scholarly journals Multi-modal signal evolution in birds: re-examining a standard proxy for sexual selection

2018 ◽  
Vol 285 (1889) ◽  
pp. 20181557 ◽  
Author(s):  
Christopher R. Cooney ◽  
Hannah E. A. MacGregor ◽  
Nathalie Seddon ◽  
Joseph A. Tobias
Keyword(s):  
Sexual Selection ◽  
Interspecific Interactions ◽  
Habitat Type ◽  
Negative Relationship ◽  
Key Factors ◽  
Phenotypic Data ◽  
Species Pairs ◽  
Multiple Alternative ◽  
Mating Signal ◽  
Diversification Hypothesis

Sexual selection is proposed to be an important driver of speciation and phenotypic diversification in animal systems. However, previous phylogenetic tests have produced conflicting results, perhaps because they have focused on a single signalling modality (visual ornaments), whereas sexual selection may act on alternative signalling modalities (e.g. acoustic ornaments). Here, we compile phenotypic data from 259 avian sister species pairs to assess the relationship between visible plumage dichromatism—a standard index of sexual selection in birds—and macroevolutionary divergence in the other major avian signalling modality: song. We find evidence for a strong negative relationship between the degree of plumage dichromatism and divergence in song traits, which remains significant even when accounting for other key factors, including habitat type, ecological divergence and interspecific interactions. This negative relationship is opposite to the pattern expected by a straightforward interpretation of the sexual selection–diversification hypothesis, whereby higher levels of dichromatism indicating strong sexual selection should be related to greater levels of mating signal divergence regardless of signalling modality. Our findings imply a ‘trade-off’ between the elaboration of visual ornaments and the diversification of acoustic mating signals, and suggest that the effects of sexual selection on diversification can only be determined by considering multiple alternative signalling modalities.

Influence of habitat on home-range size in the short-beaked echidna

2012 ◽  
Vol 60 (1) ◽  
pp. 46 ◽  
Author(s):  
Jenny Sprent ◽  
Stewart C. Nicol
Keyword(s):  
Home Range ◽  
Spatial Ecology ◽  
Habitat Type ◽  
Negative Relationship ◽  
Home Range Size ◽  
Range Size ◽  
Home Ranges ◽  
Location Data ◽  
Significant Negative Relationship ◽  
Solitary Species

The size of an animal’s home range is strongly influenced by the resources available within it. In productive, resource-rich habitats sufficient resources are obtainable within a smaller area, and for many species, home ranges are smaller in resource-rich habitats than in habitats with lower resource abundance. Location data on 14 male and 27 female echidnas (Tachyglossus aculeatus) fitted with tracking transmitters, in the southern midlands of Tasmania, were used to test the influence of habitat type on home-range size. We hypothesised that as woodland should offer more shelter, food resources and refuges than pasture, echidnas living in woodland would have smaller home ranges than those living in pasture areas. We found significant differences between the sexes. Male echidnas had a significantly larger mean home range than females and a quite different relationship between home-range size and habitat type from females. There was no relationship between the proportion of woodland within male home ranges and home-range size whereas female echidnas had a highly significant negative relationship. This suggests that home-range size of female echidnas is highly influenced by the amount of woodland within it, but the home-range size of male echidnas is controlled by factors other than habitat. This pattern is consistent with the spatial ecology of many other solitary species with a promiscuous mating system. The home ranges of females are scaled to encompass all necessary resources for successfully raising their young within a minimal area, whilst the large home ranges of males are scaled to maximise access to females.

scholarly journals Does human influence on coastal grasslands habitats affect predation pressure on snakes?

2013 ◽  
Vol 13 (1) ◽  
pp. 366-370 ◽  
Author(s):  
Mauricio Beux dos Santos ◽  
Mauro Cesar Lamim Martins de Oliveira ◽  
Tatiane Penteado Gonçalves ◽  
Francis de Mattos Almeida ◽  
Daniel Loebmann ◽  
...  
Keyword(s):  
South America ◽  
Interspecific Interactions ◽  
Predation Rate ◽  
Predation Pressure ◽  
Key Factors ◽  
Human Influence ◽  
Real Effect ◽  
The Real ◽  
Disturbed Areas ◽  
Predation Rates

The loss and modification of habitats by humans have been considered key factors in the decline of diversity of species worldwide. However, the real effect caused by these disturbances on the biota is still poorly understood. The assessment of the changes in the network of interspecific interactions, such as predation rates on the native fauna, can be an important tool to diagnose the functionality of disturbed ecosystems. In this study we evaluate the predation rate on snakes in coastal grasslands in South America under human influence. Predation rate of artificial snakes, unlike that obtained in other studies, was lower in human-altered areas than preserved ones. Our findings may be due to a reduction in the abundance and/or richness of species of native predators in more disturbed areas.

