Scalp hair-whorl orientation of Japanese individuals is random; hence,the trait's distribution is not genetically determined

Because the features of clockwise versus anti-clockwise orientation of hair-whorl coiling developed on a person's scalp is (partially, albeit significantly) correlated with that individual's right- versus left-hand-use preference (i.e., handedness) in the US and British subjects, these traits have been recently suggested to be determined biologically and through a common genetic mechanism. Here I report results of a serendipitously made observation with the Japanese population that helps to scrutinize validity of partial correlation between these attributes and to ascertain whether the underlying gene's frequency variations exist in different gene pools. Surprisingly, the whorl orientation in the Japanese individuals was found to be random, although their handedness variation is similar to that of the US population. Therefore, the whorl orientation trait is not genetically determined in the Japanese population. This result supports the idea that separate decisions must be made during embryogenesis for developing handedness and hair-whorl features at least in Japanese individuals. A recent study found the lack of association between whorl orientation and handedness in the German population, yet previous studies suggested that their scalp hair orientation is genetically determined. Therefore, pronounced genetic variation for the hair-whorl trait exists between individuals of different geographical regions. As hand preference exhibits “complex correlation” with brain hemispheric functional specialization, implications of these findings are discussed here with the goal to define biology of brain hemispheric laterality determination.     

Role of red light in hair-whorl formation induced by blue light in Acetabularia mediterranea

After a pre-treatment with red light, hair formation at the growing tip of the siphonaceous green alga Acetabularia mediterranea Lamour. (= A. acetabulum (L.) Silva) can be induced by a pulse of blue light. Red light is needed again after the inductive blue-light pulse if the new whorl of hairs is to develop within the next 24 h. In order to investigate the role of this red light, the duration of the red irradiation was varied and combined with periods of darkness. The response of hair-whorl formation was dependent on the total amount of red light, regardless of whether the red irradiation followed the blue pulse immediately or was separated from it by a period of darkness. Furthermore, periods of exposure to the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1-1dimethylurea had a similar effect to darkness. Both observations indicate that this red irradiation acts as a light source for photosynthesis. Whether or not the red light had an additional effect via phytochrome was tested in another type of experiment. The dependence of hair-whorl formation on red-light irradiance in the presence of simultaneous far-red irradiation was determined for the pre-irradiation period as well as for the irradiation period after the blue pulse. In both experiments, far-red light caused a small promotion of hair-whorl formation when low irradiances of red light were used. However, these differences were attributable to a low level of photosynthetic activity (which in fact was measurable) caused by red light reflected in the growth chamber. Furthermore, lowering the proportion of active phytochrome by far-red light would be expected to suppress hair-whorl formation. The influence of far-red light was also tested in a strain of Acetabularia mediterranea that developed hair whorls in about 20% of cells even when kept in complete darkness after the blue-light pulse. Far-red irradiation had no effect. These results strongly indicate that phytochrome is not involved in hair-whorl formation. Rather it is concluded that the effects of red light are caused by photosynthesis.Abbreviation DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea     

Excess of counterclockwise scalp hair-whorl rotation in homosexual men

While most men prefer women as their sexual partners, some are bisexual and others are homosexuals. It has been debated for a long time whether a person’s sexual preference is innate, learned, or due to a combination of both causes. It was recently discovered that the human right-versus-left-hand use preference and the direction of scalp hair-whorl rotation develop from a common genetic mechanism. Such a mechanism controls functional specialization of brain hemispheres. Whether the same mechanism specifying mental makeup influences sexual preference was determined here by comparing hair-whorl rotation in groups enriched with homosexual men with that in males at large. Only a minority of 8.2% (n = 207) unselected ‘control’ group of males had counterclockwise rotation. In contrast, all three samples enriched with homosexual men exhibited highly significant (P< 0.0001), 3.6-fold excess (29.8%,n = 272) counterclockwise rotation. These results suggest that sexual preference may be influenced in a significant proportion of homosexual men by a biological/genetic factor that also controls direction of hair-whorl rotation.     

