Relevance of unilateral and bilateral sexual polyploidization in relation to intergenomic recombination and introgression in Lilium species hybrids

Sexual polyploids were induced in diploid (2n = 2x = 24) interspecific F1 hybrids of Longiflorum × Asiatic (LA) and Oriental × Asiatic (OA) Lilium hybrids by backcrossing to Asiatic (AA) parents as well as by sib-mating of the F1 LA hybrids. A majority of the BC1 progenies were triploid and the progenies from sib-mating were tetraploid or near tetraploids. Genomic in situ hybridization (GISH) technique was applied to assess the intergenomic recombination in the BC1 populations of LA and OA hybrids obtained after unilateral sexual polyploidization. A total of 63 LA (LA × AA and AA × LA) and 53 OA hybrids were analysed. LA hybrids were originated through the functioning of 2n gametes either as 2n eggs or 2n pollen while those of OA hybrids originated through functional 2n pollen of diploid OA genotype. In both type of crosses, a majority of the progenies had originated through First Division Restitution (FDR) mechanism of functional 2n gamete either with or without a cross over. However, there were nine LA- and four OA-genotypes where Indeterminate Meiotic Restitution (IMR) was the mechanism of 2n gamete formation. Based on GISH, total amount of introgression of Longiflorum and Oriental genome into Asiatic genome was determined. Most of the BC progenies exhibited recombination and the amount of recombination was higher in LA hybrids as compared to OA hybrids. Intergenomic recombination was also determined cytologically in the 16 plants of sib-mated LA hybrids where both parents had contributed 2n gametes. Based on these results the nature of interspecific lily hybrids obtained from uni- and bilateral sexual polyploidization leading to allotriploid and allotetraploid formation is discussed in the context of introgression and intergenomic recombinatio

Natural hybridization between Populus nigra L. and P. x canadensis Moench. Hybrid offspring competes for niches along the Rhine river in the Netherlands

Black poplar (Populus nigra L.) is a major species for European riparian forests but its abundance has decreased over the decades due to human influences. For restoration of floodplain woodlands, the remaining black poplar stands may act as source population. A potential problem is that P. nigra and Populus deltoides have contributed to many interspecific hybrids, which have been planted in large numbers. As these Populus x canadensis clones have the possibility to intercross with wild P. nigra trees, their offspring could establish themselves along European rivers. In this study, we have sampled 44 poplar seedlings and young trees that occurred spontaneously along the Rhine river and its tributaries in the Netherlands. Along these rivers, only a few native P. nigra L. populations exist in combination with many planted cultivated P. x canadensis trees. By comparison to reference material from P. nigra, P. deltoides and P. x canadensis, species-specific AFLP bands and microsatellite alleles indicated that nearly half of the sampled trees were not pure P. nigra but progeny of natural hybridisation that had colonised the Rhine river banks. The posterior probability method as implemented in NewHybrids using microsatellite data was the superior method in establishing the most likely parentage. The results of this study indicate that offspring of hybrid cultivated poplars compete for the same ecological niche as native black poplars

Adders onder het gras; beschikbaarheid en bruikbaarheid van ecologische en genetische kennis over amfibieën en reptielen en de knelpunten voor beleid en beheer

Dit rapport beschrijft welke kennis over de ecologie en genetica van de Kamsalamander, Boomkikker, Hazelworm en Zandhagedis beschikbaar is en waar hiaten in die kennis zitten. Het rapport benadrukt de informatie die nodig is voor een juist habitatbeheer en geeft aan of die informatie bekend is bij terreinbeheerders en in welke mate de kennis wordt gebruikt om beheer van die terreinen te richten op ter plaatse voorkomende amfibieën en reptielen. Het rapport doet aanbevelingen om beheer, beleid en onderzoek beter op elkaar af te stemmen

Using multi-locus allelic sequence data to estimate genetic divergence among four Lilium (Liliaceae) cultivars

Next Generation Sequencing (NGS) may enable estimating relationships among genotypes using allelic variation of multiple nuclear genes simultaneously. We explored the potential and caveats of this strategy in four genetically distant Lilium cultivars to estimate their genetic divergence from transcriptome sequences using three approaches: POFAD (Phylogeny of Organisms from Allelic Data, uses allelic information of sequence data), RAxML (Randomized Accelerated Maximum Likelihood, tree building based on concatenated consensus sequences) and Consensus Network (constructing a network summarizing among gene tree conflicts). Twenty six gene contigs were chosen based on the presence of orthologous sequences in all cultivars, seven of which also had an orthologous sequence in Tulipa, used as out-group. The three approaches generated the same topology. Although the resolution offered by these approaches is high, in this case there was no extra benefit in using allelic information. We conclude that these 26 genes can be widely applied to construct a species tree for the genus Lilium

Ruimtelijke samenhang en genetische variatie van boomkikkerpopulaties in Nederland

