Exogenous selection shapes germination behaviour and seedling traits of populations at different altitudes in a Senecio hybrid zone

Background and Aims The Senecio hybrid zone on Mt Etna, Sicily, is characterized by steep altitudinal clines in quantitative traits and genetic variation. Such clines are thought to be maintained by a combination of ‘endogenous' selection arising from genetic incompatibilities and environment-dependent ‘exogenous' selection leading to local adaptation. Here, the hypothesis was tested that local adaptation to the altitudinal temperature gradient contributes to maintaining divergence between the parental species, S. chrysanthemifolius and S. aethnensis. Methods Intra- and inter-population crosses were performed between five populations from across the hybrid zone and the germination and early seedling growth of the progeny were assessed. Key Results Seedlings from higher-altitude populations germinated better under low temperatures (9-13 °C) than those from lower altitude populations. Seedlings from higher-altitude populations had lower survival rates under warm conditions (25/15 °C) than those from lower altitude populations, but also attained greater biomass. There was no altitudinal variation in growth or survival under cold conditions (15/5 °C). Population-level plasticity increased with altitude. Germination, growth and survival of natural hybrids and experimentally generated F1s generally exceeded the worse-performing parent. Conclusions Limited evidence was found for endogenous selection against hybrids but relatively clear evidence was found for divergence in seed and seedling traits, which is probably adaptive. The combination of low-temperature germination and faster growth in warm conditions might enable high-altitude S. aethnensis to maximize its growth during a shorter growing season, while the slower growth of S. chrysanthemifolius may be an adaptation to drought stress at low altitudes. This study indicates that temperature gradients are likely to be an important environmental factor generating and maintaining adaptive divergence across the Senecio hybrid zone on Mt Etn

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Genetic differentiation for size at first reproduction through male versus female functions in the widespread Mediterranean tree Pinus pinaster

Background and Aims The study of local adaptation in plant reproductive traits has received substantial attention in short-lived species, but studies conducted on forest trees are scarce. This lack of research on long-lived species represents an important gap in our knowledge, because inferences about selection on the reproduction and life history of short-lived species cannot necessarily be extrapolated to trees. This study considers whether the size for first reproduction is locally adapted across a broad geographical range of the Mediterranean conifer species Pinus pinaster. In particular, the study investigates whether this monoecious species varies genetically among populations in terms of whether individuals start to reproduce through their male function, their female function or both sexual functions simultaneously. Whether differences among populations could be attributed to local adaptation across a climatic gradient is then considered. Methods Male and female reproduction and growth were measured during early stages of sexual maturity of a P. pinaster common garden comprising 23 populations sampled across the species range. Generalized linear mixed models were used to assess genetic variability of early reproductive life-history traits. Environmental correlations with reproductive life-history traits were tested after controlling for neutral genetic structure provided by 12 nuclear simple sequence repeat markers. Key Results Trees tended to reproduce first through their male function, at a size (height) that varied little among source populations. The transition to female reproduction was slower, showed higher levels of variability and was negatively correlated with vegetative growth traits. Several female reproductive traits were correlated with a gradient of growth conditions, even after accounting for neutral genetic structure, with populations from more unfavourable sites tending to commence female reproduction at a lower individual size. Conclusions The study represents the first report of genetic variability among populations for differences in the threshold size for first reproduction between male and female sexual functions in a tree species. The relatively uniform size at which individuals begin reproducing through their male function probably represents the fact that pollen dispersal is also relatively invariant among sites. However, the genetic variability in the timing of female reproduction probably reflects environment-dependent costs of cone production. The results also suggest that early sex allocation in this species might evolve under constraints that do not apply to other conifer

Application of OCT to examination of easel paintings

We present results of applying low coherence interferometry to gallery paintings. Infrared low coherence interferometry is capable of non-destructive examination of paintings in 3D, which shows not only the structure of the varnish layer but also the paint layers

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Teaching/Communication/Extension/Profession,

Two's Company, Three's a Crowd: Experimental Evaluation of the Evolutionary Maintenance of Trioecy in Mercurialis annua (Euphorbiaceae)

