The potential role of polyploidy and hybridisation in the further evolution of the highly invasive <Emphasis Type="Italic">Fallopia</Emphasis> taxa in Europe

Japanese knotweed s.l. comprises Fallopia japonica, F. sachalinensis, F. × bohemica and any F2s or backcrosses. The parental taxa were introduced from the East to the West as garden ornamentals in the nineteenth century, and soon spread beyond the confines of the garden to become widespread and persistent weeds. Since only female F. japonica var. japonica was introduced, its impressive spread has occurred solely by vegetative means. However, the initial lack of genetic variability has been complemented by an extensive series of hybridisations in the adventive range. We examine the history, spread, reproductive biology and ecological impact of these species in the West. The role and importance of polyploidy and hybridisation in their invasion of the West is discussed, as are the implications of these factors for the potential further evolution of the group.     

Unexpected genetic diversity of Fallopia japonica from Central Europe revealed after AFLP analysis

Recently much attention has been paid to genetic aspects of invasive success in Japanese knotweed s.l. One hypothesis to explain the invasive spread of these species is a multiple introduction, which leads to a higher level of genetic diversity in the invaded range. Fallopia japonica is considered to be genetically uniform in Europe, introduced as a single female clone. However, there is some evidence suggesting that invasion history and dynamics differ between Western and Central-Eastern Europe. We used AFLP markers to characterize genetic diversity of three Fallopia taxa that occur in Poland: F. japonica, F. sachalinensis and their hybrid Fallopia × bohemica, growing in so-called ‘homogeneous’ populations, consisting of one taxon and ‘heterogeneous’ populations, composed of the three taxa cohabiting together. No polymorphism, resp. an insignificantly low variability was observed in the ‘homogeneous’ populations. In the ‘heterogeneous’ stands polymorphism was detected within each taxa, with one exception that concerns individuals of F. sachalinensis from a riparian habitat. The highest level of polymorphism was found among individuals of F. × bohemica. The most striking result of our study is the observation of polymorphism between individuals of F. japonica. The AFLP data also showed that F. × bohemica is most diverse when occurring in a heterogeneous configuration with F. japonica and F. sachalinensis in the same habitat. Our results are the first evidence of genetic diversity in F. japonica populations in Central Europe and can implicate the possibility of its multiple introduction in this region or the existence of sexual reproduction of this species.     

Asexual spread versus sexual reproduction and evolution in Japanese Knotweed s.l. sets the stage for the “Battle of the Clones”

The invasion of NW Europe by a single clone of male-sterile Fallopia japonica var. japonica by purely vegetative reproduction has demonstrated that reproduction by seed and the genetic diversity associated with it may not be an essential feature of plant invasions, at least in the short term. What is less well known is that a significant proportion of the Japanese Knotweed s.l. involved is not F. japonica var. japonica, but the hybrid between it and F. sachalinensis–F. × bohemica. This hybrid is able to backcross to either parent with the potential to replace the missing male F. japonica; by the same process, the hybrid is generating the genetic diversity so conspicuously lacking in F. japonica. In terms of understanding the population structure in a particular country, it is important to be able to identify hybrids and putative back-crosses. We bring together a mixture of published and unpublished information to provide a comprehensive section on morphological and anatomical aids to identification. Regeneration of plants from stem and rhizome fragments varies by taxon, as do responses to control techniques, underlining the importance of correct identification of these plants. In this paper we look closely at this group of taxa, with special emphasis on the role played by hybridization, with an examination of the genetic make up of seedlings produced in the wild or by artificial hybridizations, and the implications that this will have on the future directions of the invasion process.     

Effects of climatic factors on Fallopia japonica s.l. seedling establishment: evidence from laboratory experiments

The highly invasive Fallopia complex (Fallopia japonica s.l., Fallopia japonica var. japonica, Fallopia sachalinensis and the hybrid Fallopia × bohemica) is known to spread primarily vegetatively by rhizomes and stem fragments in its adventive range. Sexual reproduction has rarely been shown in Europe, despite a high production of germinable seeds. To elucidate this contradiction the aim of the present study was to determine which environmental conditions prevent seed germination or seedling establishment. Several laboratory experiments were conducted focusing on water and light supply as well as the influence of frost. According to morphological and cytological analyses of the parental plants paired with morphological analyses of the seedlings, the seeds used for these experiments were assumed to belong predominantly to the hybrid Fallopia × bohemica. Laboratory experiments revealed that seedling establishment is hampered by severe drought or strong late frost, which are, however, rare events in the study region and could not be crucial in explaining the rarity of seedlings in the field. We discuss the possible role of weather conditions that might lead to a loss of seeds or seedlings under field conditions and include a comparison of several other cited studies carried out in the adventive range of Fallopia japonica s.l. that observed either the presence or the absence of Fallopia seedlings in the field.     

