Biology subjects

Barta, Z.

Publications and source records attributed to Barta, Z..

10 recordsLinked to original sources

bioRxiv2024

Experimental comparison of mowing and mulching on snail communities in wet meadows

The condition of wet meadows nowadays depends mainly on human activities; the biodiversity and productivity of these habitats can only be maintained by appropriate management methods. Mowing and grazing are well-known traditional methods, but a new method, regular mulching - the fragmentation of plant material and its deposition in the area - is also increasingly used. The ecological impact of traditional management is still not fully known, and we know almost nothing about the effects of mulching. To better understand the impact of these methods we directly compared their effects on snails, an invertebrate taxon common in these habitats and known as good bioindicators. We experimentally manipulated management methods on two wet meadows in Northern Hungary, Europe, and surveyed their snail communities immediately before and one year after treatments. Our results showed that mowing had a detectable negative effect on the snail communities. On the other hand, mulching did not alter their characteristics. Therefore, mulching may be a more desirable method for short-term interventions on wet meadows, whilst at the same time also preserving their biodiversity.

ecology↗

bioRxiv2022

The effect of grey wolf (Canis lupus) and human disturbance on the activity of big game species in the Bükk Hills, Hungary

The recent return of wolves to the Hungarian forests escalates conflicts among stakeholders. Hunting management agencies communicate that the presence of wolves may change the behaviour of big game species leading to difficulties for hunting organization and logistics. Here, we take a data driven approach to explore the activity of wolves and big game species. For this purpose we analysed camera trap data, collected in the Bukk National Park, Hungary. To estimate avoidance among wolves, humans and games we calculated a non-parametric activity overlap coefficient ({Delta}4) and used a machine learning (XGBoost) model. Our results show that game species have higher overlap coefficient with wolf ({Delta}4 = 0.83-0.89) than with human activity ({Delta}4 = 0.26-0.52), because predators and games are active in the same periods of the day, mainly night and dawn, and human activity mainly takes place during daytime. We could detect the refugee effects in the case of all game species. Our XGBoost analyses only found a moderate negative effect of wolf on red deer occurrence, while human activity had higher importance value and lowered the occurrence of all three game species investigated. Our results may thus indicate that human disturbance might be more important in shaping game activity than the presence of the grey wolf in Hungary.

zoology↗

bioRxiv2022

Publication games: in the web of reciprocity

1The present processes of research assessment, i.e. focusing on one or a few, related, sciento-metrics, foster questionable authorship practices, like gifting authorship to non-contributing people. An especially harmful one of these unethical practices is the formation of publication cartels, where authors offer gift authorship to each other reciprocally. Here, by developing a simple model and a simulation of the publication process I investigate how beneficial cartels can be and what measure can be used to restrict them. My results indicate that publication cartels can significantly boost members productivity even if paper counts are weighted by the inverse of author number (the 1/n rule). Nevertheless, applying the 1/n rule generates conflicts of interest both among cartel members themselves and between members and non-members which might lead to the self-purification of the academic publishing industry.

scientific communication and education↗

bioRxiv2021

Seasonal variation of genotypes and reproductive plasticity in a facultative clonal freshwater invertebrate animal (Hydra oligactis) living in a temperate lake

Facultative sexual organisms combine sexual and asexual reproduction within a single life cycle, often switching between reproductive modes depending on environmental conditions. These organisms frequently inhabit variable seasonal environments, where favourable periods alternate with unfavourable periods, generating temporally varying selection pressures that strongly influence life history decisions and hence population dynamics. Due to the rapidly accelerating changes in our global environment today, understanding the dynamics of and genetic changes in facultative sexual populations inhabiting seasonal environments is critical to assess and prepare for additional challenges that will affect such ecosystems. In this study we aimed at obtaining insights of the seasonal population dynamics of the facultative sexual freshwater cnidarian Hydra oligactis through a combination of Restriction-site Associated Sequencing (RAD-Seq) genotyping and the collection of phenotypic data on the reproductive strategy of field-collected hydra strains. We found no significant genetic change during the two years in the study population. Clone lines were detected between seasons and even years, suggesting that clonal lineages can persist for a long time in a natural population. We also found that distinct genotypes differ in sexual reproduction frequency, but these differences did not affect whether genotypes reappeared across samplings. Our study describes changes in population genetic structure across the seasons in a hydra population for the first time, providing key insights into the biology of the species, while also contributing to understanding the population biology of facultative sexual species inhabiting freshwater ecosystems.

