Rapid evolution of morphology and adaptive life history in the invasive California wild radish (Raphanus sativus) and the implications for management.

Understanding the evolution and demography of invasive populations may be key for successful management. In this study, we test whether or not populations of the non-native, hybrid-derived California wild radish have regionally adapted to divergent climates over their 150-year history in California and determine if population demographic dynamics might warrant different region-specific strategies for control. Using a reciprocal transplant approach, we found evidence for genetically based differences both between and among northern, coastal and southern, inland populations of wild radish. Individual fitness was analyzed using a relatively new statistical method called 'aster modeling' which integrates temporally sequential fitness measurements. In their respective home environments, fitness differences strongly favored southern populations and only slightly favored northern populations. Demographic rates of transition and sensitivities also differed between regions of origin, suggesting that the most effective approach for reducing overall population growth rate would be to target different life-history stages in each region

Maize Germplasm Conservation in Southern California's Urban Gardens: Introduced Diversity Beyond ex situ and in situ Management.

Contemporary germplasm conservation studies largely focus on ex situ and in situ management of diversity within centers of genetic diversity. Transnational migrants who transport and introduce landraces to new locations may catalyze a third type of conservation that combines both approaches. Resulting populations may support reduced diversity as a result of evolutionary forces such as genetic drift, selection, and gene flow, yet they may also be more diverse as a result of multiple introductions, selective breeding and cross pollination among multiple introduced varietals. In this study, we measured the amount and structure of maize molecular genetic diversity in samples collected from home gardens and community gardens maintained by immigrant farmers in Southern California. We used the same markers to measure the genetic diversity and structure of commercially available maize varieties and compared our data to previously reported genetic diversity statistics of Mesoamerican landraces. Our results reveal that transnational dispersal creates an opportunity for the maintenance of maize genetic diversity beyond its recognized centers of diversity