Extreme differences in population structure and genetic diversity for three invasive congeners: knotweeds in western North America

Japanese, giant, and the hybrid Bohemian knotweeds (Fallopia japonica, F. sachalinensis and F. × bohemica) have invaded the western USA and Canada, as well as other regions of the world. The distribution of these taxa in western North America, and their mode of invasion, is relatively unresolved. Using amplified fragment length polymorphisms of 858 plants from 131 populations from British Columbia to California to South Dakota, we determined that Bohemian knotweed was the most common taxon (71 % of all plants). This result is in contrast to earlier reports of F. × bohemica being uncommon or non-existent in the USA, and also differs from the European invasion where it is rarer. Japanese knotweed was monotypic, while giant knotweed and Bohemian knotweed were genetically diverse. Our genetic data suggest that Japanese knotweed in western North America spreads exclusively by vegetative reproduction. Giant knotweed populations were mostly monotypic, with most containing distinct genotypes, suggesting local spread by vegetative propagules, whereas Bohemian knotweed spreads by both seed and vegetative propagules, over both long and short distances. The high relative abundance and genetic diversity of Bohemian knotweed make it a priority for control in North America.     

Morphological and chromosomal variation in Fallopia section Reynoutria (Polygonaceae) in Korea

We have examined morphological and chromosomal variation inFallopia sect.Reynoutria in Korea to clarify their taxonomic identities and to determine whether their morphological variability is associated with ploidy levels. Principal components analysis (PCA) of individuals from 21 populations, using major distinguishing characters, revealed the presence of four major entiries of sect.Reynoutria in Korea; these includeF. sachalinensis, F. japonica var.japonica, F. forbesii, and the Nonsan population consisting of presumed hybrids. Based on morphology, it is hypothesized that the Nonsan population was probably derived from multiple hybridization events involving the three named taxa. The results also indicate thatF. forbesii is distinct fromF. japonica var.japonica. Polyploidy is more prevalent in sect.Reynoutria than has been previously recognized.Fallopia sachalinensis in Korea occurs as dodecaploids with 2n=132; our count is the first dodecaploid count for the species, and represents the highest chromosome number known in the genus.Fallopia japonica var.japonica occurs as tetraploids (2n=44), hexaploids (2n=66), and octoploids (2n=88), whileF. forbesii occurs as hexaploids (2n=66) and octoploids (2n=88); our counts appear to be the first reported chromosome numbers forF. forbesii. Morphological analysis indicates that there is no apparent correlation between the ploidy levels in these taxa and the morphological characters that we have considered in this study except that the tetraploids ofF. japonica var.japonica tend to have somewhat thicker leaves.     

Herbivore resistance of invasive <Emphasis Type="Italic">Fallopia</Emphasis> species and their hybrids

Hybridization has been proposed as a mechanism by which exotic plants can increase their invasiveness. By generating novel recombinants, hybridization may result in phenotypes that are better adapted to the new environment than their parental species. We experimentally assessed the resistance of five exotic Fallopia taxa, F. japonica var. japonica, F. sachalinensis and F. baldschuanica, the two hybrids F. × bohemica and F. × conollyana, and the common European plants Rumex obtusifolius and Taraxacum officinale to four native European herbivores, the slug Arion lusitanicus, the moth Noctua pronuba, the grasshopper Metrioptera roeselii and the beetle Gastrophysa viridula. Leaf area consumed and relative growth rate of the herbivores differed significantly between the Fallopia taxa and the native species, as well as among the Fallopia taxa, and was partly influenced by interspecific variation in leaf morphology and physiology. Fallopia japonica, the most abundant Fallopia taxon in Europe, showed the highest level of resistance against all herbivores tested. The level of resistance of the hybrids compared to that of their parental species varied depending on hybrid taxon and herbivore species. Genotypes of the hybrid F. × bohemica varied significantly in herbivore resistance, but no evidence was found that hybridization has generated novel recombinants that are inherently better defended against resident herbivores than their parental species, thereby increasing the hybrid’s invasion success. In general, exotic Fallopia taxa showed higher levels of herbivore resistance than the two native plant species, suggesting that both parental and hybrid Fallopia taxa largely escape from herbivory in Europe.     