Trioecy is an uncommon sexual system in which males, females, and hermaphrodites co-occur as three clearly different gender classes. The evolutionary stability of trioecy is unclear, but would depend on factors such as hermaphroditic sex allocation and rates of outcrossing vs. selfing. Here, trioecious populations of Mercurialis annua are described for the first time. We examined the frequencies of females, males and hermaphrodites across ten natural populations and evaluated the association between the frequency of females and plant densities. Previous studies have shown that selfing rates in this species are density-dependent and are reduced in the presence of males, which produce substantially more pollen than hermaphrodites. Accordingly, we examined the evolutionary stability of trioecy using an experiment in which we (a) indirectly manipulated selfing rates by altering plant densities and the frequency of males in a fully factorial manner across 20 experimental plots and (b) examined the effect of these manipulations on the frequency of the three sex phenotypes in the next generation of plants. In the parental generation, we measured the seed and pollen allocations of hermaphrodites and compared them with allocations by unisexual plants. In natural populations, females occurred at higher frequencies in denser patches, a finding consistent with our expectations. Under our experimental conditions, however, no combination of plant densities and male frequencies was associated with increased frequencies of females. Our results suggest that the factors that regulate female frequencies in trioecious populations of M. annua are independent of those regulating male frequencies (density), and that the stable co-existence of all three sex phenotypes within populations is unlikely

Sex-Differential Herbivory in Androdioecious Mercurialis annua

Males of plants with separate sexes are often more prone to attack by herbivores than females. A common explanation for this pattern is that individuals with a greater male function suffer more from herbivory because they grow more quickly, drawing more heavily on resources for growth that might otherwise be allocated to defence. Here, we test this ‘faster-sex’ hypothesis in a species in which males in fact grow more slowly than hermaphrodites, the wind-pollinated annual herb Mercurialis annua. We expected greater herbivory in the faster-growing hermaphrodites. In contrast, we found that males, the slower sex, were significantly more heavily eaten by snails than hermaphrodites. Our results thus reject the faster-sex hypothesis and point to the importance of a trade-off between defence and reproduction rather than growth

The role of lateral and vertical herkogamy in the divergence of the blue- And red-flowered lineages of Lysimachia arvensis

Background and Aims: Herkogamy, or anther-stigma separation, is known to reduce self-pollen deposition, but little is known about the relative efficacy of different modes or conformations of herkogamy. We assessed the effectiveness of vertical versus lateral herkogamy in preventing or promoting self-pollen deposition in the annual herb Lysimachia arvensis, a plant with lineages that differ in flower colour, and in which flowers first display lateral and then vertical herkogamy. Because mating between the two lineages compromises fitness through the production of low-quality hybrid offspring, we tested the prediction that individuals sampled from sites occupied by both lineages should have flowers that promote autonomous self-pollen deposition and self-fertilization as a result of selection to reduce deleterious reproductive interference. Methods: We characterized variation in herkogamy within and among 25 pure and mixed populations of L. arvensis in its European range and assessed the effectiveness of lateral versus vertical herkogamy in avoiding self-pollen deposition. Results: Lateral herkogamy was more effective than vertical herkogamy in limiting self-pollen deposition. In the case of vertical herkogamy, only approach herkogamy was effective. Lineages showed consistent differences in herkogamy traits. In general, angles were smaller for blue than red flowers in most populations, and blue flowers showed approach herkogamy, while red flowers showed predominantly reverse herkogamy. In sympatry, the red lineage showed a reduction of both herkogamy traits while for the blue lineage only lateral herkogamy was reduced. Conclusions: Our results demonstrate that pollen deposition is affected not only by the degree but also the spatial conformation of herkogamy. They also highlight reduced herkogamy as a potential mechanism for promoting reproductive assurance under pollen limitation, as well as for avoiding reproductive interference between genetically divergent lineages.Ministerio de Economía y Competitividad CGL2012-33270, CGL2015-63827, BES-2013-062859, EEBB-C-15-0067

Reasons for non-suicidal self-harm in adult male offenders with and without borderline personality traits

The presented study aimed to advance understanding of the reasons for non-suicidal self-harm (NSSH) in adult male offenders, with and without borderline personality traits. 179 offenders completed self-report measures of NSSH and other clinical constructs, with 42 being identified as having self-harmed. Results were consistent with past research and supported the relative importance of intrapersonal over interpersonal functions, but also highlight that self-harm is performed rarely for one type of reason. The results also show that the presence of borderline personality traits increases the likelihood of endorsing a range of interpersonal reasons. These findings highlight the importance of understanding the range of reasons for engaging in NSSH to help manage the behaviour within the priso