Investigating the evolutionary consequences of sexual conflict through pollen and pistil traits in several Collinsia heterophylla (Plantaginaceae) populations

Abstract Sexual selection is considered to be one of the most important processes influencing the evolution and diversification of species. Sexual conflict, a subset of sexual selection theory, describes how opposing interests in the male and female reproductive systems can lead to one sex increasing its fitness at a cost to the other sex. Traits involved in this conflict may come under selection and evolve, leading to antagonistic coevolution that can increase diversification in separate populations. These forces, traditionally pertaining to animals, have only recently been considered in plants. This study investigates the potential for sexual conflict in Collinsia heterophylla, a mixed mating species (utilizing both selfing and outcrossing strategies) with two main pollen and pistil traits thought to be engaged in antagonistic coevolution during pollen competition: 1) the ability of stigmas to delay stigma receptivity in the presence of pollen, and 2) the ability of pollen to force early fertilization in immature stigmas. To explore possible evolutionary outcomes of this conflict, I performed crossing experiments in the greenhouse (within eight natural populations from four regions of California that presumably differ in mating system), as well as measured various floral traits relating to mating system and pollen competition. In the field, the potential for early pollinator visitation was investigated in order to evaluate if the conflict is likely to occur under natural conditions. In the greenhouse, I found that there was a maternal cost of early fertilization in all eight populations, indicating that the cost to the recipient individual is widespread. Across all populations, the timing of stigma receptivity was only influenced by the identity of the recipient, denoting that the female function may generally have more control over onset. Within populations, however, the male and female influence on this trait varied. There were no regional effects on either the cost or the male vs. female influence on onset, but timing of self--‐pollination appeared positively correlated to timing of stigma receptivity. Interestingly, a positive relationship was found between measures of the magnitude of the cost and the level of female control over onset, potentially suggesting selection on female control when the cost is high. Novel to this study system, I found a negative correlation between donor and recipient influence on onset within individuals; this result hints at trade--‐offs in sex--‐allocation and/or a direct genetic link between the male and female traits. In the field, I confirmed that nectar was also produced in early floral developmental stages and that seeds could be produced after pollinators visit flowers in early stages. I conclude that the result of this study is consistent with an influence of antagonistic selection on patterns of timing of stigma receptivity across populations of C. heterophylla. Further research in this area is clearly needed to illuminate the intricate forces driving plant evolution, particularly in relation to the impact of pollinators and mating system. Popular science summary: Sexual Conflict in the annual plant Collinsia heterophylla Sexual selection describes the evolutionary process in which individuals compete with each other in an effort to obtain mates. Sexual conflict is a form of sexual selection that is realized when one sex negatively impacts the opposite sex while gaining a benefit for its own. These processes are thought to be important influences on plant and animal evolution, and can be held partially responsible for shaping the multitude of diverse life forms we see today. This study evaluates the potential evolutionary consequences of sexual selection and conflict in the annual flowering plant Collinsia heterophylla, the results of which may help illuminate the significance that these forces have on plant species diversification. C. heterophylla is a flowering plant native to California. Previous studies have shown that C. heterophylla may be involved in a sexual conflict over the timing of stigma receptivity, or the time when flowers are able to be successfully fertilized. Two traits are thought to be involved in this conflict: 1) a female trait that delays stigma receptivity, which ensures that flowers are fully mature and enables fertilization by the highest quality mates, and 2) a male trait that forces early stigma receptivity, which ensures successful fertilization but incurs a cost on the receiving plant. In this study I have investigated the potential effects of these conflicting traits by performing cross-pollination experiments in the greenhouse and in the field. I conducted a large cross-pollination experiment in the greenhouse at Lund University utilizing seeds originating from eight natural C. heterophylla populations in four different regions of California. The results of this experiment allowed me to assess the intensity and prevalence of the costs of early fertilization, and whether there was a relationship between the conflicting traits within individual plants. I also conducted field experiment, the results of which assessed the relevance of the sexual conflict in natural populations. My results suggest that the cost of early fertilization occurs in all populations, indicating that the sexual conflict is widespread. I found a negative relationship between the functionality of the male and female trait within individuals, which hints at a genetic link between the traits involved in the conflict. Furthermore, I showed that flowers are successfully fertilized in early floral stages in the field, which confirms that the cost of the sexual conflict can be realized in natural populations of C. heterophylla. These observations provide further evidence that sexual conflict can be an important process influencing the evolution and diversification of plant species. Advisors: Åsa Lankinen and Josefin Madjidian Master´s Degree Project 60 credits, Plant Ecology and Systematics 2012. Department of Biology, Lund University

Multicenter phase II study of matured dendritic cells pulsed with melanoma cell line lysates in patients with advanced melanoma

<p>Abstract</p> <p>Background</p> <p>Several single center studies have provided evidence of immune activation and antitumor activity of therapeutic vaccination with dendritic cells (DC) in patients with metastatic melanoma. The efficacy of this approach in patients with favorable prognosis metastatic melanoma limited to the skin, subcutaneous tissues and lung (stages IIIc, M1a, M1b) was tested in a multicenter two stage phase 2 study with centralized DC manufacturing.</p> <p>Methods</p> <p>The vaccine (IDD-3) consisted 8 doses of autologous monocyte-derived matured DC generated in serum-free medium with granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin-13 (IL-13), pulsed with lysates of three allogeneic melanoma cell lines, and matured with interferon gamma. The primary endpoint was antitumor activity.</p> <p>Results</p> <p>Among 33 patients who received IDD-3 there was one complete response (CR), two partial responses (PR), and six patients had stable disease (SD) lasting more than eight weeks. The overall prospectively defined tumor growth control rate was 27% (90% confidence interval of 13-46%). IDD-3 administration had minimal toxicity and it resulted in a high frequency of immune activation to immunizing melanoma antigens as assessed by <it>in vitro </it>immune monitoring assays.</p> <p>Conclusions</p> <p>The administration of matured DC loaded with tumor lysates has significant immunogenicity and antitumor activity in patients with limited metastatic melanoma.</p> <p>Clinical trial registration</p> <p>NCT00107159.</p