Landscape dynamics and habitat selection by the alien invasive <Emphasis Type="Italic">Fallopia</Emphasis> (Polygonaceae) in Belgium

Habitat patch colonization dynamics and distribution patterns were analysed at a landscape scale in four invasive Fallopia (Polygonaceae) species. Fallopia sachalinensis and F. aubertii were uncommon and population expansion was not evident during the three consecutive years of study. The two most widespread species, F. japonica and F. × bohemica displayed similar habitat selection patterns with ruderal and natural/semi-natural forests favoured. The highest densities of F. japonica and F. × bohemica individuals were at the edge of preferred habitat patches with different patterns of edge selection. Linear network played an important role in species invasion, with 71% of all F. japonica and F. × bohemica occurring within a 10 m buffer of total linear networks (roads, railways, and rivers). However, the buffer represented only 14.5% of the total landscape surface. The rate of population increase was higher for F. japonica (75.8% and 35.2%, in 2002 and 2003, respectively) than for F. × bohemica (63.6% and 0% in 2002 and 2003, respectively) and was largely the result of intra-patch dynamics with low inter-patch colonization. The total surface area occupied by Fallopia clones in the landscape grew by 34.7% over 2 years of the study, with comparable area growth means for F. japonica and F. × bohemica (34.9% and 34.7%, respectively). The hypothesis that F. × bohemica exhibits higher invasive dynamics due to both clonal and sexual reproduction was not supported by our results.     

Phylogeographic analysis of the brown alga Cutleria multifida (Tilopteridales,Phaeophyceae) suggests a complicated introduction history

In depth genetic comparisons of populations of Cutleria multifida (Tilopteridales, Phaeophyceae) collected from Europe, the northwestern Pacific Ocean, Australia and New Zealand using the DNA sequences of four gene regions (the mitochondrial cox2 and cox3 genes, the intergeneric spacer region adjacent to cox3, and the open reading frame) suggested that the northwestern European and Japanese populations were considerably greater in terms of their genetic divergence than Mediterranean, Australian or New Zealand populations. The haplotypes of the populations in northwestern European (distribution range including the type locality, seven haplotypes) and Japanese populations (seven haplotypes) were unique except for one shared haplotype. There were weak but positive correlations between the geographical distance and the genetic divergence among northwestern European and Japanese populations. Moreover, both female and male gametophytes occurred in eight of the nine Japanese localities, suggesting Japanese populations showed normal sexual heteromorphic life history of the species. In light of these results, it appears that Japanese populations were native to the area despite earlier hypothesis. In contrast, Australian and New Zealand populations were composed of only one haplotype that is very close to those found in northwestern Europe and Japan, suggesting a recent introduction history from Europe (or from northeastern Asia via Europe) by ship transport to Australia and New Zealand. The Mediterranean populations included two haplotypes identical to those found in northwestern Europe and Japan, and it is suggestive of transoceanic introductions of some populations between Mediterranean and Japanese coasts.     

Impacts of the invasive plant <Emphasis Type="Italic">Fallopia japonica</Emphasis> (Houtt.) on plant communities and ecosystem processes

Fallopia japonica (Japanese knotweed) invades riparian areas and roadsides in New England. This large clonal species drastically alters the appearance of habitats by forming highly productive near-monocultures. To understand how these invasions affect ecosystem processes in New England, we quantified the impacts of F. japonica on species diversity, primary productivity, and nitrogen cycling at five locations in central Massachusetts, USA. In stands of F. japonica and in adjacent uninvaded areas, we recorded the cover of each plant species and measured the aboveground biomass and nitrogen (N) concentrations in plants, along with N retranslocation from F. japonica leaves and several soil characteristics. In addition, we severed rhizomes of peripheral F. japonica shoots to determine if clonal integration contributes to the species’ rapid spread and dominance. Stands of F. japonica had lower species diversity, but greater aboveground biomass and standing N than uninvaded areas. Nitrogen and carbon concentrations in biomass and N mineralization rates in soil did not differ between stands and adjacent areas. Rhizome severing temporarily reduced growth of F. japonica, suggesting that retranslocation of photoassimilates and/or nutrients between shoots via rhizomatal connections may maximize stand level growth rates and facilitate dominance by F. japonica.     

