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PubMed1979

Change in a secondary sexual character as evidence of incipient speciation in Drosophila silvestris.

Search for genetic changes that are pivotal in species formation has led to intraspecific studies of Drosophila silvestris, a giant species found only on the geologically new island of Hawaii. Males bear large, curved, modified bristles or cilia on the dorsal surface of the foreleg tibia and tarsus. In males from the south and west parts of the island there are two rows of cilia separated by a naked area, but in males from the north and east there is a mean of between 20 and 30 additional cilia between the two major rows on the tibia. These extra cilia are absent in closely related species of this subgroup, including the sympatric species D. heteroneura and three species from adjacent islands. Males use the foreleg tibiae in vibratory movements against the female's abdomen during courtship, so this character difference is likely to be important in the reproductive biology of the species. Inversion polymorphisms are similar in both northeast and southwest populations; they show large and strikingly parallel altitudinal shifts in frequency distributions involving the same inversions. Populations from various parts of the island cannot be distinguished by routine electrophoresis of soluble proteins encoded by 25 loci. Thus the "extra cilia" character is superimposed on a more ancient genetic background of similarity involving both chromosomal and electrophoretic polymorphisms. We interpret the extra cilia as a specific new embellishment of a secondary sexual character brought about by altered sexual selection occurring very recently in one part of the species range. This suggests incipient speciation.

Journal Article↗
PubMed1980

"Sexual" behavior in parthenogenetic lizards (Cnemidophorus).

All-female, parthenogenetic species afford a unique test of hypotheses regarding the nature and evolution of sexuality. Basic data on the behavior of parthenogens are lacking, however. We have discovered, from observations of captive Cnemidophorus uniparens, C. velox, and C. tesselatus, behavior patterns remarkably similar to the courtship and copulatory behavior of closely related sexual species. Briefly, in separately housed pairs, one lizard was repeatedly seen to mount and ride its cagemate and appose the cloacal regions. Dissection or palpation revealed that, in each instance, the courted animal was reproductively active, having ovaries containing large, preovulatory follicles, while the courting animal was either reproductively inactive or postovulatory, having ovaries containing only small, undeveloped follicles. These observations are significant for the questions they raise. For example, is this behavior a nonfunctional vestige of the species' ancestry, or is this behavior necessary for successful reproduction in the species (e.g., by priming reproductive neuroendocrine mechanisms as has been demonstrated in sexual species)?

Journal Article↗
PubMed1984

Inheritance of a secondary sexual character in Drosophila silvestris.

Reciprocal crosses were carried out between laboratory stock specimens obtained from two races of Drosophila silvestris from the island of Hawaii that differ in a quantitative secondary sexual character. The race from the Hilo side of the island has a novel attribute, consisting of an extra row of cilia on the tibia of males, which is used during courtship. With regard to this character, sex-linked genes contribute about 30% of the difference, and the remaining 70% of the difference between the races is produced by genes on at least two autosomes. The novel character appears to have been the outcome of altered sexual selection in the Hilo-side race. In an altered genetic environment, resulting from a founder event or random genetic drift, sexual selection may take a new direction. Such a shift may serve as a model for incipient speciation.

Animals↗
PubMed1986

Sexual mimicry regulates the attractiveness of mated Drosophila melanogaster females.

During mating, male Drosophila melanogaster transfer to the female's cuticle a compound (7-tricosene) that is almost absent from virgin females but is the major hydrocarbon component of the male's cuticle. During the first 3 hr after mating, the amount of 7-tricosene on a female decreases sharply but remains significantly above virgin levels. By 6 hr after mating, female synthesis of 7-tricosene has increased, and females release it when they are exposed to courting males. Transfer of 7-tricosene to immature virgin females by courting males significantly decreases their attractiveness, so 7-tricosene has demonstrable antiaphrodisiac properties. Thus, mated D. melanogaster females appear to mimic males by releasing, during courtship, an antiasphrodisiac pheromone that is almost absent from virgin females but is the most prominent hydrocarbon of the male cuticle.