Mating behavior in the ant, <Emphasis Type="Italic">Myrmecina graminicola</Emphasis> (Myrmicinae)

Summary Sexual behavior of Myrmecina graminicola in laboratory conditions is described. Virgin females, both gynomorphs and intermorphs, exhibit an inconspicuous "sexual calling", apparently depositing a sex pheromone on the substrate close by. The sexual pheromone is produced in the poison gland. Copulation needs between 40 and 60 seconds, dealation of gynomorphs follows soon after. Some observations are in marked contrast to former reports, e.g. on duration of copulation in M. graminicola (Donisthorpe, 1927: several hours) and on the source of a sex pheromone in the closely related M. nipponica (Murakami et al., 2002: pygidial gland).Received 4 February 2003; revised 19 May 2003; accepted 19 May 2003.     

Stomatal density responses of temperate woodland plants over the past seven decades of CO2 increase: a comparison of Salisbury (1927) with contemporary data

We investigated the possible effect of recent (1927-1995) increases in the concentration of atmospheric CO2 on the stomatal densities of leaves of a wide range of tree, shrub, and herb species (N = 60) by making new measurements for comparison with corresponding data reported by E. J. Salisbury in 1927--a time when ice core studies indicate CO2 concentrations ~55 mL/L lower than present. A detailed intraspecific study of the herb Mercurialis perennis showed plants of M. perennis in a Cambridgeshire woodland in 1994 had significantly lower stomatal densities, irrespective of leaf insertion point, compared with their 1927 counterparts. Comparisons made across species using evolutionary comparative methods (independent contrasts) revealed a significant (P 2 increases have influenced leaf morphology in a manner consistent with recent experiments and the palaeoecological record. Further analyses suggested that the strength of the stomatal density response was independent of life form but dependent on "exposure" and the initial leaf stomatal density. Consequently, firmer predictions for future changes in stomatal density across all species, expected as a possible result of anthropogenically related CO2 increases, may now be possible.     

Human handedness and scalp hair-whorl direction develop from a common genetic mechanism

Theories concerning the cause of right- or left-hand preference in humans vary from purely learned behavior, to solely genetics, to a combination of the two mechanisms. The cause of handedness and its relation to the biologically specified scalp hair-whorl rotation is determined here. The general public, consisting of mostly right-handers (RH), shows counterclockwise whorl rotation infrequently in 8.4% of individuals. Interestingly, non-right-handers (NRH, i.e., left-handers and ambidextrous) display a random mixture of clockwise and counterclockwise swirling patterns. Confirming this finding, in another independent sample of individuals chosen because of their counterclockwise rotation, one-half of them are NRH. These findings of coupling in RH and uncoupling in NRH unequivocally establish that these traits develop from a common genetic mechanism. Another result concerning handedness of the progeny of discordant monozygotic twins suggests that lefties are one gene apart from righties. Together, these results suggest (1) that a single gene controls handedness, whorl orientation, and twin concordance and discordance and (2) that neuronal and visceral (internal organs) forms of bilateral asymmetry are coded by separate sets of genetic pathways. The sociological impact of the study is discussed.     

New species of the Buprestid genus <Emphasis Type="Italic">Sphenoptera</Emphasis> Dejean from India and Pakistan with notes on the synonymy and nomenclature of some species of the subgenus <Emphasis Type="Italic">Sphenoptera</Emphasis> s. str. (Coleoptera,Buprestidae)

Sphenoptera (s. str.) galkae sp. n. from North Pakistan and. S. (s. str.) jacobsonorum sp. n. from India (Jammu and Kashmir State) are described and compared with closely related species. New synonymy is established for the following taxa: S. hypocrita Mannerheim, 1837 (= S. torrida Jakovlev, 1898; S. ixion Kerremans, 1912, synn. n.), S. bodemeyeri Jakovlev, 1900 (= S. quadrata Kerremans, 1909, syn. n.), S. exoleta Jakovlev, 1908 (= S. politipennis Obenberger, 1927, syn. n.), S. obruta Kerremans, 1909 (= S. chalcosoma Obenberger, 1927; S. abbreviata hetera Obenberger, 1927, synn. n.), S. tragacanthae (Klug, 1829) (= S. maledicta Obenberger, 1920; S. cilicica Obenberger, 1927; S. rambouseki Obenberger, 1927; S. klickai Obenberger, 1927; S. corrosa Obenberger, 1927; S. satrapa Obenberger, 1927; S. syriae Obenberger, 1927; S. vavrai Obenberger, 1927, synn. n.), S. magna Gory et Laporte, 1839 (= S. alexandri Obenberger, 1927, syn. n.). Lectotypes for 74 nominal species and subspecies are designated.     

