BMC ecology and evolution最新文献

Background: Most Drosophila species lay their eggs on a wide range of overripe or rotting fruits. By contrast, D. suzukii has evolved a strong preference for undamaged ripe fruits, a shift that has made it one of the most important pests of small fruits worldwide. Growing evidence suggests that this host preference shift is linked to modifications in the fly's olfactory system. Unlike D. melanogaster, D. suzukii is attracted by ripe strawberry volatile compounds for oviposition.

Results: In this study, we investigated the mechanisms underlying this behavioral divergence. We identified two strawberry volatiles, hexanoic acid and methyl butyrate, that, together recapitulate the species-specific oviposition preferences. D. suzukii is attracted by this two-component blend, whereas in D. melanogaster attraction to this blend is suppressed by an OR-dependent mechanism. In vivo calcium imaging of the antennal lobes revealed that the perception of these compounds is largely conserved between species, with only subtle differences. This suggests that the divergence in the olfactory perception of this two-component blend arises downstream of sensory neuron activity, within higher levels of olfactory processing.

Conclusions: Taken together, our results suggest that D. melanogaster has evolved an as-yet unidentified mechanism for integrating olfactory signals that suppresses attraction to unsuitable oviposition substrates when multiple key volatile are detected simultaneously.

Background: Red mullet (Mullus barbatus) is a key species in Mediterranean fisheries, yet its stock structure and population dynamics remain poorly understood due to a lack of comprehensive genomic resources. This study provides the first high-quality reference genome for M. barbatus and a comprehensive set of SNP markers to investigate its population structure and adaptive potential across the Mediterranean.

Results: Using the newly generated chromosome-level reference genome, we re-analyzed a Mediterranean-wide reduced-representation genomic dataset. Our analysis reveals a panmictic population structure with strong genetic connectivity across the species' range, likely driven by extensive larval dispersal and multigenerational gene flow. Despite minimal genome-wide differentiation, outlier analysis identified candidate loci under directional selection, linked to key biological processes such as ontogeny and environmental adaptation.

Conclusions: This study presents the first genomic resource for M. barbatus, providing valuable insights into its genetic structure and adaptive mechanisms. While the identification of loci under selection offers promising leads, these findings are preliminary due to the limited genomic coverage of the dataset. Nonetheless, they pave the way for future genomic studies to explore how M. barbatus adapts to environmental and anthropogenic pressures. These results hold significant implications for the sustainable management of Mediterranean fisheries, especially in the context of climate change and conservation.

Background: Following historic natural disturbances, interspecific hybridization has been documented between several Nothofagus species in Chilean forests. While hybridization can contribute to survival by enhancing genetic diversity, it may lead to developmental instability, reflected in higher leaf fluctuating asymmetry. Our goal was to investigate if hybrid individuals between N. pumilio and N. antarctica had developmental instabilities observable through high leaf fluctuating asymmetry and to examine evidence of potential hybridization and population genetic structure across five Nothofagus species.

Results: We collected N. pumilio, N. antarctica, and putative hybrid leaves for morphological analysis and chloroplast DNA sequencing. We also performed population genetic analysis on additional Nothofagus species (N. pumilio, N. antarctica, N. betuloides, N. dombeyi, and N. nitida) using microsatellite markers (eight loci). The putative hybrids with intermediate phenotypes displayed significantly higher fluctuating asymmetry than morphologically unambiguous N. pumilio and N. antarctica. Yet despite clear phenotypic differences, N. pumilio and N. antarctica shared cpDNA and had almost identical microsatellite composition. Our microsatellite analysis of five Nothofagus species found high allelic variation within species and subpopulations but low genetic structure between species and populations.

Conclusions: Our findings reveal possible developmental instability in putative N. pumilio and N. antarctica hybrids characterized by leaf morphology. Though nuclear ITS sequences have phylogenetically differentiated pure Nothofagus taxa, we found little to no genetic differentiation between sympatric or allopatric Nothofagus species from microsatellite data, particularly N. pumilio and N. antarctica. This is a surprising result given the clear morphological and biogeographical differences between the Chilean Nothofagus. While N. pumilio and N. antarctica are named species, matching the ecological species concept, whole genome analyses is needed to test if they are distinct enough to be classified as separate species under the phylogenetic species concept.

Background: Thyroid hormones regulate multiple physiological functions, including metabolism, reproduction, and metamorphosis. Although there are variations in thyroid hormone signaling between populations and species, the causative mutations underlying these variations have rarely been identified. Here, we investigated whether information regarding the causative genes and mutations responsible for human thyroid diseases could assist with the identification of functional mutations in natural stickleback populations, which vary in thyroid hormone signaling between marine and stream-resident ecotypes. We first determined whether Japanese stickleback populations carry mutations at orthologous sites to those carrying non-synonymous mutations causing thyroid diseases in humans and then evaluated their effects using a heterologous mammalian cell line.

Results: We found that several stickleback populations carry non-synonymous mutations in the thyroid-stimulating hormone receptor 2 (Tshr2) gene. Using a heterologous cell culture system and recombinant stickleback thyroid-stimulating hormone (TSH) 1 and TSH2, we first showed that TSHR2 responds to TSH2, but not TSH1. We also found that amino acid changes in TSHR2 at orthologous sites to those at which loss-of-function mutations have been reported in humans similarly reduce TSHR2 function in the stickleback. In contrast, an amino acid change at the site of a gain-of-function mutation in humans increased receptor function. Furthermore, we also found that TSHR1 and TSHR2 are expressed in the throat area and the brain, respectively, suggesting subfunctionalization.

