Medicine by Alexandros G. Sfakianakis,Αλέξανδρος Γ. Σφακιανάκης: M

bioRxiv Subject Collection: Evolutionary Biology

Sources of Intraspecific Morphological Variation in Vipera seoanei: Allometry, Sex, and Colour Phenotype [NEW RESULTS]

Snakes frequently exhibit ontogenetic and sexual variation in head dimensions, as well as the occurrence of distinct colour morphotypes which might be fitness-related. In this study, we used linear biometry and geometric morphometrics to investigate intraspecific morphological variation related to allometry and sexual dimorphism in Vipera seoanei, a species that exhibits five colour morphotypes, potentially subjected to distinct ecological pressures. We measured body size (SVL), tail length and head...

bioRxiv Subject Collection: Evolutionary Biology

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Latitudinal variation in cold tolerance and the role of vrille and Yolk protein 3 in enhancing cold adaptation in highly cold-tolerant insect species [NEW RESULTS]

Identifying elements that enhance insect adaptation into changing environmental conditions is challenging, especially for traits affected by multiple factors. We studied latitudinal variation in the basal cold tolerance and body colour of two highly cold-tolerant Drosophila virilis group species, D. montana and D. flavomontana, in climatically diverse locations in North America. D. montana, which is generally found on higher latitudes and altitudes than D. flavomontana, was darker and more cold-tolerant...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Population connectivity predicts vulnerability to white-nose syndrome in the Chilean myotis (Myotis chiloensis) - a genomics approach [NEW RESULTS]

Despite its peculiar distribution, the biology of the southernmost bat species in the world, the Chilean myotis (Myotis chiloensis), has garnered little attention so far. The species has a north-south distribution of c. 2800 km, mostly on the eastern side of the Andes mountain range. Use of extended torpor occurs in the southernmost portion of the range, putting the species at risk of bat white-nose syndrome (WNS), a fungal disease responsible for massive population declines in North American bats....

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Temperature change has the same effect as genetic variation on a morphological trait involved in reproductive isolation between Drosophila sister species [NEW RESULTS]

Phenotypic plasticity, the capacity of one genotype to generate distinct phenotypes in different environments, is usually thought to facilitate species divergence by opening novel ecological niches to plastic individuals. Here we reveal a case of speciation where this "plasticity first" scenario might not hold. Male genitalia are usually extremely divergent between closely related species, but relatively constant within one species. Under the lock-and-key hypothesis, rapid morphological evolution...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

How do invasion syndromes evolve? An experimental evolution approach using the ladybird Harmonia axyridis [NEW RESULTS]

Experiments comparing native to introduced populations or distinct introduced populations to each other show that phenotypic evolution is common and often involves a suit of interacting phenotypic traits. We define such sets of traits that evolve in concert and contribute to the success of invasive populations as an "invasion syndrome". The invasive Harlequin ladybird Harmonia axyridis displays such an invasion syndrome with, for instance, females from invasive populations being larger and heavier...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Evolution of cross-tolerance to environmental stresses in populations of Drosophila melanogaster selected for increased resistance to cold stress [NEW RESULTS]

Empirical studies on the promiscuous species of Drosophila revealed that the laboratory evolution of resistance to a certain type of environmental stress can impact the ability of the organism to resist other kinds of stresses. The mechanisms of resistance to a particular stress are specialized and costly, then, mechanisms of resistance to other stresses can be negatively affected. However, it is also possible that at least a part of the stress resistance mechanisms is generic. With this premise...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Meta-population structure and the evolutionary transition to multicellularity [NEW RESULTS]

The evolutionary transition to multicellularity has occurred on numerous occasions, but transitions to complex life forms are rare. While the reasons are unclear, relevant factors include the intensity of within- versus between-group selection that are likely to shape the course of life cycle evolution. A highly structured environment eliminates the possibility of mixing between evolving lineages, thus ensuring strong competition between groups. Less structure intensifies competition within groups,...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Transposable element landscape in Drosophila populations selected for longevity [NEW RESULTS]

