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Trade-offs are crucial for species divergence and reproductive isolation. Trade-offs between investment in growth versus defense against herbivores are implicated in tropical forest diversity. Empirically exploring the role of growth-defense trade-offs in closely related species' reproductive isolation can clarify the eco-evolutionary dynamics through which growth-defense trade-offs contribute to diversity. Costus villosissimus and C. allenii are recently diverged, interfertile, and partially sympatric neotropical understory plant species primarily isolated by divergent habitat adaptation. This divergent adaptation involves differences in growth rate, which may constrain investment in defense. Here, we investigate growth-defense trade-offs and how they relate to the divergent habitat adaptation that isolates these species. We characterize leaf toughness and chemistry, evaluate the feeding preferences of primary beetle herbivores in controlled trials and field-based experiments, and investigate natural herbivory patterns. We find clear trade-offs between growth and defense: slower-growing C. allenii has tougher leaves and higher defensive chemical concentrations than faster-growing C. villosissimus. Costus villosissimus has rapid growth-based drought avoidance, enabling growth in drier habitats with few specialist herbivores. Therefore, growth-defense trade-offs mediate synergistic biotic and abiotic selection, causing the divergent habitat adaptation that prevents most interspecific mating between C. villosissimus and C. allenii. Our findings advance understanding of ecological speciation by highlighting the interplay of biotic and abiotic selection that dictates the outcome of trade-offs.

The gut microbiota is crucial for host nutrition and adaptation to the environment. The nonobligate cave frog Oreolalax rhodostimatus, which normally inhabit caves year-round. In this study, we compared captive Oreolalax rhodostimatus tadpoles to cave-dwelling Oreolalax rhodostimatus tadpoles to investigate the relationship between gut microbiota and the host's dietary and environmental adaptations. Macrogenomic analyses showed that Proteobacteria were the most abundant phylum in both cave and captive individuals. However, cave individuals had a significantly higher proportion of Proteobacteria, Firmicutes, and Planctomycetes in their gut microbial community than captive individuals. At the genus level, there was a significant difference in gut microbe composition between cave and captive individuals. Deefgea was found to be more abundant in the gut microbiota of cave individuals, while Bacteroides was more abundant in captive individuals. Combining their gut microbiota with actual action revealed that the Oreolalax rhodostimatus tadpoles are omnivorous. The abundance of metabolic pathways involved proteins and carbohydrates, was significantly higher in captive individuals. This may be due to the fact that cave tadpoles need to expand their food range to ensure energy supply under high survival pressure, compared to captive tadpoles, which showed relatively low feeding pressure. This implies that food resources, gut microbiota, feeding habits, and preferences are all related to habitat adaptation. [ABSTRACT FROM AUTHOR]

Introduction: Based on previous analyses of Syntrichia norvegica and S. ruralis, the idea of panmictic populations in Scandinavia can be rejected, despite the high dispersal capacities of wind-dispersed spores. We tested, using comprehensive European datasets, whether intraspecific phylogeographical structure reflects glacial and post-glacial history. We expected different entities to indicate immigration from known Late Glacial Maximum refugial areas, and habitat differentiation. Methods: Using plastid markers (atpB–rbcL and rpl16), we investigated 45 and 190 Scandinavian and 17 and 15 non-Scandinavian specimens of Syntrichia norvegica and S. ruralis, respectively. Key results: We revealed four intraspecific entities in Syntrichia norvegica. Two were from the Scandinavian mountains and the Alps, and one from the Scandinavian mountains only. The fourth was widespread across the Scandinavian mountains, the northern lowlands, and the Baltic Sea islands Öland and Gotland. For S. ruralis, we recovered five entities, of which three were from both Scandinavia and the Alps. One of these occurred in strongly calcareous habitats in southern Scandinavia and the Alps and dominated on Öland and Gotland. One entity was widely distributed only in Scandinavia. One was restricted to the border between boreo-nemoral and southern-boreal Scandinavia. Conclusions: The plastid haplotype distribution patterns suggest glacial survival of Syntrichia norvegica and S. ruralis in refugia south, east and possibly within ice-covered areas of Scandinavia. We hypothesise that one S. ruralis entity evolved adaptations to strongly calcareous habitats. The dominance or prevalence of specific haplotypes of both species on Öland and Gotland contributes to the unique biodiversity of these islands. [ABSTRACT FROM AUTHOR]

This study was conducted to determine some bioecological characteristics of Lepomis gibbosus (L. 1758), commonly known as pumpkinseed sunfish, which spreads in Gökpınar Dam Lake (GDL) in Denizli Province. The fish samples were captured with an experimental seine net and multimesh gillnet from May 2019 to April 2020. During the samplings, certain physicochemical parameters of GDL were measured, habitat utilization, relations to environmental variables, feeding habits and interspecific interactions with other fishes of L. gibbosus individuals were observed. It is observed that GDL provides a suitable habitat for L. gibbosus in terms of water quality and other ecological requirements. A total of 1005 L. gibbosus individuals, consisting of 302 females, 605 males, and 98 juveniles, were sampled throughout the study, and biometric studies were conducted. In the population males were found to be dominant. The averages were determined as follows; total length as 5.82±2.09 cm (2.46-11.34), weight as 4.94±4.67g (0.20-34.65), and condition factor as 1.71±0.24. The ages were determined between 0+ to II+and Age-length relationship (VBGE) was estimated as 𝐿𝑡=19.85(1 - 𝑒-0.2744(𝑡+0.272)) Spawning occurs between April and June in individuals at the age of I+. It has been observed that the species exhibits good growth rates in this habitat, displays opportunistic omnivorous feeding behavior, preys on another invasive alien species, Gambusia holbrooki, present in the lake, and competes with the same species for habitat sharing. It has been determined that L. gibbosus has formed a self-sustaining population in GDL, but it utilizes a limited lake area as its habitat. In conclusion, GDL is considered as a hydrologically unstable and highly variable habitat. L. gibbosus population of GDL exhibits significant similarities in terms of bioecological characteristics with populations that spread outside its natural spreading area. As L.gibbosus is an exotic fish and might be have invasive traits, it is necessary to monitor of the population regularly, and control measures should be taken to prevent its spread to other inland water bodies. [ABSTRACT FROM AUTHOR]

SignificanceIn marine ecosystems, transmission of microbial symbionts between host generations occurs predominantly through the environment. Yet, it remains largely unknown how host genetics, symbiont competition, environmental conditions, and geography shape the composition of symbionts acquired by individual hosts. To address this question, we applied population genomic approaches to four species of deep-sea hydrothermal vent snails that live in association with chemosynthetic bacteria. Our analyses show that environment is more important to strain-level symbiont composition than host genetics and that symbiont strains show genetic variation indicative of adaptation to the distinct geochemical conditions at each vent site. This corroborates a long-standing hypothesis that hydrothermal vent invertebrates affiliate with locally adapted symbiont strains to cope with the variable conditions characterizing their habitats.