Toward an Evolved Concept of Landrace

[EN] The term "landrace" has generally been defined as a cultivated, genetically heterogeneous variety that has evolved in a certain ecogeographical area and is therefore adapted to the edaphic and climatic conditions and to its traditional management and uses. Despite being considered by many to be inalterable, landraces have been and are in a constant state of evolution as a result of natural and artificial selection. Many landraces have disappeared from cultivation but are preserved in gene banks. Using modern selection and breeding technology tools to shape these preserved landraces together with the ones that are still cultivated is a further step in their evolution in order to preserve their agricultural significance. Adapting historical landraces to present agricultural conditions using cutting-edge breeding technology represents a challenging opportunity to use them in a modern sustainable agriculture, as an immediate return on the investment is highly unlikely. Consequently, we propose a more inclusive definition of landraces, namely that they consist of cultivated varieties that have evolved and may continue evolving, using conventional or modern breeding techniques, in traditional or new agricultural environments within a defined ecogeographical area and under the influence of the local human culture. This includes adaptation of landraces to new management systems and the unconscious or conscious selection made by farmers or breeders using available technology. In this respect, a mixed selection system might be established in which farmers and other social agents develop evolved landraces from the variability generated by public entities.This work has been partially funded by the European Union's Horizon 2020 research and innovation program under grant agreements no. 634651 (TRADITOM) and no. 677379 (G2PSOL).Casañas Artigas, F.; Simo, J.; Casals, J.; Prohens Tomás, J. (2017). Toward an Evolved Concept of Landrace. Frontiers in Plant Science. 8. https://doi.org/10.3389/fpls.2017.00145S1458Almirall, A., Bosch, L., Romero del Castillo, R., Rivera, A., & Casañas, F. (2010). ‘Croscat’ Common Bean (Phaseolus vulgaris L.), a Prototypical Cultivar within the ‘Tavella Brisa’ Type. HortScience, 45(3), 432-433. doi:10.21273/hortsci.45.3.432Bitocchi, E., Bellucci, E., Rau, D., Albertini, E., Rodriguez, M., Veronesi, F., … Nanni, L. (2015). European Flint Landraces Grown In Situ Reveal Adaptive Introgression from Modern Maize. PLOS ONE, 10(4), e0121381. doi:10.1371/journal.pone.0121381BITOCCHI, E., NANNI, L., ROSSI, M., RAU, D., BELLUCCI, E., GIARDINI, A., … PAPA, R. (2009). Introgression from modern hybrid varieties into landrace populations of maize (Zea maysssp.maysL.) in central Italy. Molecular Ecology, 18(4), 603-621. doi:10.1111/j.1365-294x.2008.04064.xBosch, L., Casañas, F., Sánchez, E., Pujolà, M., & Nuez, F. (1998). Selection L67, a Pure Line with True Seed Type of the Ganxet Common Bean (Phaseolus vulgaris L.). HortScience, 33(5), 905-906. doi:10.21273/hortsci.33.5.905Casals, J., Bosch, L., Casañas, F., Cebolla, J., & Nuez, F. (2010). Montgrí, a Cultivar within the Montserrat Tomato Type. HortScience, 45(12), 1885-1886. doi:10.21273/hortsci.45.12.1885Causse, M., Desplat, N., Pascual, L., Le Paslier, M.-C., Sauvage, C., Bauchet, G., … Bouchet, J.-P. (2013). Whole genome resequencing in tomato reveals variation associated with introgression and breeding events. BMC Genomics, 14(1), 791. doi:10.1186/1471-2164-14-791Ellstrand, N. C. (2014). Is gene flow the most important evolutionary force in plants? American Journal of Botany, 101(5), 737-753. doi:10.3732/ajb.1400024Ellstrand, N. C., Meirmans, P., Rong, J., Bartsch, D., Ghosh, A., de Jong, T. J., … Hooftman, D. (2013). Introgression of Crop Alleles into Wild or Weedy Populations. Annual Review of Ecology, Evolution, and Systematics, 44(1), 325-345. doi:10.1146/annurev-ecolsys-110512-135840Ellstrand, N. C., Prentice, H. C., & Hancock, J. F. (1999). Gene Flow and Introgression from Domesticated Plants into Their Wild Relatives. Annual Review of Ecology and Systematics, 30(1), 539-563. doi:10.1146/annurev.ecolsys.30.1.539Ferreira, J. J., Campa, A., Pérez-Vega, E., Rodríguez-Suárez, C., & Giraldez, R. (2011). Introgression and pyramiding into common bean market class fabada of genes conferring resistance to anthracnose and potyvirus. Theoretical and Applied Genetics, 124(4), 777-788. doi:10.1007/s00122-011-1746-xGarcía-Martínez, S., Grau, A., Alonso, A., Rubio, F., Valero, M., & Ruiz, J. J. (2011). UMH 1200, a Breeding Line within the Muchamiel Tomato Type Resistant to Three Viruses. HortScience, 46(7), 1054-1055. doi:10.21273/hortsci.46.7.1054Gompert, Z., & Buerkle, C. A. (2016). What, if anything, are hybrids: enduring truths and challenges associated with population structure and gene flow. Evolutionary Applications, 9(7), 909-923. doi:10.1111/eva.12380Harlan, J. R. (1965). The possible role of weed races in the evolution of cultivated plants. Euphytica, 14(2), 173-176. doi:10.1007/bf00038984Jarvis, D. I., & Hodgkin, T. (1999). Wild relatives and crop cultivars: detecting natural introgression and farmer selection of new genetic combinations in agroecosystems. Molecular Ecology, 8(s1), S159-S173. doi:10.1046/j.1365-294x.1999.00799.xMesseguer, J. (2003). Plant Cell, Tissue and Organ Culture, 73(3), 201-212. doi:10.1023/a:1023007606621Nogué, F., Mara, K., Collonnier, C., & Casacuberta, J. M. (2016). Genome engineering and plant breeding: impact on trait discovery and development. Plant Cell Reports, 35(7), 1475-1486. doi:10.1007/s00299-016-1993-zProhens, J., Muñoz-Falcón, J. E., Rodríguez-Burruezo, A., Ribas, F., Castro, Á., & Nuez, F. (2009). ‘H15’, an Almagro-type Pickling Eggplant with High Yield and Reduced Prickliness. HortScience, 44(7), 2017-2019. doi:10.21273/hortsci.44.7.2017Simó, J., del Castillo, R. R., Almirall, A., & Casañas, F. (2012). ‘Roquerola’ and ‘Montferri’, First Improved Onion (Allium cepa L.) Cultivars for «Calçots» Production. HortScience, 47(6), 801-802. doi:10.21273/hortsci.47.6.801Villa, T. C. C., Maxted, N., Scholten, M., & Ford-Lloyd, B. (2005). Defining and identifying crop landraces. Plant Genetic Resources, 3(3), 373-384. doi:10.1079/pgr200591Zeven, A. C. (1998). Euphytica, 104(2), 127-139. doi:10.1023/a:101868311923

