Low Levels of Extra-Pair Paternity in a Neotropical Duetting Songbird, the Rufous-and-White Wren (Thryothorus rufalbus)

Molecular analyses have confirmed that the majority of socially monogamous birds follow a genetically promiscuous reproductive strategy. Most such studies, however, have addressed species of the North Temperate Zone; tropical species are grossly underrepresented, although most of Earth\u27s biodiversity is concentrated in the tropics. In this study, we describe the genetic mating strategy of the Rufous-and-white Wren (Thryothorus rufalbus), a socially monogamous duetting neotropical songbird. Over 8 years of studying a marked population in Costa Rica, we recorded genetic data from 51 broods. Microsatellite analysis of four variable loci revealed that the Rufous-and-white Wren follows a mixed reproductive strategy, where extra-pair young are found in a small minority of broods. Three of 158 nestlings (2%) were the result of extra-pair fertilizations; three of the 51 broods (6%) contained a nestling with alleles mismatched to its social father. We assigned paternity of two of the extra-pair nestlings to males in territories adjacent to the cuckolded males. During behavioral observations, we observed within-pair copulations rarely and extra-pair copulations never. The rate of extra-pair paternity we report here is lower than the average reported for socially monogamous birds in the North Temperate Zone but comparable to rates in three closely related tropical wrens. Rufous-and-white Wrens are renowned for their coordinated vocal duets. We compared rates of extra-pair paternity among socially monogamous tropical birds, contrasting four duetting species against twelve nonduetting species and found lower levels of extra-pair paternity in the former group, suggesting that duetting and low levels of extra-pair paternity are related

Role of genomics and transcriptomics in selection of reintroduction source populations

The use and importance of reintroduction as a conservation tool to return a species to its historical range where it has become extirpated will only increase as climate change and human development accelerate habitat loss and population extinctions. Although the number of reintroduction attempts has rapidly increased over the past two decades, the success rate is generally low. As a result of population differences in fitness-related traits and divergent responses to environmental stresses, there is a high likelihood for differential performance among potential source populations upon reintroduction. It is well known that population performance upon reintroduction is highly variable and it is generally agreed that selecting an appropriate source population is a critical component of a successful reintroduction

Transcriptome response of Atlantic salmon (Salmo salar) to competition with ecologically similar non-native species

Non-native species may be introduced either intentionally or unintentionally, and their impact can range from benign to highly disruptive. Non-native salmonids were introduced into Lake Ontario, Canada, to provide recreational fishing opportunities; however, the establishment of those species has been proposed as a significant barrier to the reintroduction of native Atlantic salmon (Salmo salar) due to intense interspecific competition. In this study, we compared population differences of Atlantic salmon in transcriptome response to interspecific competition. We reared Atlantic salmon from two populations (LaHave River and Sebago Lake) with fish of each of three non-native salmonids (Chinook salmon Oncorhynchus tshawytscha, rainbow trout O. mykiss, and brown trout S. trutta) in artificial streams. We used RNA-seq to assess transcriptome differences between the Atlantic salmon populations and the responses of these populations to the interspecific competition treatments after 10 months of competition in the stream tanks. We found that population differences in gene expression were generally greater than the effects of interspecific competition. Interestingly, we found that the two Atlantic salmon populations exhibited similar responses to interspecific competition based on functional gene ontologies, but the specific genes within those ontologies were different. Our transcriptome analyses suggest that the most stressful competitor (as measured by the highest number of differentially expressed genes) differs between the two study populations. Our transcriptome characterization highlights the importance of source population selection for conservation applications, as organisms with different evolutionary histories can possess different transcriptional responses to the same biotic stressors. The results also indicate that generalized predictions of the response of native species to interactions with introduced species may not be appropriate without incorporating potential population-specific response to introduced species

Phenotypic integration of behavioural and physiological traits is related to variation in growth among stocks of Chinook salmon

The selection for a single organismal trait like growth in breeding programs of farmed aquaculture species can counterintuitively lead to lowered harvestable biomass. We outbred a domesticated aquaculture stock of Chinook salmon (Oncorhynchus tshawytscha (Walbaum in Artedi, 1792)) with seven wild stocks from British Columbia, Canada. We then examined how functionally related traits underlying energy management – diel variation in cortisol and foraging, social, and movement behaviours — predicted stock-level variation in growth during the freshwater life history stage, which is a performance metric under aquaculture selection. Outbreeding generated significant variation in diel cortisol secretion and behaviours across stocks, and these traits co-varied, suggesting tight integration despite hybridization. The coupling of nighttime cortisol exposure with the daytime behavioural phenotype was the strongest predictor of stock-level variation in body mass. Our results suggest that selection for an integrated phenotype rather than on a single mechanistic trait alone can generate the greatest effect on aquaculture fish growth under outbreeding practices. Furthermore, selecting for these traits at the stock level may increase efficiency of farming methods designed to consistently maximize fish performance on a large scale

