Check of the taxonomy of freshwater fishes of Iraq

A stochastic theory of community food webs. VI. Heterogeneous alternatives to the cascade model

Percolation on the Fitness Hypercube and the Evolution of Reproductive Isolation

The hypothesis that sexual selection promotes speciation has rarely been tested. We identified 70 evolutionarily independent events of feather ornaments in birds. For each focal species we noted the number of ornamented and nonornamented species belonging to its genus and its number of subspecies, as well as its mating system and the extent of its geographic range. For purposes of comparison, we randomly chose a second, nonornamented species for which we obtained information on the number of subspecies, and in cases in which the nonornamented species was in the same genus, we chose a third, nonornamented species in a related genus and obtained the same information. We then noted the number of species in each genus and the difference in numbers of species, or species richness, between paired genera. For the genera of the focal ornamented species, we regressed number of ornamented species on number of nonornamented species and found a positive relationship. As number of species per genus rose, number of ornamented species per genus rose more rapidly, indicating that more speciose genera have a higher proportion of ornamented species than less speciose genera. We then took the deviations from this regression, the residual number of species, and regressed them on the differences in species richness between the paired genera. This relationship was positive indicating that ornamented genera with more than the expected number of ornamented species were more speciose with respect to their paired genera than were genera with fewer than the expected number of ornamented species. Finally, we compared the deviations from this regression, the residual number of ornamented species, with species' mating system and found a greater residual number of ornamented species among species whose mating system is associated with greater skew in male mating success and thus more intense sexual selection. Ornamented species had more subspecies than nonornamented species, even when controlling for geographic range, suggesting an association between subspeciation and ornaments.

Determinants of orchid species diversity in world islands.

Macrophyte assemblages in fishponds under different fish farming management

IntroductionSarcopenia, an age-related disease, has become a major public health concern, threatening muscle health and daily functioning in older adults around the world. Changes in the gut microbiota can affect skeletal muscle metabolism, but the exact association is unclear. The richness of gut microbiota refers to the number of different species in a sample, while diversity not only considers the number of species but also the evenness of their abundances. Alpha diversity is a comprehensive metric that measures both the number of different species (richness) and the evenness of their abundances, thereby providing a thorough understanding of the species composition and structure of a community.MethodsThis meta-analysis explored the differences in intestinal microbiota diversity and richness between populations with sarcopenia and non-sarcopenia based on 16 s rRNA gene sequencing and identified new targets for the prevention and treatment of sarcopenia. PubMed, Embase, Web of Science, and Google Scholar databases were searched for cross-sectional studies on the differences in gut microbiota between sarcopenia and non-sarcopenia published from 1995 to September 2023 scale and funnel plot analysis assessed the risk of bias, and performed a meta-analysis with State v.15. 1.ResultsA total of 17 randomized controlled studies were included, involving 4,307 participants aged 43 to 87 years. The alpha diversity of intestinal flora in the sarcopenia group was significantly reduced compared to the non-sarcopenia group: At the richness level, the proportion of Actinobacteria and Fusobacteria decreased, although there was no significant change in other phyla. At the genus level, the abundance of f-Ruminococcaceae; g-Faecalibacterium, g-Prevotella, Lachnoclostridium, and other genera decreased, whereas the abundance of g-Bacteroides, Parabacteroides, and Shigella increased.DiscussionThis study showed that the richness of the gut microbiota decreased with age in patients with sarcopenia. Furthermore, the relative abundance of different microbiota changed related to age, comorbidity, participation in protein metabolism, and other factors. This study provides new ideas for targeting the gut microbiota for the prevention and treatment of sarcopenia.Systematic Review Registrationhttps://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=475887, CRD475887.

Drought has a strong impact on the growth of plant populations, and the number of different species in a plant community plays an important role in the drought adaptation of the community's progeny. In this paper, a mathematical model is developed to analyze how the number of different species in a plant community under a long-term irregular drought cycle is adaptive to drought in future generations, and thus how the plant community benefits from it. This paper uses biomass to quantify the growth of plant populations and changes in plant communities, and uses a large amount of visual data for visual analysis. First, a logistic growth model of plant population biomass change is developed based on temperature accumulation, precipitation and interspecific competition as influencing factors. The correlation coefficients were then obtained using the collected plant population biomass to predict the changes in total plant biomass and species richness, and the interspecific competition model was then used to calculate the values of total community biomass after final stabilization based on logistic, and the system of differential equations was solved using the Runge-Kutta Methods was finally concluded that the biomass of the community after final stabilization showed a positive correlation with the number of species and species type, and showed a strong positive correlation with species type and a weak positive correlation with species number.