Algae for biofuel:will the evolution of weeds limit the enterprise?

Algae hold promise as a source of biofuel. Yet the manner in which algae are most efficiently propagated and harvested is different from that used in traditional agriculture. In theory, algae can be grown in continuous culture and harvested frequently to maintain high yields with a short turnaround time. However, the maintenance of the population in a state of continuous growth will likely impose selection for fast growth, possibly opposing the maintenance of lipid stores desiriable for fuel. Any harvesting that removes a subset of the population and leaves the survivors to establish the next generation may quickly select traits that escape harvesting. An understanding of these problems should help identify methods for retarding the evolution and enhancing biofuel production

Crops gone wild: evolution of weeds and invasives from domesticated ancestors.

The evolution of problematic plants, both weeds and invasives, is a topic of increasing interest. Plants that have evolved from domesticated ancestors have certain advantages for study. Because of their economic importance, domesticated plants are generally well-characterized and readily available for ecogenetic comparison with their wild descendants. Thus, the evolutionary history of crop descendants has the potential to be reconstructed in some detail. Furthermore, growing crop progenitors with their problematic descendants in a common environment allows for the identification of significant evolutionary differences that correlate with weediness or invasiveness. We sought well-established examples of invasives and weeds for which genetic and/or ethnobotanical evidence has confirmed their evolution from domesticates. We found surprisingly few cases, only 13. We examine our list for generalizations and then some selected cases to reveal how plant pests have evolved from domesticates. Despite their potential utility, crop descendants remain underexploited for evolutionary study. Promising evolutionary research opportunities for these systems are abundant and worthy of pursuit

Spontaneous Hybridization between Maize and Teosinte

The closest wild relatives of maize, Zea mays ssp. mays are various Zea taxa known as "teosinte.” Hybrids between maize and the teosinte taxon, Zea mays ssp. mexicana, often occur when the 2 are sympatric in Mexico. Measuring the spontaneous hybridization rate of the 2 taxa would shed light on the mechanisms contributing to the evolution and persistence of these hybrid swarms. We conducted a series of field experiments in Riverside, CA, to measure the natural hybridization rates between maize and 2 teosinte taxa, Z. m. ssp. mexicana and Zea mays ssp. parviglumis. We planted teosinte within and near maize plantations. Hybrids were identified by progeny testing for a maize-specific herbicide resistance allele and a teosinte-specific allozyme allele. Hybridity was confirmed by growing putative hybrid progeny to maturity to evaluate whether they had the characteristic morphology of maize × teosinte hybrids. We found that maize and Z. m. ssp. mexicana naturally hybridize at a low rate (<1%), whereas Z. m. ssp. parviglumis hybridizes with the crop at a high rate (≫50%