Pollination in alpine Norway: flowering phenology, insect visitors, and visitation rates in two plant communities

1993 ◽  
Vol 71 (8) ◽  
pp. 1072-1079 ◽  
Author(s):  
Ørjan Totland
Keyword(s):  
Plant Communities ◽  
Interspecific Interactions ◽  
Flowering Phenology ◽  
Alpine Plant ◽  
Visitation Rates ◽  
Species Pairs ◽  
Alpine Plant Communities ◽  
Selection For ◽  
Insect Visitors ◽  
Key Words Alpine

Pollination studies in European alpine communities are few. The objective of this study was to describe the pollination ecology in two alpine plant communities at Finse, southwestern Norway. Because of late snowmelt and early winter at Finse, the time available for flowering and seed maturation is restricted. Flowering was concentrated at the beginning of the season in both communities, and large overlaps in flowering time were found for most species. In one of the communities, flowering peaks were significantly clumped, whereas in the other they were randomly distributed through the season. However, in this community, five insect-pollinated species flowered simultaneously early in the season. Diptera almost exclusively dominated the visitor assemblage. Most plant species pairs had high overlaps in flower visitor species. Species flowering simultaneously attracted the same visitor species. In one community, eight species pairs flowered sequentially and shared visitors. Visitation rates were highest at the lowest elevated site. The results are compared with those obtained in other alpine areas. It is argued that selection for an early flowering is probably stronger than selection pressures resulting from interspecific interactions. Key words: alpine, Diptera, flowering phenology, flower visitors, season length, visitation rate.

scholarly journals Natural and sexual selection act on different axes of variation in avian plumage color

2015 ◽  
Vol 1 (2) ◽  
pp. e1400155 ◽  
Author(s):  
Peter O. Dunn ◽  
Jessica K. Armenta ◽  
Linda A. Whittingham
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Habitat Type ◽  
Sexual Differences ◽  
Plumage Color ◽  
Evolutionary Transitions ◽  
Testes Size ◽  
Selection For ◽  
Bird Coloration ◽  
Natural And Sexual Selection

The bright colors of birds are often attributed to sexual selection on males, but in many species both sexes are colorful and it has been long debated whether sexual selection can also explain this variation. We show that most evolutionary transitions in color have been toward similar plumage in both sexes, and the color of both sexes (for example, bright or dull) was associated with indices of natural selection (for example, habitat type), whereas sexual differences in color were primarily associated with indices of sexual selection on males (for example, polygyny and large testes size). Debate about the evolution of bird coloration can be resolved by recognizing that both natural and sexual selection have been influential, but they have generally acted on two different axes: sexual selection on an axis of sexual differences and natural selection on both sexes for the type of color (for example, bright or dull).

scholarly journals Organización del tiempo docente y su relación con la satisfacción laboral: Evidencia para el caso chileno

2017 ◽  
Vol 25 ◽  
pp. 64
Author(s):  
Veronica Cabezas ◽  
María Paz Medeiros ◽  
David Inostroza ◽  
Constanza Gómez ◽  
Vicente Loyola
Keyword(s):  
Job Satisfaction ◽  
Positive Relationship ◽  
Collaborative Work ◽  
Negative Relationship ◽  
Teacher Job Satisfaction ◽  
Key Factors ◽  
Conditional Models ◽  
The Relationship ◽  
Positive Effect ◽  
Actual Teaching

The literature indicates that teachers lack of time to adequately prepare and fulfill their responsibilities, is one of the key factors that negatively influence levels of teacher job satisfaction. Considering a representative sample of teachers in Santiago of Chile (N=950) and using conditional models, this study explores the relationship between teacher job satisfaction that work in subsidized schools, and the time available to these teachers for realizing activities over and above actual teaching hours: contracted non-teaching hours and additional overtime. This study uses a questionnaire that incorporates, in addition to the overtime, information about how teachers use their time, identifying the type of activities they are involved in, and if they are involved individually or as a group. The results indicate that there is a robust positive relationship between the number of contracted non-teaching hours and teacher job satisfaction, and a negative relationship with respect to overtime. Also identified the relevance of being adequately resourced with formal instances to engage in collaborative work for planning and prepare class materials, since it is linked to a positive effect on teacher job satisfaction.