Alkenes↗
PubMed1986

Neuroanatomy influences speciation rates among anurans.

Evolutionary divergence among animal courtship signals is an important component of the speciation process. In anurans, the preferential response of females to the mating call of conspecific males often maintains reproductive isolation among populations. Much of the information in the call is initially processed in the inner ear, and there is considerable variation in the structure of this organ among lineages of frogs. This variation is responsible for differences in the frequency range to which frog species are sensitive and thus influences the frequency range over which mating calls can effectively diverge. Data suggest that this influence of neuroanatomy on mating call divergence is partly responsible for the different rates of speciation among lineages of frogs.

Journal Article↗
PubMed1986

Animal art: Variation in bower decorating style among male bowerbirds Amblyornis inornatus.

Courtship bowers of the bowerbird Amblyornis inornatus, the most elaborately decorated structures erected by an animal other than humans, vary geographically and individually. Bowers in the south Kumawa Mountains are tall towers of sticks glued together, resting on a circular mat of dead moss painted black, and decorated with dull objects such as snail shells, acorns, and stones. Bowers in the Wandamen Mountains are low woven towers covered by a stick hut with an entrance, resting on a green moss mat and decorated with colorful objects such as fruits, flowers, and butterfly wings. Young males build simpler bowers, and adult males differ among themselves. Experiments with poker chips of seven colors offered as decorations showed that individual birds prefer some colors over others, individuals and populations differ in these preferences, certain objects are placed in specific parts of the bower, and birds steal chips from neighbors. Bower style may be partly learned. Hence, geographically varying bower styles may be a culturally transmitted trait, like human art styles.

Journal Article↗
PubMed1987

Geographic dialects in blind mole rats: role of vocal communication in active speciation.

We compared and contrasted the physical structure of male "courtship" calls of 59 subterranean mole rats belonging to the Spalax ehrenbergi superspecies in Israel, comprising 11 populations of four chromosomal species (2N = 52, 54, 58, and 60). We also conducted behavioral auditory discrimination tests of 144 females of the four species in the laboratory. The results indicate that each chromosomal species has a vocal dialect significantly different from all others, although the call of 2N = 60, the last derivative of speciation, is not yet fully differentiated. Females of 2N = 52, 54, and 58 preferred their homospecific mates' calls, whereas females of 2N = 60 did not. We conclude that call differentiation builds up gradually and provides an efficient ethological reproductive premating isolation mechanism between the emerging species in the active speciation of mole rats in Israel.

Animals↗
PubMed1990

Disruptive sexual selection in Colias eurytheme butterflies.

Sexual selection on male pheromone composition in Colias eurytheme (Pieridae) butterflies has the remarkable effect of increasing the variability of this trait. Sexual selection on important traits is generally thought to have a strong stabilizing effect on intraspecific variation of those characters. In this species, however, the male courtship pheromone is highly variable in the relative proportions of its three chemical constituents. Stabilization and/or canalization of this polygenic character in a population is impeded by the disproportionate mating success of males in one portion of the character distribution with alba (white morph) females, and of those in the opposite portion with orange (colored morph) females.

Journal Article↗
PubMed1994

Mast cells with gonadotropin-releasing hormone-like immunoreactivity in the brain of doves.

Using an antiserum (LR-1) raised against mammalian gonadotropin-releasing hormone (GnRH), we previously identified a nonneuronal cell that was more numerous in the medial habenula (MH) of courting ring doves than in individuals housed in visual isolation. The current studies suggest that they are mast cells. Both acidic toluidine blue and toluidine blue dissolved in water/butanediol revealed metachromatic cells with a distribution and morphology similar to that obtained by immunostaining with the GnRH antiserum in the MH. Some cells had granules reactive to safranin in the presence of alcian blue, indicative of a highly sulfated proteoglycan of the heparin family. Immunocytochemical studies demonstrated that all MH cells containing GnRH-like immunoreactivity contained histamine, another mast cell marker. The GnRH-immunoreactive cells had a unilobular, ovoid nucleus. Secretory granules within the cells were electron dense and displayed a variety of internal structures. Fine filamentous processes appeared evenly distributed on the cell surface whether cells were located on the pial surface or within the brain parenchyma. All of these features are characteristic of mast cells. To test whether the epitope recognized by the GnRH antiserum was produced by the mast cells or endocytosed from the cerebrospinal fluid, an iodinated GnRH analog was injected intracerebroventricularly at the initiation of courtship. Radioautography revealed no radioactive cells in the brain, indicating that the GnRH antibody recognized a molecule synthesized by the nonneuronal cells rather than internalized by a receptor-mediated mechanism. These observations suggest an interaction between a component of the immune network and specific regions of the central nervous system.

