scholarly journals Flies improve the salience of iridescent sexual signals by orienting toward the sun

2020 ◽  
Vol 31 (6) ◽  
pp. 1401-1409 ◽  
Author(s):  
Thomas E White ◽  
Tanya Latty
Keyword(s):  
Fold Increase ◽  
Visual Signals ◽  
The Sun ◽  
Sexual Signals ◽  
Structural Colors ◽  
Selection For ◽  
Effective Use ◽  
Male Ornaments ◽  
Male Signals ◽  
Do So

Abstract Sunlight is the ultimate source of most visual signals. Theory predicts strong selection for its effective use during communication, with functional links between signal designs and display behaviors a likely result. This is particularly true for iridescent structural colors, whose moment-to-moment appearance bears a heightened sensitivity to the position of signalers, receivers, and the sun. Here, we experimentally tested this prediction using Lispe cana, a muscid fly in which males present their structurally colored faces and wings to females during ground-based sexual displays. In field-based assays, we found that males actively bias the orientation of their displays toward the solar azimuth under conditions of full sunlight and do so across the entire day. This bias breaks down, however, when the sun is naturally concealed by heavy cloud or experimentally obscured. Our modeling of the appearance of male signals revealed clear benefits for the salience of male ornaments, with a roughly 4-fold increase in subjective luminance achievable through accurate display orientation. These findings offer fine-scale, causal evidence for the active control of sexual displays to enhance the appearance of iridescent signals. More broadly, they speak to predicted coevolution between dynamic signal designs and presentation behaviors, and support arguments for a richer appreciation of the fluidity of visual communication.

scholarly journals Flies improve the salience of iridescent sexual signals by orienting toward the sun

2020 ◽  
Author(s):  
Thomas E. White ◽  
Tanya Latty
Keyword(s):  
Fold Increase ◽  
Visual Signals ◽  
The Sun ◽  
Sexual Signals ◽  
Ultimate Source ◽  
Selection For ◽  
Effective Use ◽  
Male Ornaments ◽  
Male Signals ◽  
Do So

AbstractSunlight is the ultimate source of most visual signals. Theory predicts strong selection for its effective use during communication, with functional links between signal designs and display behaviours a likely result. This is particularly true for iridescent structural colours, whose moment-to-moment appearance bears a heightened sensitivity to the position of signallers, receivers, and the sun. Here we experimentally tested this prediction using Lispe cana, a muscid fly in which males present their structurally coloured faces and wings to females during ground-based sexual displays. In field-based assays we found that males actively bias the orientation of their displays toward the solar azimuth under conditions of full sunlight and do so across the entire day. This bias breaks down, however, when the sun is naturally concealed by heavy cloud or experimentally obscured. Our modelling of the appearance of male signals revealed clear benefits for the salience of male ornaments, with a roughly four-fold increase in subjective luminance achievable through accurate display orientation. These findings offer fine-scale, causal evidence for the active control of sexual displays to enhance the appearance of iridescent signals. More broadly, they speak to predicted coevolution between dynamic signal designs and presentation behaviours, and support arguments for a richer appreciation of the fluidity of visual communication.

scholarly journals On sun-spot periodicities. —Preliminary notice

1906 ◽  
Vol 77 (515) ◽  
pp. 141-145 ◽  
Keyword(s):  
Fourier Coefficients ◽  
The Sun ◽  
Energy Diagram ◽  
Sun Spots ◽  
Do So ◽  
Periodic Changes

In cases where it is necessary to separate true periodic changes from other variations, which during short periods of time often simulate periodicities, the method of the periodogram is at present the only one which can give definite results. In view of the importance of the questions connected with the changes in the frequency of the sun-spots, I have, therefore, undertaken the considerable labour of forming a complete periodogram of sun-spot variability as far as the data at my disposal allow me to do so. The following is a brief abstract of the results; the investigation will be presented shortly:— The periodogram, as already explained, is the diagram representing the intensity of periodic variations as determined from the sum of the squares of the two Fourier coefficients belonging to each assumed period. This diagram represents for any regular or irregular change exactly what the energy diagram gives us for a luminous disturbance which is analysed by a spectroscope.