Distribution patterns of indigenous non‐volant terrestrial mammals on 257 Australian islands were examined in relation to environmental parameters and the effects of human‐induced disturbance during prehistoric and historic times on island species numbers. Species occurrence for individual species, for taxonomic and trophic groups, and for all species together was related to environmental parameters using regression analysis and the extreme‐value function model. Patterns of occurrence were examined separately within three major biogeographic regions derived by pattern analysis. The number of species known to have occurred on these islands during historic times was adequately predicted from area alone. No statistically significant improvement in predicted species number was gained by including island elevation, mean annual rainfall, isolation from the mainland or the number of potentially competing species present on the island. Similarly, no single factor other than area was found to influence consistently the presence of individual species. We conclude that the occurrence of indigenous non‐volant terrestrial mammal species on these islands indicates a relictual rather than equilibrial fauna. Visitation by Aboriginal people during prehistoric times did not significantly increase mammal extinctions on islands. Examination of patterns of species richness for a given area on a regional basis showed that islands in and around Bass Strait and Tasmania (Bass Region) were the most species‐rich, islands off the northern coasts were slightly less rich, and islands off the south western coasts had fewest species. This is in contrast to the usual latitudinal gradient in species richness patterns. However, islands off the northern and eastern coasts had an overall greater number of different species. When considered in relation to the number of different species of mammals occurring within each region, islands of a given size in Bass Region typically bore a higher proportion of this species pool than other regions. The Bass Region was found to be particularly rich in macropoid herbivores and dasyurid carnivores and insectivores. Analyses indicated that there is a very strong relationship between the presence of exotics as a whole and the local extinction of native mammals. Many mammal species formerly widespread on the Australian mainland are now restricted totally to islands (nine species) or are threatened with extinction on the mainland and have island populations of conservation significance (ten species). In all, thirty‐five islands protect eighteen taxa of Australian threatened mammals. The land‐use and management of these islands is of considerable importance to nature conservation. The introduction of exotic mammals to these islands should be prevented; any introductions that occur should be eradicated immediately.

A male child, maintained in a controlled environment, was monitored each month for bacteria, yeasts, and filamentous fungi recovered from the mouth, nasal passages, feces, and nine body surface sites. Three natural microbial categories became apparent. Incident microorganisms were recovered from within the isolator but did not establish permanent residence. Of the 53 incident types isolated, 20 were filamentous fungi and 4 were yeasts. Some genera, such as Fusobacterium, Lactobacillus, Neisseria, and Rothia, which were commonly found in the reference group, did not become permanent inhabitants. Transient microorganisms were repeatedly recovered but could not be demonstrated within the isolated environment at the end of the study. The loss of only a few of the 19 transient species could be associated with antimicrobial therapy. Permanent microorganisms consisted of Pencillium citrinum and 17 bacterial types, of which alpha-hemolytic streptococci, Staphylococcus edpidermidis subgroups II and V, Micrococcus groups 1 and 2, Clostridium bifermentans, and Propionibacterium acnes were recovered throughout the entire 9 years of the study. The number of CFUs recovered from each sample type was generally not unlike that from the reference group of healthy male adults. Also, the number of different aerobic species recovered from the feces was within the normal range of that of the reference group. In contrast, the number of different species recovered from all other samples was less than that commonly found in the reference group.

80-year-old Siberian larch plantations situated on the border of southern and middle taiga subzones in Eastern Fennoscandia were studied. Total surveyed 6 forest sites located in the landscape with respect to the same environmental conditions. After the larch plantations had been planted in 1935 by Finnish foresters, studied forest communities developed without noticeable human interventions. Species composition of larch communities was defined within the boundaries of a permanent plot, on the others the forest sites within the borders of the natural forest associations, which are comparable in size to the size of permanent plots larch communities. Analysis of the forest stand characteristics of the studied forest sites showed that the Siberian larch plantations are well adapted and have a high competition ability compared with spruce and pine stands. The conditions generated by Siberian larch proved to be quite favorable for many species of ground cover: the number of vascular plant species was by two times higher in the larch forest stands than in the neighboring zonal spruce stands of the wood sorrel and bilberry types. The structures of ground cover in the larch forest stands are more complex: first layer was comprised by plant species that prefer low canopy density and fertile soils; the second layer was presented by shade tolerant plant species. At the same time, the projective cover of mosses decreased although the number of moss species and their patchiness were increased. In spite of the markedly different number of species, of the ecological and ecological-coenotic structures of the studied forest communities were differed marginally. The number of species in the larch forest stands increased by both shade-tolerant and light-demanding species. Improved soil fertility in the larch forest resulted in an increase of the number of meso-eutrophic species that are typical for southern taiga zone. Generally speaking, the introduction of larch into zonal communities of spruce forests influences on the structure of ground cover structure more significantly than the variation of biotope factors within the study area.