The article serves as a guide for analyzing human settlements in rural areas, offering support for the new housing of cultural interest policy in Colombia. It focusses on the sociocultural dimension and the human experience of a home by examining the vernacular techniques and practices used for construction projects and habitat adaptation. The proposed approach provides a practical means of gathering architectural and cultural information by establishing close relationships with communities. It will enable academics, architects, construction companies and public entities to develop sustainable, viable and appropriate projects in vulnerable areas.

Main conclusion: Transcriptional and metabolic regulation of lignin biosynthesis and lignification plays crucial roles in Avicennia marina pneumatophore development, facilitating its adaptation to coastal habitats. Avicennia marina is a pioneer mangrove species in coastal wetland. To cope with the periodic intertidal flooding and hypoxia environment, this species has developed a complex and extensive root system, with its most unique feature being a pneumatophore with a distinct above- and below-ground morphology and vascular structure. However, the characteristics of pneumatophore lignification remain unknown. Studies comparing the anatomy among above-ground pneumatophore, below-ground pneumatophore, and feeding root have suggested that vascular structure development in the pneumatophore is more like the development of a stem than of a root. Metabolome and transcriptome analysis illustrated that the accumulation of syringyl (S) and guaiacyl (G) units in the pneumatophore plays a critical role in lignification of the stem-like structure. Fourteen differentially accumulated metabolites (DAMs) and 10 differentially expressed genes involved in the lignin biosynthesis pathway were targeted. To identify genes significantly associated with lignification, we analyzed the correlation between 14 genes and 8 metabolites and further built a co-expression network between 10 transcription factors (TFs), including 5 for each of MYB and NAC, and 23 enzyme-coding genes involved in lignin biosynthesis. 4-Coumarate-CoA ligase, shikimate/quinate hydroxycinnamoyl transferase, cinnamyl alcohol dehydrogenase, caffeic acid 3-O-methyltransferase, phenylalanine ammonia-lyase, and peroxidase were identified to be strongly correlated with these TFs. Finally, we examined 9 key candidate genes through quantitative real-time PCR to validate the reliability of transcriptome data. Together, our metabolome and transcriptome findings reveal that lignin biosynthesis and lignification regulate pneumatophore development in the mangrove species A. marina and facilitate its adaptation to coastal habitats. [ABSTRACT FROM AUTHOR]

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ABSTRACT Plant growth-promoting bacteria (PGPB) are a group of beneficial microorganisms that include 60 bacterial genera, such as Bacillus, Pseudomonas, and Burkholderia, which widely colonize plant leaves and soil, promote plant growth, and/or inhibit pathogen infection. However, the genetic factors underpinning adaptation of PGPB to plant leaves and soil remain poorly understood. In this study, we performed a comparative functional genome analysis approach to investigate the functional genes of 195 leaf-associated (LA) and 283 soil-associated (SA) PGPB strains and their roles in adapting to their environment, using 95 strains from other-associated (OA) environmental habitats with growth-promoting or antimicrobial functions as negative controls. Comparison analysis of the enrichment of nonredundant (NR) protein sequence databases showed that cytochrome P450, DNA repair, and motor chemotaxis genes were significantly enriched in LA PGPB strains related to environmental adaptation, while cell wall-degrading enzymes, TetR transcriptional regulatory factors, and sporulation-related genes were highly enriched in SA PGPB strains. Additionally, analysis of carbohydrate-active enzymes demonstrated that glycosyltransferases (GTs) and glycoside hydrolases (GHs) were abundant families in all PGPB strains, which is in favor of plant growth, and enriched in SA PGPB strains. Except for most Bacillus strains, SA PGPB genomes contained significantly more secondary metabolism clusters than LA PGPB. Most LA PGPB contained hormone biosynthesis genes, which may contribute to plant growth promotion, while SA PGPB harbored numerous carbohydrate and antibiotic metabolism genes. In summary, this study further deepens our understanding of the habitat adaptation and biocontrol characteristics of LA and SA PGPB strains. IMPORTANCE Plant growth-promoting bacteria (PGPB) are essential for the effectiveness of biocontrol agents in plant phyllosphere and rhizosphere. However, little is known about the ecological adaptation of PGPB to different habitats. In this study, comparative functional genome analysis of leaf-associated (LA), soil-associated (SA), and other-associated (OA) PGPB strains was performed. We found that genes related to the metabolism of hormones were enriched in LA PGPB. Carbohydrate and antibiotic metabolism genes were enriched in SA PGPB, which likely facilitated their adaptation to the plant growth environment. Our findings provide genetic insights on LA and SA PGPB strains’ ecological adaptation and biocontrol characteristics.

Lactobacillus kefiranofaciens is often found in fermented dairy products. Many strains of this species have probiotic properties, contributing to the regulation of immune metabolism and intestinal flora. This species was added to the list of lactic acid bacteria that can be added to food in China, in 2020. However, research on the genomics of this species is scarce. In this study we undertook whole genome sequencing analysis of 82 strains of L. kefiranofaciens from different habitats, of which 9 strains were downloaded from the NCBI RefSeq (National Center for Biotechnology Information RefSeq). The mean genome size of the 82 strains was 2.05 ± 0.25 Mbp, and the mean DNA G + C content was 37.47 ± 0.42%. The phylogenetic evolutionary tree for the core genes showed that all strains belonged to five clades with clear aggregation in relation to the isolation habitat; this indicated that the genetic evolution of L. kefiranofaciens was correlated to the isolation habitat. Analysis of the annotation results identified differences in the functional genes, carbohydrate active enzymes (CAZy) and bacteriocins amongst different isolated strains, which were related to the environment. Isolates from kefir grains had more enzymes for cellulose metabolism and a better ability to use vegetative substrates for fermentation, which could be used in feed production. Isolates from kefir grains also had fewer kinds of bacteriocin than isolates from sour milk and koumiss; helveticin J and lanthipeptide class I were not found in the isolates from kefir grains. The genomic characteristics and evolutionary process of L. kefiranofaciens were analyzed by comparative genomics and this paper explored the differences in the functional genes amongst the strains, aiming to provide a theoretical basis for the research and development of L. kefiranofaciens. [ABSTRACT FROM AUTHOR]