Animals↗
PubMed1995

Chemical signals in the marine environment: dispersal, detection, and temporal signal analysis.

Chemical signals connect most of life's processes, including interorganismal relationships. Detection of chemical signals involves not only recognition of a spectrum of unique compounds or mixtures of compounds but also their spatial and temporal distribution. Both spectral and temporal signal processing determine what is a signal and what is background noise. Each animal extracts its unique information from the chemical world and uniquely contributes to it. Lobsters have provided important information on temporal signal processing. Marine chemical signals can be measured with high spatio-temporal resolution giving us a novel view of the lobster's environment. Lobster chemoreceptor cells have flicker fusion frequencies of 4 Hz and can integrate stimuli over 200 ms, closely corresponding to odor sampling behavior with 4-Hz "sniffs." Using this information, spatial odor gradients can be determined from temporal analysis of odor patches typical of turbulent dispersal. Lobsters appear to use this information to locate odor sources. Lobster social behavior depends greatly on chemical signals. Urine carries important information for courtship, dominance, and individual recognition. A novel gland in the nephropore is strategically located to release its products into the urine. Urine, in turn, is injected into the gill current, which jets water 1-2 m ahead of the animal. Lobsters control three different currents that carry chemical signals to and from them. The study of odor dynamics has only just begun. It will be exciting to see how signal dispersal, receptor temporal tuning, neural processing, and animal behavior interact to enhance signals for communication and detection and to reduce signals for chemical camouflage.

Aggression↗
PubMed1999

Survival of reproductive behaviors in estrogen receptor beta gene-deficient (betaERKO) male and female mice.

Previously, it was shown that the lack of a functional estrogen receptor (ER) alpha gene (ERalpha) greatly affects reproduction-related behaviors in both female and male mice. However, widespread expression of a novel second ER gene, ERbeta, demanded that we examine the possible participation of ERbeta in regulation of these behaviors. In dramatic contrast to our results with ERalpha knockout (alphaERKO) males, betaERKO males performed at least as well as wild-type controls in sexual behavior tests. Moreover, not only did betaERKO males exhibit normal male-typical aggressive behavior, including offensive attacks, but they also showed higher levels of aggression than wild-type mice under certain conditions of social experience. These data revealed a significant interaction between genotype and social experience with respect to aggressive behavior. Finally, females lacking a functional beta isoform of the ER gene showed normal lordosis and courtship behaviors, extending in some cases beyond the day of behavioral estrus. These results highlight the importance of ERalpha for the normal expression of natural reproductive behaviors in both sexes and also provide a background for future studies evaluating ERbeta gene contributions to other, nonreproductive behaviors.

Aggression↗
PubMed1999

Female choice increases offspring fitness in an arctiid moth (Utetheisa ornatrix).

In Utetheisa ornatrix (Lepidoptera, Arctiidae), the female mates preferentially with larger males. Having a larger father results in the eggs being more richly endowed with defensive pyrrolizidine alkaloid (which the female receives from the male with the sperm package, in quantity proportional to the male's body mass, and passes on to the eggs); having a larger father also results in the sons and daughters themselves being larger (body mass is heritable in Utetheisa). We provide evidence herein that these consequences enhance the fitness of the offspring. Eggs sired by larger males are less vulnerable to predation (presumably because of their higher alkaloid content), whereas sons and daughters, by virtue of being larger, are, respectively, more successful in courtship and more fecund. The female Utetheisa, therefore, by being choosy, reaps both direct phenotypic and indirect genetic benefits.