Quantifying hummingbird preference for floral trait combinations: The role of selection on trait interactions in the evolution of pollination syndromes

Darwin recognized the flower's importance for the study of adaptation and emphasized that the flower's functionality reflects the coordinated action of multiple traits. Here we use a multitrait manipulative approach to quantify the potential role of selection acting on floral trait combinations underlying the divergence and maintenance of three related North American species of Silene (Caryophyllaceae). We artificially generated 48 plant phenotypes corresponding to all combinations of key attractive traits differing among the three Silene species (color, height, inflorescence architecture, flower orientation, and corolla‐tube width). We quantified main and interaction effects of trait manipulation on hummingbird visitation preference using experimental arrays. The main effects of floral display height and floral orientation strongly influenced hummingbird visitation, with hummingbirds preferring flowers held high above the ground and vertically to the sky. Hummingbirds also prefer traits in a nonadditive manner as multiple two‐way and higher order interaction effects were important predictors of hummingbird visitation. Contemporary trait combinations found in hummingbird pollinated S. virginica are mostly preferred. Our study demonstrates the likelihood of pollination syndromes evolving due to selection on trait combinations and highlights the importance of trait interactions in understanding the evolution of complex adaptations.     

Diversification of floral orientation in Lonicera is associated with pollinator shift and flowering phenology

Floral orientation has been suggested to be a functional floral trait that can enhance reproductive fitness through adaptation to both biotic factors (e.g., pollination) and abiotic factors (e.g., temperature). However, whether those factors drive the diversification of floral orientation needs to be explored through multiple related species. Phylogenetic relationships in Lonicera were identified by incorporating the species’ floral orientation (upward vs. downward) and pollinator types. Furthermore, transitions in floral orientation were evaluated together with pollinator shift, and seven Lonicera species were used to detect the influence of floral orientation on pollination and reproductive success. The relationship between temperature and the angle of floral orientation was investigated. Floral orientation in Lonicera showed that most of the closely related species within the same node displayed a similar pattern of floral orientation, and pollinator shift can lead to transitions between upward and downward orientation. Additionally, the angle of floral orientation increased with flowering phenology from spring to summer, and changing floral orientation significantly decreased pollination and seed production. Moreover, the average daily temperature during flowering phenology was significantly correlated with the angle of floral orientation. Our results indicate that pollinator shift could be an important event, leading to the diversification of floral orientation. Results of field investigations inferred that floral orientation should be a functional floral trait adapted to flowering phenology. Downward-facing flowers might help decrease heat loss to adapt to cold conditions. This study disentangled the influences of historical events and local adaptation on the evolution of floral orientation.     

Fish functional diversity as an indicator of resilience to industrial fishing in Patagonia Argentina

The relationship between fish functional diversity and fishing levels at which its baselines shift is important to identify the consequences of fishing in ecosystem functioning. For the first time, the authors of this study implemented a trait-based approach in the Argentine Patagonian Sea to identify the vulnerability and spatiotemporal changes in functional diversity of fish assemblages incidentally captured by a trawling fleet targeting the Argentine red shrimp Pleoticus muelleri (Spence Bate, 1888) between 2003 and 2014. The authors coupled seven fish trophic traits to a reconstructed fish assemblage for the study area and by-catch and evaluated changes in fish species richness and four complementary functional diversity measures (functional richness, redundancy, dispersion and community trait values) along with fishing intensity, temporal use, latitudinal location and depth of fishing grounds, and vessel length. Resident fishes larger than 30 cm in length, with depressed and fusiform bodies, intermediate to high trophic levels, and feeding in benthic, demersal and midwater areas were vulnerable to by-catch. In addition, fish assemblages exhibited a low functional trait redundancy, likely related to species influxes in a biogeographic ecotone with tropicalisation signs. Significant increases in fish trait richness and dispersion poleward and deep suggested new functional roles in these grounds, matching trends in community body size, reproductive load, maximum depth and trophic level. Finally, a temporal increase in fish species and functional trait removal in fishing grounds led to trait homogenisation since 2003. The authors identified that tipping points in temperate fish functional trait diversity showed the importance of trait-based approaches within ecosystem-based fisheries management.     

Unraveling the Relationship between Trait Negative Affectivity and Habitual Symptom Reporting

Objective

In two studies, we aimed at further elucidating the relationship between trait negative affectivity (NA) and habitual symptom reporting (HSR) by relating these variables to measures of executive function, trait questionnaires, and effects of emotion induction.

