Background: The highly polymorphic copy number variation (CNV) in the salivary amylase gene (AMY1) has been associated with obesity in different populations. However, some authors have failed to reproduce these findings. Aim: To investigate the association between AMY1 CNV and obesity in young adults of Portuguese origin. Subjects and methods: This study evaluated AMY1 gene copy number (CN) in 262 individuals: 155 females and 107 males, aged 18–34 years-old (mean age = 21.08). The number of AMY1 copies was estimated in a QX100 droplet digital PCR (ddPCR) system (Bio-Rad Laboratories, Hercules, CA). Results: Defining a case group with obese and overweight individuals, logistic regression did not show a significant association between AMY1 CNV and risk of overweight/obesity in the whole population (p = 0.489). However, after testing case-control data in the sub-set of samples above the third quartile (CN ≥10), a significant association was found between lower AMY1 copy number and risk of obesity (OR = 0.532; p = 0.034), even when adjusted for age and sex (OR = 0.527; p = 0.039). In concordance, all participants with >10 AMY1 copies were normal weight controls (n = 20) or overweight (n = 6). Conclusion: The results suggest that high AMY1 gene copy number protects against obesity in Portuguese young adults.

Several eucalypt species are known for their capacity to massively regenerate through seeds in recently burned areas, becoming an ecological problem in regions where the species is not native. Here we study the demography and the development of highly dense Eucalyptus globulus wildling populations established one year after a fire and test two methods to control these populations. We monitored five mixed E. globulus stands across one year, in Central Portugal. We established a set of plots in each stand, with three treatments: mechanical cutting, herbicide spraying and no disturbance (control plots). Herbicide was applied in four concentrations. We tagged randomly selected plants in the control plots to monitor their growth. The initial mean wildling density was 322,000 plants ha⁻¹, the highest ever recorded in the introduced range. Wildling density was significantly dependent on the density of surrounding adult E. globulus trees. Wildling density in control plots decreased 30% in one year, although showing positive variations over time because of new recruitment. Despite seasonal growth differences, wildlings showed a high growth rate throughout the year, reaching 15.6 cm month⁻¹ in the summer. The growth rate of tagged wildings was positively affected by solar radiation and negatively affected by evapotranspiration and maximum temperature. Mechanical cutting reduced wildling density by 97% while herbicide treatment reduced density between 80% (for the lowest concentration) and 99% (for the highest concentration). Herbicide-treated plants were more likely to resprout than cut plants. Regardless of the control method adopted (cutting or herbicide), management strategies should include the follow-up of the treated areas, to detect the establishment of new recruits and resprouting.

Eucalyptus globulus Labill. is a widespread forest tree species, reported as naturalized across the introduced range, often showing abundant natural regeneration after wildfires. This paper studies a post-fire cohort of seedlings derived from a small, isolated E. globulus stand in central Portugal. The aim is to better understand the genetic dynamics and dispersal mechanisms of naturally established E. globulus populations in the introduced range. The seedling density at 55 m from adult trees was 12,000 ha⁻¹, the farthest seedling being registered at 101 m. Post-fire expansion occurred in a southward direction, in accordance with predominant wind. Seedlings had significantly lower levels of genetic diversity (Ae = 5.8.; He = 0.8) than adult trees (Ae = 6.5; He = 0.8). Crossings were strongly unbalanced, with only eight trees contributing to the sampled seedlings, and one single tree contributing to 52% of these seedlings. Moreover, the co-ancestry amongst seedlings more than doubled (from θ = 0.03 to 0.076), and the population status number was around one third of the value registered for the adult population (from Ns = 16.2 to 6.6). Despite its isolation, external pollen was detected in the stand, and appears to have travelled at least 700 m, contributing to 22% of the offspring. Overall, the seedling cohort is much less diverse than the parent trees, with expected lower resilience and persistence to environmental stresses.