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An invasive thrips species (Klambothrips myopori, Thysanoptera), originally from Australia, attacks and inflicts severe damage to endemic Myoporum species in Hawai‘i. There is concern that the thrips will cause local extinctions of Myoporum in Hawai‘i. This study examined susceptibility of different Myoporum populations from various Hawaiian Islands to K. myopori infestation and dieback of aerial plant parts. Experimental exposures of plants from different populations were conducted in common garden studies. All M. sandwicense populations included in the study were highly susceptible to infestation and severe dieback of leaves and shoots occurred. Plants from a single M. stellatum population were less susceptible to attack and subsequent dieback of stems. Management options for populations under pressure from K. myopori are discussed.

The genus Echinochloa constitutes some of the most prominent weed species found in rice (Oryza sativa L.) production worldwide. The taxonomy of Echinochloa is complex due to its morphological variations. The morphophysiological diversity and taxonomic characteristics of Echinochloa ecotypes infesting rice fields in Texas are unknown. A total of 54 Echinochloa ecotypes collected during late-season field surveys in 2015 and 2016 were characterized in a common garden in 2017. Plants were characterized for 14 morphophysiological traits, including stem angle; stem color; plant height; leaf color; leaf texture; flag leaf length, width, and angle; days to flowering; panicle length; plant biomass; seed shattering; seed yield; and seed dormancy. Principal component analysis indicated that 4 (plant height, flag leaf length, seed shattering, and seed germination) of the 14 phenological traits characterized here had significantly contributed to the overall morphological diversity of Echinochloa spp. Results showed wide interpopulation diversity for the measured traits among the E. colona ecotypes, as well as diverse intrapopulation variability in all three Echinochloa species studied, including barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], junglerice [Echinochloa colona (L.) Link], and rough barnyardgrass [Echinochloa muricata (P. Beauv.) Fernald]. Taxonomical classification revealed that the collection consisted of three Echinochloa species, with E. colona being the most dominant (96%), followed by E. crus-galli (2%), and E. muricata (2%). Correlation analysis of morphophysiological traits and resistance status to commonly used preemergence (clomazone, quinclorac) and postemergence herbicides (propanil, quinclorac, imazethapyr, and fenoxaprop-ethyl) failed to show any significant association. Findings from this study provided novel insights into the morphophysiological characteristics of Echinochloa ecotypes in rice production in Texas. The morphological diversity currently present in Echinochloa ecotypes could contribute to their adaptation to selection pressure imposed by different management tools, emphasizing the need for a diversified management approach to effectively control this weed species.

Seeds of Purshia tridentata, a shrub of semi-arid North America, require chilling to become non-dormant. Using seeds produced from controlled crosses in a common garden, we examined effects of ovule parent, pollen parent, and year of production on germination percentage in response to chilling for 2 weeks at 2°C. Differences among ovule parents accounted for most of the variance in chilling response, and these differences (2 to 83% germination) were consistent across years. Differences among pollen parents were also significant, producing a two- to five-fold difference in mean germination percentage. Differences among years were significant but small. Ovule parent by year interactions showed that among-year variation in ripening environment did not affect ovule parents equally. There was no significant pollen parent by year interaction, suggesting that the effect of maturation environment was mediated through maternal tissues. In reciprocal crosses, two plants that showed contrasting dormancy levels as ovule parents produced seeds with similar dormancy as pollen parents, indicating that the genetic difference between them was at the testa level. Two plants that produced seeds with contrasting dormancy as pollen parents showed a similar but stronger pattern of contrast as ovule parents, showing that the genetic difference between them was at both embryo and endosperm or testa level. Testa or endosperm genotype was primarily responsible for chilling response of intact seeds, while embryo genotype affected chilling response and also exercised primary control over low temperature germination rate, whether of excised embryos or of intact seeds.