Animals↗
PubMed2003

Enhancer-dependent 5'-splice site control of fruitless pre-mRNA splicing.

The Drosophila fruitless (fru) gene encodes a transcription factor that essentially regulates all aspects of male courtship behavior. The use of alternative 5'-splice sites generates fru isoforms that determine gender-appropriate sexual behaviors. Alternative splicing of fru is regulated by TRA and TRA2 and depends on an exonic splicing enhancer (fruRE) consisting of three 13-nucleotide repeat elements, nearly identical to those that regulate alternative sex-specific 3'-splice site choice in the doublesex (dsx) gene. dsx has provided a useful model system to investigate the mechanisms of enhancer-dependent 3'-splice site choice. However, little is known about enhancer-dependent regulation of alternative 5'-splice sites. The mechanisms of this process were investigated using an in vitro system in which recombinant TRA/TRA2 could activate the female-specific 5'-splice site of fru. Mutational analysis demonstrated that one 13-nucleotide repeat element within the fruRE is required and sufficient to activate the regulated female-specific splice site. As was established for dsx, the fruRE can be replaced by a short element encompassing tandem 13-nucleotide repeat elements, by heterologous splicing enhancers, and by artificially tethering a splicing activator to the pre-mRNA. Complementation experiments showed that Ser/Arg-rich proteins facilitate enhancer-dependent 5'-splice site activation. We conclude that splicing enhancers function similarly in activating regulated 5'- and 3'-splice sites. These results suggest that exonic splicing enhancers recruit multiple spliceosomal components required for the initial recognition of 5'- and 3'-splice sites.

5' Untranslated Regions↗
PubMed2003

A biography of James Ramsay Hunt (1874-1937).

James Ramsay Hunt (1874-1937) was a pre-eminent twentieth-century American neurologist. The name of Ramsay Hunt is known today because several neurological disorders bear his name, including the herpetic geniculate ganglion syndrome and a form of ataxia and myoclonus. Despite his importance in the field of neurology, few biographical details have been recorded about Hunt's life. One of the authors of this report recently located Hunt's daughter. This biographical sketch was based on interviews conducted with her and review of documents in her possession, including letters written by Hunt. Details are depicted about Hunt's family background and childhood, medical education and early professional development, courtship and marriage, wartime experiences, family and social life, daily routine and professional development, as well as illness and death.

Herpes Zoster Oticus↗
PubMed2003

Behavioral genomics and the study of speciation at a porous species boundary.

Porous species boundaries are characterized by differential gene flow, where some regions of the genome experience divergent evolution while others experience the homogenizing effects of gene flow. If species can arise or remain distinct despite gene flow between them, speciation can only be understood on a gene by gene level. To understand the genetics of speciation, we therefore must identify the targets of selection that cause divergent evolution and identify the genetic architecture underlying such "speciation phenotypes". This will enable characterization of genomic regions that are "free to flow" between species, and those that diverge in the face of gene flow. We discuss this problem in the genus Laupala, a morphologically cryptic, flightless group of crickets that has radiated in Hawaii. Because songs are used in courtship and always distinguish close relatives of Laupala as well as species in sympatry, we argue that songs in Laupala are speciation phenotypes. Here, we present our approaches to identify the underlying genomic regions and song genes that differentiate closely related species. We discuss what is known about the genetic basis of this species difference derived from classic quantitative genetics and quantitative trait locus mapping experiments. We also present a model of the molecular expression of cricket song to assist in our goal to identify the genes involved in song variation. As most species are sympatric and exchange genes with congeners, we discuss the importance of understanding the genetic and genomic architecture of song as a speciation phenotype that must be characterized to identify differential patterns of gene flow at porous species boundaries.

Journal Article↗
PubMed2005

Bioactive fractions containing methyl eugenol-derived sex pheromonal components in haemolymph of the male fruit fly Bactrocera dorsalis (Diptera: Tephritidae).

