Dopamine biases decisions by limiting temporal integration.

Motivations bias our responses to stimuli, producing behavioural outcomes that match our needs and goals. Here we describe a mechanism behind this phenomenon: adjusting the time over which stimulus-derived information is permitted to accumulate towards a decision. As a Drosophila copulation progresses, the male becomes less likely to continue mating through challenges1-3. We show that a set of copulation decision neurons (CDNs) flexibly integrates information about competing drives to mediate this decision. Early in mating, dopamine signalling restricts CDN integration time by potentiating Ca2+/calmodulin-dependent protein kinase II (CaMKII) activation in response to stimulatory inputs, imposing a high threshold for changing behaviours. Later into mating, the timescale over which the CDNs integrate termination-promoting information expands, increasing the likelihood of switching behaviours. We suggest scalable windows of temporal integration at dedicated circuit nodes as a key but underappreciated variable in state-based decision-making.

Long-term neuropeptide modulation of female sexual drive via the TRP channel in Drosophila melanogaster.

Connectomics research has made it more feasible to explore how neural circuits can generate multiple outputs. Female sexual drive provides a good model for understanding reversible, long-term functional changes in motivational circuits. After emerging, female flies avoid male courtship, but they become sexually receptive over 2 d. Mating causes females to reject further mating for several days. Here, we report that pC1 neurons, which process male courtship and regulate copulation behavior, exhibit increased CREB (cAMP response element binding protein) activity during sexual maturation and decreased CREB activity after mating. This increased CREB activity requires the neuropeptide Dh44 (Diuretic hormone 44) and its receptors. A subset of the pC1 neurons secretes Dh44, which stimulates CREB activity and increases expression of the TRP channel Pyrexia (Pyx) in more pC1 neurons. This, in turn, increases pC1 excitability and sexual drive. Mating suppresses pyx expression and pC1 excitability. Dh44 is orthologous to the conserved corticotrophin-releasing hormone family, suggesting similar roles in other species.

Genital and Subjective Sexual Arousal in Androphilic Women and Gynephilic Men in Response to the Copulatory Movements of Different Animal Species.

Research has repeatedly shown marked differences in men's and women's sexual response patterns; genital response in men tends to be elicited by cues that correspond to their sexual preference (preferred gender), while women's genital response is less sensitive to gender cues and more sensitive to the presence and intensity of other sexual cues (e.g., sexual activities). We tested whether the cue of copulatory movement in a general sexual context elicited a genital response in androphilic women but not in gynephilic men. If so, women should react to stimuli depicting not only the non-preferred gender but also other animal species differing in phylogenetic distance to humans. We studied the genital and self-reported arousal of 30 gynephilic men and 28 androphilic women to two sexual videos depicting penetrative human sexual intercourse (female-male and female-female) and nine videos depicting animal copulation. Neither women nor men showed genital or subjective sexual arousal to non-human sexual stimuli. Moreover, both sexes demonstrated a highly cue-specific pattern of arousal. Our results suggest that copulatory movement displayed in non-human species is not a sexual cue that can elicit genital or subjective sexual arousal in humans.

Kisspeptin administration may promote precopulatory behavior in male rats independently or supplementally to testosterone and contribute to proceptive behavior in female partners, reducing mating failure.

Kisspeptin is a peptide that plays an important role through its effects on the hypothalamus-pituitary-gonadal (HPG) axis. It has also been implicated in sexual behavior. The present study investigated whether the relationship between kisspeptin and sexual behavior is independent of the HPG axis, i.e., testosterone. Sexual behavior was examined after the administration of kisspeptin to gonadally intact male rats and gonadectomized male rats that received testosterone supplementation. Other male rats were also observed for sexual behavior once a week from 2 to 5 weeks after gonadectomy and receiving kisspeptin for the sixth postoperative week. Sexual behavior in female rats serving as the partner for each male was also observed. Female rats were not administered kisspeptin in the present study. The results obtained showed that the administration of kisspeptin increased precopulatory behavior in gonadally intact male rats and gonadectomized male rats that received testosterone supplementation and proceptive behavior in their female partners. Precopulatory behavior in males and receptive behavior in females increased, while copulatory behavior in males and receptive behavior in females remained unchanged. Furthermore, the administration of kisspeptin increased precopulatory behavior in gonadectomized males, but did not affect receptive behavior in females. These results suggest that kisspeptin affected males independently and/or supplementally to testosterone, and also that changes in the presence of testosterone in males had an impact on proceptive behavior in their female partners. In conclusion, kisspeptin may involve an as-yet-unidentified neural pathway in sexual desire independently of the HPG axis.

