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51.
Sun Lixing; Wilczynski Walter; Rand A. Stanley; Ryan Michael J. 《Behavioral ecology》2000,11(1):102-109
Female phonotaxis in túngara
(Physalaemus pustulosus)and cricket (Acris crepitans) frogs
is biased toward male advertisementcalls or call components of lower
frequency. This behavioralbias might result in part from a mismatch between
the spectralcharacteristics of the advertisement call and the most sensitive
frequencyof the peripheral end organ implicated in reception of thesesounds.
In both species, females are tuned to frequencies lowerthan average for the
calls in their population. This mismatch,however, represents the situation
during short-distance communication.Female frogs can also use the call to
detect choruses at longdistances, and the spectral distribution of call
energy canvary with transmission distance. We used computer simulationsto
test the hypothesis that there is a better match betweentuning and call
spectral energy at long distances from the callingmale than at short
distances by comparing the performance (soundenergy received) of the natural
tuning curve relative to anoptimal tuning curve (i.e., one centered at the
call's dominantfrequency). The relative performance of the natural tuning
curveincreased with distance in túngara
frogs. For the twosubspecies of cricket frogs, however, the relative
performancedecreased at longer distances. The performance did not equalthe
optimal tuning curve at the distances tested. The resultsindicate that the
relationship between calls and auditory tuningcannot be optimal for both long
and short distance reception.The relationship between female tuning and call
dominant frequencymay represent a compromise between short and long distance
communication,and the bias toward short or long distances may vary among
species. 相似文献
52.
Temporal order and the evolution of complex acoustic signals 总被引:1,自引:0,他引:1
Gerhardt HC Humfeld SC Marshall VT 《Proceedings. Biological sciences / The Royal Society》2007,274(1619):1789-1794
The evolution of complex signals may be favoured by hidden preferences or pre-existing sensory biases. Females of two species of grey treefrogs (Hyla chrysoscelis and Hyla versicolor) were tested with combinations of a conspecific advertisement call and acoustic appendages. Appendages consisted of aggressive calls and segments of advertisement calls from conspecific males and males of three other species and bursts of filtered noise. When a wide variety of these acoustic appendages followed the advertisement call, the resulting compound signal was often more attractive than the same advertisement call alone. When the same appendages led advertisement calls, however, the compound signal was never more attractive and sometimes less attractive. The order effect was especially strong in tests of H. versicolor in which advertisement-call duration was decreased. These results cannot be explained by a general pre-existing bias for extra stimulation per se. Rather, order and other effects may constrain the evolution and subsequent modification of complex and extravagant signals, examples of which have been reported for a wide range of taxa. 相似文献
53.
Palenchar PM 《The protein journal》2008,27(5):283-291
Analysis of the Arabidopsis thaliana, Saccharomyces cerevisiae, Mus musculus, Escherichia coli, Bacillus subtilis, Thermoplasma acidophilum, and Sulfolobus tokodaii genomes demonstrate that many amino acid biases occur at the N- and C-termini of proteins, a statistically significant number of these biases are evolutionarily conserved, and these biases occur in amino acids beyond the first and last five amino acids. Analyses designed to shed light on the mechanism causing amino acid biases suggest that in at least some cases the bias is caused by forces acting at the nucleic acid level. It is also demonstrated that in E. coli functionally related proteins show similar biases at the N- and C-termini suggesting that the mechanisms causing the biases are complex and in some cases are related to function. 相似文献
54.
Esther Sebastián-González Jon Morant Marcos Moleón Daniel Redondo-Gómez Zebensui Morales-Reyes Roberto Pascual-Rico Juan Manuel Pérez-García Eneko Arrondo 《Global Ecology and Biogeography》2023,32(8):1302-1310
Aim
Despite the increasing scientific evidence on the importance of carrion in the ecology and evolution of many vertebrates, scavenging is still barely considered in diet studies. Here, we draw attention to how scientific literature has underestimated the role of vertebrates as scavengers, identifying the ecological traits that characterize those species whose role as scavengers could have gone especially unnoticed.Location
Global.Time Period
1938–2022.Major Taxa Studied
Terrestrial vertebrate scavengers.Methods
We analysed and compared (a) the largest database available on scavenging patterns by carrion-consuming vertebrates, (b) 908 diet studies about 156 scavenger species and (c) one of the most complete databases on bird and mammal diets (Elton Traits database). For each of these 156 species, we calculated their scavenging degree (i.e. proportion of carcases where the species is detected consuming carrion) as a proxy for carrion consumption, and related their ecological traits with the probability of being identified as scavengers in diet studies and in the Elton Traits database.Results
More than half of the species identified as scavengers at monitored carcasses were not assigned carrion as food source in their diet studies nor in the Elton Traits database. Using a subset of study sites, we found a direct relationship between a species' scavenging degree and its rate of carrion biomass removal. In addition, scavenger species, which were classified as non-predators and mammals had a lower probability of being identified as scavengers in diet studies and in the Elton Traits database, respectively.Main Conclusions
Our results clearly indicate an underestimation of the role of scavenging in vertebrate food webs. Given that detritus recycling is fundamental to ecosystem functioning, we encourage further recognition and investigation of the role of carrion as a food resource for vertebrates, especially for non-predator species and mammals with higher scavenging degree. 相似文献55.
