Postcastration retention of sexual behaviour in the male BDF1 mouse: The role of experience

Male BDF₁ mice (the F₁ progeny of a cross between C57BL/6 females with DBA/2 males) show a remarkable retention of sexual behaviour following castration. Two experiments were conducted to describe in detail the postcastration copulatory performance of the BDF₁ male mouse and to determine to what extent such performance is influenced by experience prior to castration. Experiment I found that castration leads to significant increases in the number of mounts and intromissions needed to reach ejaculation, and to a significant increase in ejaculation latency. Experiment II found that although precastrational sexual experience is not essential for the performance of the ejaculatory reflex after castration, it does influence the frequency of its occurrence. Furthermore, type of postweaning social experience influenced the display of ejaculatory behaviour by non-experienced castrates, as those with female social experience were superior to those with social experience with males or no social experience. The interactions of experience, hormones and genotype in the control of sexual behaviour in the BDF₁ male are discussed.     

Size-dependent male mating behaviour and sexual harassment in a population of Atlantic mollies (Poecilia mexicana) from a sulphur creek

The Atlantic molly Poecilia mexicana inhabits a variety of habitats. In previous studies, small males from clear-water populations showed considerably more sexual behaviours than large males. Males from a sulphur creek, the El Azufre, or from a sulphur cave (cave molly) showed comparatively low sexual activity, and typical size-dependent mating behaviour was either absent or large males showed even more sexual behaviour than smaller ones. Sexually deprived cave molly males increased their sexual activity, but small males still did not show more sexual behaviour than large ones, suggesting that the genetic basis for typical size-dependent mating behaviour has been lost. Likely, the extreme abiotic conditions (hypoxia and toxic hydrogen sulphide) have selected against energetically costly behaviours. In this paper, we examined how El Azufre males would respond to sexual deprivation. We found these males to also increase their sexual activity after sexual deprivation but, unlike cave mollies, small males now showed more sexual behaviour than large ones, suggesting that the genetic basis for this behaviour is not lost in this population. Differences between populations may be due to the less harsh characteristics of El Azufre (e.g. less H₂S), resulting in weaker selection against energy-consuming behaviours. Furthermore, we tested for potential costs of male sexual harassment for females in terms of reduced feeding efficiency in the presence of a male, as was shown for P. mexicana from a clear-water population, but was not found in cave mollies or the El Azufre fish. Test females were either starved for 1 week to increase hunger levels or male sexual deprivation and female starvation were combined; however, we found no evidence for male sexual harassment even after these treatments. Our results parallel previous findings in the cave molly and suggest that El Azufre males have lost specific behavioural traits that cause sexual harassment.     

Reproductive behaviour evolves rapidly when intralocus sexual conflict is removed

Background

Intralocus sexual conflict can inhibit the evolution of each sex towards its own fitness optimum. In a previous study, we confirmed this prediction through the experimental removal of female selection pressures in Drosophila melanogaster, achieved by limiting the expression of all major chromosomes to males. Compared to the control populations (C_1-4) where the genomes are exposed to selection in both sexes, the populations with male-limited genomes (ML_1-4) showed rapid increases in male fitness, whereas the fitness of females expressing ML-evolved chromosomes decreased [1].

Methodology/Principal Findings

Here we examine the behavioural phenotype underlying this sexual antagonism. We show that males expressing the ML genomes have a reduced courtship level but acquire the same number of matings. On the other hand, our data suggest that females expressing the ML genomes had reduced attractiveness, stimulating a lower rate of courtship from males. Moreover, females expressing ML genomes tend to display reduced yeast-feeding behaviour, which is probably linked to the reduction of their fecundity.

Conclusion/Significance

These results suggest that reproductive behaviour is shaped by opposing selection on males and females, and that loci influencing attractiveness and foraging were polymorphic for alleles with sexually antagonistic expression patterns prior to ML selection. Hence, intralocus sexual conflict appears to play a role in the evolution of a wide range of fitness-related traits and may be a powerful mechanism for the maintenance of genetic variation in fitness.     