scholarly journals Rapid courtship evolution in grouse (Tetraonidae): contrasting patterns of acceleration between the Eurasian and North American polygynous clades

2007 ◽  
Vol 274 (1613) ◽  
pp. 1079-1086 ◽  
Author(s):  
Allen Spaulding
Keyword(s):  
Sexual Selection ◽  
Mating Success ◽  
Male Mating ◽  
Sexually Dimorphic ◽  
Sexually Selected Traits ◽  
Species Pairs ◽  
Rapid Divergence ◽  
Nucleotide Divergence ◽  
Selected Traits ◽  
Dimorphic Species

Sexual selection is thought to be a powerful diversifying force, based on large ornamental differences between sexually dimorphic species. This assumes that unornamented phenotypes represent evolution without sexual selection. If sexual selection is more powerful than other forms of selection, then two effects would be: rapid divergence of sexually selected traits and a correlation between these divergence rates and variance in mating success in the ornamented sex. I tested for these effects in grouse (Tetraonidae). For three species pairs, within and among polygynous clades, male courtship characters had significantly greater divergence than other characters. This was most pronounced for two species in Tympanuchus . In the Eurasian polygynous clade, relative courtship divergence gradually increased with nucleotide divergence, suggesting a less dramatic acceleration. Increase in relative courtship divergence was associated with mating systems having higher variance in male mating success. These results suggest that sexual selection has accelerated courtship evolution among grouse, although the microevolutionary details appear to vary among clades.

Internationalization Strategy of Small and Medium-Sized Family Businesses: Some Influential Factors

2005 ◽  
Vol 18 (1) ◽  
pp. 77-89 ◽  
Author(s):  
Zulima Fernández ◽  
María J. Nieto
Keyword(s):  
Negative Relationship ◽  
Influential Factors ◽  
Family Ownership ◽  
Internationalization Process ◽  
International Expansion ◽  
Key Factors ◽  
Family Smes ◽  
Negative Effect ◽  
Internationalization Strategy

This article studies some aspects of the internationalization strategy of family SMEs. After examining the various problems facing family SMEs as regards internationalization, in terms of lack of resources, some mechanisms are discussed to counteract their negative effect. Using a wide sample of Spanish SMEs, we confirm the existence of a negative relationship between family ownership and internationalization, measured by export activities. We also analyze the role of generational changeovers and stable relationships with other firms through shareholding or agreements aimed to promote international expansion. These mechanisms are set out to provide family SMEs with the necessary resources that have proved to be key factors in a successful internationalization process.

scholarly journals Spatial Patterns of Macrozoobenthos Assemblages in a Sentinel Coastal Lagoon: Biodiversity and Environmental Drivers

2021 ◽  
Vol 9 (5) ◽  
pp. 461
Author(s):  
Soilam Boutoumit ◽  
Oussama Bououarour ◽  
Reda El Kamcha ◽  
Pierre Pouzet ◽  
Bendahhou Zourarah ◽  
...  
Keyword(s):  
Habitat Type ◽  
Environmental Drivers ◽  
Key Factors ◽  
Linear Modeling ◽  
Sediment Distribution ◽  
Water Parameters ◽  
Ph Values ◽  
Zostera Noltei ◽  
Modeling Analysis ◽  
Macrofauna Communities

This study presents an assessment of the diversity and spatial distribution of benthic macrofauna communities along the Moulay Bousselham lagoon and discusses the environmental factors contributing to observed patterns. In the autumn of 2018, 68 stations were sampled with three replicates per station in subtidal and intertidal areas. Environmental conditions showed that the range of water temperature was from 25.0 °C to 12.3 °C, the salinity varied between 38.7 and 3.7, while the average of pH values fluctuated between 7.3 and 8.0. In vegetated habitats, biomass values of the seagrass Zostera noltei Hornemann ranged between 31.7 gDW/m² and 170.2 gDW/m² while the biomass of the seagrass Ruppia cirrhosa (Petagna) Grande between 54.2 gDW/m² and 84.7 gDW/m². Sediment analyses showed that the lagoon is mainly composed of sandy and silty sediments. We recorded 37,165 individuals of macrofauna distributed in 63 taxa belonging to 50 families, with a mean abundance value of 4582.8 ind/m² and biomass average of 22.2 g/m². Distance-based linear modeling analysis (DISTLM) identified sediment characteristics, water parameters and habitat type (biomass of Z. noltei) as the major environmental drivers influencing macrozoobenthos patterns. Our results clearly revealed that the hydrographic regime (marine and terrestrial freshwater), sediment distribution and characteristics and the type of habitat (vegetated vs unvegetated substrate) are the key factors determining the species composition and patterns of macrozoobenthos assemblages.