Methods

Healthy female participants (N = 75) were selected on their scores for trait NA and for the Checklist for Symptoms in Daily Life. Three groups were compared: (1) low NA-low HSR; (2) high NA-low HSR; and (3) high NA-high HSR (low NA-high HSR did not occur). In study 1, participants underwent a Parametric Go/No-go Task and a Stroop Color-Word test, and trait questionnaires measured alexithymia and absorption. Forty-five participants (N = 15 in each group) were further engaged in study 2 to induce state NA using an affective picture paradigm.

Results

Impaired inhibition on the Stroop and Go/No go Task characterized high trait NA, but not high HSR, whereas alexithymia and absorption were elevated in HSR, regardless of trait NA. Negative picture viewing induced elevated state NA in all groups, but only high HSR also reported more bodily symptoms. This effect was moderated, but not mediated by state NA.

Conclusion

High trait NA is a vulnerability factor but not a sufficient condition to develop HSR. Deficient inhibition is related to the broad trait of NA, whereas the moderating effect of state NA on symptom reporting is specific for high HSR. Understanding processes related to alexithymia and absorption may specifically help to explain elevated HSR.     

Identification of quantitative trait loci for four morphologic traits under water stress in rice （Oryza sativa L.）

Late season drought coinciding with the rice booting to heading stage affects the development of plant height,panicle exsertion,and flag leaf size,and causes significant yield loss.In this study,a recombinant inbred line population derived from a cross between paddy and upland cultivars was used for data collection of the morphologic traits under well water and drought stress conditions.bought stress was applied at the stage of panicle initiation in the field in 2002 and at the booting stage in PVC pipes in 2003.The data from stress con ditions and their ratios(tait measured under stress condition/trait measured under well water condition)or differences(trait measured under stress condition minus trait measured under well water condition)were used for OTL analysis.Totally,17 and 36 QTLs for these traits were identified in 2002 and 2003,respectively,which explained a range of 2.58%-29.82%Of the phenotypic variation.Among them,six QTLs were commonly identified in the two years,suggesting that the drought stress in the two years was different.The genetic basis of these traits will provide useful information for improving rice late season drought resistance,and their application as indirect indices in rice late season drought resistance screening was also discussed.     