5. On a Monochromatic Rainbow

1889 ◽  
Vol 15 ◽  
pp. 135-137
Author(s):  
John Aitken
Keyword(s):  
The Sun ◽  
The South ◽  
Band Form ◽  
Horizontal Band ◽  
Do So

A monochromatic rainbow looks like a contradiction in terms. As a rainbow of this kind was, however, seen lately, its occurrence seems worth putting on record. On the afternoon of Christmas day I went for a walk in the direction of the high ground to the south of Falkirk. Shortly after starting I observed in the east what appeared to be a peculiar pillar-like cloud, lit up with the light of the setting sun. What specially attracted my attention was that the streak of illumination was vertical, and not the usual horizontal band-form we are accustomed to. I looked in the direction of the sun to see if I could trace any peculiar opening in the clouds through which the light passed, but failed to do so.

scholarly journals 37 Opportunities for using a functional chip in beef

2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 18-19
Author(s):  
E John Pollack
Keyword(s):  
Target Population ◽  
Beef Industry ◽  
Evaluation Systems ◽  
Animal Management ◽  
Functional Variants ◽  
Fertile Ground ◽  
Selection For ◽  
Related Population ◽  
Do So ◽  
Universal Application

Abstract Adoption of DNA technology in the beef industry has experienced an accelerating trajectory. The well-accepted and adopted applications are now parentage testing and, more recently, the inclusion of marker data into genetic evaluation systems to produce “genomic enhanced EPDs” (GE-EPD). Neither of these applications requires the markers to be functional variants; however, to produce GE-EPD’s does require the traits (or correlated traits) be in the suite of traits for which EPDs are produced. This does not allow for expansion of the use of the technology to several novel, economically important characteristics. To do so requires discovery populations closely related to the target population if typical marker panels are used and would require retraining as the target population moves away from the discovery population in its degree of relatedness. Knowledge of functional mutations is hypothesized to eliminate the necessity of a closely related population to the point of potentially universal application (across breeds) of the variant contribution to the phenotype(s) of interest. Applications that would then represent significant contribution to the genetic and management programs in beef production would be in the segments of the industry “downstream” of the seedstock industry. Breed independent predictive panels for commercial heifer replacement selection, for feedlot animal management and for product characteristics are fertile ground for the use of functional variants. These applications would target predicting animal performance, and as such would also allow for non-additive effects to be considered. If the variant tool is built as one panel including traits of interest to each segment of the industry, then valuable information becomes available each time ownership of the animal, or products derived from harvesting that animal, occurs.

Patterns in the evolution of nares size and secondary palate length in anomodont therapsids (Synapsida): implications for hypoxia as a cause of end-Permian tetrapod extinctions

2008 ◽  
Vol 82 (3) ◽  
pp. 528-542 ◽  
Author(s):  
Kenneth D. Angielczyk ◽  
Melony L. Walsh
Keyword(s):  
Atmospheric Oxygen ◽  
Term Trend ◽  
Weak Evidence ◽  
Secondary Palate ◽  
Respiratory Efficiency ◽  
Rigorous Study ◽  
Selection For ◽  
Long Term Trend ◽  
Do So

Seemingly consistent proportional differences in several palatal structures have been noted between Permian and Triassic anomodont therapsids for nearly a century. These patterns have been cited as evidence in support of a decline in atmospheric oxygen concentrations that may have contributed to end-Permian terrestrial extinctions. However, it is not known whether the observed differences are significant, or whether they stem from continued directional selection. If they are not significant, or if their timing does not match that proposed for the oxygen decline, support for the hypoxia-based extinction scenario would be weakened. We tested whether the internal nares and bony secondary palate, two palatal features proposed to be related to respiratory efficiency, are significantly larger in Triassic anomodonts, and whether the variation can be attributed to a long-term tendency for increase. Results based on raw data indicate that Triassic anomodonts have significantly larger secondary palates than Permian anomodonts. They also have significantly larger internal nares, but only when primitive, morphologically-divergent specimens are not considered. Although nares and palate size are correlated with stratigraphic occurrence, available data reject the hypothesis that the observed differences were the result of a long-term trend. Most of these findings are consistent with the predictions of the hypoxia scenario. However, removing the effects of body size and phylogeny causes some of the differences to break down, indicating that if selection for increased respiratory efficiency affected these characters, it was most likely not the only factor to do so. Therefore, the characters provide only weak evidence in support of the hypoxia scenario, and we recommend against their use for this purpose. Our results emphasize the need for caution when invoking presumed differences between Permian and Triassic vertebrates as support for hypoxia, or other extinction scenarios, without a rigorous study of the character(s) in question.