Attitudes and sexual behaviours of unmarried people with HIV/AIDS living in the Niger Delta region of Nigeria

Background Increasing morbidity and mortality associated with HIV/AIDS may be attributable to the lifestyle of individuals. Appropriate sexual behaviour and lifestyle modification may be helpful strategies for prevention and control of HIV/AIDS in many countries.Aim The study was designed to assess the impact of attitudes and sexual behaviour on control of HIV/AIDS among unmarried people living with HIV/AIDS in Uyo, a community in the Niger Delta region of Nigeria.Method A total of 365 unmarried individuals living with HIV/AIDS were assessed at the HIV clinic of the University of Uyo Teaching Hospital. Attitudes and sexual behaviour were evaluated using the Attitude and Sexual Behaviour Questionnaire adapted from previous studies.Results Of the 365 individuals living with HIV/AIDS, 142 (38.9%) were male and 223 (61.1%) were female. The majority of the subjects were below 50 years of age. The mean ages (± SD) of men and women were 36.8 ± 3.9 and 29.2 ± 1.7 years, respectively. Sexual attitudes and behaviours were variable. There was no change in the partner''s reaction to sex for 28.9% of men and 27.8% of women, abstinence in 7.7% of men and 8.1% of women, and breakdown of the relationship with the partner for 4.9% of men and 7.2% of women. More women than men agreed to undergo testing after their partners had tested positive for HIV. Sexual activity was higher in women than men, with 4.9% of men and 10.3% of women reporting daily sexual intercourse, 16.2% of men and 15.7% of women reporting weekly intercourse, and occasional sexual intercourse being reported by 44.4% of both men and women. After testing positive, 58.4% of male partners and 56.9% of female partners were persuaded to use condoms during sexual intercourse.Conclusion This study has demonstrated unhealthy attitudes and sexual behaviour among individuals living with HIV/AIDS in the Niger Delta region of Nigeria. This can potentially limit efforts and investment in controlling HIV/AIDS in this region. Therefore there is a need to initiate concrete policies and programmes that would encourage people living with HIV/AIDS in the Niger Delta region to adopt a healthy lifestyle.     

Failure of a variety of antiestrogens to mimic estrogen action in the induction of sexual receptivity in a female lizard

The purpose of the present study was to determine whether nonsteroidal antiestrogens could act as estrogens by inducing or facilitating estrogen-induced sexual receptivity in a female lizard (Anolis carolinensis). Experiments were conducted to (1) test the ability of enclomiphene (ENC) and zuclomiphene (ZUC) to induce sexual receptivity in estrogen-untreated ovariectomized females; (2) to determine the effect of ENC and ZUC pretreatment on E₂B induction of sexual receptivity; and (3) to examine the ability of a variety of antiestrogens to act as estrogens by inducing sexual receptivity in females pretreated with a behaviorally ineffective estrogen treatment regimen.     

Effects of prostaglandin E2 and indomethacin on sexual behavior in the female rat

Prostaglandin E₂ (PGE₂) facilitated sexual behavior in estrogen-primed ovariectomized or ovariectomized-adrenalectomized rats. Administration of indomethacin, an inhibitor of prostaglandin synthesis, attenuated the effectiveness of estrogen and progesterone in inducing sexual receptivity in ovariectomized rats. Concurrent administration of PGE₂ with indomethacin restored sexual behavior only when administered early in the estrogen-priming period but not if administered along with the progesterone. Our studies support the likelihood of a role of prostaglandins in the control of sexual behavior in the female rat.     

Effects of estrogen deprivation on brain estrogen and progestin receptor levels and the activation of female sexual behavior

Ovariectomy (OVX) in rats is followed by a decline in behavioral sensitivity to combined estrogen and progesterone therapy. The purpose of this study was to further characterize this behavioral change, and to explore its biochemical basis in terms of estrogen and progesterone receptor concentrations in the brain. Sexually inexperienced female rats were used 5 (short-term) or 35 (long-term) days after OVX. Short- and long-term OVX animals were injected with estradiol-17β (E₂; 36 μg/kg body wt, iv) then subjected to one of the following three treatment schedules. (1) Animals were treated with progesterone (1 mg, sc in oil) 20–21 hr after E₂ injection, then tested at 24 hr for female sexual behavior. (2) One or twelve hours after the E₂, cell nuclear estrogen receptors (ER_n) were measured in the pituitary (PIT) and pooled preoptic area and mediobasal hypothalamus (POA-MBH). (3) Twenty-four hours after E₂, progestin receptor (PR_c) concentrations were measured in cytoplasmic fractions prepared from PIT and POA-MBH. Long-term OVX animals showed a reduced capacity to exhibit proceptive and receptive sexual behavior, and a lower PR_c level in the PIT and POA-MBH 24 hr after E₂ injection than animals that had been OVX for only 5 days. However, no differences were observed between long- and short-term OVX rats with respect to ER_n concentrations in PIT and POA-MBH cell nuclei 1 or 12 hr after E₂. Thus, it appears that the decline in behavioral responsiveness to E₂ which occurs after ovariectomy cannot be attributed to a decrease in the ability of E₂ to translocate estrogen receptors into POA-MBH cell nuclei, but is more probably associated with a change in the biochemical processes subsequent to ER_n binding. One of these processes may well be the induction of cytoplasmic progestin receptors.     

