Patterns, causes, and consequences of connectivity within a coral reef fish metapopulation

Population connectivity influences virtually all ecological and evolutionary processes within metapopulations including population dynamics, persistence, and divergence. A comprehensive analysis of connectivity must consider the exchange of both individuals and alleles among populations, representing demographic and genetic connectivity, respectively. For many marine species, connectivity is driven by larval dispersal. However, despite the widespread recognition that dispersal is key to predicting metapopulation dynamics and effectively managing networks of marine reserves, empirical data are scarce due to the methodological challenges of tracking larvae. This dissertation is an integrative study of the patterns, causes, and consequences of marine connectivity using the sponge-dwelling reef fish Elacatinus lori as a study system. I begin by describing the distribution and abundance patterns of E. lori and its host sponge on the Belize barrier reef. Next, I study demographic connectivity by using genetic parentage analysis to quantify dispersal. I conduct an intra-population study to identify self-recruiting dispersal trajectories and develop a method to approximate a dispersal kernel based on the distribution of habitat patches. I then complete a large-scale parentage analysis to produce the first statistically-robust marine dispersal kernel. I find that dispersal declines exponentially with respect to distance in E. lori, with no dispersal events exceeding 16.2 km. Notably, dispersal probabilities are unrelated to the number of days an individual spends in the larval phase and other biological variables. Finally, to elucidate the long-term microevolutionary consequences of genetic connectivity, I investigate spatial genetic structure in the Belizean metapopulation. In a preliminary study based on mitochondrial and microsatellite data, I find high levels of pairwise genetic differentiation between sites separated by only 20 km. In a follow-up study, I use a high-throughput multiplex approach to resolve fine-scale patterns of genetic structure throughout the species' range. Seascape genetic analyses reveal that genetic connectivity is consistent with the shape of the dispersal kernel. Collectively, this dissertation generates novel insights regarding the spatial scale at which marine fish populations are connected. Given the alarming rate of population declines on coral reefs globally, these results have important and time-sensitive conservation implications

Different distribution of the genetic subtypes of the Prader–Willi syndrome in the elderly

The Prader–Willi syndrome (PWS) is a genetic disorder caused by the absent expression of the paternal copy of maternally imprinted genes in chromosome region 15q11–13. The frequencies of different subtypes in PWS are usually given in literature as 70% deletion, 25–30% maternal uniparental disomy (mUPD) and 3–5% others (imprinting centre (IC) defects and translocations). Little is known about factors that influence the frequency of genetic subtypes in PWS. The study sample comprised 102 adults with clinically and genetically confirmed PWS, contacted through the Dutch Prader–Willi Parent Association and through physicians specialized in treating persons with intellectual disabilities. Genetic testing showed 55 persons (54%) with a paternal deletion, 44 persons (43%) with an mUPD and 3 persons (3%) with a defect of the IC. The observed distribution in our study differed from that in literature (70% deletion, 30% mUPD), which was statistically significant (z-score: P<0.05). This was mainly caused by a higher proportion of mUPD in the advanced age groups. Differences in maternal age and BMI of persons with PWS could not explain the differences in distribution across the age groups. Our study population had a much broader age range, compared with other studies, because of a predominance of elderly people (40+ years) with PWS. In other studies, these elderly persons might have been undiagnosed and/or underreported because of a lack of genetic diagnosis. The results underline both the need for correct genetic diagnosis in all persons with PWS and adjustment of the guidelines for preventive management in adulthood

Behavioral phenotype in adults with Prader–Willi syndrome

Prader-Willi syndrome (PWS) is characterized by temper tantrums, impulsivity, mood fluctuations, difficulty with change in routine, skinpicking, stubbornness and aggression. Many studies on behavior in PWS are limited by sample size, age range, a lack of genetically confirmed diagnosis of PWS and inconsistent assessment of behavior. The aim of this study was to explore systematically the relation between behavioral problems and age groups, genetic subtypes and BMI categories in an adult PWS population. Participants were contacted via the Dutch Prader-Willi Parent Association and through physicians specialized in persons with ID. Behaviors were studied using the Developmental Behavior Checklist for Adults (DBC-A). The forms were completed by the main caregivers of 98 adults with a genetically confirmed diagnosis of PWS. Differences between age groups were statistically significant (ANOVA, p = 0.03). DBC-A total scores were higher in the consecutive age groups, with the most behavioral problems in the oldest age groups. Differences between genetic subtypes were also statistically significant (ANOVA,