis; however, exposure to a contrasting novel environment can trigger release of otherwise unobservable (cryptic) genetic variation. We conducted a waterlogging experiment on a common garden trial of Scots pine, (L.

Planting exotic relatives has increased the threat posed by to the Caledonian pine populations of Scotland.

To manage emerging forest diseases and prevent their occurrence in the future, it is essential to determine the origin(s) of the pathogens involved and identify the management practices that have ultimately caused disease problems. One such practice is the widespread planting of exotic tree species within the range of related native taxa. This can lead to emerging forest disease both by facilitating introduction of exotic pathogens and by providing susceptible hosts on which epidemics of native pathogens can develop.

High mutation rates explain low population genetic divergence at copy-number-variable loci in Homo sapiens.

Copy-number-variable (CNV) loci differ from single nucleotide polymorphic (SNP) sites in size, mutation rate, and mechanisms of maintenance in natural populations. It is therefore hypothesized that population genetic divergence at CNV loci will differ from that found at SNP sites. Here, we test this hypothesis by analysing 856 CNV loci from the genomes of 1184 healthy individuals from 11 HapMap populations with a wide range of ancestry.

Reconstructing the plant mitochondrial genome for marker discovery: a case study using Pinus.

Whole-genome-shotgun (WGS) sequencing of total genomic DNA was used to recover ~1 Mbp of novel mitochondrial (mtDNA) sequence from Pinus sylvestris (L.) and three members of the closely related Pinus mugo species complex. DNA was extracted from megagametophyte tissue from six mother trees from locations across Europe, and 100-bp paired-end sequencing was performed on the Illumina HiSeq platform.

Characterisation of Ramularia collo-cygni laboratory mutants resistant to succinate dehydrogenase inhibitors.

Background: Ramularia collo-cygni (Rcc) is responsible for Ramularia leaf spot (RLS), a foliar disease of barley contributing to serious economic losses. Protection against the disease has been almost exclusively based on fungicide applications, including succinate dehydrogenase inhibitors (SDHIs). In 2015, the first field isolates of Rcc with reduced sensitivity to SDHIs were recorded in some European countries.

Has Scots pine (Pinus sylvestris) co-evolved with Dothistroma septosporum in Scotland? Evidence for spatial heterogeneity in the susceptibility of native provenances.

Spatial heterogeneity in pathogen pressure leads to genetic variation in, and evolution of, disease-related traits among host populations. In contrast, hosts are expected to be highly susceptible to exotic pathogens as there has been no evolution of defence responses. Host response to pathogens can therefore be an indicator of a novel or endemic pathosystem.

Hidden in plain view: Cryptic diversity in the emblematic Araucaria of New Caledonia.

Premise Of The Study: Cryptic species represent a conservation challenge, because distributions and threats cannot be accurately assessed until species are recognized and defined. Cryptic species are common in diminutive and morphologically simple organisms, but are rare in charismatic and/or highly visible groups such as conifers. New Caledonia, a small island in the southern Pacific is a hotspot of diversity for the emblematic conifer genus Araucaria (Araucariaceae, Monkey Puzzle trees) where 13 of the 19 recognized species are endemic.

Maintenance of species boundaries in a Neotropical radiation of Begonia.

A major goal of evolutionary biology is to determine the mechanisms generating biodiversity. In Begonia, one of the largest plant genera (1900+ species), it has been postulated that the high number of endemic species is a by-product of low gene flow among populations, which predisposes the group to speciation. However, this model of divergence requires that reproductive barriers accumulate rapidly among diverging species that overlap in their geographic ranges, otherwise speciation will be opposed by homogenizing gene flow in zones of secondary contact.

Does complete plastid genome sequencing improve species discrimination and phylogenetic resolution in Araucaria?

Obtaining accurate phylogenies and effective species discrimination using a small standardized set of plastid genes is challenging in evolutionarily young lineages. Complete plastid genome sequencing offers an increasingly easy-to-access source of characters that helps address this. The usefulness of this approach, however, depends on the extent to which plastid haplotypes track morphological species boundaries.

Evolutionary diversification of new Caledonian Araucaria.

New Caledonia is a global biodiversity hotspot. Hypotheses for its biotic richness suggest either that the island is a 'museum' for an old Gondwana biota or alternatively it has developed following relatively recent long distance dispersal and in situ radiation. The conifer genus Araucaria (Araucariaceae) comprises 19 species globally with 13 endemic to this island.

Molecular identification and relative abundance of cryptic Lophodermium species in natural populations of Scots pine, Pinus sylvestris L.