Genetics of sexual isolation based on courtship song between two sympatric species: Drosophila ananassae and D. pallidosa

Sexual isolation has been considered one of the primary causes of speciation and its genetic study has the potential to reveal the genetics of speciation. In Drosophila, the importance of courtship songs in sexual isolation between closely related species has been well investigated, but studies analysing the genetic basis of the difference in the courtship songs associated with sexual isolation are less well documented. Drosophila ananassae and Drosophila pallidosa are useful for studies of sexual isolation, because of their sympatric distribution and absence of postmating isolation. Courtship songs are known to play a crucial role in sexual isolation between these two species, and the female discrimination behaviour against the courting male has been revealed to be controlled by a very narrow region on the second chromosome. In this study we investigated the genetic basis controlling the song differences associated with their sexual isolation, using intact and wingless males with chromosomes substituted between species. The results obtained from F₁ hybrid males between these species indicate the dominance of the song characters favoured by D. pallidosa females. In addition, the results obtained from backcross F₂ males indicate that chromosome 2 had a major effect on the control of the song characters associated with sexual isolation.     

Sexual harassment in a live-bearing fish (<Emphasis Type="Italic">Poecilia mexicana</Emphasis>): influence of population-specific male mating behaviour

We investigated male sexual behaviour and the cost of sexual harassment, as measured by the reduction of female feeding time in the presence of a male, in a cave-dwelling population of Poecilia mexicana, in which sexual harassment does not occur naturally. We asked whether the lack of sexual harassment in this population is due to low sexual activity of the males, or low feeding motivation of the females. We experimentally increased the sexual activity of males or the females feeding motivation, or we used a combination of both treatments. Female feeding time was not lower in the presence of a male than in the presence of a female after sexual deprivation of the males or food deprivation of the females. Only in the combined experiment was female feeding time lower in the presence of a large male than in the presence of a small male, indicating a weak effect of sexual harassment by large males. Virgin females did not suffer a cost of sexual harassment, indicating that sexual experience does not cause the lack of sexual harassment in cave mollies. Males from a surface population, where sexual harassment occurs, significantly reduced the feeding time of cave-dwelling females even though these males exhibited surprisingly little sexual behaviour. The sexual activity of cave mollies did not correlate with male body size in any experiment, indicating that even after sexual deprivation, small cave molly males do not switch to the alternative mating behaviour known in surface-dwelling P. mexicana, where sexual activity is correlated negatively with male body size.     

Inheritance of parental genomes in progenies of Poa pratensis L. from sexual and apomictic genotypes as assessed by RAPD markers and flow cytometry

 Moving gene(s) responsible for the apomictic trait into crop plants that naturally reproduce through a sexual process would open up new areas in plant breeding and agricultural systems. Kentucky bluegrass (Poa pratensis L.) is one of the most important forage and turf grasses in temperate climates. It reproduces through facultative aposporous parthenogenesis, but the reproductive behaviour ranges naturally from nearly obligate apomixis to complete sexuality. In addition to apomictic reproduction, sexual hybridization may take place. Selfing may also occur, and occasionally reduced egg cells may develop through parthenogenesis generating (poly)haploids. The inheritance of parental genomes was assessed in Kentucky bluegrass progenies by employing RAPD markers in combination with flow cytometry (FCM). Nine progenies from different crosses carried out between completely sexual and highly apomictic genotypes were evaluated in order to probe the reproductive behaviour of the mother plants and to distinguish the different classes of aberrant plants. Not only were maternals and balanced B_II hybrids recorded, but so were (poly)triploid B_III hybrids, selfs, and (poly)haploids. The application of these techniques demonstrated that FCM analysis accurately distinguishes the n, 2n, and 3n ploidy levels of progenies, and that RAPD markers unequivocally recognize progenies of apomictic and hybrid origin. The occurrence of aneusomaty was documented in one of the selected sexual genotypes, whose crossed progeny plants manifested two distinct classes of ploidy. The nomenclature B_I was adopted to refer to hybrids with a hypodiploid nuclear condition. On the whole, the FCM analysis confirmed most of the RAPD data. The combined evaluation of DNA markers and DNA contents proved to be an efficient screening tool for scoring maternal plants, assessing the genetic origin of aberrant plants, and quantifying the inheritance of parental genomes in Kentucky bluegrass. Hybrid populations from sexual×apomictic matings that segregate for the mode of reproduction represent a valuable basis for attempting to identify molecular markers linked to the apomixis gene(s). Received: 11 November 1996/Accepted: 22 November 1996     

