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41.
Agostina Torres;Sara E. Kuebbing;Katharine L. Stuble;Samantha A. Catella;Martín A. Núñez;Mariano A. Rodriguez-Cabal; 《Ecology letters》2024,27(1):e14360
Communities worldwide are losing multiple species at an unprecedented rate, but how communities reassemble after these losses is often an open question. It is well established that the order and timing of species arrival during community assembly shapes forthcoming community composition and function. Yet, whether the order and timing of species losses can lead to divergent community trajectories remains largely unexplored. Here, we propose a novel framework that sets testable hypotheses on the effects of the order and timing of species losses—inverse priority effects—and suggests its integration into the study of community assembly. We propose that the order and timing of species losses within a community can generate alternative reassembly trajectories, and suggest mechanisms that may underlie these inverse priority effects. To formalize these concepts quantitatively, we used a three-species Lotka-Volterra competition model, enabling to investigate conditions in which the order of species losses can lead to divergent reassembly trajectories. The inverse priority effects framework proposed here promotes the systematic study of the dynamics of species losses from ecological communities, ultimately aimed to better understand community reassembly and guide management decisions in light of rapid global change. 相似文献
42.
Zhongning Zhao Jacqueline Goedhals Joaquín Verdú-Ricoy Adriaan Jordaan Neil Heideman 《Acta zoologica》2020,101(3):311-323
We compared the eye anatomy of the scotopic fossorial Acontias orientalis, Acontias rieppeli and Typhlosaurus vermis with that of the photopic surface-living Trachylepis punctatissima, with particular reference to the retina. The findings were compared with published data on gecko species (Röll, 2001), to determine whether similar trends existed. The vestigial eye of T. vermis was not comparable with that of the other three skink species. The findings in A. orientalis, A. rieppeli and T. punctatissima were as follows: (a) A. rieppeli lacked a conus papillaris, (b) A. orientalis, A. rieppeli and T. punctatissima were pure-cone species but lacked a fovea, (c) estimated cone density in A. orientalis and A. rieppeli was lower than that in T. punctatissima, (d) the ellipsoid cone segment was smaller and the paraboloid segment larger in A. orientalis and A. rieppeli with the reverse in T. punctatissima, (e) VCL%, ONL%, OPL% and GCL% in A. orientalis and A. rieppeli were significantly greater than that of T. punctatissima, (f) INL% and IPL% in T. punctatissima was significantly greater, and (g) T. punctatissima had abundant Müller cells and fibres. Findings in the gecko species were congruent with those of the three skink species of the present study. 相似文献
43.
Fabian Pérez-Miranda Omar Mejía Alfonso A. González-Díaz Norberto Martínez-Méndez Eduardo Soto-Galera Gerardo Zúñiga Oldrich Říčan 《Journal of fish biology》2020,96(6):1370-1378
In the present study we evaluated the putative cases of sympatric speciation in the genus Herichthys by studying the variation in head shape using principal component analysis, phylomorphospace and reconstructions of the ancestral states of feeding preferences. Herichthys includes both allopatric and sympatric sister species, as well as sympatric unrelated species and thus offers great potential for evolutionary studies of putatively sympatric speciation. Herichthys is the northernmost group of cichlids in America and one of the most ecologically disparate genera within Middle American cichlids. Fifteen anatomical points were recorded on the heads of 293 specimens of the 11 species recognized within the genus. The results show that in spite of having wide variation in consumed diets, most species of Herichthys are close in morphospace. However, morphological variation was great among the two pairs of sympatric sister species in agreement with the suggested sympatric model of speciation. 相似文献
44.
The bumblebee, Bombus terrestris, is an important pollinator commercially used on a global scale. The exported subspecies B. t. terrestris has colonised diverse environments, in some cases displacing wild pollinators to the verge of local extinction. In this sense, the native Iberian subspecies B. t. lusitanicus may be threatened by the subspecies B. t. terrestris, naturally distributed from the Pyrenees to Central Europe but also observed in southern Spain due to escapes from commercial nests. Mitochondrial genomes have a low recombination rate and a small effective population size owing to their maternal inheritance, thus providing an accurate approach to study hybridisation events between populations. Therefore, we present the sequences of the mitogenomes of both subspecies as a molecular framework to select suitable markers to detect possible introgression events between them. We used metagenomics to obtain approximately 17 kbp of the mitogenome from both subspecies. Their mitogenomes differed in 358 bp (excluding the AT-rich region). Four mitogenomic fragments were selected to be tested as subspecific diagnostic markers. A RFLP detected in the gene nad2 (NADH dehydrogenase subunit 2) has proven to be an efficient, quick and cost-effective tool to assess the dispersion of the non-endemic subspecies into Iberian native populations. Subspecific haplotypes were observed in both morphological subspecies, suggesting introgression events in the northern natural contact area and in the new human-mediated contact area in the south of the Iberian Peninsula. 相似文献
45.