Maize x Teosinte Hybrid Cobs Do Not Prevent Crop Gene Introgression

Maize x Teosinte Hybrid Cobs Do Not Prevent Crop Gene Introgression. Whether introgression from crops to wild relatives can occur is an important component of transgene risk assessment. In the case of maize, which co-occurs with its wild relative teosinte in Mexico, the possibility of introgression has been controversial. Maize is cross-compatible with teosinte, and spontaneous hybridization is known to occur. Some scientists have hypothesized that the maize x teosinte cob infructescence will prevent progeny dispersal, thus preventing introgression. Motivated by a prior study where we found maize x teosinte hybrid fruits naturally dispersed under field conditions, we tested whether hybrid cobs hold their fruits as tightly as maize cobs. We found the force required to detach hybrid fruits was substantially and significantly less than that for maize. Consequently, we expect that introgression of transgenes from maize into teosinte in Mexico should occur largely unimpeded by the hybrid cob.La mazorca o elote híbrido de maíz x teocintle no impide la introgresión de genes transgénicos provenientes del cultivo. La introgresión entre el maíz cultivado y el maíz silvestre, o teocintle, es un componente importante en la evaluación ambiental relacionada con los riesgos de la introducción de genes transgénicos. La posibilidad de introgresión entre el maíz domesticado y el teocintle ha sido un tema controversial, en particular en México, donde maíz y teocintle coexisten. El maíz es compatible con el teocintle y la hibridización espontánea ocurre entre ellos. Algunos científicos han planteado como hipótesis que al cruzar el maíz con teocintle, la estructura interna de la infrutescencia que sujeta los frutos conocida como la mazorca de maíz o el elote, impide la dispersión de la progenie evitando que la introgresión ocurra. Los resultados de un estudio previo evidencian la dispersión de los frutos híbridos del maíz x teocintle en condiciones naturales. Motivados por estos resultados, hemos decidido investigar si la mazorca o el elote de las infrutescencias del híbrido sujetan los frutos con una fuerza comparable o mayor a la del maíz. Nuestras mediciones implican que la fuerza necesaria para liberar los frutos híbridos son substancial y significativamente menores que aquellas necesarias para desprender los frutos del maíz. Como conclusión sugerimos que en México, la mazorca o el elote no representan una barrera que impida la introgresión de los genes transgénicos del maíz al teocintle

Cirsium species show disparity in patterns of genetic variation at their range-edge, despite similar patterns of reproduction and isolation

Genetic variation was assessed across the UK geographical range of Cirsium acaule and Cirsium heterophyllum. A decline in genetic diversity and increase in population divergence approaching the range edge of these species was predicted based on parallel declines in population density and seed production reported seperately. Patterns were compared with UK populations of the widespread Cirsium arvense.Populations were sampled along a latitudinal transect in the UK and genetic variation assessed using microsatellite markers. Cirsium acaule shows strong isolation by distance, a significant decline in diversity and an increase in divergence among range-edge populations. Geographical structure is also evident in C. arvense, whereas no such patterns are seen in C.heterophyllum. There is a major disparity between patterns of genetic variation in C. acaule and C. heterophyllum despite very similar patterns in seed production and population isolation in these species. This suggests it may be misleading to make assumptions about the geographical structure of genetic variation within species based solely on the present-day reproduction and distribution of populations

Big baby, little mother:tsetse flies are exceptions to the juvenile small size principle

While across the animal kingdom offspring are born smaller than their parents, notable exceptions exist. Several dipteran species belonging to the Hippoboscoidea superfamily can produce offspring larger than themselves. In this essay, the blood‐feeding tsetse is focused on. It is suggested that the extreme reproductive strategy of this fly is enabled by feeding solely on highly nutritious blood, and producing larval offspring that are soft and malleable. This immense reproductive expenditure may have evolved to avoid competition with other biting flies. Tsetse also transmit blood‐borne parasites that cause the fatal diseases called African trypanosomiases. It is discussed how tsetse life history and reproductive strategy profoundly influence the type of vector control interventions used to reduce fly populations. In closing, it is argued that the unusual life history of tsetse warrants their preservation in the areas where human and animal health is not threatened