Necrophilic behaviour in wild stump-tailed macaques (Macaca arctoides).

Necrophilic behavior (attempted copulation with corpses) has been scarcely reported in non-human primates, especially in the wild. Here is the first case of necrophilic behavior observed in wild stump-tailed macaques in Thailand. Six groups of total N > 460 individuals have been identified and habituated. The corpse of an adult female was found and directly observed for 2 days and by camera trap for 3 days. The cause of death could not be identified, but no prominent physical injury was detected. Within 3 days of the observation, three different males attempted copulation with the corpse. Noteworthy for this observation was that not only males in the group of the dead female but also males from different groups interacted with the corpse. Taken together, these observations suggest that some cues emanating from the corpse coupled with a nonresistant/passive orientation may have triggered these responses in the males. Given that necrophiliac responses have been scarcely reported in non-human primates, our findings provide new insight into these behaviors and to comparative thanatology in general.

Sox21b underlies the rapid diversification of a novel male genital structure between Drosophila species.

The emergence and diversification of morphological novelties is a major feature of animal evolution.1,2,3,4,5,6,7,8,9 However, relatively little is known about the genetic basis of the evolution of novel structures and the mechanisms underlying their diversification. The epandrial posterior lobes of male genitalia are a novelty of particular Drosophila species.10,11,12,13 The lobes grasp the female ovipositor and insert between her abdominal tergites and, therefore, are important for copulation and species recognition.10,11,12,14,15,16,17 The posterior lobes likely evolved from co-option of a Hox-regulated gene network from the posterior spiracles10 and have since diversified in morphology in the D. simulans clade, in particular, over the last 240,000 years, driven by sexual selection.18,19,20,21 The genetic basis of this diversification is polygenic but, to the best of our knowledge, none of the causative genes have been identified.22,23,24,25,26,27,28,29,30 Identifying the genes underlying the diversification of these secondary sexual structures is essential to understanding the evolutionary impact on copulation and species recognition. Here, we show that Sox21b negatively regulates posterior lobe size. This is consistent with expanded Sox21b expression in D. mauritiana, which develops smaller posterior lobes than D. simulans. We tested this by generating reciprocal hemizygotes and confirmed that changes in Sox21b underlie posterior lobe evolution between these species. Furthermore, we found that posterior lobe size differences caused by the species-specific allele of Sox21b significantly affect copulation duration. Taken together, our study reveals the genetic basis for the sexual-selection-driven diversification of a novel morphological structure and its functional impact on copulatory behavior.

Intra-horn insemination in the alpaca Vicugna pacos: Copulatory wounding and deep sperm deposition.

Alpacas (Vicugna pacos) are reported to be the rare mammal in which the penis enters the uterus in mating. To date, however, only circumstantial evidence supports this assertion. Using female alpacas culled for meat, we determined that the alpaca penis penetrates to the very tips of the uterine horns, abrading the tract and breaking fine blood vessels. All female alpacas sacrificed one hour or 24 hours after mating showed conspicuous bleeding in the epithelium of some region of their reproductive tract, including the hymen, cervix and the tips of each uterine horn, but typically not in the vagina. Unmated females showed no evidence of conspicuous bleeding. Histological examination of mated females revealed widespread abrasion of the cervical and endometrial epithelium, injuries absent in unmated females. Within one hour of mating, sperm were already present in the oviduct. The male alpaca's cartilaginous penis tip with a hardened urethral process is likely responsible for the copulatory abrasion. The entire female reproductive tract interacts with the penis, functioning like a vagina. Alpacas are induced ovulators, and wounding may hasten delivery of the seminal ovulation-inducing factor beta-NGF into the female's blood stream. There is no evidence of sexual conflict in copulation in alpaca, and thus wounding may also be one of a variety of mechanisms devised by mammals to induce a beneficial, short-term inflammatory response that stimulates blastocyst implantation, the uterine remodeling associated with placental development, and thus the success of early pregnancy.

