A test of the evolution of increased competitive ability in two invaded regions

Non-native plant species invasions can have significant ecological and economic impacts. Finding patterns that predict and explain the success of non-native species has thus been an important focus in invasion ecology. The evolution of increased competitive ability (EICA) hypothesis has been a frequently used framework to understand invasion success. Evolution of increased competitive ability predicts that (1) non-native populations will escape from coevolved specialist herbivores that were present within the native range and this release from specialist herbivores should result in relaxed selection pressure on specialist-related defense traits, (2) there will be a trade-off between allocation of resources for resistance against specialist herbivores and allocation to traits related to competitive ability, and (3) this shift will allow more allocation to competitive ability traits. We tested the predictions of EICA in the model plant Mimulus guttatus, a native of western North America (WNA). We compared how well the predictions of EICA fit patterns in two non-native regions, the United Kingdom (UK), an older more successful invasion, and eastern North America (ENA), a younger less successful invasion. We completed extensive herbivore surveys and grew plants derived from multiple populations in each region in a common greenhouse environment to test adherence to the predictions of EICA. We found evidence of specialist herbivore escape in the UK, but not the ENA plants. Compared to native plants the UK plants had lower levels of resistance traits, were taller, and produced larger and more flowers, while the ENA plants had mostly equivalent traits to the WNA plants. Plants from the UK conformed to the predictions of EICA more closely than those from ENA. The UK invasion is an older, more successful invasion, suggesting that support for EICA predictions may be highest in more successful invasions

Genome characterization of a Potato virus S (PVS) variant from tuber sprouts of Solanum phureja Juz. et Buk.

Potato virus S (PVS) is a prevalent virus in potato fields in Colombia and the rest of the world. PVS has been classified into two separate lineages, PVSO (Ordinary) and PVSA (Andean), which are genetically distinct. In this study, the complete genome sequence of a new PVS isolate (PVS_Antioquia) was obtained using High-throughput sequencing (Illumina HiSeq-2000) from tuber sprouts of Solanum phureja (var. Criolla Colombia). The PVS_Antioquia genome comprises 8,483 nt that code for six ORFs: RdRp (223 kDa), TGBp1-3 (25kDa, 12kDa, 7kDa) CP (32.3 kDa) and NABP (11 kDa) and share a high sequence identity with respect to the PVS_RVC (95%) from Colombia, in contrast to 81 to 82% identity with respect to the PVSA and PVSO isolates from around the world. This genome information was used to design RT-qPCR primers that are specific for the Colombian PVS strains (RVC and Antioquia) which were validated in S. phureja leaf and tuber samples. These primers detected PVS in 80 and 60% of a set of fifteen leaf and tuber samples, respectively, suggesting a high incidence of this virus in the potato crops of Antioquia

Strongly asymmetric hybridization barriers shape the origin of a new polyploid species and its hybrid ancestor

PREMISE OF THE STUDY:Hybridization between diploids and tetraploids can lead to new allopolyploid species, often via a triploid intermediate. Viable triploids are often produced asymmetrically, with greater success observed for “maternal-excess” crosses where the mother has a higher ploidy than the father. Here we investigated the evolutionary origins ofMimulus peregrinus, an allohexaploid recently derived from the triploidM. ×robertsii, to determine whether reproductive asymmetry has shaped the formation of this new species.  METHODS:We used reciprocal crosses between the diploid (M. guttatus) and tetraploid (M. luteus) progenitors to determine the viability of triploidM. ×robertsiihybrids resulting from paternal- vs. maternal-excess crosses. To investigate whether experimental results predict patterns seen in the field, we performed parentage analyses comparing natural populations ofM. peregrinusto its diploid, tetraploid, and triploid progenitors. Organellar sequences obtained from pre-existing genomic data, supplemented with additional genotyping was used to establish the maternal ancestry of multipleM. peregrinusandM. ×robertsiipopulations.  KEY RESULTS:We found strong evidence for asymmetric origins ofM. peregrinus, but opposite to the common pattern, with paternal-excess crosses significantly more successful than maternal-excess crosses. These results successfully predicted hybrid formation in nature: 111 of 114M. ×robertsiiindividuals, and 27 of 27M. peregrinus, had anM. guttatusmaternal haplotype.  CONCLUSION:This study, which includes the firstMimuluschloroplast genome assembly, demonstrates the utility of parentage analysis through genome skimming. We highlight the benefits of complementing genomic analyses with experimental approaches to understand asymmetry in allopolyploid speciation

