Search results for "evolutionary"

Differential Greek and northern African migrations to Sicily are supported by genetic evidence from the Y chromosome

2009

The presence or absence of genetic heterogeneity in Sicily has long been debated. Through the analysis of the variation of Y-chromosome lineages, using the combination of haplogroups and short tandem repeats from several areas of Sicily, we show that traces of genetic flows occurred in the island, due to ancient Greek colonization and to northern African contributions, are still visible on the basis of the distribution of some lineages. The genetic contribution of Greek chromosomes to the Sicilian gene pool is estimated to be about 37% whereas the contribution of North African populations is estimated to be around 6%. In particular, the presence of a modal haplotype coming from the southern…

Analysis of DNA sequence variation within marine species using Beta-coalescents

2013

We apply recently developed inference methods based on general coalescent processes to DNA sequence data obtained from various marine species. Several of these species are believed to exhibit so-called shallow gene genealogies, potentially due to extreme reproductive behaviour, e.g. via Hedgecock's "reproduction sweepstakes". Besides the data analysis, in particular the inference of mutation rates and the estimation of the (real) time to the most recent common ancestor, we briefly address the question whether the genealogies might be adequately described by so-called Beta coalescents (as opposed to Kingman's coalescent), allowing multiple mergers of genealogies. The choice of the underlying…

2021

Studies on the function of PRDM9 in model systems and its evolution during vertebrate divergence shed light on the basic molecular mechanisms of hybrid sterility and its evolutionary consequences. However, information regarding PRDM9-homolog, PRDM7, whose origin is placed in the primate evolutionary tree, as well as information about the fast-evolving DNA-binding zinc finger array of strepsirrhine PRDM9 are scarce. Thus, we aimed to narrow down the date of the duplication event leading to the emergence of PRDM7 during primate evolution by comparing the phylogenetic tree reconstructions of representative primate samples of PRDM orthologs and paralogs. To confirm our PRDM7 paralogization patt…

Whole mitochondrial genomes unveil the impact of domestication on goat matrilineal variability

2015

Background The current extensive use of the domestic goat (Capra hircus) is the result of its medium size and high adaptability as multiple breeds. The extent to which its genetic variability was influenced by early domestication practices is largely unknown. A common standard by which to analyze maternally-inherited variability of livestock species is through complete sequencing of the entire mitogenome (mitochondrial DNA, mtDNA). Results We present the first extensive survey of goat mitogenomic variability based on 84 complete sequences selected from an initial collection of 758 samples that represent 60 different breeds of C. hircus, as well as its wild sister species, bezoar (Capra aega…

Does fragmentation of wetlands affect gene flow in sympatric Acrocephalus warblers with different migration strategies?

2015

Wetlands are naturally patchy habitats, but patchiness has been accentuated by the extensive wetlands loss due to human activities. In such a fragmented habitat, dispersal ability is especially important to maintain gene flow between populations. Here we studied population structure, genetic diversity and demographic history of Iberian and North African populations of two wetland passerines, the Eurasian reed warbler Acrocephalus scirpaceus and the moustached warbler Acrocephalus melanopogon. These species are closely related and sympatric in our study sites, but the reed warbler is a long-distance migrant and widespread bird while the moustached warbler is resident or migrates over short d…

The Random Neural Network Model for the On-line Multicast Problem

2005

In this paper we propose the adoption of the Random Neural Network Model for the solution of the dynamic version of the Steiner Tree Problem in Networks (SPN). The Random Neural Network (RNN) is adopted as a heuristic capable of improving solutions achieved by previously proposed dynamic algorithms. We adapt the RNN model in order to map the network characteristics during a multicast transmission. The proposed methodology is validated by means of extensive experiments.

Molecular evolution: Evidence for the monophyletic origin of multicellular animals

1995

Aging in Sponges

2003

The sponges (phylum Porifera) are the lowest and phylogenetically oldest, still extant phylum of Metazoa [1, 2]. These animals are considered as the evolutionary earliest living relicts of the successful transition from the (perhaps) unicellular to the multicellular state [2]. Evidence has been presented by molecular phylogenetic analysis that sponges share a common ancestor with the other metazoan phyla, the hypothetical Urmetazoa [2, 3].

2001

Symbioses between unicellular and multicellular organisms have contributed significantly to the evolution of life on Earth. As exemplified by several studies of bacterium-insect symbioses, modern genomic techniques are providing exciting new information about the molecular basis and the biological roles of these complex relationships, revealing for instance that symbionts have lost many genes for functions that are provided by the host, but that they can provide amino acids that the host cannot synthesize.

Evolutionary biology and beliefs : how ideology can draw different social stances from science

2016

Agreeing that there are often strong connections between fields of science and the ideological convictions of those producing the science, this essay shows that the connections are often complex and rarely straightforward. Taking the example of evolutionary biology, by looking at three key figures ? Herbert Spencer, Charles Darwin and Alfred Russel Wallace ? it is shown how very different social beliefs can lead to very different social conclusions being drawn from one?s science. It is argued that this message should be kept firmly in mind by those who today would draw social conclusions from science, for instance suggesting that Darwinian evolutionary biology leads straight to the social p…