Observation of female-male mounting in the carrion crow.

In the biological sciences, sexual behaviours in non-human animals are traditionally investigated in the context of reproduction and direct fitness benefits. While the evolutionary functions of non-conceptive sexual behaviours ('socio-sexual behaviours') remain less well explored, these interactions and displays have been suggested to be important for shaping and maintaining social relationships. Here, we report an observation of a captive female carrion crow, Corvus corone corone, mounting her co-housed male partner. We highlight the importance of more systematic research, reporting, and discussions of rarely observed behaviours in social evolution research, including considerations for behaviours that transcend binary or heteronormative frameworks, for a more comprehensive understanding of non-conceptive socio-sexual behaviours.

Males conditionally inseminate at three female body locations according to female mating history and female maturity status in a squid.

In some squids, such as those in the family Loliginidae, upon copulation, females receive and store male-delivered sperm capsules, spermatangia, at two different body locations: the buccal membrane and the distal end of the oviduct. This insemination site dimorphism is associated with alternative reproductive strategies. However, in Loliolus sumatrensis, a species of Loliginidae, the females possess three insemination sites: buccal membrane (BM), basal left IV arm (ARM) and lateral head behind the left eye (EYE), therefore we studied such the unusual phenomena. We developed microsatellite markers and genotyped the paternity of each spermatangium on three sites. We found multiple paternity at every single site and simultaneous usage of all three sites by a few males. The seasonal dynamics of a population in the Seto Inland Sea revealed a set priority for the initial use of insemination sites as BM, followed by ARM and then EYE, whereas the maximum number of stored spermatangia was greater in EYE > ARM > BM. Female maturity status was correlated with the usage pattern of insemination sites but not with the number of stored spermatangia at any insemination site. These results suggest that a male squid inseminates at different locations according to female mating history and female maturity status.

Mating-induced release of oxytocin in the mouse lateral septum: Implications for social fear extinction.

In mammals, some physiological conditions are associated with the high brain oxytocin (OXT) system activity. These include lactation in females and mating in males and females, both of which have been linked to reduced stress responsiveness and anxiolysis. Also, in a murine model of social fear conditioning (SFC), enhanced brain OXT signaling in lactating mice, specifically in the lateral septum (LS), was reported to underlie reduced social fear expression. Here, we studied the effects of mating in male mice on anxiety-related behaviour, social (and cued) fear expression and its extinction, and the activity of OXT neurons reflected by cFos expression and OXT release in the LS and amygdala. We further focused on the involvement of brain OXT in the mating-induced facilitation of social fear extinction. We could confirm the anxiolytic effect of mating in male mice irrespective of the occurrence of ejaculation. Further, we found that only successful mating resulting in ejaculation (Ej+) facilitated social fear extinction, whereas mating without ejaculation (Ej-) did not. In contrast, mating did not affect cues fear expression. Using the cellular activity markers cFos and pErk, we further identified the ventral LS (vLS) as a potential region participating in the effect of ejaculation on social fear extinction. In support, microdialysis experiments revealed a rise in OXT release within the LS, but not the amygdala, during mating. Finally, infusion of an OXT receptor antagonist into the LS before mating or into the lateral ventricle (icv) after mating demonstrated a significant role of brain OXT receptor-mediated signaling in the mating-induced facilitation of social fear extinction.

Description of an automatic copulation induction system used to establish a free-mating laboratory colony of Nyssorhynchus deaneorum from Brazil

BACKGROUND Nyssorhynchus deaneorum is a potential malaria vector because it has been shown to be competent to transmit Plasmodium vivax and Plasmodium falciparum, and because it exhibits antropophilic and endophilic behaviors in some regions of the Amazon. This profile makes Ny. deaneorum a useful mosquito for experiments that model Plasmodium-vector interactions in the Amazon. OBJECTIVE Herein we describe how a free-mating colony of Ny. deaneorum has been established using an automated light stimulation system. METHODS Mosquitoes were captured in São Francisco do Guaporé, Rondônia. The F1 generation was reared until adult emergence at which point copulation was induced using an automatic copulation induction system (ACIS). FINDINGS After four generations, natural mating and oviposition began to occur without light stimulation. The number of pupae and adult mosquitoes increased from the F5 to F10 generations. The new Ny. deaneorum colony exhibited susceptibility to P. vivax. MAIN CONCLUSIONS Automated light stimulation is an effective method for establishing an Ny. deaneorum colony under laboratory conditions as it produces enough adults to create a stenogamic colony. The establishment of a stable, P. vivax-susceptible colony of Ny. deaneorum makes it possible to model parasite-vector interactions and to test novel drug therapies that target parasite development in mosquitoes.