The multi-locus phylogenetic species recognition approach and population genetic analysis of Amplified Fragment Length Polymorphism (AFLP) markers were used to delineate Lophodermium taxa inhabiting needles of Scots pine (Pinus sylvestris) in native pinewoods within Scotland. These analyses revealed three major lineages corresponding to the morphological species Lophodermium seditiosum and Lophodermium conigenum, fruiting on broken branches, and Lophodermium pinastri, fruiting on naturally fallen needles. Within L.

Evolutionary dynamics of emblematic Araucaria species (Araucariaceae) in New Caledonia: nuclear and chloroplast markers suggest recent diversification, introgression, and a tight link between genetics and geography within species.

Background: New Caledonia harbours a highly diverse and endemic flora, and 13 (out of the 19 worldwide) species of Araucaria are endemic to this territory. Their phylogenetic relationships remain largely unresolved. Using nuclear microsatellites and chloroplast DNA sequencing, we focused on five closely related Araucaria species to investigate among-species relationships and the distribution of within-species genetic diversity across New Caledonia.

Genotypic variation in a foundation tree (Populus tremula L.) explains community structure of associated epiphytes.

Community genetics hypothesizes that within a foundation species, the genotype of an individual significantly influences the assemblage of dependent organisms. To assess whether these intra-specific genetic effects are ecologically important, it is required to compare their impact on dependent organisms with that attributable to environmental variation experienced over relevant spatial scales. We assessed bark epiphytes on 27 aspen (Populus tremula L.

The evolution of sex ratio differences and inflorescence architectures in Begonia (Begoniaceae).

Premise Of The Study: A major benefit conferred by monoecy is the ability to alter floral sex ratio in response to selection. In monoecious species that produce flowers of a given sex at set positions on the inflorescence, floral sex ratio may be related to inflorescence architecture. We studied the loci underlying differences in inflorescence architecture between two monoecious Begonia species and related this to floral sex ratios.

Patterns of mating, generation of diversity, and fitness of offspring in a Geum hybrid swarm.

To understand the evolutionary consequences of hybridization between the outcrossing plant Geum rivale (Rosaceae) and the selfer Geum urbanum, we tested the predictions of two simple models that assume either (A) low or (B) high pollen fitness in hybrids. Model A predicts only four genotypic classes (G. rivale, G.

Development and characterization of microsatellite markers for Central American Begonia sect. Gireoudia (Begoniaceae).

Premise Of The Study: Transcriptome sequence data were used to design microsatellite primers for two widespread Central American Begonia species, B. heracleifolia and B. nelumbiifolia, to investigate population structure and hybridization.

Molecular evidence indicates that subarctic willow communities in Scotland support a diversity of host-associated Melampsora rust taxa.

Rare and threatened subarctic willow scrub communities in the UK are the subject of ongoing conservation programmes, yet little is known about the diversity of fungal taxa that they support. Isolates of the rust genus Melampsora were sampled from 112 leaves of eight subarctic willow (Salix) taxa and their hybrids from twelve sites in the UK. In order to determine the number of Melampsora taxa present in the samples, isolates were sequenced for the Internal Transcribed Spacer (ITS) region of rDNA and data were subject to phylogenetic analysis.

Conserving taxonomic complexity.

Traditional species-based conservation programmes are appropriate in situations where species are readily identifiable. However, in certain taxonomically complex groups of organisms, generally characterized by the presence of uniparental lineages and reticulate evolution, it is not possible to classify biodiversity into discrete and unambiguous species. Attempts to impose species-based conservation on such taxonomically complex groups are proving untenable, and threaten to divert scarce resources and taxonomic expertise from the conservation of other priority groups.

Effective seed dispersal across a fragmented landscape.

The role of seed dispersal in maintaining genetic connectivity among forest fragments has largely been ignored because gene flow by pollen is expected to predominate. By using genealogical reconstruction, we investigated gene flow after establishment of seeds in a wind-pollinated, wind-dispersed tree. Our data show that seed dispersal is the main vector of gene flow among remnants and that long-distance dispersal is common across a chronically fragmented landscape.

Historical and contemporary mating patterns in remnant populations of the forest tree Fraxinus excelsior L.

Genetic variation at microsatellite markers was used to quantify genetic structure and mating behavior in a severely fragmented population of the wind-pollinated, wind-dispersed temperate tree Fraxinus excelsior in a deforested catchment in Scotland. Remnants maintain high levels of genetic diversity, comparable with those reported for continuous populations in southeastern Europe, and show low interpopulation differentiation (E = 0.080), indicating that historical gene exchange has not been limited (Nm = 3.