Inheritance of steroid-independent male sexual behavior in male offspring of B6D2F1 mice

The importance of gonadal steroids in modulating male sexual behavior is well established. Individual differences in male sexual behavior, independent of gonadal steroids, are prevalent across a wide range of species, including man. However, the genetic mechanisms underlying steroid-independent male sexual behavior are poorly understood. A high proportion of B6D2F1 hybrid male mice demonstrates steroid-independent male sexual behavior (identified as “maters”), providing a mouse model that opens up avenues of investigation into the mechanisms regulating male sexual behavior in the absence of gonadal hormones. Recent studies have revealed several proteins that play a significant factor in regulating steroid-independent male sexual behavior in B6D2F1 male mice, including amyloid precursor protein (APP), tau, and synaptophysin. The specific goals of our study were to determine whether steroid-independent male sexual behavior was a heritable trait by determining if it was dependent upon the behavioral phenotype of the B6D2F1 sire, and whether the differential expression of APP, tau, and synaptophysin in the medial preoptic area found in the B6D2F1 sires that did and did not mate after gonadectomy was similar to those found in their male offspring. After adult B6D2F1 male mice were bred with C57BL/6J female mice, they and their male offspring (BXB₁) were orchidectomized and identified as either maters or “non-maters”. A significant proportion of the BXB₁ maters was sired only from B6D2F1 maters, indicating that the steroid-independent male sexual behavior behavioral phenotype of the B6D2F1 hybrid males, when crossed with C57BL/6J female mice, is inherited by their male offspring. Additionally, APP, tau, and synaptophysin were elevated in in the medial preoptic area in both the B6D2F1 and BXB₁ maters relative to the B6D2F1 and BXB₁ non-maters, respectively, suggesting a potential genetic mechanism for the inheritance of steroid-independent male sexual behavior.     

Perception of risk of HIV/AIDS and sexual behaviour in Kenya

The association between perception of risk of HIV infection and sexual behaviour remains poorly understood, although perception of risk is considered to be the first stage towards behavioural change from risk-taking to safer behaviour. Using data from the 1998 Kenya Demographic and Health Survey, logistic regression models were fitted to examine the direction and the strength of the association between perceived risk of HIV/AIDS and risky sexual behaviour in the last 12 months before the survey. The findings indicate a strong positive association between perceived risk of HIV/AIDS and risky sexual behaviour for both women and men. Controlling for sociodemographic, sexual exposure and knowledge factors such as age, marital status, education, work status, residence, ethnicity, source of AIDS information, specific knowledge of AIDS, and condom use to avoid AIDS did not change the direction of the association, but altered its strength slightly. Young and unmarried women and men were more likely than older and married ones to report risky sexual behaviour. Ethnicity was significantly associated with risky sexual behaviour, suggesting a need to identify the contextual and social factors that influence behaviour among Kenyan people.     

Effects of density dependent sex allocation on the dynamics of a simultaneous hermaphroditic population: Modelling and analysis

In this work we present a mathematical model describing the dynamics of a population where sex allocation remains flexible throughout adult life and so can be adjusted to current environmental conditions. We consider that the fractions of immature individuals acquiring male and female sexual roles are density dependent through nonlinear functions of a weighted total population size. The main goal of this work is to understand the role of life-history parameters on the stabilization or destabilization of the population dynamics.The model turns out to be a nonlinear discrete model which is analysed by studying the existence of fixed points as well as their stability conditions in terms of model parameters. The existence of more complex asymptotic behaviours of system solutions is shown by means of numerical simulations.Females have larger fertility rate than males. On the other hand, increasing population density favours immature individuals adopting the male role. A positive equilibrium of the system exists whenever fertility and survival rates of one of the sexual roles, if shared by all adults, allow population growing while the opposite happens with the other sexual role. In terms of the female inherent net reproductive number, η_F, it is shown that the positive equilibria are stable when η_F is larger and closed to 1 while for larger values of η_F a certain asymptotic assumption on the investment rate in the female function implies that the population density is permanent. Depending on the other parameters values, the asymptotic behaviour of solutions becomes more complex, even chaotic. In this setting the stabilization/destabilization effects of the abruptness rate in density dependence, of the survival rates and of the competition coefficients are analysed.     