Total number of species versus Total Number of different species

The effects of patch size on the colonisation and succession of intertidal invertebrates and algae were investigated in an estuary near Sydney, New South Wales, Australia. The specific aim was to test explicitly for the presence of a species-area relationship, and examine whether this could be explained by the random placement hypothesis (i.e. that the number of species per unit area was the same on patches of different sizes). In addition, I tested the extent to which differences in numbers of species reflected differences in the composition of assemblages. Wooden panels of three different sizes (10 x 10 cm, 20 x 20 cm and 40 x 40 cm) were placed in the field on intertidal oyster leases in each of two different experimental trials: spring (October 1994) and summer (January 1995). Independent replicate measures of the number of colonising species on panels were obtained after different periods of time, up to 25 months. I also obtained measures of abundance of individual species and composition of assemblages on panels of different sizes. This allowed specific tests of the hypothesis that the size of the patch being colonised is important in structuring these assemblages. The strength of the species-area relationship increased through time on panels submersed in October, but the trend was reversed for panels submersed in January. There was a significant interaction between factors of patch size and time of submersion for multivariate measures of differences in composition among replicates. The random placement hypothesis was supported in certain situations, but not in others. When rejected, it was for different reasons on panels submersed in the two different trials. Panels initiated in October tended to have proportionally greater numbers of species per unit area on larger panels, while the panels initiated in January tended to have more species per unit area on smaller panels. There was an identifiable relationship between differences in numbers of species and differences in species composition for panels submersed in October. This was not true, however, for panels submersed in January, where the species-area relationship did not hold after longer periods. The succession of organisms through time was, overall, more important in structuring the assemblages than was the size of the patch being colonised. The species-area relationship should not necessarily be regarded as a truism - it did not always hold in this system. The initial timing of experiments with respect to recruitment and succession influenced the results.

Effect Of Chitinase On Il-8 Production In Human Respiratory Epithelial Cells

Bat assemblage structure in two dry forests of Colombia: Composition, species richness, and relative abundance

The relation between foliage complexity and bird species diversity has been studied by several investigators. Some (MacArthur and MacArthur 1961, MacArthur et al., 1962, Recher 1969, Karr 1971, Karr and Roth 1971) found that the complexity of the vertical distribution of leaves, as measured by foliage height diversity ( FHD ) , was a good predictor of bird species diversity (BSD). Other investigators (Terborgh 1967, Balda 1969, Lovejoy 1972) have found little correlation between FHD and BSD. BSD, as measured by a statistic derived from information theory, necessitates knowledge of the number of individuals of each species as well as number of species. In mature tropical forests, estimates of population size are difficult because such a large proportion of the bird species do not typically occur in low strata where they can be readily netted and marked. Orians ( 1969) avoided this problem in Costa Rican forests by comparing only the number of bird species (bird species richness, BSR) to FHD. He suggested that the range of resource types permanently above threshold values in tropical forests was the major factor determining bird species richness. However, in all these relations between foliage complexity and the number of bird species inhabiting the foliage, the assumption is made that the community is in an equilibrium or saturated state, that is, new species can enter the community only if they exclude a species already present. The Amazon Basin presents a distinct difficulty in applying FHD-BSD (BSR) correlations. Due to numerous historical changes in climate, continuous forest apparently alternated with forest islands (refugia) surrounded by non-forest vegetation throughout the Pleistocene and post-Pleistocene (Haffer 1969, Vanzolini 1973). It is now generally recognized that islands with similar habitat harbor different numbers of species depending on the area and distance of the island from the mainland species pool (MacArthur and Wilson 1967). Island-like effects are also recognized for continental habitats that occur in patches