Dioscorea bulbifera is a serious invader of various ecosystems in Florida, where plants generated by its two morphotypes climb aggressively and smother supporting vegetation. There is a dearth of published research on its invasive biological attributes including vine growth and biomass production by plants generated from bulbils. Herein, we assessed these parameters in common garden studies by planting bulbils from four biomass categories (PBBCs I–IV) of both morphotypes. Vine lengths, longevity-based growth rates (VLGR), biomass, and quantities of leaves and daughter bulbils in both morphotypes showed positive correlation with the biomass of planted parental bulbils. This indicated similarity between corresponding attributes in two morphotypes. Total vine length showed strong positive correlation with VLGR, biomass, and quantities of leaves and bulbils. Overall vine longevity among plants from PBBCs I–IV did not significantly differ whereas the total vine lengths, VLGRs, number of branches, and quantities of leaves and bulbils increased with the biomass of the parental bulbils. Plants recruited by smaller bulbils allocated more biomass to leaves and tubers compared to stems and bulbils, whereas the plants recruited by larger bulbils allocated more biomass to leaves and bulbils compared to tubers and stems. Higher proportion of biomass allocation to leaves and bulbils presumably ensures immediate faster growth, longer vines, and a greater number of daughter bulbils for future recruitment of new plants. Vine length (associated with faster growth rate, capable of blanketing supporting structures and producing large quantities of bulbils) has been noted as the primary invasive biological attribute that facilitates D. bulbifera's status as a noxious exotic weed in Florida. Control measure that can reduce vine length should reduce or eliminate the invasive behavior of D. bulbifera in Florida. Nomenclature: Air-potato, Dioscorea bulbifera L. Management Implications: The exotic invasive air potato vine D. bulbifera has become a serious problem for public and private land managers across Florida and beyond by blanketing and smothering native vegetation. Despite its common occurrence in Florida, there are no published research data related to the role of propagule biomass on the resulting vines' growth rate, biomass, and invasive biological traits. We conducted common garden studies using vegetative propagules (parent bulbils) ranging from small to large biomass and examined the growth and biomass of the plants generated from these bulbils. Biomass of the parent bulbils of both morphotypes was positively correlated with total vine lengths, growth rates, and the number of branches, leaves, and bulbils. The vine longevity of plants generated by bulbils of all sizes was not significantly different. However, the total vine length, vine growth rates, and the number of branches, leaves, and bulbils increased with the biomass of the parent bulbils. Plants recruited by smaller bulbils allocated a major proportion of total biomass to leaves and tubers compared to the stems and bulbils, whereas the larger bulbils allocated a greater proportion of total biomass to bulbils and leaves compared to tubers and stems. Total vine length was positively correlated with the total plant biomass. Reduced vine length should have concomitant negative impacts on leaf and bulbil production. These reductions should, in turn, negatively affect (1) plant biomass and the number of branches and leaves that are responsible for causing smothering effects on invaded plant communities and (2) bulbil production that will have direct negative impact on plant recruitment and invasion of the new areas. Therefore, control measures that reduce seasonal vine length should reduce the quantity of bulbils and hence invasiveness of D. bulbifera vines in Florida.

Climate change threatens native plant populations and plant communities globally. It is critical that land managers have a clear understanding of climate change impacts on plant species and populations so that restoration efforts can be adjusted accordingly. This paper reviews the development and use of seed transfer guidelines for restoration in the face of global climate change, with an emphasis on the role of common garden studies in predicting climate change impacts. A method is presented for using genecological common garden data to assess population vulnerability to changing environmental conditions that includes delineation of geographical regions where habitats are likely to become marginal, assessment of shifting climatic selection pressures on plant traits, and identification of source material that is likely to be adapted to changing conditions. This method is illustrated using a genecological dataset for bluebunch wheatgrass (Pseudoroegneria spicata). The demonstration indicates that bluebunch populations will be vulnerable to extirpation in areas of their current range, that selection pressures will increase on a trait important to climatic adaptation, and that promising seed sources exist that may be able to persist under novel conditions. Additional avenues for expansion of the presented methods are discussed, and the use of common garden data for management in the context of evolution and changing climates is considered.

We studied the relationships between population size, reproduction and population growth rate in 23 populations of the rare, short-lived plant Gentianella germanica. We also investigated a possible correlation of population size effects with environmental variation in climate, topography, soil, vegetation, and management. To ascertain whether the differences between populations have a genetic basis, we grew 20 seed families from each of the populations in a common garden experiment. In 1993, population sizes ranged from 40 to 5000 flowering plants in the field populations (geometric mean 386). Plants in small populations had fewer seeds per fruit and fewer seeds per plant than plants in larger populations, whereas seed mass was independent of population size. From 1993 to 1995 population size decreased in most populations (mean annual population growth rate 0.876), and this decrease was larger in small populations than in large populations. In the common garden the positive correlation between the number of surviving plants per planted seed and original population size increased steadily over time. After 17 months there were significantly more flowering plants and more flowers per planted seed for seeds from large populations than for those from small populations. Although environmental variables accounted for significant variation in population growth rate and plant performance both in the field and in the common garden, effects of population size detected in stepwise multiple regressions were not confounded with environmental effects. We conclude that the reduced performance observed in plants from smaller populations was explained by genetic effects rather than by habitat quality, although pollinator limitation may have contributed to fitness reductions in the field. The observed patterns suggest further reductions of population sizes in Gentianella germanica in the future, especially in already small populations. Our study lends support to the view that genetic problems are a major concern in plant conservation.

