Most aquatic ecosystems are increasingly threatened by the introduction and spread of alien macrophytes, which can alter community structure and ecosystem functioning through competition. This study examined the interactions between the naturalized aquatic macrophyte Pontederia crassipes Mart. (water hyacinth) and two introduced species, Hydrocotyle umbellata L. and Salvinia auriculata Aubl, under open-air experimental conditions. Plants were grown in mixed cultures in two environmental setups, deep water (DW) and constructed wetlands (CW), using water from the El-Mahmoudia Canal to evaluate interspecific competition and growth performance. The results revealed that P. crassipes had a generally positive effect on H. umbellata, while it rapidly declined and died within three months in all mixed cultures, suggesting limited competitive ability under the tested conditions. H. umbellata showed significantly enhanced growth in CW compared to DW, with increased petiole length, laminae index, and rhizoid length, indicating its adaptability and competitive potential in structured aquatic environments. Although S. auriculata exhibited no statistically significant differences between CW and DW, it consistently performed slightly better in CW and demonstrated a competitive edge by displacing P. crassipes in mixed cultures. However, when H. umbellata and S. auriculata were grown together, both species experienced reduced growth, especially in petiole and rhizoid length, highlighting the impact of interspecific competition. These findings suggest that under the experimental conditions examined, P. crassipes showed no clear evidence of a competitive effect, whereas interactions between H. umbellata and S. auriculata should be considered in the management of aquatic plant communities, particularly in constructed wetlands.
This paper presents a mathematical prey-predator model to investigate the intricate, non-linear relationships between phytoplankton, zooplankton, and fish in a marine ecosystem. The model incorporates fundamental ecological processes, including logistic phytoplankton growth, zooplankton grazing on phytoplankton, and fish predation on zooplankton. Additionally, we consider the impact of extreme environmental pressures, including a fear effect, on the marine ecosystem. First, we examine the positivity and boundedness of the proposed model. Furthermore, all the equilibrium points are determined, and the local stability of the system is analyzed around each equilibrium point. The research also explores the impact of rising environmental pressure on population sizes among species. It concludes that greater environmental pressure could drive the system to extinction via a branch point bifurcation. Minimal environmental pressure will destabilize the system via a Hopf bifurcation. We also explore the impact of the fear cost on the zooplankton population and conclude that greater fear costs can cause system instability via another Hopf bifurcation. Theoretical calculations are confirmed by numerical simulations carried out using Mathematica and MATLAB software.
It has previously been thought that the social brain hypothesis applies in its full quantitative form only to primates because only primates have bonded social groups. However, previous tests have overlooked the fact that the social brain hypothesis actually consists of a series of grades, not a single homogenous relationship. The presence of grades can cause conventional regression analysis to radically underestimate the slope of a relationship. Here, we test whether the social brain relationship with grades explains the pattern of group sizes observed in carnivores and insectivores. Using more appropriate brain indices and less error-prone statistical methods, we show that carnivores do exhibit a quantitative social brain relationship. More importantly, they map directly onto the primate socio-cognitive grades, dividing between loose sociality and bonded sociality paralleling the pattern observed in primates. Although insectivores do not exhibit a full quantitative social brain relationship, their neocortex size does increase with the transition from solitary to a loose form of pairliving in a way similar to that found in other mammals and birds. These findings suggest that common trajectories and constraints might underlie social evolution in all mammals. In particular, a transition from a solitary lifestyle to a form of pairliving may have been an important early transition in the evolution of mammalian sociality. These results raise questions as to whether the different carnivore grades exhibit similar kinds of cognition to those found in the corresponding primate grades.
Gaining a clear picture of how microevolutionary change unfolds in natural populations demands high-resolution genomic data sampled repeatedly over time. While seasonal adaptation has been documented in Drosophila melanogaster, long-term directional genomic changes within single natural populations remain poorly resolved, particularly in understudied regions such as the Eastern Mediterranean and Anatolia. Here, we present a seven-year (2015–2021) temporal Pool-Seq analysis of a natural D. melanogaster population sampled from a single locality (Yeşilöz, Ankara, Turkey). We analyzed Pool-Seq samples collected in June, August, September, and October, representing post-winter emergence, peak summer temperatures, and autumn transition shocks. Using multiple ANCOVA models across 1,526,725 SNPs, we identified 9,055 SNPs showing significant directional allele frequency shifts across years (Benjamini–Hochberg q < 0.05). These SNPs mapped to 395 genes harboring HIGH or MODERATE functional impact variants. The sensitivity model excluding the low-coverage September 2015 cohort yielded 8,200 year-significant SNPs with highly consistent results, demonstrating that this cohort did not bias our primary findings. A second, highly conservative joint-correction model identified a core set of 627 SNPs. Across all models, seasonal allele frequency variation within years was negligible, and climatic principal components (temperature and humidity-related) explained no additional variance beyond the overall year effect. Gene Ontology enrichment analysis revealed a pronounced over-representation of genes associated with zinc ion binding, transition metal ion binding, and metallopeptidase activity (Molecular Function). Length-adjusted logistic regression confirmed these associations were independent of gene size, whereas an initially significant cellular component term (plasma membrane) did not survive length control and was not interpreted further. Overall, our findings provide compelling evidence for sustained directional genomic change in a natural D. melanogaster population, with primary functional targets concentrated in transcriptional regulation (zinc-finger, metal-ion binding) and proteolytic processes.
The Amaranthus genus (Amaranthaceae), which includes approximately 70 species globally, poses a significant risk of biological invasion in China. The current study simulated the potential distribution of three invasive Amaranthus species (Amaranthus blitum L., Amaranthus spinosus L. and Amaranthus palmeri S.Wats.) under climate scenarios in China. The models achieved excellent prediction performance, with A. blitum, A. spinosus and A. palmeri having area under the curve values of 0.948, 0.926 and 0.928, respectively. Temperature Seasonality (BIO4) is the primary factor influencing the distribution of A. blitum, while the distribution of A. spinosus is mainly driven by both Temperature Seasonality (BIO4) and Annual Precipitation (BIO12). The distribution of A. palmeri is determined by both Precipitation Seasonality (BIO15) and elevation (Elev). Under current climate conditions, the highly suitable areas for A. blitum and A. spinosus are concentrated in South and Southwest China, whereas those for A. palmeri, are primarily distributed in the North China Plain. Under future climate scenarios, the suitable areas for A. blitum exhibited a high degree of climate envelope conservatism, with its distribution centroid showing only a slight localized southwestward fluctuation around its original distribution. In contrast, the suitable areas for A. spinosus exhibited a slight overall expansion toward the northeast, and its centroid showed signs of retreating southwestward under SSP585-2070s. Amaranthus palmeri had a significant and long-distance shift northwestward, which is strongly linked to changing thermal conditions. This study revealed the spatiotemporal dynamics of three invasive Amaranthus species under current and future climate scenarios and provides a scientific basis for developing proactive early warning management response strategies for these invasive species in China.
