Search results for " Selection"

A Combined Multi-Cohort Approach Reveals Novel and Known Genome-Wide Selection Signatures for Wool Traits in Merino and Merino-Derived Sheep Breeds.

2019

Merino sheep represents a valuable genetic resource worldwide. In this study, we investigated selection signatures in Merino (and Merino-derived) sheep breeds using genome-wide SNP data and two different approaches: a classical F-ST-outlier method and an approach based on the analysis of local ancestry in admixed populations. In order to capture the most reliable signals, we adopted a combined, multi-cohort approach. In particular, scenarios involving four Merino breeds (Spanish Merino, Australian Merino, Chinese Merino, and Sopravissana) were tested via the local ancestry approach, while nine pair-wise breed comparisons contrasting the above breeds, as well as the Gentile di Puglia breed, …

Larval life history, transmission strategies, and the evolution of intermediate host exploitation by complex life-cycle parasites

2007

Complex life-cycle parasites use their intermediate hosts both as an energy source and as a vessel for transmission to the next host in the life cycle. Parasites that grow rapidly to a large size may have high fitness (e.g. time spent in uninfective stages is limited), yet those that grow too aggressively may reduce host viability and their own probability of successful transmission. I examined aspects of both the growth and transmission strategy of an acanthocephalan (Acanthocephalus lucii) in its isopod intermediate host. In an experimental infection, the relative rate of larval parasite growth slowed over time, and eventually parasites seemed to reach a threshold biomass sustainable by t…

Liikunnan aineenopettajakoulutuksen opiskelijavalinnat muutoksessa

2012

Island selection on mammalian life-histories: genetic differentiation in offspring size

2008

BACKGROUND: Since Darwin's pioneering work, evolutionary changes in isolated island populations of vertebrates have continued to provide the strongest evidence for the theory of natural selection. Besides macro-evolutionary changes, micro-evolutionary changes and the relative importance of natural selection vs. genetic drift are under intense investigation. Our study focuses on the genetic differentiation in morphological and life-history traits in insular populations of a small mammal the bank vole Myodes glareolus. RESULTS: Our results do not support the earlier findings for larger adult size or lower reproductive effort in insular populations of small mammals. However, the individuals li…

Genome-wide mapping of signatures of selection using a high-density array identified candidate genes for growth traits and local adaptation in chicke…

2023

Abstract Background Availability of single nucleotide polymorphism (SNP) genotyping arrays and progress in statistical analyses have allowed the identification of genomic regions and genes under selection in chicken. In this study, SNP data from the 600 K Affymetrix chicken array were used to detect signatures of selection in 23 local Italian chicken populations. The populations were categorized into four groups for comparative analysis based on live weight (heavy vs light) and geographical area (Northern vs Southern Italy). Putative signatures of selection were investigated by combining three extended haplotype homozygosity (EHH) statistical approaches to quantify excess of haplotype homoz…

Semantics of Voids within Data: Ignorance-Aware Machine Learning

2021

Operating with ignorance is an important concern of geographical information science when the objective is to discover knowledge from the imperfect spatial data. Data mining (driven by knowledge discovery tools) is about processing available (observed, known, and understood) samples of data aiming to build a model (e.g., a classifier) to handle data samples that are not yet observed, known, or understood. These tools traditionally take semantically labeled samples of the available data (known facts) as an input for learning. We want to challenge the indispensability of this approach, and we suggest considering the things the other way around. What if the task would be as follows: how to buil…

Tutkiva oppiminen evoluution opetuksessa lukiossa

2017

Uusi opetussuunnitelma velvoittaa opettajia kokeellisuuden ja tutkimuksellisuuden hyödyntämiseen opetuksessa, ja eräs keino tähän on tutkiva oppiminen. Tutkivassa oppimisessa tietoa ei omaksuta suoraan oppikirjasta tai opettajalta, vaan sitä hankitaan tieteelle tuttujen toimintamallien, kuten kysymysten, hypoteesien, selitysten ja kokeiden avulla. Tutkivan oppimisen vaiheet muodostavat yhdessä tutkivan oppimisen polun, jossa tieto tarkentuu vaihe vaiheelta. Opiskelijoita voidaan haastaa tutkivassa oppimisessa eri tavalla riippuen ovatko tutkimuskysymykset, menetelmät tai ratkaisut annettu heille etukäteen. Tutkivaa oppimista voidaan hyödyntää erilaisten aihepiirien opetuksessa kaikenikäiste…

Introgression of mitochondrial DNA among Myodes voles: consequences for energetics?

2011

Background Introgression of mitochondrial DNA (mtDNA) is among the most frequently described cases of reticulate evolution. The tendency of mtDNA to cross interspecific barriers is somewhat counter-intuitive considering the key function of enzymes that it encodes in the oxidative-phosphorylation process, which could give rise to hybrid dysfunction. How mtDNA reticulation affects the evolution of metabolic functions is, however, uncertain. Here we investigated how morpho-physiological traits vary in natural populations of a common rodent (the bank vole, Myodes glareolus) and whether this variation could be associated with mtDNA introgression. First, we confirmed that M. glareolus harbour mtD…

Predicting valuable forest habitats using an indicator species for biodiversity

2020

Intensive management of boreal forests impairs forest biodiversity and species of old-growth forest. Effective measures to support biodiversity require detection of locations valuable for conservation. We applied species distribution models (SDMs) to a species of mature forest, the northern goshawk (Accipiter gentilis, goshawk), that is often associated with hotspots of forest biodiversity. We located optimal sites for the goshawk on a landscape scale, assessed their state under intensified logging operations and identified characteristics of goshawks' nesting sites in boreal forests. Optimal sites for the goshawk covered only 3.4% of the boreal landscape and were mostly located outside pro…

Do large‐scale associations in birds imply biotic interactions or environmental filtering?

2023

Aim There has been a wide interest in the effect of biotic interactions on species' occurrences and abundances at large spatial scales, coupled with a vast development of the statistical methods to study them. Still, evidence for whether the effects of within-trophic-level biotic interactions (e.g. competition and heterospecific attraction) are discernible beyond local scales remains inconsistent. Here, we present a novel hypothesis-testing framework based on joint dynamic species distribution models and functional trait similarity to dissect between environmental filtering and biotic interactions. Location France and Finland. Taxon Birds. Methods We estimated species-to-species association…