The technique of stable hydrogen and oxygen isotope tracing has become an important means to study the mechanism of water movement due to its high sensitivity and traceability. In this study, four dominant tree species in the karst forest of Maolan, Guizhou Province, were selected, and their water-use strategies and the mechanism of maintenance of tree species diversity were investigated using the stable hydrogen and oxygen isotope tracing technique. The results show that: (1) The regional precipitation varied evidently with the alternation of seasons, i.e., the values of δD and δ18O in precipitation had a positive bias in spring and a negative bias in summer and autumn. The value of deuterium excess (d-excess) was between 11.67‰ and 31.02‰, with a mean value of 22.98‰. (2) The soil temperature (ST), soil water content (SWC) and precipitation, which have a significant positive correlation, imposed a joint impact on the dynamics of the soil evaporative fractionation. (3) The line-conditioned excess (LC-excess) varied seasonally in different water bodies, i.e., the relative evaporative fractionation of the rhizosphere soil of deciduous tree species was stronger than that of evergreen tree species, and the evaporative fractionation of hydrogen and oxygen isotopes in the leaf water of evergreen tree species was stronger than that of deciduous tree species in spring and summer. However, that of the latter was stronger than that of the former in autumn. (4) The soil water was the most important potential water source for dominant tree species in karst terrain (71%), followed by epikarstic water, which made up an effective supplement (29%). (5) Finally, trees of different life forms and species varied in capacity and proportion in terms of using the potential water sources in different seasons, i.e., deciduous tree species had a greater capacity for using water from potential sources and variable water-use strategies. This may be a major water-limiting mechanism that maintains photosynthesis in the leaves of evergreen tree species (leaves are evergreen and plants continue to grow via photosynthesis) and constrains photosynthesis in deciduous tree species (leaves fall and plants become dormant and stop growing). These results lead to the conclusion that the dominant tree species in karstic forests resist water stress and adjust water-use strategies towards each potential water source to adapt to the harsh karstic habitat through root plasticity and leaf defoliation. [ABSTRACT FROM AUTHOR]

Diverse archaea, including many unknown species and phylogenetically deeply rooted taxa, survive in extreme environments. They play crucial roles in the global carbon cycle and element fluxes in many terrestrial, marine, saline, host-associated, hot-spring, and oilfield environments. There is little knowledge of the diversity of chemoreceptors that are presumably involved in their habitat adaptation. Thus, we have explored this diversity through phylogenetic and comparative genomic analyses of complete archaeal genomes. The results show that chemoreceptors are significantly richer in archaea of mild environments than in those of extreme environments, that specific ligand-binding domains of the chemoreceptors are strongly associated with specific habitats, and that the number of chemoreceptors correlates with genome size. The results indicate that the successful adaptation of archaea to specific habitats has been associated with the acquisition and maintenance of chemoreceptors, which may be crucial for their survival in these environments. IMPORTANCE Archaea are capable of sensing and responding to environmental changes by several signal transduction systems with different mechanisms. Much attention is paid to model organisms with complex signaling networks to understand their composition and function, but general principles regarding how an archaeal species organizes its chemoreceptor diversity and habitat adaptation are poorly understood. Here, we have explored this diversity through phylogenetic and comparative genomic analyses of complete archaeal genomes. Signaling sensing and adaptation processes are tightly related to the ligandbinding domain, and it is clear that evolution and natural selection in specialized niches under constant conditions have selected for smaller genome sizes. Taken together, our results extend the understanding of archaeal adaptations to different environments and emphasize the importance of ecological constraints in shaping their evolution. [ABSTRACT FROM AUTHOR]

ABSTRACT Microbial diversification is driven by geographic and ecological factors, but how the relative importance of these factors varies among species, geographic scales, and habitats remains unclear. Streptomyces, a genus of antibiotic-producing, spore-forming, and widespread bacteria, offers a robust model for identifying the processes underlying population differentiation. We examined the population structure of 37 Streptomyces olivaceus strains isolated from various sources, showing that they diverged into two habitat-associated (free-living and insect-associated) and geographically disparate lineages. More frequent gene flow within than between the lineages confirmed genetic isolation in S. olivaceus. Geographic isolation could not explain the genetic isolation; instead, habitat type was a strong predictor of genetic distance when controlling for geographic distance. The identification of habitat-specific genetic variations, including genes involved in regulation, resource use, and secondary metabolism, suggested a significant role of habitat adaptation in the diversification process. Physiological assays revealed fitness trade-offs under different environmental conditions in the two lineages. Notably, insect-associated isolates could outcompete free-living isolates in a free-iron-deficient environment. Furthermore, substrate (e.g., sialic acid and glycogen) utilization but not thermal traits differentiated the two lineages. Overall, our results argue that adaptive processes drove ecological divergence among closely related streptomycetes, eventually leading to dispersal limitation and gene flow barriers between the lineages. S. olivaceus may best be considered a species complex consisting of two cryptic species. IMPORTANCE Both isolation by distance and isolation by environment occur in bacteria, and different diversification patterns may apply to different species. Streptomyces species, typified by producing useful natural products, are widespread in nature and possess high genetic diversity. However, the ecological processes and evolutionary mechanisms that shape their distribution are not well understood. Here, we show that the population structure of a ubiquitous Streptomyces species complex matches its habitat distribution and can be defined by gene flow discontinuities. Using comparative genomics and physiological assays, we reveal that gains and losses of specific genomic traits play a significant role in the transition between free-living and host-associated lifestyles, driving speciation of the species. These results provide new insights into the evolutionary trajectory of Streptomyces and the notion of species.

Lactobacillus kefiranofaciens is often found in fermented dairy products. Many strains of this species have probiotic properties, contributing to the regulation of immune metabolism and intestinal flora. This species was added to the list of lactic acid bacteria that can be added to food in China, in 2020. However, research on the genomics of this species is scarce. In this study we undertook whole genome sequencing analysis of 82 strains of L. kefiranofaciens from different habitats, of which 9 strains were downloaded from the NCBI RefSeq (National Center for Biotechnology Information RefSeq). The mean genome size of the 82 strains was 2.05 ± 0.25 Mbp, and the mean DNA G + C content was 37.47 ± 0.42%. The phylogenetic evolutionary tree for the core genes showed that all strains belonged to five clades with clear aggregation in relation to the isolation habitat; this indicated that the genetic evolution of L. kefiranofaciens was correlated to the isolation habitat. Analysis of the annotation results identified differences in the functional genes, carbohydrate active enzymes (CAZy) and bacteriocins amongst different isolated strains, which were related to the environment. Isolates from kefir grains had more enzymes for cellulose metabolism and a better ability to use vegetative substrates for fermentation, which could be used in feed production. Isolates from kefir grains also had fewer kinds of bacteriocin than isolates from sour milk and koumiss; helveticin J and lanthipeptide class I were not found in the isolates from kefir grains. The genomic characteristics and evolutionary process of L. kefiranofaciens were analyzed by comparative genomics and this paper explored the differences in the functional genes amongst the strains, aiming to provide a theoretical basis for the research and development of L. kefiranofaciens.