ecology↗

bioRxiv2021

Regulatory Modules of Human Thermogenic Adipocytes: Functional Genomics of Meta-Analyses Derived Marker-Genes

Recently, ProFAT and BATLAS scores have been offered to determine thermogenic status of adipocytes using expression pattern of brown and white marker-genes. In this work, we investigated the functional context of these genes. Although the two meta-analyses based marker-gene lists have little overlap, their enriched pathways show strong coincides suggesting they may better characterize adipocytes. We demonstrate that functional genomics of the annotated genes in common pathways enables an extended analysis of thermogenesis regulation, generates testable hypotheses supported by experimental results in human adipocytes with different browning potential and may lead to more global conclusions than single-state studies. Our results imply that different biological processes shape brown and white adipocytes with presumed transitional states. We propose that the thermogenic adipocyte phenotype require both repression of whitening and induction of browning. These simultaneous actions and hitherto unnoticed regulatory modules, such as the exemplified HIF1A that may directly act at UCP1 promoter, can set new direction in obesity research. HighlightsO_LIIntegrated pathways better characterize brown adipocytes than marker-genes C_LIO_LIDifferent processes shape the brown and white adipocyte phenotypes C_LIO_LIThermogenic phenotype may require simultaneous repression of whitening and induction of browning C_LIO_LIProtein network analyses reveals unnoticed regulatory modules of adipocyte phenotype C_LIO_LIHIF1A may regulate thermogenesis by direct control of UCP1 gene-expression C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=186 SRC="FIGDIR/small/428057v2_ufig1.gif" ALT="Figure 1"> View larger version (75K): org.highwire.dtl.DTLVardef@b4c730org.highwire.dtl.DTLVardef@813b58org.highwire.dtl.DTLVardef@5f3398org.highwire.dtl.DTLVardef@344eb5_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2020

Experimental manipulation of body size alters senescence in hydra

Body size has a fundamental impact on the ecology and physiology of animals. Large size, for instance, is often associated with increased fecundity and reproductive success. A persistent correlation between body size and individual longevity is also observed across the animal world, although this relationship proved difficult to understand due to the inseparability of body size from growth rate and the widespread collinear relationship between body size with other life history traits. Here, we used Hydra oligactis, a freshwater cnidarian with high tissue plasticity and inducible ageing as an experimental system to understand the causal roles of body size on reproduction and senescence. We first show that large size predicts accelerated sexual development, increased fecundity and reduced survival in a population sample of this species kept under common garden conditions in the laboratory. Next, using phenotypic engineering, we experimentally increased or decreased body size by reciprocally grafting pieces of the body column differing in size between hydra polyps. Experimentally reduced body size was associated with delayed sexual development and reduced fecundity. In parallel, post-reproductive survival was significantly higher in polyps with reduced size. These results suggest that small hydra can physiologically detect their reduced body size and adjust reproductive decisions to achieve a higher post-reproductive survival. Our observations offer a new perspective on why smaller individuals within a species live longer by suggesting a growth-independent link between body size, reproduction and senescence.

evolutionary biology↗

bioRxiv2020

Varietas delectat: groups with diverse personalities mitigate physiological stress in a songbird

Social groups often consist of diverse phenotypes, including personality types, and this diversity is known to affect the functioning of the group as a whole. Social selection theory proposes that group composition (i.e. social environment) also influences the performance of individual group members. However, the effect of group behavioural composition on group members remains largely unexplored, and it is still contentious whether individuals benefit more in a social environment with homogeneous or diverse behavioural composition. We experimentally formed groups of house sparrows Passer domesticus with high and low diversity of personality (exploratory behaviour), and found that their physiological state (body condition, physiological stress and oxidative damage) improved with increasing group-level diversity of personality. These findings demonstrate that group personality composition affects the condition of group members and individuals benefit from social heterosis (i.e. associating with a diverse set of behavioural types). This aspect of the social life can play a key role in affiliation rules of social animals and might explain the evolutionary coexistence of different personalities in nature.

