摘要: Pheromones are communication chemicals and regulatory signals used by animals and represent unique tools for organisms to mediate behaviors and make decisions to maximize their fitness. Phenotypic plasticity refers to the innate capacity of a species to tolerate a greater breadth of environmental conditions across which it adapts to improve its survival, reproduction, and fitness. The pinewood nematode, Bursaphelenchus xylophilus, an invasive nematode species, was accidentally introduced from North America into Japan, China, and Europe; however, few studies have investigated its pheromones and phenotypic plasticity as a natural model. Here, we demonstrated a novel phenomenon, in which nematodes under the condition of pheromone presence triggered increased reproduction in invasive strains (JP1, JP2, CN1, CN2, EU1, and EU2), while it simultaneously decreased reproduction in native strains (US1 and US2). The bidirectional effect on fecundity, mediated by presence/absence of pheromones, is henceforth termed pheromone-regulative reproductive plasticity (PRRP). We further found that synthetic ascaroside asc-C5 (ascr#9), the major pheromone component, plays a leading role in PRRP and identified 2 candidate receptor genes, Bxydaf-38 and Bxysrd-10, involved in perceiving asc-C5. These results suggest that plasticity of reproductive responses to pheromones in pinewood nematode may increase its fitness in novel environments following introduction. This opens up a new perspective for invasion biology and presents a novel strategy of invasion, suggesting that pheromones, in addition to their traditional roles in chemical signaling, can influence the reproductive phenotype among native and invasive isolates. In addition, this novel mechanism could broadly explain, through comparative studies of native and invasive populations of animals, a potential underlying factor behind of the success of other biological invasions.

摘要: Many species are shifting towards higher altitudes in response to global warming, but how these upslope-shifting species will respond to hypoxic environments at high altitudes remains unclear. Hypoxia can be especially challenging for viviparous reproduction because of the limitation of oxygen supply to the female and her developing embryos. To investigate the effect of hypoxia on viviparous females and their offspring we acclimated pregnant females of a high-altitude dwelling viviparous lizard (Phr ynocephalus vlangalii) to local oxygen and hypoxia conditions, respectively. We then recorded maternal body temperatures, postpartum body condition, as well as offspring morphology and locomotor performance. We found that pregnant females had higher body temperatures and advanced their parturition under hypoxic acclimation. However, maternal body condition, offspring morphology and locomotor performance were unaffected by the hypoxic conditions during gestation. Our study suggests that upslope-shifting viviparous lizards respond to hypoxic environments by plastically adjusting their body temperatures to reduce parturition time, without short-term costs to offspring traits.

摘要: Nonlinear phenomena are commonly shown in the vocalization of animals and exerts different adaptive functions. Although some studies have pointed out that nonlinear phenomena can enhance the individual identification of male Odorrana tormota, whether the nonlinear phenomena play a specific role in the sexual selection of O. tormota remain unclear. Here we presented evidence that there was a significant negative correlation (Pearson: n = 30, r = 0.65, P < 0.001) between the nonlinear phenomena content and snout-vent length in the male O. tormota, and two-choice amplexus experiments showed that female O. tormota preferred male with smaller body size containing higher nonlinear phenomena content in its calls. Phonotaxis experiments also revealed that females preferred calls with higher nonlinear phenomena content. Additionally, compared to the calls with lower nonlinear phenomena content and higher fundamental frequency, there was shorter response time in phonotactic behaviour of female induced by the calls with higher nonlinear phenomena content and lower fundamental frequency. We argue that the nonlinear phenomena content in the calls of male O. tormota can convey its body size information and may provide important clues for female frogs in darkened surroundings to identify males' body size during mate choice, meanwhile, higher nonlinear phenomena content in males' calls may increase the attractiveness of males to females. The results of this study provide confirmation that, for O. tormota, nonlinear phenomena have specific function in mate choice.