Phase II trial of biochemotherapy with interferon α, dacarbazine, cisplatin and tamoxifen in metastatic melanoma: a Southwest Oncology Group trial

The therapeutic benefit of adding interferon α (IFNα) to established single-agent and combination chemotherapy regimens for the treatment of metastatic melanoma has not been proven. We designed the present study to estimate the response rate of IFNα, dacarbazine, cisplatin and tamoxifen in patients who had not been treated with systemic therapy for advanced disease. Using a schedule similar to that which had previously been shown to favor IFNα plus dacarbazine over dacarbazine alone, we treated patients with an “induction” regimen of IFNα, 15 mU m −2 day −1 intravenously 5 days/week for 3 weeks. Following induction, schedules of IFNα, 5 mU m −2  day −1 subcutaneously three times a week, and tamoxifen, 10 mg orally twice a day, were begun. Dacarbazine, 250 mg m −2  day −1 and cisplatin 33 mg m −2  day −1 for 3 consecutive days were repeated every 4 weeks, and subcutaneous IFNα and oral tamoxifen were continued until the discontinuation of chemotherapy. We treated 25 patients (18 men and 7 women, median age 52 years) and observed only 1 objective response (response rate 4%, 95% confidence interval 0.1%–20%). The toxicities of the regimen consisted of moderate myelosuppression and constitutional side-effects. On the basis of the low antitumor activity of this regimen, we do not recommend it for further study or for use as standard therapy of metastatic melanoma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42256/1/432-125-5-292_91250292.pd

A clone together : exploring the causes and consequences of range divergence between sexual and asexual Easter daisies

Sexual and asexual organisms exhibit a wide variety of biological differences that can impact their ecological and evolutionary trajectories. One result of these differences is that closely related sexual and asexual taxa often exhibit range divergence, with asexuals typically having larger geographic ranges and being found at higher latitudes and elevations. This pattern, termed “geographical parthenogenesis”, has been documented in numerous plant and animal systems and a variety of potential mechanisms have been proposed. Hypotheses relate to differences in reproductive assurance (asexuals can reproduce without mates, while most sexuals require mates), genetic consequences of sexuality vs asexuality, selection on clonal lineages, ecological impacts of sexuality and asexuality, and demographic differences between reproductive modes. In this thesis, I explore several of these potential drivers of geographical parthenogenesis in Townsendia hookeri, a subalpine perennial flowering plant in the Asteraceae that has diploid sexual and polyploid apomictic (reproducing asexually through seed) forms with divergent but overlapping ranges. Population genomic analyses of apomicts in T. hookeri revealed largely monoclonal populations and geographically widespread clones, suggesting that apomictic range expansion may have been aided by “general-purpose genotypes” that can withstand an array of environmental conditions. Results from a large-scale, multi-year reciprocal transplant garden experiment showed that sexual populations had comparable performance when planted into the apomictic range as into their own, but that fitness of apomictic individuals generally declined in sexual regions. This provides evidence that while sexuals are likely limited by dispersal (they cannot reach suitable habitat outside of their current range), apomicts are not well adapted to the ecological conditions (biotic and/or abiotic) in the sexual range. When comparing early life history traits between sexuals and apomicts, apomicts were found to have increased germination success and improved seed dispersal traits in comparison to sexuals. These traits are expected to have given apomicts a colonization advantage, which (along with reproductive assurance) has likely contributed to their increased range size. Overall, the work presented in this thesis highlights the intricate nature of geographical parthenogenesis in Townsendia hookeri, and underscores the need to investigate complex biological phenomena using a diverse suite of approaches.Science, Faculty ofBotany, Department ofGraduat

Mantle flow through a tear in the Nazca slab inferred from shear wave splitting

A tear in the subducting Nazca slab is located between the end of the Pampean flat slab and normally subducting oceanic lithosphere. Tomographic studies suggest mantle material flows through this opening. The best way to probe this hypothesis is through observations of seismic anisotropy, such as shear wave splitting. We examine patterns of shear wave splitting using data from two seismic deployments in Argentina that lay updip of the slab tear. We observe a simple pattern of plate-motion-parallel fast splitting directions, indicative of plate-motion-parallel mantle flow, beneath the majority of the stations. Our observed splitting contrasts previous observations to the north and south of the flat slab region. Since plate-motion-parallel splitting occurs only coincidentally with the slab tear, we propose mantle material flows through the opening resulting in Nazca plate-motion-parallel flow in both the subslab mantle and mantle wedge.NSF [EAR-0738935, EAR-0739001, EAR-1565475]; Colorado College Patricia Buster Scholarship Fund; National Science Foundation through the Seismological Facilities for the Advancement of Geoscience and EarthScope (SAGE) Proposal of the National Science Foundation [EAR-1261681]6 month embargo; published online: 13 July 2017This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]