Een modelanalyse van de ruimtelijke samenhang heeft plaatsgevonden van een netwerkpopulatie van de boomkikker (Hyla arborea) in Midden-Limburg. De bezettingskans van poelen is bepaald met een regressiemodel en de ruimtelijke samenhang van de leefgebieden is geanalyseerd met het dispersiemodel Smallsteps. Het herstel-scenario 2010 biedt goede potenties voor de uitbreiding van de netwerkpopulatie. Er zijn echter nog enkele zwakke schakels in de ruimtelijke samenhang geconstateerd. Bovendien dient door het nemen van maatregelen nog meer in het huidige verspreidingsgebied van de boomkikker geinvesteerd te worden. Een genetische analyse in de Achterhoek maakt aannemelijk dat herkolonisatie heeft plaatsgevonden vanuit vier bronpopulaties. Hierbij zijn vier populatieclusters ontstaan die genetisch sterk verschillend zijn. De genetische diversiteit in de Doort (Midden-Limburg) is vergelijkbaar met populaties in de Achterhoek maar kleiner dan in twee Zwitserse populatie

Microsatellite variation and population structure of a recovering tree frog (Hyla arborea L.) metapopulation

Numbers and sizes of populations of the European tree frog in The Netherlands have dramatically decreased in the second half of the last century due to extensive habitat destruction and fragmentation. We have studied the genetic structure of a slowly recovering meta-population. Strong genetic differentiation, estimated at eight microsatellite loci, was found between clusters of populations (F (st)-values above 0.2). Within clusters, consisting of ponds within a radius of about 5 km, European tree frog populations were less differentiated (F (st)<0.08) and exact tests showed that most of the ponds within clusters were not significantly differentiated. Although local population sizes have been increasing since 1989, and some new ponds have been colonised in the direct vicinity of ponds that have been populated continuously, little evidence for gene flow between clusters of ponds was found (only one exception). Furthermore, levels of genetic diversity were low compared to populations in comparable areas elsewhere in Europe. Therefore, a continuous conservation effort is needed to prevent any further loss of genetic diversity. The alleviation of important barriers to dispersal between the clusters should be given a high priority for the restoration of the meta-population as a whole

Living in fragments: Genetic variation in spatially structured populations

In de Achterhoek gaat het met de boomkikker weer wat beter dankzij beschermingsmaatregelen. Men heeft geprobeerd de lokale populaties in vijf clusters te verstevigen door in de directe omgeving nieuwe poelen te graven, het landhabitat te verbeteren en verbindingen te maken tussen lokale poelen. Toch ligt het gevaar van uitsterving ook hier nog steeds op de loer omdat de leefgebieden relatief klein en geïsoleerd zijn. Dit maakt de eveneens relatief kleine populaties kwetsbaar, bijvoorbeeld voor inteelt, omdat de genetische variatie in de populaties laag is. Inteelt, op zijn beurt, maakt populaties extra gevoelig voor toevallige omstandigheden als droogte of andere extreme (weers)omstandigheden. Paul Arens constateerde dat er tussen de clusters weinig genetische uitwisseling is, terwijl de genetische variatie binnen het hele gebied nu al gevaarlijk laag is. Recent is de belangrijkste populatie in een van de clusters bijvoorbeeld uitgestorven. Volgens Arens moeten er daarom met spoed natuurlijke verbindingen, zogenaamde corridors, tussen de clusters worden aangelegd. Dit geldt ook voor de leefgebieden van de heikikker, hoewel de genetische variatie binnen deze soort tot nu toe minder te lijden lijkt te hebben gehad van landschapsversnippering dan de boomkikker. Het leefgebied van planten en dieren in Nederland is in de laatste honderd jaar dramatisch kleiner geworden en versnipperd. Paul Arens onderzocht de consequenties voor de genetische variatie van deze natuurverarming niet alleen bij de boom- en de heikikker maar ook bij de zwarte populier, de boszegge en het dalkruid. Hij vond bij alle vijf de soorten schadelijke effecten van de versnippering van het leefgebied en/of ander menselijk handelen. Voor de drie plantensoorten lijkt vooral het ontbreken van voldoende dynamiek, die condities voor bloei en/of zaadkieming creëren, de belangrijkste oorzaak voor de achteruitgang van lokale populaties

Autosomal and sex-linked microsatellite loci in the green oak leaf roller Tortrix viridana L.

Eight microsatellite markers were developed for the lepidopteran species Tortrix viridana using an enrichment protocol. The loci were highly variable with number of alleles ranging from four to 38. Six of the eight loci were in Hardy¿Weinberg equilibrium. The other two were linked to the Z-chromosome. Values of observed heterozygosity ranged for the autosomal loci from 0.510 to 0.957. All loci will be useful to study dispersal and the autosomal loci, as well for phylogeographical studies