In vitro culture techniques can be used to study the unique growth habits of plants as well as the ecological factors that influence seedling growth and development (i.e., in vitro ecology) such as adaptation to local environmental conditions. The in vitro seedling ecology of Calopogon tuberosus var. tuberosus from Michigan, South Carolina, and Florida was studied with emphasis on timing of corm formation and biomass allocation. In vitro seedling growth and development were monitored for 20 weeks. Corm formation was most rapid in Michigan seedlings, but was progressively delayed in southern populations. Similarly, biomass allocation to corms was highest in Michigan seedlings while south Florida seedlings exhibited the lowest corm biomass allocation. Shoot senescence in vitro also began earlier in more northern populations. The rapid corm formation and biomass allocation in seedlings from more northern populations represents an adaptive response to a shorter growing season. The relative differences in corm formation, biomass allocation, and shoot senescence in C. tuberosus seedlings suggest that in vitro common garden studies are useful to assess the degree of ecotypic differentiation among populations for a wide range of ecological factors. Additionally, these in vitro techniques can be transferred to numerous species worldwide.

In vitro culture techniques can be used to study the unique growth habits of plants as well as the ecological factors that influence seedling growth and development (i.e., in vitro ecology) such as adaptation to local environmental conditions. The in vitro seedling ecology of Calopogon tuberosus var. tuberosus from Michigan, South Carolina, and Florida was studied with emphasis on timing of corm formation and biomass allocation. In vitro seedling growth and development were monitored for 20 weeks. Corm formation was most rapid in Michigan seedlings, but was progressively delayed in southern populations. Similarly, biomass allocation to corms was highest in Michigan seedlings while south Florida seedlings exhibited the lowest corm biomass allocation. Shoot senescence in vitro also began earlier in more northern populations. The rapid corm formation and biomass allocation in seedlings from more northern populations represents an adaptive response to a shorter growing season. The relative differences in corm formation, biomass allocation, and shoot senescence in C. tuberosus seedlings suggest that in vitro common garden studies are useful to assess the degree of ecotypic differentiation among populations for a wide range of ecological factors. Additionally, these in vitro techniques can be transferred to numerous species worldwide.

Results of a recent common-garden study provide evidence needed to delineate appropriate seed transfer zones for the native grass Festuca roemeri (Pavlick) E. B. Alexeev (Poaceae). That information has been used to develop pre-variety germplasm releases to provide ecologically and genetically appropriate seeds for habitat restoration, erosion control, and other revegetation projects in 5 regions of the Pacific Northwest, US. Seed sources for these composite populations were chosen to represent a broad base of genetic diversity found within each region, while using plants that overlap in flowering time, have average to high seed yield, and originate at similar elevations. The process of selecting appropriate seed sources and developing the germplasm releases is described here. Ongoing and future investigations are likely to include seed production technology, establishment methods, stand management, and adaptation to diverse sites and specific uses.

1. Local adaptation and phenotypic plasticity are two important characteristics of alpine plants to overcome the threats caused by global changes. Among alpine species, Arabis alpina is characterised by an unusually wide altitudinal amplitude, ranging from 800 to 3,100 m of elevation in the French Alps. Two non-exclusive hypotheses can explain the presence of A. alpina across this broad ecological gradient: adaptive phenotypic plasticity or local adaptation, making this species especially useful to better understand these phenomena in alpine plant species. 2. We carried out common garden experiments at two different elevations with maternal progenies from six sites that differed in altitude. We showed that (1) key phenotypic traits (morphotype, total fruit length, growth, height) display significant signs of local adaptation, (2) most traits studied are characterised by a high phenotypic plasticity between the two experimental gardens and (3) the two populations from the highest elevations lacked morphological plasticity compared to the other populations. 3. By combining two genome scan approaches (detection of selection and association methods), we isolated a candidate gene (Sucrose-Phosphate Synthase 1). This gene was associated with height and local average temperature in our studied populations, consistent with previous studies on this gene in Arabidopsis thaliana. 4. Synthesis. Given the nature of the traits involved in the detected pattern of local adaptation and the relative lack of plasticity of the two most extreme populations, our findings are consistent with a scenario of a locally adaptive stress response syndrome in high elevation populations. Due to a reduced phenotypic plasticity, an overall low intra-population genetic diversity of the adaptive traits and weak gene flow, populations of high altitude might have difficulties to cope with, e.g. a rise of temperature.