Effects of prostaglandins E1 and F2α on serum luteinizing hormone concentration and on some sexual functions in male rabbits

PGE₁(50μg/animal) and PGF_2α (250 μg/animal) caused a transient in serum LH at 5 min after injection. PGE₁ (250 μg/animal) had a biphasic effect on serum LH. A small peak was obtained at 5 min, and a second, larger peak at 60 min after injection. It is suggested that the first peak is a result of the stress associated with injection of the PGs, whereas the second peak represents a physiological effect of PGE. Subcutaneous injection of PGE₁ (1 mg in arachis oil b.i.d.) for 10 days did not affect the concentration of LH in serum, the function of the accessory sexual glands or the sexual activity. PGF_2α, given at the same dose and in the same manner, increased the sexual activity but left all other variables unaffected. The pituitary responsiveness to LH-RH was unaltered by the treatment with PGE₁ and PGF_2α.     

Corpus allatum function during sexual maturation of male Diploptera punctata

ABSTRACT. The effect of allatectomy on synthesis of accessory reproductive gland secretion, spermatophore production and sexual behaviour in male Diploptera punctata was investigated during the first 6 weeks of adult life. After allatectomy, synthesis of the secretion and production of spermatophores was slightly reduced relative to sham-operated animals (by 16%), but not relative to normal animals. However, sexual behaviour of the operated animals appeared normal. Thus, the corpora allata (CA) may not be necessary for the sexual functioning of male D.punctata. The synthesis of C₁₆ juvenile hormone (C₁₆ JH; JH III) by isolated pairs of CA from individual males was followed during this period and, at all times, the rate of synthesis was less than 8pmolh^-1 per pair, a rate similar to that observed in pregnant females. The significance of this continued synthesis of JH by male CA is unknown, although it may be related to the maintenance of general metabolic activities.     

Limbic-midbrain lesions and ACTH-induced excessive grooming.

The induction of excessive grooming by intraventricular administration of ACTH_1–24 was studied in rats with lesions in midbrain-limbic structures. Such areas have been reported to be implicated in mediating ACTH-induced effects on avoidance behavior, sexual excitement or stretching and yawning. Electrolytic lesions in the septal complex, the anterior hypothalamic/preoptic area, the mammillary bodies, the amygdala, the posterior thalamus and dorsal or ventral hippocampus did not interfere with ACTH-induced excessive grooming. Lesioning of the hippocampal complex by aspiration led to an inhibition of excessive grooming depending on the degree of hippocampal damage. Amygdala and hippocampal lesions enhanced the display of stretching and yawning activity after treatment with the peptide. The data indicate differences in the neural substrates mediating the effect of ACTH on extinction of conditioned avoidance behavior, excessive grooming, sexual excitement and stretching and yawning.     

Maturation of sexual behavior in laboratory male mice: a role of genotype

Sexual behaviour and testosterone output in response to a receptive female were investigated in male mice of three inbred strains BALB/cLac, CBA/Lac and PT at puberty (45 days of age) and in adulthood (90 days of age). The animals were exposed for 10 min to a receptive female separated by a plastic grill, which would not allow contact between male and female. Male and female behaviour was recorded by measuring the time the male or female spent at the grill and the number of approaches to it (sexual motivation). The grill was then removed and the number of mounts and chemoinvestigatory behavior towards a female (nasal and anogenital sniffing) was recorded for each male. An increase in serum concentration and testicular content of testosterone was used as an endocrine index of the sensitivity to female pheromones. It has been shown the significant genotype and developmental effects on sexual behaviour and the hormonal response to sexual stimuli. The pubertal BALB/cLac males were characterised by the adult pattern of sexual motivation, chemoinvestigatory behaviour and the evident testosterone respond to a female. Males of the strain PT showed the lowest sexual motivation, chemoinvestigatory behavior towards a receptive female and no testosterone responses at both ages. This is a very different situation with the CBA/Lac's who showed the developmental increase in the sexual motivation, sniffing behaviour and the endocrine reflex, and the highest level of sexual behaviour but the moderate testosterone respond to a female at adulthood. The data obtained suggest genotype related asynchrony in maturation of the olfactory system, pituitary-gonadal axis and neural circuits of sexual behavior, and their independent genetic control. So, the set of mice strains investigated represents a useful tool for genetic and endocrine study of sexual behavior and the chemosensory control of testicular steroidogenesis.     

