Single nucleotide polymorphisms unravel hierarchical divergence and signatures of selection among Alaskan sockeye salmon (Oncorhynchus nerka) populations

<p>Abstract</p> <p>Background</p> <p>Disentangling the roles of geography and ecology driving population divergence and distinguishing adaptive from neutral evolution at the molecular level have been common goals among evolutionary and conservation biologists. Using single nucleotide polymorphism (SNP) multilocus genotypes for 31 sockeye salmon (<it>Oncorhynchus nerka</it>) populations from the Kvichak River, Alaska, we assessed the relative roles of geography (discrete boundaries or continuous distance) and ecology (spawning habitat and timing) driving genetic divergence in this species at varying spatial scales within the drainage. We also evaluated two outlier detection methods to characterize candidate SNPs responding to environmental selection, emphasizing which mechanism(s) may maintain the genetic variation of outlier loci.</p> <p>Results</p> <p>For the entire drainage, Mantel tests suggested a greater role of geographic distance on population divergence than differences in spawn timing when each variable was correlated with pairwise genetic distances. Clustering and hierarchical analyses of molecular variance indicated that the largest genetic differentiation occurred between populations from distinct lakes or subdrainages. Within one population-rich lake, however, Mantel tests suggested a greater role of spawn timing than geographic distance on population divergence when each variable was correlated with pairwise genetic distances. Variable spawn timing among populations was linked to specific spawning habitats as revealed by principal coordinate analyses. We additionally identified two outlier SNPs located in the major histocompatibility complex (MHC) class II that appeared robust to violations of demographic assumptions from an initial pool of eight candidates for selection.</p> <p>Conclusions</p> <p>First, our results suggest that geography and ecology have influenced genetic divergence between Alaskan sockeye salmon populations in a hierarchical manner depending on the spatial scale. Second, we found consistent evidence for diversifying selection in two loci located in the MHC class II by means of outlier detection methods; yet, alternative scenarios for the evolution of these loci were also evaluated. Both conclusions argue that historical contingency and contemporary adaptation have likely driven differentiation between Kvichak River sockeye salmon populations, as revealed by a suite of SNPs. Our findings highlight the need for conservation of complex population structure, because it provides resilience in the face of environmental change, both natural and anthropogenic.</p

Increased Inter-Colony Fusion Rates Are Associated with Reduced COI Haplotype Diversity in an Invasive Colonial Ascidian Didemnum vexillum

Considerable progress in our understanding of the population genetic changes associated with biological invasions has been made over the past decade. Using selectively neutral loci, it has been established that reductions in genetic diversity, reflecting founder effects, have occurred during the establishment of some invasive populations. However, some colonial organisms may actually gain an ecological advantage from reduced genetic diversity because of the associated reduction in inter-colony conflict. Here we report population genetic analyses, along with colony fusion experiments, for a highly invasive colonial ascidian, Didemnum vexillum. Analyses based on mitochondrial cytochrome oxidase I (COI) partial coding sequences revealed two distinct D. vexillum clades. One COI clade appears to be restricted to the probable native region (i.e., north-west Pacific Ocean), while the other clade is present in widely dispersed temperate coastal waters around the world. This clade structure was supported by 18S ribosomal DNA (rDNA) sequence data, which revealed a one base-pair difference between the two clades. Recently established populations of D. vexillum in New Zealand displayed greatly reduced COI genetic diversity when compared with D. vexillum in Japan. In association with this reduction in genetic diversity was a significantly higher inter-colony fusion rate between randomly paired New Zealand D. vexillum colonies (80%, standard deviation ±18%) when compared with colonies found in Japan (27%, standard deviation ±15%). The results of this study add to growing evidence that for colonial organisms reductions in population level genetic diversity may alter colony interaction dynamics and enhance the invasive potential of newly colonizing species

Chick Timer™ software proves an accurate disturbance minimising tool for monitoring hatching success in little spotted kiwi (<i>Apteryx owenii</i>)

<div><p>Measuring hatching success in birds is important for assessing population viability, but nests are often cryptic and may be abandoned if birds are disturbed during nesting. We evaluated the suitability of Wildtech New Zealand Ltd's Chick Timer™ radio telemetry software for monitoring hatching success in little spotted kiwi (<i>Apteryx owenii</i>). The software provided accurate reports of activity levels and times of nest emergence by adult birds. Eighty four per cent of incubation attempts and 70% of first hatching events were detected, with no false indications of incubation or hatching. Our results suggest that this technology will facilitate studies of hatching success in little spotted kiwi and other large birds with cryptic or inaccessible nests. A ground truthing study such as this one, however, is required before full implementation of the software in any species.</p></div

The Psychosocial Impact of Cleft in a Western Australian Cohort Across 3 Age Groups

BACKGROUND:: Management of a cleft of the lip and/or palate (CL/P) involves a multidisciplinary team approach lasting from birth to potentially postskeletal maturity. This condition is complex, with both medical and psychosocial implications that may place individuals with a cleft at higher risk of developing psychosocial problems. METHODOLOGY:: A self-administered questionnaire was completed by a sample from the Western Australian cleft population comprising 3 age groups: child (n = 100), adolescent (n = 101), and adult (n = 158). RESULTS:: Public speaking, being photographed, special relationships, and participation in school were identified as the areas most impacted by having a cleft. Hearing and speech were reported to have a higher importance than facial and dental appearance. Participants rated support given to them by their parents as the most important, with high ratings for treatment providers. For teasing, the impact of cleft was significantly higher among participants with cleft lip and palate for both the adolescent and adult age groups. There was little significant difference by gender across the variables, which suggests that males are just as likely to require support as females. CONCLUSION:: The impact of a cleft across multiple psychosocial domains needs to be recognized and addressed as part of craniofacial team care across age groups