Geographically congruent large‐scale patterns of plastid haplotype variation in the European herbs Silene dioica and S. latifolia (Caryophyllaceae)

The closely related dioecious herbs Silene latifolia and Silene dioica are widespread and predominantly sympatric in Europe. The species are interfertile, but morphologically and ecologically distinct. A study of large‐scale patterns of plastid DNA (polymerase chain reaction–restriction fragment length polymorphism) haplotypes in a sample of 198 populations from most of the European ranges of both species revealed extensive interspecific haplotype sharing. Four of the 28 detected haplotypes were frequent (found in > 40 populations) and widespread. Three of these frequent haplotypes occurred in both species and the geographic distribution of each haplotype was broadly congruent in both species. Each of these three, shared and widespread haplotypes is likely to have colonized central and/or northern Europe after the last glaciation from one or more of refugial areas in southern Europe. Interspecific hybridization and plastid introgression within refugial regions and/or during the early stages of postglacial expansion is the most plausible explanation for the broadly similar distribution patterns of the shared, frequent chloroplast haplotypes in the two species. The fourth frequent, widespread haplotype was absent from S. latifolia and almost entirely restricted to Nordic S. dioica. It is most likely that this haplotype spread into the Nordic countries from a central or northern European source or from a refugial area in Russia. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 153–170.     

Seed characteristics and germination limitations in the highly invasive <Emphasis Type="Italic">Fallopia japonica</Emphasis> s.l. (Polygonaceae)

The species in the Japanese knotweed complex (Fallopia japonica s.l. and its hybrids) are among the most invasive plants on earth. Their expansion and reproduction in the introduced range have been mostly due to vegetative reproduction, but observations of low seedling numbers and hybridization processes exist. Knowledge of factors affecting germination characteristics is essential if the risk of sexual reproduction is to be assessed, and its impact on the ability of the species to spread and adapt to different environments. This study aims to examine the germination success of Fallopia japonica s.l. seeds of different ages, quality, and storage conditions. Irrespective of age and even after natural overwintering in the soil, seeds germinated quite well (48–79%). Ungerminated seeds collected in autumn of 2008 were characterized by a low weight/length ratio (W/L), low nutrient concentrations, and a greenish tepal coloration. These differences may be due to alternative male taxa participating in the pollination process. Spring collected seeds were subject to strong predation by birds. In contrast to the high germination observed under laboratory conditions, seed germination or early establishment in the field was inhibited and only a few seedlings were observed. Although the factors that inhibit the establishment of mature seeds in the field remain unknown, there is a clear risk that sexual reproduction could gain importance in the future as a result of changing environmental conditions or genetic adaptation. Not only would this facilitate expansive dispersal by wind, but it might also increase the potential for further adaptation of the species complex.     

Seasonal patterns of partitioning and remobilization of 14C in the invasive rhizomatous perennial Japanese knotweed (Fallopia japonica (Houtt.) Ronse Decraene)

Resource partitioning between shoot growth, storage and reproduction is poorly understood in many clonal plant species. This study documents seasonal patterns of growth, ¹⁴C-labelled photoassimilate distribution and remobilization in the invasive rhizomatous species Fallopia japonica (Japanese knotweed). Biomass accumulation above- and below-ground in F. japonica was rapid. By September, rhizome biomass had increased 18-fold from the initial harvest in May (representing 48% of total plant biomass) and this was maintained over winter. Patterns of ¹⁴C allocation from F. japonica shoots labelled at different times of year show that as the season progressed, the rhizomes became an increasingly important sink for current assimilate (the percentage of ¹⁴C recovered from rhizomes was 35% in August and 67% in September) and the corresponding retention of assimilate by established shoots declined. The percentage of ¹⁴C exported to roots was greatest in August. Relatively little photoassimilate was exported to other shoots on the plant, or to flowers. Recycling of photoassimilate was fairly tight in this species and ¹⁴C fixed by shoots in early May 1999 or September 1999 was remobilized to the rhizome prior to shoot senescence and death. Some of this ¹⁴C was then remobilized to new shoots early the following spring. These characteristics may contribute to the success of F. japonica in colonizing a variety of contrasting habitats, often with serious management implications.     