Caracterización del comportamiento y las señales vibratorias en Euthyrhynchus floridanus (Hemiptera: Pentatomidae) durante el cortejo y la cópula / Characterization of the behavioral and vibrational signals in Euthyrhynchus floridanus (Hemiptera: Pentatomidae) during courtship and copulation

Euthyrhynchus floridanus (Linnaeus) (Hemiptera: Pentatomidae) is a neotropical species belonging to the family Pentatomidae with over 4 000 species described, and is distributed from Florida to Brazil. This study describes the sexual behavior and reported for the first time the production of substrate vibrations by males and females during copulatory behavior and mating. Courtship and copulatory behavior, as well as the diverse signals, were recorded with a phonographic cartridge connected to a video camera. Female vibrations were reproduced in the absence of females and the responses by males were recorded. At least three types of substrate vibrations were distinguished in males and one in females, and these signals were characterized by their low frequency, varying from 127 to 180Hz. The sounds of E. floridianus males were significantly different in frequency, duration and number of pulses, both in courtship and in copulation, for the purring and drumming sounds. The production of sounds in this species is associated principally with mechanical, stimulatory behavior during courtship and copulation. Patterns of behavior and their relation to substrate vibrations suggest that these signals are important for the males in the context of mate location and sexual selection.

Euthyrhynchus floridanus (Linnaeus) (Hemiptera: Pentatomidae) es una especie neotropical perteneciente a la familia Pentatomidae con más de 4 000 especies descritas, y se distribuye desde la Florida hasta Brasil. Este estudio describe el comportamiento sexual y reporta por primera vez la producción de vibraciones de sustrato por machos y hembras durante el comportamiento precopulatorio y la cópula. Se grabó tanto el comportamiento de cortejo y de cópula como las diversas señales producidas utilizando un cartucho fonográfico, conectado a una cámara de video. Posteriormente se reprodujo las vibraciones de las hembras en ausencia de estas y se registró las respuestas de los machos. Se distinguieron al menos tres vibraciones de sustrato distintas para los machos y una para las hembras, y se caracterizaron por ser señales de baja frecuencia que van desde los 127 hasta 180Hz. Las sonidos de los machos en E. floridianus fueron significativamente diferentes en la frecuencia, duración y número de pulsos tanto en el cortejo como en la cópula para los sonidos de ronroneo y tamborileo. La producción de sonidos en esta especie se asoció principalmente con comportamientos estimulatorios- mecánicos durante el cortejo y copula. Patrones de comportamiento y su relación con las vibraciones del sustrato sugiere que estas señales pueden ser importantes para los machos en el contexto de la localización de su compañera y la selección sexual.

Avaliação de dois métodos para condicionamento e coleta de sêmen em quatro espécies do gênero Mazama / Assessment of two methods for conditioning and semen collection in four species of Mazama genus

O desenvolvimento de técnicas não invasivas para a obtenção de sêmen de cervídeos facilita a criação de bancos genômicos, que são importantes instrumentos para a conservação ex situ e in situ. Este trabalho teve como objetivo criar uma metodologia não-invasiva de coleta de sêmen e comparar duas técnicas de coleta em quatro espécies do gênero Mazama: M. americana, M. gouazoubira, M. nana e M. nemorivaga. Para tanto, foram utilizados seis machos (M) e duas fêmeas (F) da espécie M. americana, 3M e 2F de M. gouazoubira, 1M e 1F de M. nana e 2M e 1F de M. nemorivaga. Para cada técnica testada, foi realizado um período de habituação dos animais ao manejo. Em seguida, duas técnicas de condicionamento e coleta foram avaliadas. Na primeira delas foi utilizada uma fêmea em estro com desvio lateral do pênis para vagina artificial (FEDL), obtendo-se a coleta de 50% dos indivíduos (100% dos machos de M. gouazoubira e 50% dos machos de M. americana), não obtendo ejaculados das demais espécies. Na segunda técnica, utilizando um manequim taxidermizado com urina de fêmea em estro (MUFE) não foi possível a coleta de nenhum ejaculado. Em todas as fases foi observado o comportamento do macho quanto ao tempo de interesse e aproximação, reflexo de "Flehmen", ato de cheirar ou lamber, exposição do pênis, ereção, número de falsas montas, tentativas de cópula e ocorrência de agressividade entre os animais.