Population structure and genetic diversity of native and invasive populations of Solanum rostratum (Solanaceae)

Aims: We investigate native and introduced populations of Solanum rostratum, an annual, self-compatible plant that has been introduced around the globe. This study is the first to compare the genetic diversity of Solanum rostratum between native and introduced populations. We aim to (1) determine the level of genetic diversity across the studied regions; (2) explore the likely origins of invasive populations in China; and (3) investigate whether there is the evidence of multiple introductions into China. Methods: We genotyped 329 individuals at 10 microsatellite loci to determine the levels of genetic diversity and to investigate population structure of native and introduced populations of S. rostratum. We studied five populations in each of three regions across two continents: Mexico, the U.S.A. and China. Important Findings: We found the highest genetic diversity among Mexican populations of S. rostratum. Genetic diversity was significantly lower in Chinese and U.S.A. populations, but we found no regional difference in inbreeding coefficients (FIS) or population differentiation (FST). Population structure analyses indicate that Chinese and U.S.A. populations are more closely related to each other than to sampled Mexican populations, revealing that introduced populations in China share an origin with the sampled U.S.A. populations. The distinctiveness between some introduced populations indicates multiple introductions of S. rostratum into China

Population genomic and historical analysis suggests a global invasion by bridgehead processes in Mimulus guttatus

© 2021, The Author(s). Imperfect historical records and complex demographic histories present challenges for reconstructing the history of biological invasions. Here, we combine historical records, extensive worldwide and genome-wide sampling, and demographic analyses to investigate the global invasion of Mimulus guttatus from North America to Europe and the Southwest Pacific. By sampling 521 plants from 158 native and introduced populations genotyped at >44,000 loci, we determined that invasive M. guttatus was first likely introduced to the British Isles from the Aleutian Islands (Alaska), followed by admixture from multiple parts of the native range. We hypothesise that populations in the British Isles then served as a bridgehead for vanguard invasions worldwide. Our results emphasise the highly admixed nature of introduced M. guttatus and demonstrate the potential of introduced populations to serve as sources of secondary admixture, producing novel hybrids. Unravelling the history of biological invasions provides a starting point to understand how invasive populations adapt to novel environments

Trait correlates and functional significance of heteranthery in flowering plants

Flowering plants display extraordinary diversity in the morphology of male sexual organs, yet the functional significance of this variation is not well understood. Here, we conducted a comparative analysis of floral correlates of heteranthery – the morphological and functional differentiation of anthers within flowers – among angiosperm families to identify traits associated with this condition. • We performed a phylogenetic analysis of correlated evolution between heteranthery and several floral traits commonly reported from heterantherous taxa. In addition, we quantified the effect of phylogenetic uncertainty in the observed patterns of correlated evolution by comparing trees in which polytomous branches were randomly resolved. • Heteranthery is reported from 12 angiosperm orders and is phylogenetically associated with the absence of floral nectaries, buzz-pollination and enantiostyly (mirror-image flowers). These associations are robust to particularities of the underlying phylogenetic hypothesis. • Heteranthery has probably evolved as a result of pollinator-mediated selection and appears to function to reduce the conflict of relying on pollen both as food to attract pollinators and as the agent of male gamete transfer. The relative scarcity of heteranthery among angiosperm families suggests that the conditions permitting its evolution are not easily met despite the abundance of pollen-collecting bees and nectarless flowers

On the Evolutionary Modification of Self-Incompatibility: Implications of Partial Clonality for Allelic Diversity and Genealogical Structure