The Backstaff and the Determination of Latitude at Sea in the Seventeenth Century

1986 ◽  
Vol 39 (2) ◽  
pp. 259-268 ◽  
Author(s):  
Gerald Forty
Keyword(s):  
Eighteenth Century ◽  
Seventeenth Century ◽  
Sixteenth Century ◽  
The Sun ◽  
Measuring Instrument ◽  
Final Version ◽  
The Cross ◽  
Effective Use ◽  
New Instruments

In a previous paper the writer considered the problems of establishing latitude at sea in the sixteenth century and in part based his conclusions on the results of experiments made with modern replicas of the quadrant, the mariner's astrolabe and in particular the cross-staff, these being the instruments in use at the time. Reference was made to the backstaff or Davis quadrant which, though first described by John Davis in its simplest form in 1595 was not in effective use in its final version until well into the seventeenth century. It remained, together with the cross-staff, the principal altitude-measuring instrument in use at sea until the introduction of instruments of reflection in the eighteenth century and indeed continued in use long after that time, no doubt because it was cheaper than the new instruments, but perhaps also in part because of the ingrained conservatism of seafarers. The name ‘backstaff’ can be used generically to refer to all those instruments with which the observer turns his back on the Sun (e.g. the Gunter's bow), but they all post-dated and derived in concept from the Davis quadrant, which remained the most common in England and elsewhere. (The French knew it as le quartier anglais.) It is in this sense that the term is used here.

Selection for increased resistance to a granulosis virus in the potato moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

1983 ◽  
Vol 73 (1) ◽  
pp. 1-9 ◽  
Author(s):  
D. T. Briese ◽  
H. A. Mende
Keyword(s):  
Resistance Gene ◽  
Laboratory Strain ◽  
Fold Increase ◽  
Phthorimaea Operculella ◽  
Field Conditions ◽  
Granulosis Virus ◽  
Selection For

AbstractSerial exposure of a susceptible laboratory strain of Phthorimaea operculella (Zell.) recently obtained from the field to granulosis virus over six generations produced a 140-fold increase in LD50. The evidence suggests that this was due to a change in frequency of a resistance gene within the population. An attempt to select for even greater resistance in an already highly resistant laboratory strain resulted in only a small increase, due mainly to reduced variability in response of the population. The implications of resistance to viral insecticides developing under field conditions are discussed.

scholarly journals Social learning and evolution: the cultural intelligence hypothesis

2011 ◽  
Vol 366 (1567) ◽  
pp. 1008-1016 ◽  
Author(s):  
Carel P. van Schaik ◽  
Judith M. Burkart
Keyword(s):  
Social Learning ◽  
Cognitive Abilities ◽  
Cultural Intelligence ◽  
Social Deprivation ◽  
Learning Ability ◽  
Learning Performance ◽  
Selection For ◽  
Cultural Skills ◽  
Independent Individual ◽  
Do So