Induction of sexual receptivity in ovariectomized female rats by subcutaneous implants of estradiol-17β

Ovariectomized female rats were implanted with estradiol-17β (E₂)-filled Silastic capsules at various times and the display of sexual receptivity in response to progesterone (P) treatment, 42 hr after the initiation of E₂ treatment, was observed. Exposure to E₂ for 24 hr or less was insufficient to prepare the animals to respond to P treatment. Implantation of E₂-filled capsules for 48 hr, however, brought all animals into sexual receptivity. Anti-estrogen treatment, both at the time of implantation of E₂-filled capsules and 24 hr after implantation, partially inhibited the effect of a 48-hr exposure to E₂ on the display of sexual behavior. Continued presence of e₂ may be necessary for display of sexual receptivity by Ovariectomized rats.     

Plasmodium berghei serine/threonine protein phosphatase PP5 plays a critical role in male gamete fertility

Sexual development in malaria parasites involves multiple signal transduction pathways mediated by reversible protein phosphorylation. Here, we functionally characterised a protein phosphatase, Ser/Thr protein phosphatase 5 (PbPP5), during sexual development of the rodent malaria parasite Plasmodium berghei. The recombinant protein phosphatase domain displayed obvious protein phosphatase activity and was sensitive to PP1/PP2A inhibitors including cantharidic acid (IC₅₀ = 122.2 nM), cantharidin (IC₅₀ = 74.3 nM), endothall (IC₅₀ = 365.5 nM) and okadaic acid (IC₅₀ = 1.3 nM). PbPP5 was expressed in both blood stages and ookinetes with more prominent expression during sexual development. PbPP5 was localised in the cytoplasm of the parasite and highly concentrated beneath the parasite plasma membrane in free merozoites and ookinetes. Targeted deletion of the pbpp5 gene had no influence on asexual blood-stage parasite multiplication or the survival curve of the infected hosts. However, male gamete formation and fertility were severely affected, resulting in almost complete blockade of ookinete conversion and oocyst development in the Δpbpp5 lines. This sexual development defect was rescued by crossing Δpbpp5 with the female defective Δpbs47 parasite line, but not with the male defective Δpbs48/45 line, thus confirming the essential function of the pbpp5 gene in male gamete fertility. Furthermore, the aforementioned PP1/PP2A inhibitors all had inhibitory effects on exflagellation of male gametocytes and ookinete conversion. In particular, endothall, a selective inhibitor of PP2A, completely blocked exflagellation and ookinete conversion at ～548.3 nM. This study elucidated an essential function of PbPP5 during male gamete development and fertility.     

Environmental constraints on the growth,photosynthesis and reproductive development of Dryas octopetala at a high Arctic polar semi-desert,Svalbard

Opportunities exist in high Arctic polar semidesert communities for colonisation of unvegetated ground by long-lived clonal plants such as Dryas octopetala. This can be achieved by lateral spread of vegetative ramets, or by sexual reproduction and seedling recruitment. The objectives of this study were (1) to determine whether these two means of proliferation show differential sensitivity to contrasting components of the abiotic environment (temperature, soil nutrient and water availability) and (2) to evaluate the potential for D. octopetala to respond to climate change by an increase in cover and biomass in polar semi-desert communities. Factorial environmental manipulations of growing season temperature, soil nutrient and water status were conducted over 3 years at a polar semi-desert community in Svalbard, Norway (78°56.12N, 11°50.4E) and both clonal and sexual reproductive performance, together with instantaneous net photosynthesis (P_n), were recorded during the third season (1993). D. octopetala capitalised rapidly on an amelioration in the availability of inorganic nutrients (N, P and K) by an expansion in leaf area and biomass supported by increased P_n per unit leaf weight, and by apparent luxury uptake of nutrients (particularly P). Several facets of sexual reproductive development and seed viability were markedly improved by elevated temperatures or soil nutrient availability. Thus although D. octopetala is a long-lived clonal plant, with many traits characteristic of stress resistance syndrome, it showed considerable phenotypic plasticity in response to environmental manipulations. The results support the hypothesis that clonal growth confers survival potential during unfavourable years, together with the ability to capitalise on nutrient flushes and recycle nutrients internally. Continued investment in sexual reproduction ensures that seed setting is successful during favourable years, even if these occur infrequently. Cimate warming in the high Arctic could thus result in changes in the cover, biomass and the relative significance of clonal versus sexual proliferation of D. octopetala (and thus the genetic diversity of the population) but the long-term responses will probably be constrained by lack of available nutrients.