Phenotypic integration of behavioural and physiological traits is related to variation in growth among stocks of Chinook salmon

The selection for a single organismal trait like growth in breeding programs of farmed aquaculture species can counter-intuitively lead to lowered harvestable biomass. We outbred a domesticated aquaculture stock of Chinook salmon (Oncorhynchus tshawytscha) with 7 wild stocks from British Columbia, Canada. We then examined how functionally related traits underlying energy management - diel variation in cortisol; foraging, social, and movement behaviours - predicted stock-level variation in growth during the freshwater life history stage, a performance metric under aquaculture selection. Outbreeding generated significant variation in diel cortisol secretion and behaviours across stocks, and these traits covaried, suggesting tight integration despite hybridization. The coupling of nighttime cortisol exposure with daytime behavioural phenotype was the strongest predictor of stock-level variation in body mass. Our results suggest selecting for an integrated phenotype rather than on single mechanistic traits alone can generate the greatest effect on aquaculture fish growth under outbreeding practices. Furthermore, selecting for these traits at the stock level may increase efficiency of farming methods designed to consistently maximize fish performance on a large scale

Differential invasion success in aquatic invasive species: the role of within- and among-population genetic diversity

© 2017, Springer International Publishing AG Switzerland. Despite a well-developed theoretical basis for the role of genetic diversity in the colonization process, contemporary investigations of genetic diversity in biological invasions have downplayed its importance. Observed reductions in genetic diversity have been argued to have a limited effect on the success of establishment and impact based on empirical studies; however, those studies rarely include assessment of failed or comparatively less-successful biological invasions. We address this gap by comparing genetic diversity at microsatellite loci for taxonomically and geographically paired aquatic invasive species. Our four species pairs contain one highly successful and one less-successful invasive species (Gobies: Neogobius melanostomus, Proterorhinus semilunaris; waterfleas: Bythotrephes longimanus, Cercopagis pengoi; oysters: Crassostrea gigas, Crassostrea virginica; tunicates: Bortylloides violaceous, Botryllus schlosseri). We genotyped 2717 individuals across all species from multiple locations in multiple years and explicitly test whether genetic diversity is lower for less-successful biological invaders within each species pair. We demonstrate that, for gobies and tunicates, reduced allelic diversity is associated with lower success of invasion. We also found that less-successful invasive species tend to have greater divergence among populations. This suggests that intraspecific hybridization may be acting to convert among-population variation to within-population variation for highly successful invasive species and buffering any loss of diversity. While our findings highlight the species-specific nature of the effects of genetic diversity on invasion success, they do support the use of genetic diversity information in the management of current species invasions and in the risk assessment of potential future invaders

Neutral genetic variation in adult Chinook salmon (Oncorhynchus tshawytscha) affects brain-to-body trade-off and brain laterality

Low levels of heterozygosity can have detrimental effects on life history and growth characteristics of organisms but more subtle effects such as those on trade-offs of expensive tissues and morphological laterality, especially of the brain, have not been explicitly tested. The objective of the current study was to investigate how estimated differences in heterozygosity may potentially affect brain-to-body trade-offs and to explore how these heterozygosity differences may affect differential brain growth, focusing on directional asymmetry in adult Chinook salmon (Oncorhynchus tshawytscha) using the laterality and absolute laterality indices. Level of inbreeding was estimated as mean microsatellite heterozygosity resulting in four ‘inbreeding level groups’ (Very High, High, Medium, Low). A higher inbreeding level corresponded with a decreased brain-to-body ratio, thus a decrease in investment in brain tissue, and also showed a decrease in the laterality index for the cerebellum, where the left hemisphere was larger than the right across all groups. These results begin to show the role that differences in heterozygosity may play in differential tissue investment and in morphological laterality, and may be useful in two ways. Firstly, the results may be valuable for restocking programmes that wish to emphasize brain or body growth when crossing adults to generate individuals for release, as we show that genetic variation does affect these trade-offs. Secondly, this study is one of the first examinations to test the hypothesized relationship between genetic variation and laterality, finding that in Chinook salmon there is potential for an effect of inbreeding on lateralized morphology, but not in the expected direction