Cassilda Pereira Inês S. Rodrigues Liliana M.G. Pereira Johnny Lisboa Rute D. Pinto Leonor Araújo Pedro Oliveira Roland Benz Nuno M.S. dos Santos Ana do Vale 《Cellular microbiology》2020,22(1)
Apoptosis‐inducing protein of 56 kDa (AIP56) is a major virulence factor of Photobacterium damselae subsp. piscicida, a gram‐negative pathogen that infects warm water fish species worldwide and causes serious economic losses in aquacultures. AIP56 is a single‐chain AB toxin composed by two domains connected by an unstructured linker peptide flanked by two cysteine residues that form a disulphide bond. The A domain comprises a zinc‐metalloprotease moiety that cleaves the NF‐kB p65, and the B domain is involved in binding and internalisation of the toxin into susceptible cells. Previous experiments suggested that disruption of AIP56 disulphide bond partially compromised toxicity, but conclusive evidences supporting the importance of that bond in intoxication were lacking. Here, we show that although the disulphide bond of AIP56 is dispensable for receptor recognition, endocytosis, and membrane interaction, it needs to be intact for efficient translocation of the toxin into the cytosol. We also show that the host cell thioredoxin reductase‐thioredoxin system is involved in AIP56 intoxication by reducing the disulphide bond of the toxin at the cytosol. The present study contributes to a better understanding of the molecular mechanisms operating during AIP56 intoxication and reveals common features shared with other AB toxins. 相似文献
46.
Aingeru Martínez Juliana Barros Ana Lúcia Gonçalves Cristina Canhoto 《Freshwater Biology》2020,65(8):1475-1483
- Salinisation (i.e. increased ion concentrations) in fresh waters is a growing threat worldwide that impacts freshwater communities. However, less is known about how increased salt concentrations affect key ecosystem processes such as leaf decomposition.
- We designed a laboratory experiment to assess the effects of a concentration gradient (1, 3, and 6 g/L) of three different salts (NaCl, CaCl2 and CH3CO2K), on leaf litter decomposition mediated by microbial decomposers and the larvae of a cased caddis fly (Schizopelex festiva, Trichoptera). Leaf discs of Quercus robur inoculated with microbial decomposers (a mixture of 5 fungal species) were incubated in microcosms under every possible salt × concentration combination and without salt addition (control), with a single individual of the cased caddis fly. Half of the leaf disks were not available for consumption by the trichopteran and represent a microbial only treatment when leaf mass loss was measured.
- Leaf decomposition driven by microbial decomposers was not affected by salinity despite the fact that all salt treatments depressed fungal biomass and microbial respiration compared to the control. However, the caddis flies were strongly affected by the high salt concentrations and consumed less leaf material at 6 g/L salt concentrations compared to control microcosms. The feeding activity of the trichopteran further depended on the salt type: CaCl2 had the most deleterious effects.
- Salinisation of fresh waters depresses leaf litter decomposition, mainly through deleterious effects on detritivores, the magnitude of the response being dependent on the ionic composition. Our results reiterate the need to reduce terrestrial run-off of salts into fresh waters because salinisation (especially increased levels of CaCl2) affects invertebrates and the key ecosystem processes they drive.
47.
Paula da Fonseca-Pereira Paulo V.L. Souza Liang-Yu Hou Saskia Schwab Peter Geigenberger Adriano Nunes-Nesi Stefan Timm Alisdair R. Fernie Ina Thormählen Wagner L. Araújo Danilo M. Daloso 《Plant, cell & environment》2020,43(1):188-208
Thioredoxins (TRXs) are important proteins involved in redox regulation of metabolism. In plants, it has been shown that the mitochondrial metabolism is regulated by the mitochondrial TRX system. However, the functional significance of TRX h2, which is found at both cytosol and mitochondria, remains unclear. Arabidopsis plants lacking TRX h2 showed delayed seed germination and reduced respiration alongside impaired stomatal and mesophyll conductance, without impacting photosynthesis under ambient O2 conditions. However, an increase in the stoichiometry of photorespiratory CO2 release was found during O2-dependent gas exchange measurements in trxh2 mutants. Metabolite profiling of trxh2 leaves revealed alterations in key metabolites of photorespiration and in several metabolites involved in respiration and amino acid metabolism. Decreased abundance of serine hydroxymethyltransferase and glycine decarboxylase (GDC) H and L subunits as well as reduced NADH/NAD+ ratios were also observed in trxh2 mutants. We further demonstrated that the redox status of GDC-L is altered in trxh2 mutants in vivo and that recombinant TRX h2 can deactivate GDC-L in vitro, indicating that this protein is redox regulated by the TRX system. Collectively, our results demonstrate that TRX h2 plays an important role in the redox regulation of mitochondrial photorespiratory metabolism. 相似文献
48.