Abstract Background Obligate sulfur oxidizing chemolithoauthotrophic strains of Hydrogenovibrio crunogenus have been isolated from multiple hydrothermal vent associated habitats. However, a hydrogenase gene cluster (encoding the hydrogen converting enzyme and its maturation/assembly machinery) detected on the first sequenced H. crunogenus strain (XCL-2) suggested that hydrogen conversion may also play a role in this organism. Yet, numerous experiments have underlined XCL-2’s inability to consume hydrogen under the tested conditions. A recent study showed that the closely related strain SP-41 contains a homolog of the XCL-2 hydrogenase (a group 1b [NiFe]-hydrogenase), but that it can indeed use hydrogen. Hence, the question remained unresolved, why SP-41 is capable of using hydrogen, while XCL-2 is not. Results Here, we present the genome sequence of the SP-41 strain and compare it to that of the XCL-2 strain. We show that the chromosome of SP-41 codes for a further hydrogenase gene cluster, including two additional hydrogenases: the first appears to be a group 1d periplasmic membrane-anchored hydrogenase, and the second a group 2b sensory hydrogenase. The region where these genes are located was likely acquired horizontally and exhibits similarity to other Hydrogenovibrio species (H. thermophilus MA2-6 and H. marinus MH-110 T ) and other hydrogen oxidizing Proteobacteria (Cupriavidus necator H16 and Ghiorsea bivora TAG-1 T ). The genomes of XCL-2 and SP-41 show a strong conservation in gene order. However, several short genomic regions are not contained in the genome of the other strain. These exclusive regions are often associated with signs of DNA mobility, such as genes coding for transposases. They code for transport systems and/or extend the metabolic potential of the strains. Conclusions Our results suggest that horizontal gene transfer plays an important role in shaping the genomes of these strains, as a likely mechanism for habitat adaptation, including, but not limited to the transfer of the hydrogen conversion ability.

Spiders can modify their web construction behaviour according to environmental conditions. Here, we examined how the web structure of Tetragnatha tenuissima differentiates depending on habitat type (swamp or river edge) at La Selva Biological Station, Costa Rica. We characterized the web architecture based on length, number of radii, and the spiral spacing relative to web length. There were no significant differences on the length or number of radii between the webs present in the swamp and river habitats. In terms of the spiral spacing relative to web length, there was a significant difference between habitats, with less distance in river-side webs than in the ones on swamps. This could be explained by the potential differential resource availability on each environment. Therefore, habitat type appears as an explanatory variable for differences on the web structure of T. tenuissima. Due to the small number of identifiable individuals of other Tetragnatha species, the effect of congeneric species co-occurrence on web structure remains as a factor to be tested in future research. [ABSTRACT FROM AUTHOR]

The pigmentation patterns of many carnivorous mammals comprise contrasting white patches of hair in different parts of the body whose evolution remains largely misunderstood. Some felids (Felidae) exhibit conspicuous white spots on the posterior part of the ears, while the ear color of others is uniform. On the basis that ear movement in felids has a role in intraspecific communication and that color contrast enhances detection, here it is hypothesized that white spots on ears may be particularly adaptive under conditions of poor visibility and thus be associated with the occupancy of closed habitats. This prediction was tested using phylogenetic logistic regression models with all species of extant felids. Results show a clear association between the occurrence of white spots on ears and preference for closed habitats, and this is independent of body size and whether species that occupy both closed and open habitats are considered as closed- or open-habitat specialists. Phylogenetic signal analyses indicate that the occurrence of white spots on ears is a highly conserved trait while habitat preferences are evolutionarily labile, suggesting that the presence of white spots may have partly contributed to the adaptation of felids to closed habitats. These findings indicate that some subtle pigment traits have fulfilled a significant role in determining the success of habitat occupancy by felids and possibly other mammals, which in turn has driven the evolutionary maintenance of such traits. [ABSTRACT FROM AUTHOR]

Bears are currently represented by eight species among Carnivora. Being all particularly large and generally plantigrade limits to certain extent their functional morphology so that inferences about their past diversification are difficult to achieve. We analyzed variation in bears' elbow joint size and shape to reconstruct paleobiology of Quaternary fossil species. By using 2D geometric morphometrics, we were able to discriminate with high degree of accuracy species, locomotor and habitat adaptations among extant bears. The giant panda and the spectacled bear are well characterized by an enlarged medial epicondyle, while large members of the genus Ursus can be distinguished by their relatively longer and wider trochlea. Elbow joint size varies consistently among ecological categories of extant bears and is generally selected by discriminant function models providing a high degree of classification accuracy (> 80%). American genera Arctotherium and Arctodus are predicted as non-climbing species potentially adapted to open and mixed environments in agreement with their potentially opportunistic feeding behavior. They retain a wide medial epicondyle probably in relation to a high degree of forelimb dexterity. Cave bears are equally predicted as non-climbers adapted to open habitats while the middle Pleistocene Ursus deningeri and fossil Ursus arctos are generally classified as scansorial species with a preference towards mixed habitats. Our study is the first to demonstrate that fragmentary distal epiphyses also can be useful for interpreting functional morphology and ecological adaptations within the family Ursidae. [ABSTRACT FROM AUTHOR]

Fragmentary long bone material from fossil Carnivora is rarely considered to support palaeoenvironmental reconstructions. Here, we use morphometry of the radius in extant carnivorans of the dog family (Canidae) to reconstruct the palaeobiology of extinct canids from Olduvai Gorge, Tanzania (Bed I and II) and Koobi Fora, Kenya. We use radius morphometrics to predict adaptation to prey size and introduce a new method for quantifying canid habitat adaptations based on the geographic distributions of the extant species sampled. Linear Discriminant Function Analyses (DFA) and cluster neighbour-joining algorithms are employed to investigate radial morphometrics as described by 29 linear measurements. Results of our analyses suggest that a phylogenetic signal is present in radial morphometrics, even if it does not allow us to accurately discriminate among genera. A binary prey size categorisation of “small-medium” versus “large” prey can be more accurately predicted than a habitat categorisation scheme (Open, Mixed, Closed). The East African fossil specimens examined show morphometric affinities with the golden jackal (Canis aureus) and coyote (Canis latrans) and are likely attributable to the genus Canis. Fragmentary fossil specimens from Olduvai Gorge are predicted as habitat generalists (Open for Bed I and Mixed for Bed II) adapted for hunting small-medium prey, whereas the specimen from Koobi Fora was predicted as inhabiting mixed habitats and adapted for killing large prey. This study supports the inclusion of fossil Canidae in palaeoecological analyses attempting to clarify the palaeoenvironment of early hominin fossil sites.