The development of noninvasive techniques for obtaining semen from deer facilitates the creation of genome banks, which are important tools for ex situ and in situ conservation. This study aimed to establish a noninvasive method of semen collection and compare two techniques of collection in four species of the genus Mazama: M. americana, M. gouazoubira, M. nana and M. nemorivaga. To achieve this, 6 males (M) and 2 females (F) of the species M. Americana, 3M and 2F of M. gouazoubira, 1M and 1F of M. nana and 2M and 1F of M. nemorivaga were used. For each technique tested, a period of habituation to animal handling was conducted; then, the two conditioning techniques and collection were evaluated. In the first, a female in estrus was used with lateral deviation of the penis to an artificial vagina (FEDL), yielding collection from 50% of the males (100% from M. gouazoubira and 50% from M. americana), with no ejaculate from the remaining species. In the second technique, using a taxidermized dummy with urine from females in estrus (MUFE), no semen collection was possible. During all stages, male behavior was observed regarding the time of interest and approximation, the "Flehmen" response, the act of sniffing or licking, exposure of the penis, erection, number of false mounts, attempts at copulation and the occurrence of aggression between the deer.

Copulatory behaviour and the process of intromission in Anastrepha ludens (Diptera: Tephritidae)

Complex genitalia occur in many arthropods and in some species extreme female morphologies lead to serious mechanical difficulties for males. Tephritid flies offer examples of such complex genitalia. Because of their economic importance and the extensive use of sterile male releases for tephritid control in Texas and Mexico, studies have been done on various aspects of their basic reproductive biology, but the process of intromission has received little attention. The distiphallus of the male of Anastrepha ludens is complex. One membranous sac on the distiphallus is capable of rhythmic cycles of inflation and deflation. Inflations of the sac near the base of the distiphallus probably help propel the aedeagus deeper into the female along with stiffening of the basiphallus and may drive the genital rod (which does not transfer sperm) into the ventral receptacle. We were unable to establish an association between some of the behaviours displayed by males during mating and intromission process. Rev. Biol. Trop. 59 (1): 291-297. Epub 2011 March 01.

En muchos artrópodos, se observan genitales complejos; la morfología extrema en las hembras podría conducir a serios problemas mecánicos para los machos (Kamimura & Matsuo 2001). Las moscas tefrítidas tienen ejemplos de tales órganos genitales complejos. Debido a su importancia económica y la amplia utilización de machos estériles para el control biológico en Texas y México, se han realizado estudios sobre diversos aspectos de su biología reproductiva, pero el proceso de penetración ha recibido muy poca atención. El distiphallus de los machos de Anastrepha ludens es complejo. Un saco membranoso en el distiphallus es capaz de realizar ciclos rítmicos de inflación y deflación. El inflado de la bolsa cerca de la base del distiphallus, junto con la rigidez del basiphallus probablemente ayuda a impulsar el edeagus más profundamente en la hembra y orientar la vara genital (que no transfiere esperma) en la región del receptáculo ventral. No pudimos establecer una asociación entre algunas de las conductas mostradas por los machos durante el apareamiento y el proceso de intromisión.

Rat dorsal prostate is necessary for vaginal adhesion of the seminal plug and sperm motility in the uterine horns

The rat prostate comprises dorsal, ventral and lateral lobes that are morphologically and biochemically distinct. Lesions to these structures are expected to affect the quality of the ejaculate and male fertility. In experiment 1, we analyzed ejaculate parameters of males that had chemical lesions of the dorsal or ventral lobes. At pre-lesion and at 5 and 20 days post-lesion males were mated, and after ejaculation, seminal fluid and seminal plug were obtained from the mated females. In experiment 2, the ventral lobes were ablated, and the ejaculate was analyzed. In experiment 3, the fertility of males with chemically-lesioned dorsal lobes or ablation of the ventral lobes was evaluated. Chemical lesion of the dorsal lobe prevented the adhesion of the seminal plug to vaginal walls. When these males were tested at 5-days postlesion, no sperm were found in uterus, and at 20-days post-lesion, the few sperm encountered showed slow progressive motility. None of the females that mated with dorsal lobe-lesioned males became pregnant. However, chemical lesion or ablation of the ventral lobes did not affect ejaculate or fertility. Our results indicate that the dorsal prostatic lobes are indispensable for reproductive success in males, and define parameters of ejaculate with which fertility can be estimated.