The intra-strand Parity Rule 2 of DNA (PR2) states that A=T and G=C within each strands. Useful corollaries of PR2 are G/(G+C)=A/(A+T)=0.5, G/(G+A)=C/(C+T)=G+C, G/(G+T)=C/(C+A)=G+C. Here. A, T, G, and C represent relative contents of the four nucleotide residues in a specific strand of DNA, so that A+T+G+C=1. Thus, deviations from the PR2 is a sign of strand-specific (or asymmetric) mutation and/or selection pressures. The present study delineates the symmetric and asymmetric effects of mutations on the intra-genomic heterogeneity of the G+C content in the human genome. The results of this study on the human genome are: (1) When both two- and four-codon amino acids were combined, only slight departures from the PR2 were observed in the total ranges of G+C content of the third-codon position. Thus, the G+C heterogeneity is likely to be caused by symmetric mutagenesis between the two strands. (2) The above result makes the deamination of cytosine due to double-strand breathing of DNA [Mol. Biol. Evol. 17 (2000) 1371] and/or incorporation of the oxidized guanine (8-oxo-guanine) opposite adenine during DNA replication (dGTP-oxidation hypothesis) as the most likely candidates for the major cause of the diversities of the G+C content. (3) Patterns of amino acid-specific PR2-biases detected by plotting PR2 corollaries against the G+C content of third codon position revealed that eight four-codon amino acids can be divided into three types by the second codon letter: (a) C2-type (Ala, Pro, Ser4, and Thr), (b) G2-type (Arg4 and Gly), and (c) T2-type (Leu4 and Val). (4) Most of the asymmetric plot patterns of the above three classes in PR2 biases can be explained by C2→T2 deamination of C2pG3 of C2-type to T2pG3 (T2-type) in both human and chicken. This explains the existence of some preferred codons in human and chicken. However, these biases (asymmetric) hardly contribute to the overall G+C content diversity of the third codon position. 相似文献
56.
Alexander N. Schmidt‐Lebuhn Nunzio J. Knerr Carlos E. González‐Orozco 《Journal of Biogeography》2012,39(11):2072-2080
Aim Our aims were (1) to compare observed, estimated and predicted patterns of species richness using the Australian native Asteraceae as an example, (2) to identify candidates for hotspots of diversity for the study group, and (3) to examine the distortion of our perception of the spatial distribution of species richness through uneven or misdirected sampling efforts. Location Australia. Methods Based on data from Australia’s Virtual Herbarium, we calculated and visualized observed species richness, the Chao1 estimate of richness, the C index of collecting completeness, and an estimate of richness derived from environmental niche modelling for grid cells at a resolution of 1°. The 20 cells with the highest diversity values were used to define hotspots of diversity. Results Uneven collecting activity results in misleading diversity patterns for the family Asteraceae. While observed species richness is much higher in central Australia than in other parts of the arid interior, this is an artefact resulting from the area being a hotspot of collecting activity. The mountain ranges of south‐eastern Australia and Tasmania are candidates for unbiased hotspots of species richness. Main conclusions Vast areas of the Australian interior are insufficiently sampled on a local scale, although most of them can be expected to be relatively species poor. Some areas in the south‐east and south‐west of the continent remain undersampled relative to their high species richness. Observed species numbers, estimators and environmental niche‐modelling all have their unique advantages and disadvantages for the inference of patterns of diversity. 相似文献
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60.
Florian Orgeret Andra Thiebault Kit M. Kovacs Christian Lydersen Mark A. Hindell Sarah Ann Thompson William J. Sydeman Pierre A. Pistorius 《Ecology letters》2022,25(1):218-239
Understanding climate change impacts on top predators is fundamental to marine biodiversity conservation, due to their increasingly threatened populations and their importance in marine ecosystems. We conducted a systematic review of the effects of climate change (prolonged, directional change) and climate variability on seabirds and marine mammals. We extracted data from 484 studies (4808 published studies were reviewed), comprising 2215 observations on demography, phenology, distribution, diet, behaviour, body condition and physiology. The likelihood of concluding that climate change had an impact increased with study duration. However, the temporal thresholds for the effects of climate change to be discernibly varied from 10 to 29 years depending on the species, the biological response and the oceanic study region. Species with narrow thermal ranges and relatively long generation times were more often reported to be affected by climate change. This provides an important framework for future assessments, with guidance on response- and region-specific temporal dimensions that need to be considered when reporting effects of climate change. Finally, we found that tropical regions and non-breeding life stages were poorly covered in the literature, a concern that should be addressed to enable a better understanding of the vulnerability of marine predators to climate change. 相似文献