Recently, specimens belonging to the genus ' Haplochromis' have been found in the Ituri River (Congo basin). They clearly do not belong to any of the species known from the Congo basin, but strongly resemble ' H'. aeneocolor from the Lake Edward/George system. We examined whether this population represents a new species or is conspecific with ' H'. aeneocolor. A morphological comparative study was executed based on 11 counts and 23 measurements on 64 specimens. The results revealed the Ituri specimens to differ from the types of ' H'. aeneocolor in snout length, premaxillary pedicel length and eye diameter. Since these few differences are correlated, and head morphology is known to be subject to adaptive responses in haplochromine cichlids, they were considered the result of morphological adaptation to a riverine habitat rather than an indication of heterospecificity. Probably, ' H'. aeneocolor has accidentally been introduced into the Ituri region together with tilapias used in aquaculture, and has subsequently established a stable population in a riverine environment. As fish introductions can have a severe impact on aquatic ecosystems, improving our knowledge as well as a good management of aquacultural activities is essential. [ABSTRACT FROM AUTHOR]

• In order to investigate the role of differential adaptation for the evolution of reproductive barriers, we conducted a multi-site transplant experiment with the dioecious sister species Silene dioica and S. latifolia and their hybrids. • Crosses within species as well as reciprocal first-generation (F1) and second-generation (F2) interspecific hybrids were transplanted into six sites, three within each species' habitat. Survival and flowering were recorded over 4 yr. • At all transplant sites, the local species outperformed the foreign species, reciprocal F1 hybrids performed intermediately and F2 hybrids underperformed in comparison to F1 hybrids (hybrid breakdown). Females generally had slightly higher cumulative fitness than males in both within- and between-species crosses and we thus found little evidence for Haldane's rule acting on field performance. The strength of selection against F1 and F2 hybrids as well as hybrid breakdown increased with increasing strength of habitat adaptation (i.e. the relative fitness difference between the local and the foreign species) across sites. • Our results suggest that differential habitat adaptation led to ecologically dependent postzygotic reproductive barriers and drives divergence and speciation in this Silene system. [ABSTRACT FROM AUTHOR]

The geospatial patterns of four species of native entomopathogenic nematodes in Florida were previously shown to be related to soil properties that affect soil water potential. Here we compared the responses to water potential of 3rd stage, infective juvenile (IJ) Steinernema sp. (Sx) and S. diaprepesi (Sd) in controlled conditions. The two species were selected because they are closely related (S. glaseri-group), but tend to occupy different habitats. In columns of sandy soil with moisture gradients ranging from field capacity (6% w:w) to saturated (18%), Sx migrated toward wetter soil whereas Sd migrated toward drier soil. Survival of two isolates each of Sx and Sd for seven days in the absence of food was greatest at 18% and 6% soil moisture, respectively. After three cycles of migration through soil to infect insect larvae 10 cm distant, Sd dominated EPN communities when soil columns were maintained at 6% moisture, whereas Sx was dominant in soil maintained at 18% moisture. When rehydrated after 24 h on filter paper at 90% RH, 50% of Sd survived compared to no Sx. Two isolates of Sd also survived better than two isolates of Sx during up to 24 h in a hypertonic solution (30% glycerol). The behavioral responses of both species to water potential and osmotic gradients were consistent with surveys in which Sx was recovered only from flatwoods ecoregions with shallow water tables and poorly drained soils, whereas Sd most frequently inhabited the central ridge ecoregion comprising well-drained soils and deeper water tables. Comparative proteomic analysis revealed differential expression of proteins involved in thermo-sensation (guanylyl cyclase and F13E6-4) and mechano-sensation and movement (paramyosin, Actin 3, LET-99, CCT-2), depending on whether Sd was in soil at 6% or 18% moisture. Proteins involved in metabolism, lectin detoxification, gene regulation and cell division also differed between the two conditions. Our data suggest the plausibility of modifying soil moisture conditions in flatwoods orchards in ways that favor more desirable (effective) EPN species. Similarly, these particular behavioral traits are likely to be useful in guiding the selection or engineering of EPN species for use in different ecoregions.

Locally available resources can be shared within clonal plant systems through physiological integration, thus enhancing their survival and growth. Most epiphytes exhibit clonal growth habit, but few studies have tested effects of physiological integration (resource sharing) on survival and growth of epiphytes and whether such effects vary with species. We conducted two experiments, one on individuals (single ramets) and another on groups (several ramets within a plot), with severed and intact rhizome treatments (without and with physiological integration) on two dominant epiphytic ferns (Polypodiodes subamoena and Lepisorus scolopendrium) in a subtropical montane moist forest in Southwest China. Rhizome severing (preventing integration) significantly reduced ramet survival in the individual experiment and number of surviving ramets in the group experiment, and it also decreased biomass of both species in both experiments. However, the magnitude of such integration effects did not vary significantly between the two species. We conclude that resource sharing may be a general strategy for clonal epiphytes to adapt to forest canopies where resources are limited and heterogeneously distributed in space and time.

This minireview highlights the importance of endophytic fungi for sustainable agriculture and horticulture production. Fungal endophytes play a key role in habitat adaptation of plants resulting in improved plant performance and plant protection against biotic and abiotic stresses. They encode a vast variety of novel secondary metabolites including volatile organic compounds. In addition to protecting plants against pathogens and pests, selected fungal endophytes have been used to remove animal toxicities associated with fungal endophytes in temperate grasses, to create corn and rice plants that are tolerant to a range of biotic and abiotic stresses, and for improved management of post-harvest control. We argue that practices used in plant breeding, seed treatments and agriculture, often caused by poor knowledge of the importance of fungal endophytes, are among the reasons for the loss of fungal endophyte diversity in domesticated plants and also accounts for the reduced effectiveness of some endophyte strains to confer plant benefits. We provide recommendations on how to mitigate against these negative impacts in modern agriculture. [ABSTRACT FROM AUTHOR]

• Background and Aims In orchid species that have populations occurring in strongly contrasting habitats, mycorrhizal divergence and other habitat-specific adaptations may lead to the formation of reproductively isolated taxa and ultimately to species formation. However, little is known about the mycorrhizal communities associated with recently diverged sister taxa that occupy different habitats. • Methods In this study, 454 amplicon pyrosequencing was used to investigate mycorrhizal communities associating with Epipactis helleborine in its typical forest habitat and with its presumed sister species E. neerlandica that almost exclusively occurs in coastal dune habitats. Samples of the phylogenetically more distant E. palustris, which co-occurred with E. neerlandica, were also included to investigate the role of habitat-specific conditions on mycorrhizal communities. • Results A total of 105 operational taxonomic units (OTUs) of putative orchid mycorrhizal fungi were observed in the three studied species. The majority of these fungi were endophytic fungi of Helotiales and ectomycorrhizal fungi belonging to Thelephoraceae, Sebacinaceae and Inocybaceae. In addition, a large number of other ectomycorrhizal taxa were detected, including Cortinarius, Cenococcum, Tuber, Geopora, Wilcoxina, Meliniomyces, Hebeloma, Tricholoma, Russula and Peziza. Mycorrhizal communities differed significantly between the three species, but differences were most pronounced between the forest species (E. helleborine) and the two dune slack species (E. neerlandica and E. palustris). • Conclusion The results clearly showed that recently diverged orchid species that occupy different habitats were characterized by significantly different mycorrhizal communities and call for more detailed experiments that aim at elucidating the contribution of habitat-specific adaptations in general and mycorrhizal divergence in particular to the process of speciation in orchids. [ABSTRACT FROM AUTHOR]