Genotyping of five single nucleotide polymorphisms in the OCA2 and HERC2 genes associated with blue‐brown eye color in the Japanese population

Human eye color is a polymorphic phenotype influenced by multiple genes. It has recently been reported that three single nucleotide polymorphisms (SNPs) within intron 1 of the OCA2 gene (rs7495174, rs4778241, rs4778138) and two SNPs in intron 86 (rs12913832) and the 3′ UTR region (rs1129038) of the HERC2 gene—located in the upstream of the OCA2 locus —have a high statistical association with human eye color. The present study is the first to examine in detail the genotype and haplotype frequencies for these five SNPs in an Asian (Japanese) population (n = 523) comprising solely brown‐eyed individuals. Comparison of the genotype and haplotype distributions in Japanese with those in African and European subjects revealed significant differences between Japanese and other populations. Analysis of haplotypes consisting of four SNPs at the HERC2‐OCA2 locus (rs12913832/rs7495174/rs4778241/rs4778138) showed that the most frequent haplotype in the Japanese population is A‐GAG (0.568), while the frequency of this haplotype is rather low in the European population, even in the brown‐eyed group (0.167). The haplotype distribution in the Japanese population was significantly different from that in the brown‐eyed European group (F_ST = 0.18915). Copyright © 2009 John Wiley & Sons, Ltd.     

Systematics of <Emphasis Type="Italic">Mycosphaerella</Emphasis> species associated with the invasive weed <Emphasis Type="Italic">Fallopia japonica</Emphasis>, including the potential biological control agent <Emphasis Type="Italic">M. polygoni-cuspidati</Emphasis>

Native to Japan, Fallopia japonica, most frequently referred to as Japanese knotweed, is a highly problematic invasive weed, particularly in the UK and North America. During surveys for natural enemies of this plant in Japan, two species of Mycosphaerella were collected. One of these was identified as M. polygoni-cuspidati, and is redescribed and neotypified. Causing a damaging leaf spot disease of F. japonica throughout its natural range in Japan, it is absent from the host’s exotic range. The restriction of M. polygoni-cuspidati to F. japonica in its center of origin, together with its severe impact on host fitness, indicates that this is a coevolved natural enemy with high potential as a classical biological control agent for the long-term management of this ecologically and economically important weed. In the field, the fungus has a reduced life cycle, with only spermogonia and pseudothecia (ascomata) being formed. Ascospores are the primary source of infection, and studies show that the mycelium from in vitro cultures is also infective and hyphae penetrate mainly via the stomata. A further, undescribed species of Mycosphaerella co-occurs with M. polygoni-cuspidati, here proposed as the new species M. shimabarensis. Both species have been studied using cultural, morphological and molecular phylogenetic methods.     

Fine‐scale spatial and temporal population genetics of Aedes japonicus,a new US mosquito,reveal multiple introductions

The newly introduced mosquito Aedes japonicus has expanded from its original range in Northeastern Asia to 29 US states (including Hawaii) plus Canada and northern Europe. Our objectives were to test an earlier hypothesis of multiple introductions of this species to the Northeastern US and evaluate putative temporal changes in genetic makeup. Using a panel of seven microsatellite loci, we confirmed the existence of two abundant genetic forms in specimens originally collected in 1999–2000 (F_ST value based on microsatellite data = 0.26) that matches the disjunctive distribution of mitochondrial haplotypes. To examine the distribution of the two genetic ‘types’ across Pennsylvania we created a fine‐scale genetic map of Ae. japonicus using 439 specimens collected from 54 Pennsylvania counties in 2002–2003. We also made direct comparisons between collections in 1999–2000 and new collections made in 2004–2005 obtained from the same areas in the northeastern US. We observed that the strong association between mtDNA haplotype and microsatellite signature seen in 1999–2000 had weakened significantly by 2002 across Pennsylvania, a trend continued to some extent in 2004–2005 in PA, NJ, and NY, indicating that once easily distinguishable separate introductions are merging. The two expanding genetic forms create a complex correlation between spatial and genetic distances. The existence of multiple introductions would be obscured without sampling early and across time with highly polymorphic molecular markers. Our results provide a high‐resolution analysis of the spatial and temporal dynamics of a newly introduced disease vector and argue that successive introductions may be a common pattern for invasive mosquitoes.     

