Search results for "evolutionary"

A Successful Crowdsourcing Approach for Bird Sound Classification

2023

Automated recorders are increasingly used in remote sensing of wildlife, yet automated methods of processing the audio remains challenging. Identifying animal sounds with machine learning provides a solution, but optimizing the models requires annotated training data. Producing such data can require much manual effort, which could be alleviated by engaging masses to contribute to research and share the workload. Birdwatchers are experts on identifying bird vocalizations and form an ideal focal audience for a citizen science project aiming for the required multitudes of annotated avian audio data. For this purpose, we launched a web portal that was targeted and advertised to Finnish birdwatc…

Human brain evolution : how the increase of brain plasticity made us a cultural species

2016

Why are humans so different from other primate species? What makes us so capable of creating language, art and music? The specializations in human brain anatomy that are responsible for our unique behavioral and cognitive traits evolved over a very short period of evolutionary time (between six and eight million years). Recent evidence suggests that, alongside a reorganization of the brain and an increase in its size, neural plasticity may also play a major role in explaining the evolutionary history of our species. Plasticity is the propensity of the brain to be molded by external influences, including the ecological, social and cultural context. The impact of these environmental influence…

2015

AbstractThe genetic conflict between parents and their offspring is a cornerstone of kin selection theory and the gene-centred view of evolution, but whether it actually occurs in natural systems remains an open question. Conflict operates only if parenting is driven by genetic trade-offs between offspring performance and the parent’s ability to raise additional offspring, and its expression critically depends on the shape of these trade-offs. Here we investigate the occurrence and nature of genetic conflict in an insect with maternal care, the earwig Forficula auricularia. Specifically, we test for a direct response to experimental selection on female future reproduction and correlated res…

The effect of genetic robustness on evolvability in digital organisms

2008

Abstract Background Recent work has revealed that many biological systems keep functioning in the face of mutations and therefore can be considered genetically robust. However, several issues related to robustness remain poorly understood, such as its implications for evolvability (the ability to produce adaptive evolutionary innovations). Results Here, we use the Avida digital evolution platform to explore the effects of genetic robustness on evolvability. First, we obtained digital organisms with varying levels of robustness by evolving them under combinations of mutation rates and population sizes previously shown to select for different levels of robustness. Then, we assessed the abilit…

Cancer growth dynamics: stochastic models and noise induced effects

2009

In the framework of the Michaelis‐Menten (MM) reaction kinetics, we analyze the cancer growth dynamics in the presence of the immune response. We found the coexistence of noise enhanced stability (NES) and resonant activation (RA) phenomena which act in an opposite way with respect to the extinction of the tumor. The role of the stochastic resonance (SR) in the case of weak cancer therapy has been analyzed. The evolutionary dynamics of a system of cancerous cells in a model of chronic myeloid leukemia (CML) is investigated by a Monte Carlo approach. We analyzed the effects of a targeted therapy on the evolutionary dynamics of normal, first‐mutant and cancerous cell populations. We show how …

Temperature dependence of spontaneous mutation rates.

2021

Mutation is the source of genetic variation and the fundament of evolution. Temperature has long been suggested to have a direct impact on realized spontaneous mutation rates. If mutation rates vary in response to environmental conditions, such as the variation of the ambient temperature through space and time, they should no longer be described as species-specific constants. By combining mutation accumulation with whole-genome sequencing in a multicellular organism, we provide empirical support to reject the null hypothesis of a constant, temperature-independent mutation rate. Instead, mutation rates depended on temperature in a U-shaped manner with increasing rates toward both temperature…

Variation in RNA virus mutation rates across host cells.

2014

It is well established that RNA viruses exhibit higher rates of spontaneous mutation than DNA viruses and microorganisms. However, their mutation rates vary amply, from 10−6 to 10−4 substitutions per nucleotide per round of copying (s/n/r) and the causes of this variability remain poorly understood. In addition to differences in intrinsic fidelity or error correction capability, viral mutation rates may be dependent on host factors. Here, we assessed the effect of the cellular environment on the rate of spontaneous mutation of the vesicular stomatitis virus (VSV), which has a broad host range and cell tropism. Luria-Delbrück fluctuation tests and sequencing showed that VSV mutated similarly…

Adaptive trends of sequence compositional complexity over pandemic time in the SARS-CoV-2 coronavirus

2021

In the brief time since the outbreak of the COVID 19 pandemic, and despite its proofreading mechanism, the SARS-CoV-2 coronavirus has accumulated a significant amount of genetic variability through recombination and mutation events. To test evolutionary trends that could inform us on the adaptive process of the virus to its human host, we summarize all this variability in the Sequence Compositional Complexity (SCC), a measure of genome heterogeneity that captures the mutational and recombinational changes accumulated by a nucleotide sequence along time. Despite the brief time elapsed, we detected many differences in the number and length of compositional domains, as well as in their nucleot…

Aggressive mimicry coexists with mutualism in an aphid

2015

Understanding the evolutionary transition from interspecific exploitation to cooperation is a major challenge in evolutionary biology. Ant-aphid relationships represent an ideal system to this end because they encompass a coevolutionary continuum of interactions ranging from mutualism to antagonism. In this study, we report an unprecedented interaction along this continuum: aggressive mimicry in aphids. We show that two morphs clonally produced by the aphid Paracletus cimiciformis during its root-dwelling phase establish relationships with ants at opposite sides of the mutualism-antagonism continuum. Although one of these morphs exhibits the conventional trophobiotic (mutualistic) relations…

Phylogeny and inflorescences of Berberidaceae — a morphological survey

1995

The 13 genera of Berberidaceae are investigated morphologically and cladistically in order to examine the phylogenetic relationships among the extant taxa. Cladistic analysis of 59 morphological characters using PAUP resulted in one most parsimonious tree. In the present paper main emphasis is put on inflorescence morphological features, which contributes eight characters to the current data matrix. The analysis resulted in four major clades. Nandina has a basal position, and the next clade includes Berberis and Mahonia. Ranzania is sister genus to Jeffersonia, Diphylleia/Podophyllum and Leontice/Bongardia. These all form the sister group to a clade in which Achlys is sister taxon to Epimed…