Mangrove associates are a category of plants that can grow and reproduce on both intertidal coastal zones and land. As subtropical coastal zones are characterized by high sun light and temperature, how mangrove associates adapt to such an environment is an important issue. Some researches show that mangrove associates are similar to land plant as well as thalassophyte in certain morphological structures and biochemical characteristics. However, there are few studies focusing on plant physiological characteristics of mangrove associates, especially in leaf gas exchange characteristics. Hibiscus tiliaceus(Malvaceae)is a pantropical mangrove associate that usually occurs in coastal zones. It is widely used for the conservation of sea banks, architecture and medicine. In order to disentangle the photosynthetic physiological mechanims underlying its habitat adaptation to high light and temperature under south subtropical climate, leaf gas exchange characteristics of H. tiliaceus were measured using LI-6400 portable photosynthesis system(Li-Cor Inc, USA)at Mangrove Natural Reserve of Qi'ao Island of Zhuhai City, Guangdong Province during July and August of 2013. The nature reserve(22°23'40'' N, 113°36'40'' E)is characterized by a typical south subtropical monsoon climate. The diurnal changes in photosynthetic rate(Pn), stomatal conductance(Gs), intercellular CO2 concentration(Ci)and transpiration rate(E)in H. tiliaceus all exhibited a mono-peak modal, and the peak value of Pn occurring at noon was around 26.8 μmol CO2 · m-2 · s-1 without obvious photoinhibition during the daytime. The high photosynthetic rate in H. tiliaceus was associated with high stomatal conductance, which was probably related to anatomical features of leaves, such as high stomatal density and dense trichomes in the lower leaf epidermis. Analysis of light response curves revealed that its light saturation point was 800 μmol photons·m-2 ·s-1 and its light compensation point was 26 μmol photons·m-2 ·s-1. The net photosynthesis at saturating irradiances was high at 27.8 μmol CO2 · m-2 · s-1. These photosynthesis parameters, along with high daily mean photosynthetic rate(19.6 μmol CO2 · m-2 · s-1)in H. tiliaceus suggested that this mangrove associate was characterized as a typical sun plant species. The results showed that the fast growth of H. tiliaceus might be attributed to its high and stable photosynthetic capacity, thus providing basic data for further revealing the eco-physiological mechanism underlying habitat adaptation of H. tiliaceus and other mangrove associates to coastal environment with high temperature and high light in summer. These results can also provide theoretical supports for its planting and reforestation practices. [ABSTRACT FROM AUTHOR]

Locally available resources can be shared within clonal plant systems through physiological integration, thus enhancing their survival and growth. Most epiphytes exhibit clonal growth habit, but few studies have tested effects of physiological integration (resource sharing) on survival and growth of epiphytes and whether such effects vary with species. We conducted two experiments, one on individuals (single ramets) and another on groups (several ramets within a plot), with severed and intact rhizome treatments (without and with physiological integration) on two dominant epiphytic ferns (Polypodiodes subamoena and Lepisorus scolopendrium) in a subtropical montane moist forest in Southwest China. Rhizome severing (preventing integration) significantly reduced ramet survival in the individual experiment and number of surviving ramets in the group experiment, and it also decreased biomass of both species in both experiments. However, the magnitude of such integration effects did not vary significantly between the two species. We conclude that resource sharing may be a general strategy for clonal epiphytes to adapt to forest canopies where resources are limited and heterogeneously distributed in space and time. [ABSTRACT FROM AUTHOR]

The blattid cockroach Periplanetaarabica (Bey-Bienko, 1938) has been poorly understood since its original description. In this study, male and female (including nymph) of P.arabica are paired using DNA barcoding, and their morphological characters (including both external characteristics and genitalia) are described. A detailed comparative morphological study of this species and the closely related Periplanetaamericana (Linnaeus, 1758) and Periplanetalateralis Walker, 1868 was carried out to explore phylogenetically relevant characters., (Xin-Xing Luo, Qian-Qian Li, Alireza Zamani, Yan-Li Che, Zong-Qing Wang.)

* Background and Aims The advantage of clonal integration (resource sharing between connected ramets of clonal plants) varies and a higher degree of integration is expected in more stressful and/or more heterogeneous habitats. Clonal facultative epiphytes occur in both forest canopies (epiphytic habitats) and forest understories (terrestrial habitats). Because environmental conditions, especially water and nutrients, are more stressful and heterogeneous in the canopy than in the understorey, this study hypothesizes that clonal integration is more important for facultative epiphytes in epiphytic habitats than in terrestrial habitats. * Methods In a field experiment, an examination was made of the effects of rhizome connection (connected vs. disconnected, i.e. with vs. without clonal integration) on survival and growth of single ramets, both young and old, of the facultative epiphytic rhizomatous fern Selliguea griffithiana (Polypodiaceae) in both epiphytic and terrestrial habitats. In another field experiment, the effects of rhizome connection on performance of ramets were tested in small (10 x 10 cm²) and large (20 x 20 cm²) plots in both epiphytic and terrestrial habitats. * Key Results Rhizome disconnection significantly decreased survival and growth of S. griffithiana in both experiments. The effects of rhizome disconnection on survival of single ramets and on ramet number and growth in plots were greater in epiphytic habitats than in terrestrial habitats. * Conclusions Clonal integration contributes greatly to performance of facultative epiphytic ferns, and the effects were more important in forest canopies than in forest understories. The results therefore support the hypothesis that natural selection favours genotypes with a higher degree of integration in more stressful and heterogeneous environments. [ABSTRACT FROM AUTHOR]