Copulatory courtship song in Lutzomyia migonei (Diptera: Psychodidae)

Lutzomyia migonei is a vector of leishmaniasis with a wide distribution in South America, which could favour population differentiation and speciation. Cryptic species of the Lutzomyia longipalpis complex, the widely distributed sand fly vector of visceral leishmaniasis in Latin America, have previously been shown to display distinct copulation songs. We found that Lu. migonei males also produce a song during copulation. This "lovesong" presents short trains (6-8 pulses) with an inter-pulse interval around 26 ms and is potentially involved in cryptic female choice and insemination success.

Efectos de la cópula y el tamaño del macho sobre el comportamiento de ovipostura en la mosca estercolera Archisepsis diversiformis (Diptera: Sepsidae) / Effects of copulation and male size on the oviposition behavior of the manure fly Archisepsis diversiformis (Diptera: Sepsidae)

Effects of copulation and male size on the oviposition behavior of the manure fly Archisepsis diversiformis (Diptera: Sepsidae). I evaluated the effect of copulation as a stimulation factor for oviposition of Archisepsis diversiformis by using two different age groups of females. In addition, I tested the effect of copulation on female longevity and progeny sex ratio, taking into account female and male size, and oocyte development in relation to female age. A delay in copulation leads to a delay in oviposition. Females of both age groups started to oviposit between four and five days after copulation. The number of eggs that were laid during the first ten days after copulation, the average number of ovipositions (number of eggs laid per day) during the female’s life, and the average time between ovipositions were all similar. I found further evidence for the effect of copulation on oviposition: when females copulate, they oviposited faster than virgin females. In addition, these females laid a lower number of eggs after the age of 13 days, while females of the same age (that have copulated before, when they were two or six days old) laid a higher number of eggs (an average of 75 eggs). Oocytes in virgin females became larger with age; 57 % of the variation in the number of eggs laid by females depends on female’s longevity. As in other studies, female size had an effect on the total number of eggs laid. However, male size significantly affected the oviposition rate (total number of eggs/female longevity). Females tended to have a higher oviposition rate after copulating with larger males. These data suggest that for this fly species, sexual selection through female choice might be occurring. Rev. Biol. Trop. 57 (Suppl. 1): 239-250. Epub 2009 November 30.

Se evaluó el efecto de la cópula como factor esti­mulante de la oviposición en Archisepsis diversiformis utilizando hembras de dos edades, y en la longevidad de la hembra y en la proporción sexual de la progenie, tomando en cuenta el tamaño de hembra y macho, y el desarrollo de los ovocitos en relación a la edad de la hembra. Se demostró que una demora en copular indujo una demora en oviponer. También hubo similitud en el número de huevos puestos en los diez primeros días después de la cópula, en el número promedio de posturas (grupo de huevos puestos por día) durante toda la vida de una hembra, y en el tiempo promedio transcurrido entre posturas. Otra evidencia del efecto de la cópula en la ovipostura, fue que las hembras que copularon ovipositaron más rápido que las vírgenes. Además, éstas colocaron un número muy bajo (en prome­dio 14) de huevos a partir de los 13 días de edad, mientras que hembras de esta misma edad (que previamente habían copulado a los dos o seis días de edad) colocaron un mayor número (en promedio 75) de huevos. Como en otros estu­dios, el tamaño de la hembra tuvo un efecto significativo sobre el número total de huevos puestos. Sin embargo, el tamaño del macho afectó significativamente la tasa (Nº total de huevos/duración de la vida de la hembra) de ovipostura. Estos datos sugieren la posibilidad de que la selección sexual por elección femenina actúe en hembras de esta especie de mosca.