If social learning is more efficient than independent individual exploration, animals should learn vital cultural skills exclusively, and routine skills faster, through social learning, provided they actually use social learning preferentially. Animals with opportunities for social learning indeed do so. Moreover, more frequent opportunities for social learning should boost an individual's repertoire of learned skills. This prediction is confirmed by comparisons among wild great ape populations and by social deprivation and enculturation experiments. These findings shaped the cultural intelligence hypothesis, which complements the traditional benefit hypotheses for the evolution of intelligence by specifying the conditions in which these benefits can be reaped. The evolutionary version of the hypothesis argues that species with frequent opportunities for social learning should more readily respond to selection for a greater number of learned skills. Because improved social learning also improves asocial learning, the hypothesis predicts a positive interspecific correlation between social-learning performance and individual learning ability. Variation among primates supports this prediction. The hypothesis also predicts that more heavily cultural species should be more intelligent. Preliminary tests involving birds and mammals support this prediction too. The cultural intelligence hypothesis can also account for the unusual cognitive abilities of humans, as well as our unique mechanisms of skill transfer.

scholarly journals Female in-nest attendance predicts the number of ectoparasites in Darwin's finch species

2021 ◽  
Vol 288 (1965) ◽  
Author(s):  
Sonia Kleindorfer ◽  
Lauren K. Common ◽  
Jody A. O'Connor ◽  
Jefferson Garcia-Loor ◽  
Andrew C. Katsis ◽  
...  
Keyword(s):  
Parental Care ◽  
Investment Decisions ◽  
Food Delivery ◽  
Nest Attendance ◽  
Nest Provisioning ◽  
Selection For ◽  
Female Behaviour ◽  
Mortality Causes ◽  
The Relationship ◽  
Do So

Selection should act on parental care and favour parental investment decisions that optimize the number of offspring produced. Such predictions have been robustly tested in predation risk contexts, but less is known about alternative functions of parental care under conditions of parasitism. The avian vampire fly ( Philornis downsi ) is a myasis-causing ectoparasite accidentally introduced to the Galápagos Islands, and one of the major mortality causes in Darwin's finch nests. With an 11-year dataset spanning 21 years, we examine the relationship between parental care behaviours and number of fly larvae and pupae in Darwin's finch nests. We do so across three host species ( Camarhynchus parvulus , C. pauper , Geospiza fuliginosa ) and one hybrid Camarhynchus group. Nests with longer female brooding duration (minutes per hour spent sitting on hatchlings to provide warmth) had fewer parasites, and this effect depended on male food delivery to chicks. Neither male age nor number of nest provisioning visits were directly associated with number of parasites. While the causal mechanisms remain unknown, we provide the first empirical study showing that female brooding duration is negatively related to the number of ectoparasites in nests. We predict selection for coordinated host male and female behaviour to reduce gaps in nest attendance, especially under conditions of novel and introduced ectoparasites.

scholarly journals Melanin-Based Black Plumage Coloration is Related to Reproductive Investment in Cardueline Finches

The Condor ◽  
2005 ◽  
Vol 107 (4) ◽  
pp. 775-787 ◽  
Author(s):  
Veronika Bókony ◽  
András Liker
Keyword(s):  
Parental Care ◽  
Reproductive Effort ◽  
Reproductive Investment ◽  
Interspecific Variation ◽  
Comparative Approach ◽  
Sexual Signals ◽  
Developmental Constraints ◽  
Structural Colors ◽  
Trade Offs ◽  
Different Color

Abstract Avian color ornaments produced by different mechanisms (i.e., melanin, carotenoid, and structural colors) can communicate different sets of information due to differences in their condition or developmental constraints. Although this suggests that different color signals should be analyzed separately, few comparative studies have focused on specific types of coloration. In cardueline finches, interspecific variation in overall plumage brightness (which integrates all types of coloration) was previously shown to be affected by sexual selection and to covary with fecundity and parental care. Using a phylogenetic comparative approach, we extended this line of research and tested whether a specific component of plumage ornamentation, the melanin-based black frontal coloration of finches, showed a similar association with reproductive effort. We found that the extent of male melanization and melanin dichromatism increased in species with reduced clutch sizes, whereas female melanization was negatively correlated with incubation length. These results remained significant when we controlled for the effects of several ecological variables, and were also consistent between two alternative multivariate model-selection approaches. Our results are consistent with the hypothesis that interspecific variation in melanization may be related to fecundity and parental care through trade-offs between investment in sexual signals and parental efforts.

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