During the long-term processes of evolution and development, plant species yield a set of morphological, structural and physiological characteristics through their interactions with the environment, and these characteristics indicate their ecological adaptive strategies to the environment Within forest communities, topographic and edaphic variations often lead to habitat heterogeneity, and hence tend to directly or undirectly influence the distribution pat- terns of plant species. Thus, it is an important question that how plant species distribution is related to its ecological adaptive strategies in forest commnuties with high habitat heterogeneity. Ardisia quinquegona and Aidia canthioides are two dominant evergreen tree species in the subtropical monsoon evergreen broad-leaved forest within the 20 ha forest biodiversity monitoring plot at Dinghushan National Nature Reserve in Zhaoqing City, Guangdong Province, China. The two tree species are distributed in different habitats including mountain ridge, slope, and valley. To under- stand the relation of their ecological strategies of habitat adaptation to their distribution patterns in the forest, a comparative study was conducted on their leaf functional traits and hydraulic properties among the three different habitats. Functional traits measured include leaf area (LA), leaf thickness, leaf length/leaf width ratio, specific leaf area (SLA) , and leaf dry matter content (LDMC) , while hydraulic properties include sapwood specific hydraulic conductivity, leaf specific conductivity, huber value, wood density (WD) , leaf water potential at turgor loss point (r°) and saturated leaf water potential (π100) The results showed that A. quinquegona tended to adapt to different habitats mainly through the ad] ustment of leaf area LA, WD and osmotic regulation. In contrast to A. quinquegona, A. canthioides had a stronger ability to adapt to the environment, especially mountain ridge and slope habitats, via the strategy of "slow growth rate and high survival rate". It mainly made fine adjustment on SLA,WD and osmotic regulation, and used the strategy of efficient conservation of nutrients (low SLA, high LDMC). Moreover, the soil factors that limit leaf functional traits and plant hydraulics differed between the two studied tree species. Our results revealed that both species were suitable to survive in mount ridge and slope rather than in valley, while they differed in habitat adaptation strategies regarding leaf functional traits and hydraulic properties, although they both were dominant species in the subtropical monsoon evergreen broad-leaved forest. [ABSTRACT FROM AUTHOR]

Illuminating the ability of individuals to react to different selective forces caused by environmental differences is crucial to understand population divergence and speciation in the context of habitat adaptation. In a common environment experiment performed under standardised laboratory conditions, we examined whether female fire salamanders ( Salamandra salamandra) originating from a recently adaptively diverged population displayed behavioural phenotype differences related to larval deposition behaviour. Females of this species typically deposit their larvae in small first-order streams; however, in our study population, females also use temporary ponds. These two habitat types display major ecological differences that strongly influence larval growth and survival. We observed that females differed in larval deposition behaviour and maternal investment. Pond-type females extended larval deposition over an increased time period and tended to exhibit more deposition events compared with stream-type females. Over successive deposition events, the body condition of larvae deposited by stream-type females decreased faster than that of larvae deposited by pond-type females. These differences in larval deposition behaviour may represent a bet-hedging strategy, given that ponds are more constrained in terms of desiccation and food availability than streams. The lengthened deposition period enabled pond-type females to deposit larger larvae towards the end of the deposition period, compared with stream-type females. Although the studied population only diverged recently, we observed significant behavioural differences between differentially adapted females, demonstrating the importance of behavioural differences in habitat adaptation in the context of speciation processes. [ABSTRACT FROM AUTHOR]

1. The large flightless grasshopper Acrostira bellamyi Uvarov, endemic to the island of La Gomera ( Canary Islands), inhabits two different environments: the xeric euphorb shrubland, as is typical for congeneric Canarian species, and the humid laurel forest, a novel habitat for the genus. 2. We investigate genetic, morphological, and ecological variation among individuals of A. bellamyi from the two habitats. DNA sequence data were used to evaluate whether grasshoppers from the two environments represent distinct lineages. Morphological and trophic analyses were performed to assess phenotypic differentiation between the two different habitats. 3. Population genetic analyses support the hypothesis that the euphorb shrubland is the ancestral habitat for this species. Female laurel forest specimens are larger than those inhabiting the euphorb shrubland, and some external body parts exhibit significant morphometric differences between the two populations. Diet of shrubland individuals is completely different from that of laurel forest individuals. Although in each habitat they consume the most abundant plants, individuals are able to select food plants, which appear to be explained by their nutrient content. 4. Our results suggest that A. bellamyi has colonised laurel forest from shrubland, and that this habitat shift has resulted in genetic, morphological, and ecological changes, perhaps as an adaptation to this new habitat. [ABSTRACT FROM AUTHOR]

Background: Adaptation of Pseudomonas aeruginosa to different living conditions is accompanied by microevolution resulting in genomic diversity between strains of the same clonal lineage. In order to detect the impact of colonized habitats on P. aeruginosa microevolution we determined the genomic diversity between the highly virulent cystic fibrosis (CF) isolate CHA and two temporally and geographically unrelated clonal variants. The outcome was compared with the intraclonal genome diversity between three more closely related isolates of another clonal complex. Results: The three clone CHA isolates differed in their core genome in several dozen strain specific nucleotide exchanges and small deletions from each other. Loss of function mutations and non-conservative amino acid replacements affected several habitat- and lifestyle-associated traits, for example, the key regulator GacS of the switch between acute and chronic disease phenotypes was disrupted in strain CHA. Intraclonal genome diversity manifested in an individual composition of the respective accessory genome whereby the highest number of accessory DNA elements was observed for isolate PT22 from a polluted aquatic habitat. Little intraclonal diversity was observed between three spatiotemporally related outbreak isolates of clone TB. Although phenotypically different, only a few individual SNPs and deletions were detected in the clone TB isolates. Their accessory genome mainly differed in prophage-like DNA elements taken up by one of the strains. Conclusions: The higher geographical and temporal distance of the clone CHA isolates was associated with an increased intraclonal genome diversity compared to the more closely related clone TB isolates derived from a common source demonstrating the impact of habitat adaptation on the microevolution of P. aeruginosa. However, even short-term habitat differentiation can cause major phenotypic diversification driven by single genomic variation events and uptake of phage DNA. [ABSTRACT FROM AUTHOR]

The article presents a study which compares the morphology and histology of the cyathial nectaries in eight Euphorbia species in Europe. The study uses longitudinal sections with light microscopy to identify the structure of the cyathial glands, and softwares to measure histological parameters. Results show that the thickness of cuticle, the position of nectar stomata, and the number of rows containing the glandular tissue vary to the extent in plants living in humid, mesic, or xeric habitats.

Preliminary results obtained from histological analyses of the male reproductive organs, supplemented with field and behavioural data, indicate that Sufflogobius bibarbatus, a small, slow growing gobiid exhibiting low fecundity, which plays an important role in the food web off Namibia, where large areas of the shelf are hypoxic, spawns demersally. Large males defend benthic nests, possibly at the edge of the hypoxic shelf. Male reproductive strategy appears to be flexible, and tentative evidence to suggest that polygyny and sneaking may also occur is presented. [ABSTRACT FROM AUTHOR]

Molecular phylogeny of the four Korean Ephemera species, Ephemera orientalis, E. sachalinensis, E. strigata, and E. separigata, was inferred from 630 bp sequences of the partial mitochondrial cytochrome c oxidase I ( COI) gene. Results indicated that mean intraspecific sequence divergences were 0.70%, whereas mean interspecific divergences were 15.75%, and 17 samples were distinguished to four species correctly by COI sequences. The results also demonstrated that four species of Korean Ephemera assembled a monophyletic group with high support in maximum parsimony and maximum likelihood analyses. This Ephemera group was divided into two major clades of E. orientalis- E. sachalinensis and E. strigata- E. separigata. Furthermore, we demonstrated that this phylogeny explained altitudinal and habitat adaptations of Korean Ephemera species. The E. orientalis- E. sachalinensis clade, a widespread and lowland-adapted mayfly group, retained plesiomorphic traits such as paired stripes on abdominal segments and was regarded as plesiotypic in terms of habitat adaptation, compared to the geographically more limited and upland-adapted E. strigata- E. separigata clade. [ABSTRACT FROM AUTHOR]