Sex pheromonal components of the tephritid fruit fly Bactrocera dorsalis (Hendel), 2-allyl-4,5-dimethoxyphenol and (E)-coniferyl alcohol, are biosynthesized from a highly potent male attractant, methyl eugenol, then sequestered and stored in the rectal gland prior to their release during courtship at dusk. These sex pheromonal components have been detected in the haemolymph and crop organ. Hence, attempts were made to separate and identify the haemolymph fractions which contained the sex pheromonal components. Identification of these bioactive fractions in methyl eugenol-fed male flies using gel filtration column chromatography and biodetection using live male flies showed two fractions as highly attractive to conspecific males. These fractions show a significant increase in protein absorbance in the elution profile of haemolymph from methyl eugenol-fed males compared with that from methyl eugenol-deprived males. The molecular mass of these bioactive fractions as determined by using gel filtration was in the peptide range of 3.3 to 5.5 kDa. Subsequent gas chromatography-mass spectrometry analyses further confirmed the presence of the pheromonal components in the bioactive fractions. The presence of these methyl eugenol-derived sex pheromonal components in specific haemolymph fractions suggests the involvement of a sex pheromone binding complex.

Animals↗
PubMed1998

Time-budgets, comfort behaviours and injurious pecking of turkeys housed in pairs.

1. Large group size and high stocking density can compromise the welfare of poultry. This study, the first in a series of trials to determine the effect of these factors, examined the behaviour of turkeys under conditions in which group size and stocking density would have minimal influence, that is, when the birds were housed as pairs in pens measuring 3.0 x 3.6 m. 2. The 24 h time-budgets, frequency of comfort behaviours and incidence of injurious pecking were recorded on 12 occasions when the birds were between 4 and 22 weeks of age. 3. Over the duration of the study the proportion of time engaged in drinking or pecking other birds remained constant, but decreased for sleeping, environment pecking, wing-flapping, and running, increased for stretching, and varied throughout for feeding, standing, sitting, strutting, preening whilst standing, preening whilst sitting, and walking. 4. Some of the changes in activity were probably attributable to age effects per se. though other changes may have been related to increased musculo-skeletal weakness. 5. At 18 weeks of age, the turkeys spent a considerable proportion (30%) of time performing a sexual courtship display, strutting. Although the prevalence of this activity subsequently decreased, the likelihood of increased metabolic costs and potential for frustration indicate further investigation is warranted. 6. The turkeys behaved socially and were strongly influenced by social facilitator. 7. There were considerable differences between the behaviour of the turkeys and other common poultry species: the turkeys performed a running or frolicking behaviour and strutting, but did not exhibit other behaviours commonly observed such as dustbathing and ground-scratching whilst feeding. 8. Injurious pecking was infrequent. Only 14 bouts of behaviour likely to cause injury were recorded in 1,656 turkey-hours of continuous observation; no turkey required attention as a consequence of this behaviour. Feather pecking and cannibalism did not occur despite higher than conventional light intensities; the low frequency of injurious pecking could be attributed to the small group size/low stocking density.

Aggression↗
PubMed2004

Disco clothing, female sexual motivation, and relationship status: is she dressed to impress?

The relationship between a female's clothing choice, sexual motivation, hormone levels, and partnership status (single or not single, partner present or not present) was analyzed in 351 females attending Austrian discotheques. We digitally analyzed clothing choice to determine the amount of skin display, sheerness, and clothing tightness. Participants self-reported sexual motivation, and we assessed estradiol and testosterone levels through saliva sampling. Results show that females are aware of the social signal function of their clothing and that they in some cases alter their clothing style to match their courtship motivation. In particular, sheer clothing -although rare in the study- positively correlated with the motivation for sex. Hormone levels influenced clothing choice in many groups, with testosterone levels correlating positively with physique display. In females who had a partner but were at the disco unaccompanied by the partner, estradiol levels correlated positively with skin display and clothing tightness. Significant differences were not found, however, for clothing choice across the partnership-status groups.

Adult↗