72 research outputs found
Costs and benefits of mating-type switching
No full textData set accompanying manuscript "Repeated evolution
of self-compatibility for reproductive assurance"By Bart P.S. Nieuwenhuis, Sergio Tusso, Pernilla Bjerling, Josefine Stångberg,
Jochen B.W. Wolf and Simone ImmlerThis dataset contains the raw counts before and after competitions for competitions during asexual growth (asex_[..]) and competitions during reproduction including mating under different densities (sex_[..]). The data is analysed and plots for the manuscript are generated using the R script 'analyses_revision2.R'.Cellular Automata Simulations were performed using the script in the 'Run_simulations.R' file which requires functions in 'CA_functions.R'</p
Kin in space: social viscosity in a spatially and genetically substructured network
No full textWolf JBW, Trillmich F. Kin in space: social viscosity in a spatially and genetically substructured network. PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES. 2008;275(1647):2063-2069.Population substructuring is a fundamental aspect of animal societies. A growing number of theoretical studies recognize that who-meets-whom is not random, but rather determined by spatial relationships or illustrated by social networks. Structural properties of large highly dynamic social systems are notoriously difficult to unravel. Network approaches provide powerful ways to analyse the intricate relationships between social behaviour, dispersal strategies and genetic structure. Applying network analytical tools to a colony of the highly gregarious Galapagos sea lion (Zalophus wollebaeki), we find several genetic clusters that correspond to spatially determined 'network communities'. Overall relatedness was low, and genetic structure in the network can be interpreted as an emergent property of philopatry and seems not to be primarily driven by targeted interactions among highly related individuals in family groups. Nevertheless, social relationships between directly adjacent individuals in the network were stronger among genetically more similar individuals. Taken together, these results suggest that even small differences in the degree of relatedness can influence behavioural decisions. This raises the fascinating prospect that kin selection may also apply to low levels of relatedness within densely packed animal groups where less obvious co-operative interactions such as increased tolerance and stress reduction are important
Advanced Infrared Thermography Data Analysis for Unsteady Boundary Layer Transition Detection
No full textAdvanced data processing methods for detecting unsteady boundary layer transition in periodic aerodynamic processes by means of infrared thermography measurements are presented. The thermal radiation emitted from the heated suction surface of a pitching airfoil model in subsonic flow is measured with an infrared camera. The unsteady boundary layer transition location is detected by analyzing the difference in the infrared radiation signal over short periods of time with differential infrared thermography (DIT). The DIT method is optimized and automated in the present study, which facilitates the extension of the part of the motion period where valid DIT transition measurements are produced. Additionally, a new infrared thermography data processing method is introduced in this study. The extraction of the extrema of the measured radiation signal at fixed locations on the model surface yields instants of the motion period that relate to the occurrence of boundary layer transition. The local infrared thermography (LIT) approach can be extended to measuring the two-dimensional unsteady boundary layer transition front.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Aerodynamic
Speciation genomics [Elektronisk resurs] : A perspective from vertebrate systems
No full textSpecies are vital entities in biology. Species are generally considered to be discrete entities, consisting of a group of (usually interbreeding) individuals that are similar in phenotype and genetic composition, yet differ in significant ways from other species. The study of speciation has focussed on understanding general evolutionary mechanisms involved in the accumulation of differences both at the genetic and phenotypic level. In this thesis, I investigate incipient speciation, an early stage of divergence towards evolutionary independence in closely related natural populations. I make ample use of recent advances in sequencing technology that allow 1) characterizing phenotypic divergence at the level of the transcriptome and 2) delineate patterns of genetic variation at genome-scale from which processes are inferred by using principles of population genetic theory.In the first paper, we assembled a draft genome of the hooded crow and investigated population differentiation across a famous European hybrid zone. Comparing sequence differentiation peaks between and within the colour morphs, we could identify regions of the genome that show differentiation only between colour morphs and that could be related to gene expression profiles of the melanogenesis pathway coding for colour differences.The second paper expands on the first paper in that it includes crow population samples from across the entire Palaearctic distribution spanning two additional zones of contact between colour morphs. The results suggest that regions associated with selection against gene flow between colour morphs were largely idiosyncratic to each contact zone and emerged against a background of conserved 'islands of differentiation' due to shared linked selection.The third paper focusses on five killer whale ecotypes with distinct feeding and habitat specific adaptations. Differing levels of sequence differentiation between these ecotypes places them along a speciation continuum and provides a unique temporal cross-section of the speciation process. Using genome scans we identified regions of the genome that show ecotype specific differentiation patterns which might contain candidate genes involved in adaptation.In the fourth and final paper, I assumed a comparative genomic perspective to the problem of heterogeneous genomic differentiation during population divergence. The relatively high correlations in the diversity landscapes as well as differentiation patterns between crow, flycatcher and Darwin's Finch populations is best explained by conservation in broad-scale recombination rate and/or association with telomeres and centromeres conducive to shared, linked selection.</p
Extra‐pair paternity as a strategy to reduce the costs of heterospecific reproduction? Insights from the crow hybrid zone
No full textWithin hybrid zones of socially monogamous species, the number of mating opportunities with a conspecific can be limited. As a consequence, individuals may mate with a heterospecific (social) partner despite possible fitness costs to their hybrid offspring. Extra‐pair copulations with a conspecific may thus arise as a possible post hoc strategy to reduce the costs of hybridization. We here assessed the rate of extra‐pair paternity in the hybrid zone between all‐black carrion crows (Corvus (corone) corone ) and grey hooded crows (C. (c.) cornix ) and tested whether extra‐pair paternity (EPP) was more likely in broods where parents differed in plumage colour. The proportion of broods with at least one extra‐pair offspring and the proportion of extra‐pair offspring were low overall (6.98% and 2.90%, respectively) with no evidence of hybrid broods having higher EPP rates than purebred nests
Very-low frequency wake dynamics of an axisymmetric body
No full textThe so-called very-low-frequency (VLF) azimuthal meandering of the reversed-flow region has been shown to contribute significantly to the unsteadiness of the turbulent wake flow past a bluff body of revolution (Rigas et al. 2014; Grandemange et al. 2014). Such an erratic behavior causes a continuous change in the wake topology and, particularly due to its slow nature, has been linked with the pronounced sensitivity that turbulent wake flows typically display with respect to the boundary conditions (Klei 2012; Wolf et al. 2013; Grandemange et al. 2012). Currently, the existence of such an instability is attributed to the persistence at high Reynolds numbers of the reflectional symmetry breaking mode (RSB) at laminar regime (Fabre et al. 2008; Bury and Jardin 2012). Despite the numerous investigations, some even attempting its theoretical modeling (Rigas et al. 2015), the relation of such an instability with the main vortex shedding process has not been characterized yet. Moreover, the backflow meandering reflects a condition of indifferent equilibrium in the azimuthalradial plane, which is ultimately dictated by the axial symmetry of the flow. Such a very-low frequency dynamics however, still needs to be examined under the influence of off-nominal (i.e. asymmetric) inflow conditions. Scope of the present work is to examine how the backflow unsteadiness evolves moving away from separation and additionally, to assess how it is affected by asymmetric inflow conditions. For this purpose time-resolved stereoscopic Particle Image Velocimetry (PIV) measurements are carried in the turbulent near-wake of an ogive-cylinder at different stations downstream of the base and for varying pitch angles, whereas the velocity fluctuations are examined using a snapshot POD approach
Why time matters: Codon evolution and the temporal dynamics of dN/dS
No full textInternational audienc
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