Conclusion: Natural stickleback populations carry functional mutations in a gene involved in thyroid hormone signaling at orthologous sites to those that are responsible for disease in humans. These results suggest that human disease-causing mutations can be informative in the search for functional mutations in natural animal populations.

Background: Ekebergia capensis is a valuable tropical tree occurring on highlands of Ethiopia and used for traditional medicines, fodder for livestock and fruits are eaten by birds and other wild animals. However, it faces climate change threats and increased anthropogenic pressure, mainly, selective cutting for timber, firewood and expansions of agriculture across its range. Understanding the impacts of climate change on its suitable ranges is crucial to identify high-priority areas for its effective conservation and management plans. The study aimed to predict suitable habitats of Ekebergia capensis and examine factors influencing its distribution under current climate and future climate scenarios.

Methods: We used an ensemble modeling approach with 10 replications of five algorithms: BRT (boosted regression trees), RF (random forest), GLM (generalized linear model), GAM (generalized additive model), and Maxent (maximum entropy). Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), the true skill statistic (TSS), and visual assessment of ROC curves.

Results: The AUC and TSS of the ensemble model are 0.88 and 0.68, respectively, showing a very good performance. The currently predicted suitable habitat for Ekebergia capensis covers an area of approximately 215,869.87 km², representing 19.05% of the country. Under climate projections for the 2050s based on emission scenarios, the range of this species will decline by 31.71% under the medium (SSP2-4.5) and by 33.56% under the worst-case (SSP5-8.5) scenario. In the 2070s, the suitable habitats of this species will decrease by 45.44% and 47.14% under SSP2-4.5 and SSP5-8.5, respectively. Ekebergia capensis will lose a large portion of its suitable habitats between 2050s and 2070s, i.e., 16.92% under SSP2-4.5 and 15.24% under SSP5-8.5. This study suggests that southern, central, southwestern, and eastern highlands of Ethiopia provide suitable areas for the species. In contrast, suitable habitats in the northern part of the country will be either lost or fragmented in the future.

Conclusions: Our findings show that climate change significantly affects the suitable habitats of Ekebergia capensis. Only selected parts of its current habitat will remain suitable, while others will be lost or become isolated in the future. This species has recalcitrant seeds and cannot be stored ex-situ. Therefore, conservation efforts should prioritize in situ strategies such as habitat restoration, reintroduction, and assisted migration across its range. In addition, combining in situ efforts with carefully selected ex situ methods could offer a more comprehensive approach to conserving this species.

This study examined the ecological impact of the invasive shrub Amorpha fruticosa in marsh meadows and assessed the effectiveness of combined conservation management practices, i.e., mowing and cattle grazing, in on restoring native vegetation. Conducted in the Mártély Landscape Protection Area (Hungary), the research used a multiscale approach to compare treated non-invaded and treated invaded wetland vegetation. Information theory-based diversity metrics were employed to evaluate the impact of A. fruticosa on structural complexity and species composition. Results revealed that although A. fruticosa can significantly altered plant community structure, the implemented management strategies effectively reduced its impact. The treated invaded vegetation exhibited diversity levels compareable to native marshland communities, suggesting that mowing and grazing contributed to decreasing A. fruticose dominance. However, in the absence of untreated control stands, this pattern must be interpreted cautiously, as the observed similarity could be conclusively attributed to the applied management alone. A slight, but non-significant shift in structural diversity was also observed, implying a residual effect of invasion. This study underscores the value of active, combined conservation strategies in maintaining biodiversity and ecosystem resilience in wetland habitats. The results contribute to broader discussions on invasive species control, emphasizing the role of traditional land-use practices in mitigating the ecological effects of biological invasions.

Background: Evolutionary fitness is determined by the match between an organism's phenotype and its local environment. When mismatched, individuals may disperse to more suitable habitats. For flightless insects, however, the range of dispersal is typically limited. Numerous flightless species have, therefore, evolved a dispersal dimorphism, that is, some individuals in otherwise short-winged populations develop long wings. Wing development may be genetically or environmentally determined, but these two drivers have rarely been analysed together.

Results: We studied the inheritance and density-dependent plasticity in the dispersal dimorphism of the meadow grasshopper Pseudochorthippus parallelus. Using a full-sib half-sib breeding design, we found that the development of long wings strongly depends on rearing density, with tactile stimulation being the most likely proximate cause. Additionally, we found heritable variation in the development of long wings, both in the propensity to produce long wings and in response to density (genotype-by-environment interactions). While at high and low densities, the environmental effect dominates, genetic variation is most consequential at intermediate densities.

Conclusions: Our results have implications for the phenotype-environment match and ultimately the evolution of individualised niches. Induced dimorphisms represent a form of adaptive phenotypic plasticity by offering a much greater potential for active niche choice and both genetic and induced dispersal dimorphisms facilitate niche choice in allowing individuals to sample a greater range of environments. Our study shows that niche-related polymorphisms can evolve via selection on the sensitivity threshold.