Anete P. Lourenço Ana Paula M. Santos Hélio H. Checon Mayra R. Costa Sebastião L. Assis Júnior 《Studies on Neotropical Fauna and Environment》2020,55(2):116-128
ABSTRACT The reasons for the decline of bee diversity and abundance include the destruction and loss of natural habitats. Protected areas are created for biodiversity conservation, but these areas vary strongly in their level of vegetation disturbance. Using trap-nests, we assessed changes in solitary bee abundance, richness, and composition in areas ranging from naturally conserved to degraded. Solitary bees were sampled during an 18-month period in three areas of southeastern Brazil: a preserved area in Rio Preto State Park – PERP; a restored/altered area with exotic plants at the Federal University of the Jequitinhonha and Mucuri Valleys – JK Campus; and a degraded area in Biribiri State Park – PEBi. A total of seven species of bees built 115 nests. In the degraded area, only two nests were built. Abundance of built nests was higher in the preserved area (PERP), but diversity was higher in the restored area (JK Campus). Our results show that the solitary bee population responds positively to habitat complexity (local scale). The presence of a diverse solitary bee fauna in the restored area indicates that altered areas should also be protected as suitable areas for re-colonization of cavity-nesting bees. 相似文献
49.
Roman A. Nava;José Jesús Sigala-Rodríguez;Nathaniel Redetzke;Ivan Villalobos-Juarez;Cristian Franco-Servin-de-la-Mora;Ramses Rosales-García;Rulon W. Clark; 《Ecology and evolution》2024,14(7):e70005
Islands have played a key role in our understanding of rapid evolution. A large body of literature has examined morphological changes in response to insularity and isolation, which has yielded useful generalizations about how animals can adapt to live in very small geographic areas. However, understanding the evolution of morphological variation in insular populations often requires detailed data sets on longitudinal patterns of growth and development, and such studies typically necessitate long-term mark-recapture on a large sample of individuals. Rattlesnakes provide a unique opportunity to address some of these difficulties because the addition of rattle segments to the rattle string occurs with regular periodicity and their size directly correlates with the body size of the snake at the time of the ecdysis cycle generating the segment. Here, we used a large database of rattle segment sizes recorded from island (Isla Coronado Sur, Baja California, Mexico) and mainland (Camp Pendleton, California, United States) populations of Western Rattlesnakes (Crotalus oreganus and C. o. caliginis) that separated approximately 10,000 years ago to compare body sizes at different ecdysis cycles, which allowed us to assess differences in growth rates and patterns of sexual size dimorphism. Our results show that rattlesnakes on Isla Coronado Sur appear to be born smaller and grow more slowly than their mainland counterparts, resulting in a “dwarfed” island population. However, despite significant differences in body size, both populations exhibited the same degree of sexual dimorphism. Our study demonstrates the potential to use rattle characteristics to recover detailed estimates of fundamental demographic parameters. 相似文献
50.
Diego Suescún Juan Diego León Juan Camilo Villegas Guillermo Antonio Correa-Londoño 《Ecohydrology》2023,16(3):e2519
The functioning of tropical montane ecosystems are key provider of environmental services. However, climate and land use change interactively affect the ecohydrological and biogeochemical processes that support the provision of such services. We evaluate the effect of land use/land coverand the seasonality and intensity of the rainfall on the ecological functions of erosion control and nutrient regulation in a gradient of human intervention in the Central Andes of Colombia. Our results show that soil erosion (kg/ha/year) was higher in the transitory crop (187.7), followed by the permanent crop (98.2), and much lower in the pasture (8.0) and native forest (7.2). Our results also indicate a differential effect of land use and rainfall seasonality on erosion and nutrient transport, both processes being significantly higher in crops and lower in forest, both for the wet and dry seasons. However, the relationships between erosion and rainfall intensity varied depending on the hydrological season (in the wet seasons, no linear model was significant, while in the dry seasons, linear models for maximum rainfall intensity were significant in both crops and in the oak forest, and linear models with mean intensity were significant for both types of crops). Nitrogen exhibited the highest rates of transport, which can have important implications for water and soil pollution. Nitrogen transport via erosion (g/ha/year) was consistent with erosion results, being higher in the transitory crop (399.9) and permanent crop (265.3) that in the oak forest (6.9) and pasture (6.8). These results indicate that converting forests affects the capacity of ecosystems to provide environmental services, which is further amplified by projections of climate change. 相似文献