Experimental investigations of homomorphic self-incompatibility (SI) have revealed an unanticipated level of complexity in its expression, permitting fine regulation over the course of a lifetime or a range of environmental conditions. Many flowering plants express some level of clonal reproduction, and phylogenetic analyses suggest that clonality evolves in a correlated fashion with SI in Solanum (Solanaceae). Here, we use a diffusion approximation to explore the effects on the evolutionary dynamics of SI of vegetative propagation with SI restricted to reproduction through seed. While clonality reduces the strength of frequency-dependent selection maintaining S-allele diversity, much of the great depth typical of S-allele genealogies is preserved. Our results suggest that clonality can play an important role in the evolution of SI systems, and may afford insight into unexplained features of allele genealogies in the Solanaceae

Validación de la versión en español de la escala de evaluación del trastorno por déficit de atención e hiperactividad (ADHD-RS-IV.es) en una muestra española

Objetivos El objetivo de este estudio es validar la versión en castellano del ADHD-RS-IV (ADHD-RS-IV.es) en una muestra española. Métodos A partir de una muestra total de 652 niños y adolescentes (rango edad: 6-17 años; media [DE] = 11,14 [3,27] años), se incluyó a 518 pacientes con TDAH (criterios DSM-IV-TR) y a 134 controles sanos. Para la evaluación de la estructura factorial, la validez y la fiabilidad de la escala se realizó un análisis factorial confirmatorio (CFA) mediante structural equation modeling en una matriz de correlaciones policóricas, y usando el método de máxima verosimilitud para la estimación. Se calcularon la validez discriminante y su valor predictivo mediante curvas receiver operating characteristics. Resultados La escala en castellano mostró una consistencia interna elevada, tanto para la escala total como para sus subescalas. El coeficiente alfa de Cronbach era 0,94 para la escala total y ≥ 0,90 para las subescalas. Los valores alfa ordinales eran 0,95 para la escala total y ≥ 0,90 para las subescalas. El análisis CFA mostró un modelo de 2 factores (inatención e hiperactividad/impulsividad) intercorrelacionados. La escala ofrece buen poder discriminante (AUC = 0,97). Conclusiones La versión española del ADHD-RS-IV (ADHD-RS-IV.es) mostró una estructura bifactorial consistente con los modelos del DSM-IV-TR y DSM-5, y con el modelo propuesto por el autor de la escala original. Además, posee un alto poder discriminante, lo que lo convierte en un instrumento válido y fiable para medir la presencia y severidad de síntomas de TDAH en la población española.Objectives The purpose of this study is to validate a Spanish-language version of the 18-item ADHD Rating Scale-IV (ADHD-RS-IV.es) in a Spanish sample. Methods From a total sample of 652 children and adolescents aged 6 to 17 years (mean age was 11.14 ± 3.27), we included 518 who met the DSM-IV-TR criteria for ADHD and 134 healthy controls. To evaluate the factorial structure, validity, and reliability of the scale, we performed a confirmatory factor analysis (CFA) using structural equation modelling on a polychoric correlation matrix and maximum likelihood estimation. The scale's discriminant validity and predictive value were estimated using ROC (receiver operating characteristics) curve analysis. Results Both the full scale and the subscales of the Spanish-language version of the ADHD-RS-IV showed good internal consistency. Cronbach's alpha was 0.94 for the full scale and ≥ 0.90 for the subscales, and ordinal alpha was 0.95 and ≥ 0.90, respectively. CFA showed that a two-factor model (inattention and hyperactivity/impulsivity) provided the best fit for the data. ADHD-RS-IV.es offered good discriminant ability to distinguish between patients with ADHD and controls (AUC = 0.97). Conclusions The two-factor structure of the Spanish-language version of the ADHD-RS-IV (ADHD-RS-IV.es) is consistent with those of the DSM-IV-TR and DSM-5 as well as with the model proposed by the author of the original scale. Furthermore, it has good discriminant ability. ADHD-RS-IV.es is therefore a valid and reliable tool for determining presence and severity of ADHD symptoms in the Spanish population