scholarly journals Genomic Insights Into the Molecular Basis of Sexual Selection in Birds

2021 ◽  
Vol 9 ◽  
Author(s):  
Shubham K. Jaiswal ◽  
Ankit Gupta ◽  
Aaron B. A. Shafer ◽  
Vishnu Prasoodanan P. K. ◽  
Nagarjun Vijay ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sexual Selection ◽  
Gene Expression Regulation ◽  
Draft Genome ◽  
Honest Signal ◽  
Phenotypic Data ◽  
Genome Wide ◽  
Pavo Cristatus ◽  
Depth Analysis ◽  
Genomic Basis

Sexual selection is a well-known biological process, yet the genomic basis and patterns of sexual selection are not fully understood. The extravagant ornamental plumage of peacock (Pavo cristatus) was instrumental in shaping Charles Darwin's theory of sexual selection and is considered to be an honest signal of its immunocompetence. Here, we used the recently generated draft genome sequence of peafowl (Pavo cristatus) and carried out a comparative analysis across 11 bird genomes that encompass a range of sexual selection and also had high-quality genomic and phenotypic data publically available to study the genomic basis of sexual selection. We found that varying degree of purifying selection was the predominant mechanism of action for sexual selection at the genome-wide scale and observed that sexual selection mostly influences genes regulating gene expression and protein processing. Specifically, the genome-wide phylogenetically corrected regression analysis supported the continuous or ongoing model of sexual selection. Genes involved in nucleic acid binding and gene expression regulation, including a specific regulator of sex-determination known as TRA2A to be under positive selection in the species with high post-copulatory sexual selection manifested as high sperm competition. We also detected specific feather-related and immune-related gene-pairs evolving under similar selection pressures across the 11 species, including peacock (Pavo cristatus), which is consistent with the Hamilton-Zuk hypothesis. The comparative genomics analysis of 11 avian taxa has provided new insights on the molecular underpinnings of sexual selection and identifies specific genomic regions for future in-depth analysis.

scholarly journals Dissecting drug and prognostic lncRNA signature mediated by DNA methylation and transcription factor in colon cancer

2020 ◽  
Author(s):  
Jiayu Zhang ◽  
Zhen Shen ◽  
Zheyu Song ◽  
Jian Luan ◽  
Yezhou Li ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Colon Cancer ◽  
Drug Response ◽  
Risk Model ◽  
Negative Relationship ◽  
Epigenetic Alterations ◽  
Key Factors ◽  
Motif Occurrence ◽  
The Impact

Abstract Background: Colon cancer is still the most commonly diagnosed malignancy and leading cause of death worldwide. Apart from living habits, genetic and epigenetic changes are key factors to influence the risk of colon cancer. However, the impact of epigenetic alterations in non-coding RNAs and the consequences for colon cancer has not been fully characterized.Methods: We detected differential methylation sites (DMSs) in lncRNA promoters, and identified lncQTMs by association test. To investigate TF binding affected by DNA methylation, we characterized known TF motif occurrence among DMSs collected from MEME suit. We further combined methylome and transcriptome data to construct TF-methylation-lncRNA relationships. To study the role of lncRNAs in drug response, we used pharmacological and lncRNA profiles derived from CCLE and predict drug response by lncRNA expression level. We also used the combination of TF-methylation-lncRNA relationship to stratified patient survival information by a risk model.Results: DNA methylation display global hyper-methylation character in lncRNA promoters, and they tend to have negative relationship with the corresponding lncRNAs. Negative lncQTMs located near TSS have more significant and stronger correlation with the corresponding lncRNAs. Some lncRNAs mediated by the interplay between DNA methylation and TFs are proved markers for colon cancer. Typically, lncRNA CAHM, RP11-834C11.4 and LINC00460 are good predictors for 5 drug components (17-AAG, Sorafenib, TKI258, RAF265, Topotecan) in colon cancer. And we found HES1_cg24685006_RP4-728D4.2 and SREBF1_cg05372727_LINC00460 relationships are prognostic signatures for colon cancer.Conclusions: These findings suggested lncRNAs mediated by the interplay between DNA methylation and TFs are promising predictors for drug response, besides, combined TF-methylation-lncRNA can serve as prognostic signature for colon cancer.

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