Aislamiento reproductivo asimétrico entre Lutzomyia pseudolongipalpis y Lutzomyia longipalpis (especie C2), vectores neotropicales de leishmaniasis visceral (Diptera: Pshychodidae)

Asymmetric reproductive isolation between Lutzomyia pseudolongipalpis and Lutzomyia longipalpis (species C2), Neotropical vectors of visceral leishmaniasis (Diptera: Pshychodidae). Lutzomyia pseudolongipalpis and Lutzomyia longipalpis (species C2, L. sp n.) are two endemic species of Phlebotominae sand fly vectors from Venezuela. The two insects are sympatric and monophyletic but have deeply diverging, morphological differences. They belong to the L. longipalpis complex. A study of their reproductive isolation is necessary to understand the process of speciation and maintenance of the two sister species as two discrete taxonomic and biological entities. Cross-mating tests were conducted (homo and hetero-specific) and monitored under two criteria: biological (presence of copulation and offspring) and genetic (using two isozymic markers diagnostic for the L. longipalpis complex; enzyme diagnosis AK and HK). Results indicate reproductive isolation, with an asymmetrical genetic exchange in a direction of hybridization between the two species under experimental conditions, and production of a low number of heterozygotes. These findings support the existence of negative selection on hybrids, and explain the absence of hybrids under natural conditions, in the sympatric locality. Rev. Biol. Trop. 57 (1-2): 23-31. Epub 2009 June 30.

Lutzomyia pseudolongipalpis y Lutzomyia longipalpis (especie C2, L. n. sp) son dos especies de flebotominos vectores endémicos de Venezuela, simpátricas, monofiléticas, con profundas divergencias, morfológicamente diferentes y pertenecientes al complejo de especies L. longipalpis. El estudio de su aislamiento reproductivo es clave para entender el proceso de especiación y el mantenimiento de estas dos especies hermanas como entidades taxonómicas y biológicas discretas. Por tal motivo, se realizaron ensayos de entrecruzamiento homo y heteroespecíficos, los cuales fueron monitoreados por dos criterios: biológico (presencia de cópula y progenie) y genético (utilizando dos marcadores isoenzimáticos diagnósticos para el complejo L. longipalpis, las enzimas AK y HK). Los resultados indican aislamiento reproductivo, con un intercambio genético asimétrico hacia la hibridización en condiciones experimentales, y producción de un bajo número de heterocigotos, lo que apoya la existencia de selección negativa sobre los híbridos y explica su ausencia en condiciones naturales en la localidad simpátrica.

Reproductive isolation between sympatric and allopatric Brazilian populations of Lutzomyia longipalpis s.l. (Diptera: Psychodidae)

Lutzomyia longipalpis s.l., the main vector of Leishmania chagasi in Latin America, is a species complex although the exact number of siblings is yet unknown. In Brazil, the siblings differ in male copulatory courtship songs and pheromones that most certainly act as pre-zygotic reproductive barriers. Here we analysed the reproductive isolation between three allopatric and two sympatric populations of Lu. longipalpis s.l. from Brazil. The results indicate a strong copulatory and pre-mating isolation between the three allopatric populations. In addition, the results also indicate a stronger pre-mating isolation between the two sympatric siblings than between the three allopatric ones, suggesting a role for reinforcement in the speciation of the Lu. longipalpis s.l. complex.

Field observations of mating behavior in the neck-banded snake Scaphiodontophis annulatus (Serpentes: Colubridae)

We observed the mating behavior of the neck-banded snake Scaphiodontophis annulatus (a common species of colubrid in the South Pacific of Costa Rica) in the pre-montane wet forest of Las Cruces Biological Station (San Vito de Java, Costa Rica). Three S. annulatus were observed during courtship between 10-12 AM in a patch of primary forest. The two males were observed to interact with the female, but not signs of male-male agonistic interactions were observed. Their behavior includes grabbing and holding the female, copula, and biting during the copula.

El comportamiento de apareamiento es descrito para la serpiente Scaphiodontophis annulatus, una especie de colúbrido común en el Pacífico sur de Costa Rica. El comportamiento incluye capturar y sujetar a la hembra, mordiscos durante la cópula y coito. Dos machos fueron observados al interactuar con una sola hembra, pero no se detectó señales de interacciones antagónicas macho-macho.