Predicting microbial traits with phylogenies

Phylogeny reflects genetic and phenotypic traits in Bacteria and Archaea. The phylogenetic conservatism of microbial traits has prompted the application of phylogeny-based algorithms to predict unknown trait values of extant taxa based on the traits of their evolutionary relatives to estimate, for instance, rRNA gene copy numbers, gene contents or tolerance to abiotic conditions. Unlike the ‘macrobial'' world, microbial ecologists face scenarios potentially compromising the accuracy of trait reconstruction methods, as, for example, extremely large phylogenies and limited information on the traits of interest. We review 990 bacterial and archaeal traits from the literature and support that phylogenetic trait conservatism is widespread through the tree of life, while revealing that it is generally weak for ecologically relevant phenotypic traits and high for genetically complex traits. We then perform a simulation exercise to assess the accuracy of phylogeny-based trait predictions in common scenarios faced by microbial ecologists. Our simulations show that ca. 60% of the variation in phylogeny-based trait predictions depends on the magnitude of the trait conservatism, the number of species in the tree, the proportion of species with unknown trait values and the mean distance in the tree to the nearest neighbour with a known trait value. Results are similar for both binary and continuous traits. We discuss these results under the light of the reviewed traits and provide recommendations for the use of phylogeny-based trait predictions for microbial ecologists.Trait-based approaches in community ecology studies are becoming increasingly appealing for microbial ecologists partly because metagenomic sequencing allows surveying molecular functions (Green et al., 2008; Lauro et al., 2009; Burke et al., 2011; Raes et al., 2011; Brown et al., 2014; Fierer et al., 2014). Although genetic data can provide precise information on cellular processes or metabolic pathways, they are generally blind to other ecologically relevant phenotypic traits such as the tolerance to certain abiotic conditions or the specific growth rate (but see Vieira-Silva and Rocha, 2010). Unlike ‘macrobial'' ecologists, who can directly observe phenotypic characters of plants and animals, microbial ecologists usually face situations where most of the phenotypes of their study organisms are unknown. This difficulty relies on the fact that gathering phenotypic (physiological, morphological, biochemical) data requires culturing microbial species. The unbalanced growth of genotypic vs phenotypic information is currently challenging microbial ecologists to work with phylogenetic trees of increasing size (hundreds to thousands of species) in which the percentage of species with unknown traits becomes larger and larger.Recent evidence indicate that phylogeny reflects molecular functions and phenotypes in Bacteria and Archaea (Langille et al., 2013; Martiny et al., 2013). This is due to the phylogenetic conservatism of microbial traits (Martiny et al., 2013), which likely arises from microbial evolution mostly proceeding by vertical gene inheritance rather than horizontal gene transfer (Kurland et al., 2003, see Fraser et al., 2007 for theoretical models on the role of horizontal gene transfer in bacterial speciation). At present, the massive sequencing of microbes in the environment is providing a huge amount of genetic information that is extremely useful to reconstruct the phylogenetic relationships among microbial lineages. This fact has triggered the interest of microbial ecologists to apply the methods developed to predict unobserved trait values of extant taxa based on the traits observed in their evolutionary relatives (Kembel et al., 2012; Langille et al., 2013; Angly et al., 2014, see review in Zaneveld and Thurber, 2014). All these methods are based on the existence of a significant phylogenetic signal or, in other words, in the fact that close relatives have more similar traits than expected by chance. Phylogeny-based trait prediction procedures (PTP hereafter) in microbes have been mainly performed under the phylogenetic generalized least squares framework (Martins and Hansen, 1997; Garland and Ives, 2000). Specifically, the trait value (for continuous traits) or state (for binary traits) of the focal species have been reconstructed through ancestral state reconstructions after rerooting the phylogeny at the most recent common ancestor of the taxon with unobserved trait and the rest of the tree (Kembel et al., 2012). The accuracy of PTP methods has been typically assessed under ‘macrobial'' scenarios containing phylogenies of moderate size, with low-to-medium proportion of species with unknown traits and significant phylogenetic signals. For example, Fagan et al. (2013) predicted population growth rates of mammals in phylogenies of 42–65 species containing 54–64% of unknowns and a significant phylogenetic signal (Blomberg et al., 2003; Blomberg''s K) ranging from 0.68 to 1.42. However, the current microbial scenarios derived from high-throughput sequencing projects face large-sized phylogenies (hundreds to thousands tips) with a high number of species with unknown traits and varying phylogenetic signals jeopardizing the applicability of PTP methods (Zaneveld and Thurber, 2014).The extent to which phylogeny reflects phenotype is strongly dependent on the degree of conservatism with which the focal trait has evolved. For instance, complex traits that involve many genes (for example, photosynthesis or methanogenesis) show higher conservatism than simpler traits, such as the consumption of a specific carbon source (Martiny et al., 2013). Furthermore, certain traits such as those related to genes encoding antibiotic or metal resistance are particularly prone to be horizontally transferred (Bruins et al., 2000), a process that can blur their phylogenetic signal. Therefore, if phylogenetic relatedness is to be used to infer the phenotype, the phylogenetic conservatism of the target trait needs to be quantified in every case.Altogether, the abovementioned observations indicate that the possibility to estimate phenotypes from phylogenies depends on the amount of phylogenetic and phenotypic information available to predict the unobserved trait values. Here we provide a simulation exercise to test the accuracy of the most widely used PTP method in microbial ecology to predict continuous trait values and binary trait states of extant taxa with different amount of phenotypic and phylogenetic information. We simulated several situations faced by microbial ecologists, including phylogenies of different sizes in which a small (P=0.3), medium (P=0.6) or large (P=0.9) proportion of species have unknown trait values. The correlations between the actual and the predicted trait values were obtained for characters evolved under different degree of conservatism. Finally, we put these values in the context of the phylogenetic signals described in the literature for different continuous and binary microbial traits and provide some recommendations for future analyses aimed to predict microbial traits with the help of the phylogenetic information.     

