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2018-2019 UNCG University Libraries Open Access Publishing Fund Grant Winner.A long-standing debate in evolutionary biology concerns the relative importance of different evolutionary forces in explaining phenotypic diversification at large geographic scales. For example, natural selection is typically assumed to underlie divergence along environmental gradients. However, neutral evolutionary processes can produce similar patterns. We collected molecular genetic data from 14 European populations of Plantago lanceolata to test the contributions of natural selection versus neutral evolution to population divergence in temperature-sensitive phenotypic plasticity of floral reflectance. In P. lanceolata, reflectance plasticity is positively correlated with latitude/altitude. We used population pairwise comparisons between neutral genetic differentiation (FST and Jost's D) and phenotypic differentiation (PST) to assess the contributions of geographic distance and environmental parameters of the reproductive season in driving population divergence. Data are consistent with selection having shaped large-scale geographic patterns in thermal plasticity. The aggregate pattern of PST versus FST was consistent with divergent selection. FST explained thermal plasticity differences only when geographic distance was not included in the model. Differences in the extent of cool reproductive season temperatures, and not overall temperature variation, explained plasticity differences independent of distance. Results are consistent with the hypothesis that thermal plasticity is adaptive where growing seasons are shorter and cooler, that is, at high latitude/altitude.

• Premise of the study: Understanding how plant reproduction responds to temperature has become increasingly important because of global climate change. Temperature-sensitive plasticity in floral reflectance is likely involved in some of these responses. Such plasticity, which underlies thermoregulatory ability, affects reproductive success in Plantago lanceolata. To see whether other Plantago species also show thermal plasticity in reflectance, we measured plasticity in P. lagopus, P. coronopus, P. major, P. subulata, P. albicans, P. tomentosa, P. maritima, and P. weldenii.• Methods: We induced plants to flower at two temperatures in growth chambers and recorded floral reflectance (362–800 nm).• Key results: All species were thermally plastic in visible and near-IR regions. Species and populations differed in response. Some showed greater variation in reflectance at warm temperature, while the reverse was true for others. Plasticity was greatest in the P. lanceolata clade. Cosmopolitan species were not more plastic than were geographically restricted species.• Conclusions: The data suggest that (1) thermal plasticity is an ancestral trait for Plantago, (2) plasticities in visible and near-IR regions have evolved along different pathways within the genus, and (3) phylogenetic history partially explains this evolutionary divergence. Our data combined with those of previous studies suggest that global climate change will modify floral reflectance and color in many plant species. These modifications are likely to affect plant reproductive success.

To learn more about the basic biology of exotic relative to native tree species we conducted a greenhouse experiment comparing the germination and early seedling growth of four early successional tree species found in the southeastern United States: two exotics (Ailanthus altissima and Paulownia tomentosa) and two natives (Liquidambar styradflua and Platanus occidentalis). Five soil types and three water regimes were used for the experiment. Liquidambar and Platanus, the native species, germinated significantly more quickly and were more sensitive to soil type than were the exotics, Ailanthus and Pauloumia. Platanus grew tallest, and along with Paulownia, accumulated the greatest total biomass. Ailanthus alone exhibited a high root/shoot ratio in all soil types. In addition, species differed in their response to soil types for multiple growth traits. The results suggest that native tree species could be used to help retard the establishment of invasive tree species on bare soil.

In many plant species, the alternative respiratory pathway consisting of alternative oxidase (AOX) is affected by growth temperature. The adaptive significance of this temperature-sensitivity is unresolved. Here, leaf and spike (flower cluster) AOX protein content and spike/floral reflectance of genotypes from European Plantago lanceolata populations found in regions differing in reproductive season temperatures were measured. Cloned genotypes grown at controlled warm and cool temperatures were used to assess the natural within- and between- population variation in AOX content, temperature-sensitive phenotypic plasticity in content, and the relationship between AOX and temperature-sensitive floral/spike reflectance. AOX content and plasticity were genetically variable. Leaf AOX content, although greater at cool temperature, was relatively low and not statistically different across populations. Spike AOX content was greater than in leaves. Spike AOX plasticity differed significantly among populations and climate-types and showed significant negative correlation with floral reflectance plasticity, which also varied among populations. Genotypes with more AOX at cool than at warm temperature had greater floral reflectance plasticity; genotypes with relatively more AOX at warm temperature had less floral reflectance plasticity. The data support the hypothesis that plasticity of AOX content in reproductive tissues is associated with long-term thermal acclimatization.