Host specificity of <Emphasis Type="Italic">Euops chinesis</Emphasis>, a potential biological control agent of <Emphasis Type="Italic">Fallopia japonica</Emphasis>, an invasive plant in Europe and North America

Fallopia japonica (Houttuyn) Ronse Decraene (Polygonaceae) is a serious invasive weed in North American and Europe. In its native China, a leaf-rolling weevil, Euops chinesis (Coleoptera: Attelabidae) was found attacking F. japonica in the field. No-choice tests, multiple-choice tests, open field tests and field surveys were conducted as a measure of its host specificity. Forty-six plant species were selected from 17 families for host range testing, among which, six species, F. multiflora, F. japonica, Persicaria perfoliata, Rumex acetosa, R. japonicus and R. aquaticus, were exposed to adults in no-choice tests. However, larvae could only develop successfully on F. japonica, and this plant appeared to be the only host in the field, suggesting the weevil is host-specific. As larval development appears to depend on a fungus in the leaf rolls, the insect–fungus mutualism and risks including host specificity of the fungus should be evaluated before the insect’s introduction.     

Distribution of mitochondrial haplotypes (cytb) in Polish populations of Emys orbicularis (L., 1758)

The European pond turtle, Emys orbicularis, inhabits a wide distribution area in the western Palaearctic. Polish populations of pond turtle represent the nominotypical subspecies Emys orbicularis orbicularis. The mitochondrial DNA haplotype (cytb gene) variation among 131 turtles from 26 locations in five regions of Poland was investigated. Five haplotypes belonging to three distinct lineages were identified. Two clades (I and II) were represented by two haplotypes each, while the other clade (IV) was represented by one haplotype. Three haplotypes were reported for the first time in E. orbicularis. The eastern part of Poland is inhabited exclusively by turtles bearing haplotype Ia. The remaining four sequence variants were recorded in western Poland where only the IIb haplotype is considered endemic. The distribution of the other haplotypes in western Poland could thus reflect past introductions or accidental releases. The authors regarded the two locations (Drzeczkowo and Karpicko) that were first included in the western Poland populations as autochthonous catchment areas of haplotype Ia.     

Detection of recombinant haplotypes in wild mice (Mus musculus) provides new insights into the origin of Japanese mice

Japanese house mice (Mus musculus molossinus) are thought to be a hybrid lineage derived from two prehistoric immigrants, the subspecies M. m. musculus of northern Eurasia and M. m. castaneus of South Asia. Mice of the western European subspecies M. m. domesticus have been detected in Japanese ports and airports only. We examined haplotype structuring of a 200 kb stretch on chromosome 8 for 59 mice from throughout Eurasia, determining short segments (≈ 370–600 bp) of eight nuclear genes (Fanca, Spire2, Tcf25, Mc1r, Tubb3, Def8, Afg3l1 and Dbndd1) which are intermittently arranged in this order. Where possible we identified the subspecies origin for individual gene alleles and then designated haplotypes for concatenated alleles. We recovered 11 haplotypes among 19 Japanese mice examined, identified either as ‘intact’ haplotypes derived from the subspecies musculus (57.9%), domesticus (7.9%), and castaneus (2.6%), or as ‘recombinant’ haplotypes (31.6%). We also detected recombinant haplotypes unique to Sakhalin. The complex nature of the recombinant haplotypes suggests ancient introduction of all three subspecies components into the peripheral part of Eurasia or complicated genomic admixture before the movement from source areas. ‘Intact’domesticus and castaneus haplotypes in other Japanese wild mice imply ongoing stowaway introductions. The method has general utility for assessing the history of genetic admixture and for disclosing ongoing genetic contamination.     

Asian low‐androstenone haplotype on pig chromosome 6 does not unfavorably affect production and reproduction traits

European pigs that carry Asian haplotypes of a 1.94‐Mbp region on pig chromosome 6 have lower levels of androstenone, one of the two main compounds causing boar taint. The objective of our study was to examine potential pleiotropic effects of the Asian low‐androstenone haplotypes. A single nucleotide polymorphism marker, rs81308021, distinguishes the Asian from European haplotypes and was used to investigate possible associations of androstenone with production and reproduction traits. Eight traits were available from three European commercial breeds. For the two sow lines studied, a favorable effect on number of teats was detected for the low‐androstenone haplotype. In one of these sow lines, a favorable effect on number of spermatozoa per ejaculation was detected for the low‐androstenone haplotype. No unfavorable pleiotropic effects were found, which suggests that selection for low‐androstenone haplotypes within the 1.94 Mbp would not unfavorably affect the other eight relevant traits.