Agronomic and molecular characterization of introgression lines from the interspecific cross Oryza sativa (BG90-2) x Oryza glumaepatula (RS-16)

The reduced genetic variability of modern rice varieties (Oryza sativa) is of concern because it reduces the possibilities of genetic gain in breeding programs. Introgression lines (ILs) containing genomic fragments from wild rice can be used to obtain new improved cultivars. The objective of the present study was to perform the agronomic and molecular characterizations of 35 BC2F8 ILs from the cross O. glumaepatula x O. sativa, aiming to select high-yielding ILs to be used in rice-breeding programs. All 35 ILs were field evaluated in the season 2002/2003 in three locations and the 15 best performing ones were evaluated in the season 2003/2004 in five locations. In 2003/2004, six ILs (CNAi 9934, CNAi 9931, CNAi 9930, CNAi 9935, CNAi 9936, and CNAi 9937) showed the highest yield means and were statistically superior to the controls Metica 1 and IRGA 417. Molecular characterization of the 35 ILs was performed with 92 microsatellite markers distributed on the 12 rice chromosomes and a simple regression quantitative trait locus analysis was performed using the phenotypic data from 2002/2003. The six high-yielding ILs showed a low proportion of wild fragment introgressions. A total of 14 molecular markers were associated with quantitative trait loci in the three locations. The six high-yielding ILs were incorporated in the Embrapa breeding program, and the line CNAi 9930 is recommended for cultivation due to additional advantages of good grain cooking and milling qualities and high yield stability. The O. glumaepatula-derived ILs proved to be a source of new alleles for the development of high-yielding rice cultivars.     

Morphology of the slashed pod trait in lentil

Reducing losses from pod shatter is a major goal of most lentil (Lens culinaris) improvement programs, however, genetic variability is limited. Recently, a slashed pod trait was suggested to have potential value for reducing losses from shattering, but little was known about the trait. In this study we determined the anatomical features which were associated with the slashed pod trait. Histological specimens from ‘Brewer’ lentil (normal pods) and from germplasm lines expressing the slashed pod trait were compared to each other and to specimens from normal and reduced pod parchment pea (Pisum sativum) lines. Reduced parchment pea pods had less sclerenchyma tissue and fewer fibers than pea pods with normal parchment, but all lentil pods examined had comparable sclerenchyma tissue with similar quantities of fiber. The slashed pod trait was not the result of reduced sclerenchyma tissue (parchment) as had been previously suggested. Apparently, the slashed pod trait resulted from the stresses which develop between fiber cells within the sclerenchyma layer of the pod wall during pod maturation and drying. The trait had little effect on quality of seeds for human utilization in the environments tested but may have an undesirable effect in other environments. Although seed loss due to shatter appeared to be decreased in pods exhibiting the trait, the uncertainty of expression due to environmental influences makes the trait an unlikely candidate for use in lentil improvement programs.     

A Bayesian model for estimating population means using a link-tracing sampling design

Link-tracing sampling designs can be used to study human populations that contain "hidden" groups who tend to be linked together by a common social trait. These links can be used to increase the sampling intensity of a hidden domain by tracing links from individuals selected in an initial wave of sampling to additional domain members. Chow and Thompson (2003, Survey Methodology 29, 197-205) derived a Bayesian model to estimate the size or proportion of individuals in the hidden population for certain link-tracing designs. We propose an addition to their model that will allow for the modeling of a quantitative response. We assess properties of our model using a constructed population and a real population of at-risk individuals, both of which contain two domains of hidden and nonhidden individuals. Our results show that our model can produce good point and interval estimates of the population mean and domain means when our population assumptions are satisfied.     

Discrimination of Variation in a Male Signaling Trait Affects Detection Time in Visual Predators

In many species, expression of elaborate male characteristics likely represents a balance between sexual selection and natural selection via predation, as male traits selected to elicit rapid detection or response on the part of females also increase detection by predators. Predation costs are frequently inferred, but the underlying mechanisms associated with specific traits have rarely been directly explored. Males of the wolf spider Schizocosa ocreata (Araneae: Lycosidae) exhibit a sexually selected signaling trait (dark tufts of bristles) on their forelegs, and are sympatric with a number of visually hunting generalist predators, including cannibalistic conspecifics, that may impact spider survival. Here we use latency of orientation response of the American toad, Bufo americanus (Anura: Bufonidae), to video, 'virtual' courting S. ocreata male stimuli as an index of predator detection, and latency of orientation response of female S. ocreata to the same stimuli as an index of conspecific detection. When compared with stimuli representing the population average, elimination of the signal trait had no significant effect on predator detection but did increase latency to orient in conspecifics. Increasing the size of the signal trait had no effect on conspecific detection but did significantly reduce latency to orient for predatory toads. Results clearly indicate that for a courting male spider of a given size and vigor level, variation in the expression of a secondary sexual characteristic alone can incur differential direct costs and benefits by influencing latency of orientation to visual signals by predators and conspecifics.