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The germination behaviour of two Iberian endemic labiates, Sideritis pungens and S. chamaedryfolia selected from different habitats, ranging from very humid to semi-arid, was studied under controlled experimental conditions. A factorial experiment, combining different temperature regimes (10°, 15°, 20°, 25° or 30°C), photoperiod (total darkness and 12 h light/12 h darkness) and different pre-treatments (freezing, dry-heat, hot-water), was designed to analyze seed germination patterns and dormancy processes. The results obtained are in agreement with the ecology of the two species. Seeds are not dormant after collection and maintain high viability when preserved by standard seed bank conservation protocols. It was found out that optimal temperature for germination is 20°C for both species. Light seems to play a key role in the germination of genus Sideritis, particularly for S. chamaedryfolia, significantly inhibited by light as other psammophilous plants. Temperature and light are relevant environmental indicators, but it was found out that the germination response to these factors in the studied species is correlated with a different environmental factor, namely the availability of water resources in their habitats, which is generally a major constraint factor for seed germination in Mediterranean areas. The results indicate that germination limitations are not so much related to taxonomic position, but rather adaptations to water restrictions. [ABSTRACT FROM AUTHOR]

The article focuses on a study which investigated the relation between song frequency characteristics of great tit song in Madrid, Spain to local noise levels based on data from the city noise map. Great tit song was recorded between February 29 and May 28, 2008 from different location in the city and were carried out during work days. Findings of the study confirmed the findings of previous studies of great tits conducted in European cities. These studies demonstrated the positive link between the minimum frequency of song and the amplitude of background noise.

Invasions by pest organisms are among the main challenges for sustainable crop protection. They pose a serious threat to crop production by introducing a highly unpredictable element to existing crop protection strategies. The western flower thrips Frankliniella occidentalis (Insecta, Thysanoptera) managed to invade ornamental greenhouses worldwide within < 25 years. To shed light on possible genetic and/or ecological factors that may have been responsible for this invasion success, we studied the population genetic structure of western flower thrips in its native range in western North America. Analysis of nucleotide sequence variation and variation at microsatellite loci revealed the existence of two habitat-specific phylogenetic lineages (ecotypes) with allopatric distribution. One lineage is associated with hot/dry climates, the second lineage is restricted to cool/moist climates. We speculate that the ecological niche segregation found in this study may be among the key factors determining the invasion potential of western flower thrips. [ABSTRACT FROM AUTHOR]

Adaptation to different habitats is considered to be a major force in the generation of organismal diversity. Understanding the genetic mechanisms that produce such adaptations will provide insights into long-standing questions in evolutionary biology and, at the same time, improve predictions of plant responses to changing environmental conditions. Here we used semiquantitative RT-PCR to study the expression of eight candidate salt-tolerance genes in leaves of the highly salt-tolerant diploid hybrid species Helianthusparadoxus and its salt-sensitive progenitor species H. annuus and H. petiolaris. Samples were collected after germination and growth under four different treatments: nonsaline (control), near-natural saline, saline with increased K+, and saline with decreased Mg2+ and Ca2+. Three individuals from three populations per species were used. The hybrid species H. paradoxus constitutively under- or overexpressed genes related to potassium and calcium transport (homologues of KT1, KT2, ECA1), suggesting that these genes may contribute to the adaptation of H. paradoxus to salinity. In two other genes, variation between populations within species exceeded species level variation. Furthermore, homologues of the potassium transporter HAK8 and of a transcriptional regulator were generally overexpressed in saline treatments, suggesting that these genes are involved in sustained growth under saline conditions in Helianthus. [ABSTRACT FROM AUTHOR]

High unionized ammonia (NH 3 −N) is a major stress factor for rearing aquatic animals that can collapse the mass culture of rotifers in aquaculture facilities. In rotifer mass culture, concentrations of NH 3 -N are elevated when reaching maximum density. As NH 3 -N toxicity has temperature-dependent characteristics, tropical and temperate rotifers should be subjected to different levels of habitat-resource NH 3 -N, which could affect their physiological adaptations. To investigate the NH 3 -N tolerance of rotifers associated with reproductive adaptations to different habitats, two rotifer species in the Brachionus plicatilis species complex were studied: temperate B. plicatilis and tropical B. rotundiformis. Survival, life history parameters, and reproductive patterns were assessed under acute (lethal) and chronic (sub-lethal) NH 3 -N exposure. These rotifer species were not treated with NH 3 -N or exposed to 1.1 and 8.5 mg/L NH 3 -N for 7 days to define the biochemical (i.e., oxidative and lipid metabolism) and behavioral (swimming speed) mechanisms of ammonia species sensitivity. High concentrations of NH 3 -N (≥8.5 mg/L) suppressed rotifer growth and reproduction, resulting in substantial maturation retardation and fecundity reduction in both species. Nevertheless, the tropical B. rotundiformis was more tolerant to acute and chronic NH 3 -N exposure than the temperate B. plicatilis , with 1.5 and 1.7 fold higher LC 50 and EC 50 (for intrinsic growth rate) values at 25 °C, respectively. Furthermore, B. rotundiformis showed stronger ammonia tolerance in sexual reproductive parameters, including mixis, fertilization, and resting egg production. High sexual reproduction tolerance is important for improving rotifer stress resistance and maintaining the population under harsh environments. The two species exhibited different modulations of lipid and stress defense activities under NH 3 -N exposure. Temperate B. plicatilis showed reduced neutral lipid accumulation in the reproductive organs (vitellarium/ovary), stimulated lipid peroxidation with a high level of malondialdehyde (MDA), and disrupted antioxidant activities. In contrast, the tropical B. rotundiformis exhibited active defense responses, with enhanced antioxidant activity and lipid synthesis. These findings with molecular evidence indicate the specific ammonia sensitivity between tropical and temperate rotifers, and more active anti-stress strategies of the tropical species than the temperate species, contributing to high ammonia tolerance. The higher ammonia tolerance of tropical B. rotundiformis species may support their high-density endurance during mass culture. • NH 3 -N induced reproductivity varied between tropical and temperate rotifers. • NH 3 -N overload suppressed rotifer maturation and fecundity in both species. • NH 3 -N disrupted antioxidant and lipid metabolisms in the temperate rotifer. • Tropical rotifer had strong NH 3 -N tolerance with habitat adaptation. • NH 3 -N tolerance may support a higher density of tropical rotifer in mass culture. [ABSTRACT FROM AUTHOR]