ecology↗

bioRxiv2018

Spatio-temporal structure and reproductive success in a rook (Corvus frugilegus) colony

We have studied how individual decisions about timing of breeding and nest location affected the reproductive success of rooks by tracing the formation of a rook breeding colony in Hortobagy NP (Hungary), during the breeding season in 1999.\n\nWe have found that birds who built nests earlier also laid eggs earlier and had larger clutch size but had no had more offspring than late nesters. Distance of the nest from the centre or edge of the colony did not affect the reproductive success though rooks generally settled closer to the centre and further from the edge than it can be expected by assuming random distribution. The colony showed high breeding synchrony since date of egg laying varied less than date of nesting but synchrony did not influence the breeding success. Hatchlings survival rate and number of offspring increased with local nest density and rooks clustered their nests more than it can be expected by random settlement. Nest sites of early and late nesters did not differ regarding the distance from the centre or the edge of the colony but late nesters chose nest sites in more densely populated regions.\n\nThe results indicate that individuals may follow different strategies to increase their reproductive success. It is prospectively advantageous to build the nest and lay eggs earlier, in turn, its worth nesting in already more densely nested areas for late beginners. We suggest that a game theoretical approach may be useful if we try to understand the adaptive significance of colonial breeding.

animal behavior and cognition↗

bioRxiv2017

Demographic causes of adult sex ratio variation and their consequences for parental cooperation

The adult sex ratio (ASR) is a fundamental concept in population biology, sexual selection, and social evolution. However, it remains unclear which demographic processes generate ASR variation and how biases in ASR in turn affect social behaviour. Here, we evaluate the demographic mechanisms shaping ASR and their consequences for parental cooperation using detailed survival, fecundity, and behavioural data on 6,119 individuals from six wild shorebird populations exhibiting flexible parental strategies. We show that these closely related populations express strikingly different ASRs, despite having similar ecologies and life histories, and that ASR variation is largely driven by sex differences in the apparent survival of juveniles. Furthermore, families in populations with biased ASRs were predominantly tended by a single parent, suggesting that parental cooperation breaks down with unbalanced sex ratios. Taken together, our results indicate that sex biases emerging during early life have profound consequences for social behaviour.

ecology↗

bioRxiv2017

Reproductive mode, stem cells and regeneration in a freshwater cnidarian with post-reproductive senescence

In many basal metazoans both somatic and reproductive functions are performed by cellular derivatives of a single multipotent stem cell population. Reproduction can drain these stem cell pools, imposing a physiological cost with subsequent negative effects on somatic maintenance functions. In the freshwater cnidarian Hydra oligactis both asexual (budding) and sexual reproductive modes (production of resting eggs) are present, and both of these are dependent on a common pool of interstitial stem cells. Resting eggs tolerate abiotic conditions which neither the parental animals, nor asexual offspring can survive (e.g. freezing). Therefore, when facing unfavorable conditions and increased mortality risk, hydra polyps are expected to show higher differentiation of interstitial stem cells into germ cells (i.e. sexual reproduction), compared to other cell types needed for selfmaintenance or asexual reproduction. Here, by comparing sexually and asexually reproducing individuals to non-reproductives, we studied the physiological costs of reproduction (size of interstitial stem cell pools, their somatic derivatives and regeneration rate, which is dependent on these cell types) in H. oligactis polyps from a free-living Hungarian population prior to the onset of winter. Sexual individuals (but not asexuals) were characterized by significantly smaller interstitial stem cell pools, fewer somatic derivatives (nematoblasts involved in food capture) and lower regeneration ability compared to non-reproductives. We also found a negative correlation between germ cell counts and stem cell numbers in males (but not in females). These results show that the physiological costs of reproduction are higher for sexual individuals. They also suggest that increased differentiation of stem cells into gametes might limit investment into somatic functions in hydra polyps. Exhaustion of cellular resources (stem cells) could be a major mechanism behind the extreme post-reproductive senescence observed in this species.

evolutionary biology↗