Insights Into Comparative Analyses and Phylogenomic Implications of Acer (Sapindaceae) Inferred From Complete Chloroplast Genomes

Acer L. (Sapindaceae) is one of the most diverse and widespread plant genera in the Northern Hemisphere. It comprises 124–156 recognized species, with approximately half being native to Asia. Owing to its numerous morphological features and hybridization, this genus is taxonomically and phylogenetically ranked as one of the most challenging plant taxa. Here, we report the complete chloroplast genome sequences of five Acer species and compare them with those of 43 published Acer species. The chloroplast genomes were 149,103–158,458 bp in length. We conducted a sliding window analysis to find three relatively highly variable regions (psbN-rps14, rpl32-trnL, and ycf1) with a high potential for developing practical genetic markers. A total of 76–103 SSR loci were identified in 48 Acer species. The positive selection analysis of Acer species chloroplast genes showed that two genes (psaI and psbK) were positively selected, implying that light level is a selection pressure for Acer species. Using Bayes empirical Bayes methods, we also identified that 20 cp gene sites have undergone positive selection, which might result from adaptation to specific ecological niches. In phylogenetic analysis, we have reconfirmed that Acer pictum subsp. mono and A. truncatum as sister species. Our results strongly support the sister relationships between sections Platanoidea and Macrantha and between sections Trifoliata and Pentaphylla. Moreover, series Glabra and Arguta are proposed to promote to the section level. The chloroplast genomic resources provided in this study assist taxonomic and phylogenomic resolution within Acer and the Sapindaceae family.

Adjustable light source for low light level with nearly constant correlated color temperature

Low light level (LLL) calibration becomes more and more important since the rapid growth of remote sensing. The spectral radiance at normal higher light levels can be calibrated with good accuracy, while LLL spectral radiance cannot. If an adjustable light source can be designed at nearly constant correlated color temperature (CCT) covering several orders of magnitude, low light level spectral radiance can be obtained with the help of a photodetector. Whether or not the spectral distribution of an integrating sphere based light source is nearly constant is investigated. By adjusting the diameter of the variable aperture between the integrating sphere and tungsten lamp, the spectral radiance can be varied over 6 orders of magnitude. However, the relative spectrum in the red region increases notably when the spectral radiance is decreased to 1/100000. If the spectral radiance is decreased further, the spectral difference can be more than 300% and CCT decreases more than 250 K. By using baffles and another integrating sphere, low light level radiation source at nearly constant spectral distribution is obtained. The variation of CCT is less than 50 K over 6 orders of magnitude.

Population specific annual cycles and migration strategies in a leap-frog migrant

A common migratory pattern in birds is that northerly breeding populations migrate to more southerly non-breeding sites compared to southerly breeding populations (leap-frog migration). Not only do populations experience differences in migration distances, but also different environmental conditions, which may vary spatiotemporally within their annual cycles, creating distinctive selective pressures and migratory strategies. Information about such adaptations is important to understand migratory drivers and evolution of migration patterns. We use light-level geolocators and citizen science data on regional spring arrivals to compare two populations of common ringed plover Charadrius hiaticula breeding at different latitudes. We (1) describe and characterize the annual cycles and (2) test predictions regarding speed and timing of migration. The northern breeding population (NBP) wintered in Africa and the southern (SBP) mainly in Europe. The annual cycles were shifted temporally so that the NBP was always later in all stages. The SBP spent more than twice as long time in the breeding area, but there was no difference in winter. The NBP spent more time on migration in general. Spring migration speed was lower in the SBP compared to autumn speed of both populations, and there was no difference in autumn and spring speed in the NBP. We also found a larger variation in spring arrival times across years in the SBP. This suggests that a complex interaction of population specific timing and variation of breeding onset, length of breeding season, and proximity to the breeding area shape the annual cycle and migratory strategies. Significance statement Migration distance, climate, and the resulting composition of the annual cycle are expected to influence migration strategies and timing in birds. Testing theories regarding migration behaviours are challenging, and intraspecific comparisons over the full annual cycle are still rare. Here we compare the spatiotemporal distributions of two latitudinally separated populations of common ringed plovers using light-level geolocators. We found that there was a larger long-term variation in first arrival dates and that migration speed was slower only in spring in a temperate, short-distance migratory population, compared to an Arctic, long-distance migratory population. This suggests that a complex interaction of population specific timing and variation of breeding onset, length of breeding season and proximity to the breeding area shape the annual cycle and migratory behaviours.

OPTIMISING ROAD LIGHTING TO REDUCE ROAD TRAFFIC CRASHES

Pedestrians and motorcyclists are vulnerable road users, being over represented in road traffic collisions (RTCs). One assumed benefit of road lighting is a reduction in RTCs after dark by countering the impairment to the visual detection of hazards that occur after dark. One way to optimise the use of road lighting is to light only those sections of road where light level, and hence visibility, is an important factor. The current study used change in ambient light level on RTCs to investigate those situations where improved vision is likely to have significant impact, and therefore the situations where road lighting is of better cost-benefit effectiveness. For both motorcyclist and pedestrian RTCs there was a significant increase in overall RTC risk in darkness compared to daylight, indicating that there may be an overall benefit of road lighting. While darkness was a particular detriment at junctions for motorcyclists and on high-speed roads for pedestrians, road lighting may not be effective mitigation in either case and therefore alternative ways of increasing conspicuity should be considered.

INVESTIGATING LIGHT AND CRIME USING AMBIENT LIGHT LEVEL

A recent study investigated the influence of lighting on crime by considering the effect of change in ambient light level on crimes recorded in three US cities for the ten-year period 2010 to 2019. The results suggested a significant increase in robbery after dark, but did not suggest significant change in for any other type of crime. The current study was conducted to validate this by considering crimes recorded in three different US cities. This analysis confirmed the statistically significant increase in robbery after dark. These data do not suggest that change in ambient light level has a practically relevant effect on overall crime counts: in other words, the potential benefit of lighting for crime reduction is limited.

THE EFFECT OF CHANGES IN LIGHT LEVEL ON THE NUMBERS OF CYCLISTS

Cycling has a range of benefits and should be encouraged, but darkness may put people off from cycling due to reductions in visibility, road safety and personal security. We summarise analyses of observational data to confirm the negative impact darkness has on cycling rates. Using a Case / Control method that accounts for confounding factors such as time of day and seasonal variations in weather, we demonstrate a consistent effect of darkness across different locations and countries. The size of this effect varies though, suggesting certain unknown factors may be important in mediating the impact of darkness on cycling rates. One factor that is known to mediate the effect is road lighting. We show that increased illuminance can offset the reductions in cyclists caused by darkness and also that there may be an optimal illuminance after which no further benefits may be achieved.

LESSONS LEARNED FROM REGISTRATION OF OCCUPANCY AND USE OF LIGHTING IN OFFICES, SCHOOLS, UNIVERSITIES AND INDUSTRY BUILDINGS, A CROSS COUNTRY STUDY

The paper presents a registration of occupancy and the use of (day)light in four buildings representing respectively offices, primary schools, universities, and industry buildings; it was done across Europe in 2020. A self-registration method was used, assisted with light technical measurements outdoors and indoors. In general, occupants consider the visual environment at the workplace when they are coming in or out of the room. It happens mainly at the beginning (adjustment of blinds and switching light on) and at the end of the working day (switching light off). In the primary school building, where users move in-out many times during the day, the adjustment happens more frequently. Also use of projector generates very low general light level; covering windows and switching off the electric light happens accordingly, but the pattern is not consistent. In general, the changes in the electrical lighting use follow the occupancy pattern, not the light levels.