Knowledge about the factors restricting reproduction in many rare wetland plant species is limited. One such species is Lobelia boykinii. We conducted a study of L. boykinii to determine which factors most influence its reproductive success. We examined the species' breeding system, population dynamics, degree of pollen limitation, importance of sexual versus asexual reproduction, and the role of fungal and herbivore damage on fruit production in three Carolina bay populations in North Carolina. Pollen manipulations revealed that L. boykinii is an obligate outcrosser and that sexual reproduction is pollen-limited. Population size and density, which influence pollinator attraction, can fluctuate greatly over years in the same population. The three populations differed with respects to population size and density, capsule production, vegetative reproduction, and ramet survival, and differences are partially attributable to variation in the degree and timing of herbivory and fungal damage. Herbivory ranged from < 1% to 55% of flowering shoots. Fungal infection decreased fruit production only when it coincided with the period of floral development. Our results indicate that focusing on one ecological factor to prevent extant populations from going extinct is insufficient. Multiple intrinsic and extrinsic factors influence L. boykinii's reproductive success, and populations differ in which factors most strongly influence reproduction. Given this suite of constraints, management strategies should include maintaining as many of the largest remnant populations as possible.

Flower color in the weedy perennial Plantago lanceolata is phenotypically plastic. Darker flowers are produced at cooler ambient temperatures, and circumstantial evidence suggests that this is adaptive. The goal of this project was to investigate the chemical basis for the color plasticity. To test the hypothesis that increased anthocyanin production at low temperatures underlies the plasticity, extracts of P. lanceolata flowers produced at warm and cool temperatures were analyzed using UV/visible spectrophotometry coupled with mass spectrometry. Mass spectrometry allowed us to compare relative abundances of individual anthocyanins. Seventeen anthocyanins, derived from both cyanidin and delphinidin branches of the anthocyanin biosynthetic pathway, were detected. Most of these significantly increased in abundance under cool conditions. Genotypes differed significantly in anthocyanin levels and in their sensitivity to temperature change. Genotypes that showed greater floral color plasticity tended to show also greater temperature sensitivity with respect to anthocyanin production. Data suggest that the temperature regulation of the anthocyanin biosynthetic pathway occurs both upstream and downstream of the divergence of the cyanidin and delphinidin branches. The degree of temperature sensitivity, i.e. phenotypic plasticity, appears to be controlled downstream, whereas the overall temperature effect appears to be controlled upstream.

We explore the relationships among phenotypic plasticity, parental effects, and parental care in plants by presenting data from four experiments examining reflectance/color patterns in Plantago lanceolata. In three experiments, we measured spike (inflorescence) reflectance between 362 and 850 nm using a spectrophotometerw ith an integratings phere. Experimentss how that (1) spike reflectance changes seasonally within and outside the visible portion of the spectrum of radiant energy, (2) increasing ambient temperature causes an individual plant to produce flowering and fruiting spikes that reflect more/lighten in color (the greatest changes occur in the regions around 550 nm and between 750 and 850 nm, the visible and near-infrared regions, respectively), (3) responses are reversible, (4) genotypes within populations and populations from different latitudes differ in mean reflectance and degree of phenotypic plasticity. In a fourth experiment, we measured internal spike temperature. Darker spikes, those produced at lower temperature, got hotter than did lighter spikes in full sun. Thus, plants can partially thermoregulater eproductiona nd the embryonic development of their offspring. In light of a previous experiment, data suggest that thermoregulationp roduces adaptive parentale ffects and is a mechanism by which P. lanceolata provides parental care.

Biologists working in fields as diverse as mammalian behavior, plant ecology, microbial genetics, quantitative genetics, and insect ecology have shown that environmentally induced parental effects can be found in most kingdoms of living organisms. Such effects are diverse, have multiple causes, and can be transmitted via multiple pathways. Historically, and understandably, these effects have been studied by biologists who have focused on a particular group of organisms, such as insects or plants, or who have approached the phenomenon from a particular point of view, such as quantitative genetics, ecology, or behavior. The consequence has been the development of multiple terminologies that are not used consistently across disciplines or kingdoms. I believe these inconsistencies hinder the communication among biologists studying these effects, the development of generalized models of parental effects, and the empirical testing of adaptedness of these effects.