Transposable elements (TEs) inflict numerous negative effects on health and fitness as they replicate by integrating into new regions of the host genome. Even though organisms employ powerful mechanisms to demobilize TEs, transposons gradually lose repression during aging. The rising TE activity causes genomic instability and was implicated in age-dependent neurodegenerative diseases, inflammation and the determination of lifespan. It is therefore conceivable that long-lived individuals have improved...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Population genomics insights into the recent evolution of SARS-CoV-2 [NEW RESULTS]

The current coronavirus disease 2019 (COVID-19) pandemic is caused by the SARS-CoV-2 virus and is still spreading rapidly worldwide. Full-genome-sequence computational analysis of the SARS-CoV-2 genome will allow us to understand the recent evolutionary events and adaptability mechanisms more accurately, as there is still neither effective therapeutic nor prophylactic strategy. In this study, we used population genetics analysis to infer the mutation rate and plausible recombination events that may...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Two decades of suspect evidence for adaptive DNA-sequence evolution - Less negative selection misconstrued as positive selection [NEW RESULTS]

Evidence for biological adaptation is often obtained by studying DNA sequence evolution. Since the analyses are affected by both positive and negative selection, studies usually assume constant negative selection in the time span of interest. For this reason, hundreds of studies that conclude adaptive evolution might have reported false signals caused by relaxed negative selection. We test this suspicion two ways. First, we analyze the fluctuation in population size, N, during evolution. For example,...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Complementation can maintain a quasispecies of drug sensitive and resistant HIV [NEW RESULTS]

HIV exists as multiple genotypes in a single infected individual referred to as a quasispecies. Here we reproduced a quasispecies by moderate selective pressure using an HIV reverse transcriptase inhibitor. The drug resistant genotype never completely supplanted the drug sensitive genotype, which stabilized at about 20 percent of viral sequences. Single-cell sequencing showed that resistant genotype frequency plateaued when cells were co-infected with sensitive and resistant genotypes, suggesting...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Identifying female phenotypes that promote behavioral isolation in a sexually dimorphic species of fish (Etheostoma zonale) [NEW RESULTS]

In sexually dimorphic species characterized by exaggerated male ornamentation, behavioral isolation is often attributed to female preferences for conspecific male signals. Yet, in a number of sexually dimorphic species, male mate choice also results in behavioral isolation. In many of these cases, the female traits that mediate species boundaries are unclear. Females in sexually dimorphic species typically lack many of the elaborate traits that are present in males and that are often diagnostic of...

bioRxiv Subject Collection: Evolutionary Biology

Thu Apr 23, 2020 03:00

Megaevolutionary dynamics in reptiles and the role of adaptive radiations in evolutionary innovation [NEW RESULTS]

Adaptive radiations are long believed to be responsible for the origin of phenotypic diversity and new body plans among higher clades in the fossil record. However, few studies have assessed rates of phenotypic evolution and disparity across broad scales of time to understand the evolutionary dynamics behind the origin of major clades, or how they relate to rates of molecular evolution. Here, we provide a total evidence approach to this problem using the largest available data set on diapsid reptiles....

bioRxiv Subject Collection: Evolutionary Biology

Wed Apr 22, 2020 03:00

CONVERGENT EVOLUTION OF CONSERVED MITOCHONDRIAL PATHWAYS UNDERLIES REPEATED ADAPTATION TO EXTREME ENVIRONMENTS [NEW RESULTS]

Extreme environments test the limits of life; yet, some organisms thrive in harsh conditions. Extremophile lineages inspire questions about how organisms can tolerate physiochemical stressors and whether the repeated colonization of extreme environments is facilitated by predictable and repeatable evolutionary innovations. We identified the mechanistic basis underlying convergent evolution of tolerance to hydrogen sulfide (H2S)--a toxicant that impairs mitochondrial function--across evolutionarily...

bioRxiv Subject Collection: Evolutionary Biology

Wed Apr 22, 2020 03:00

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SAGE Publications Ltd: Journal of International Medical Research: Table of Contents