Models of poisoning effects on vulture populations show that small but frequent episodes have a larger effect than large but rare ones

Vultures are among the most threatened avian taxa in the world. When vultures aggregate in large numbers to feed, poisoned carcasses can extirpate entire populations at once. In the light of shrinking numbers worldwide, restocking and reintroduction projects, where wild or captive-bred vultures are released back into nature, constitute a crucial management tool, successfully implemented in many countries. However, reestablishment of sustainable vulture populations to their historical ranges remains a serious challenge, especially if the threat of poisoning persists, which is usually the case. In this study, we model the outcome of a restocking project where an initial colony is subject to repeated poisoning events. We use as an example the isolated population of the griffon vulture (Gyps fulvus) in Cyprus. Mathematical considerations and model simulations show that the probability of colony persistence depends on the initial population size and the intensity and frequency of the poisoning incidents. This type of scenario creates an Allee effect that requires a colony to exceed a minimum size in order to survive. Also in this scenario, a sequence of small but frequent poisoning episodes is worse on average than a few large and rare ones of the same cumulative mortality. Future population reinforcement efforts for vultures should focus on the release of adult birds in adequate numbers for the successful establishment of sustainable colonies and should involve a reduction in small but persistent sources of mortality such as the poison baiting of small canids that until now has been neglected by conservation scientists.

Are All Conservation Measures for Endangered Species Legitimate? Lines of Thinking With the European Hamster

When dealing with the protection of an endangered species, it appears more and more important to address the ethical limits and the societal perception of the implemented conservation measures. This will be illustrated here through the example of conservation programs of the European hamster (Cricetus cricetus) in France. The main threats for this critically endangered rodent are the impoverishment and fragmentation of its habitat due to recent changes in agricultural practices and urbanization. Thus, the status of this species changed from harmful to endangered in only a few decades. This must lead to acceptance of the species by citizens and especially farmers paid to destroy this species until the 1990s while nowadays to protect it. To stem the decline, several measures have been taken through the last 20 years including population reinforcement, wild animal tracking, and implementation of suitable habitats. One can, therefore, discuss the efficiency of these measures and their integration in the entire socio-ecosystem. Population reinforcement and the questions that can arise from it will first be addressed. Secondly, in situ animal monitoring and implications of the methods used will be discussed. Third, we will deal with agricultural practices favorable to the species. Finally, we will highlight the links between European hamster conservation measures and wider problematics.

Micropropagation of Ruscus aculeatus L.

Ruscus aculeatus L. is a small evergreen perennial species, is commonly used either as medicinal or ornamental plant thanks to its evegreen long-lasting branches. Currently, the species is endangered by population redutions due to habitat alteration, the lack of seed production caused by pollination failure and also because of the intense harvesting for medicical uses or for floral bouquets. Micropropagation opens new directions for its ex situ conservation, as well as to generate large scale material for natural population reinforcement or for commercial purposes. In this study, effects of BA, NAA and coconut water on shoot regeneration, IBA on root formation of Ruscus aculeatus L., and type of substrates on acclimatization and growth of seedlings were investigated. The results showed that ½MS medium supplemented with 4 mg/l BA, 0.5 mg/l NAA and 15% (v/v) coconut water, 30 g/l sucrose, and pH 5.8 was the most suitable for shoot regeneration of Ruscus aculeatus L. in vitro (20.2 shoots, shoot length of 6.0 cm). Root formation of Ruscus aculeatus L. was optimal on ½MS supplemented with 1.5 mg/l IBA, 30 g/l sucrose, and pH 5.8 (frequency of rooting 100%, shoot length of 1.9 cm with 16.66 roots per seedling). Finally, the sufficiently rooted plantlets were transferred to greenhouse for hardening. After 2 months, coconut fiber substrate was the most suitable for seedling growth and development (with survival rate of 85%, root number of 8.7 and shoot length of 7.6 cm). We have developed protocol for the rapid micropropagation of Ruscus aculeatus L. in order to create a large number of seedlings for commercial production.

CODE-SPECIFIC LEARNING RULES IMPROVE ACTION SELECTION BY POPULATIONS OF SPIKING NEURONS

Population coding is widely regarded as a key mechanism for achieving reliable behavioral decisions. We previously introduced reinforcement learning for population-based decision making by spiking neurons. Here we generalize population reinforcement learning to spike-based plasticity rules that take account of the postsynaptic neural code. We consider spike/no-spike, spike count and spike latency codes. The multi-valued and continuous-valued features in the postsynaptic code allow for a generalization of binary decision making to multi-valued decision making and continuous-valued action selection. We show that code-specific learning rules speed up learning both for the discrete classification and the continuous regression tasks. The suggested learning rules also speed up with increasing population size as opposed to standard reinforcement learning rules. Continuous action selection is further shown to explain realistic learning speeds in the Morris water maze. Finally, we introduce the concept of action perturbation as opposed to the classical weight- or node-perturbation as an exploration mechanism underlying reinforcement learning. Exploration in the action space greatly increases the speed of learning as compared to exploration in the neuron or weight space.

Seed germination ecology of the endemic Iberian winter annualsIberis pectinataandZiziphora aragonensis

The germination ecology of the winter annual Iberian endemicsIberis pectinataandZiziphora aragonensiswas investigated in order to better understand adaptations of rare species to their natural habitat and to improveex-situpropagation techniques and management of their habitat. Specifically, we analysed the following aspects: (1) influence of temperature, light conditions and seed age on germination patterns; (2) phenology of germination; (3) germinative response of buried seeds to seasonal temperature changes; and (4) temperature requirements for induction and breaking of secondary dormancy. Germination was substantially lower in darkness than with a photoperiod in both taxa, with this difference being more pronounced inZ. aragonensis. Freshly matured seeds showed conditional physiological dormancy, germinating at low and medium temperatures but not at high temperatures (28/14 and 32/18°C). Germination capability increased with time of dry storage in both species, suggesting the existence of non-deep physiological dormancy. Under greenhouse conditions, germination of both taxa was mostly concentrated in autumn (October–November), while spring percentages were less than 1% of total accumulated germination recorded during the study.I. pectinataandZ. aragonensisseeds buried and exposed to natural seasonal temperature variations in an unheated greenhouse came out of conditional dormancy in summer and re-entered it in winter, thus exhibiting an annual conditional dormancy/non-dormancy cycle. Dormant seeds of both species which were stratified at 28/14 or 32/18°C during an 8-week period, were non-dormant when they were subsequently incubated over a range of temperatures from 5 to 25/10°C. Non-dormant seeds were induced into dormancy when stratified at 5 or 15/4°C for 8 weeks, showing a particularly low germination response at high temperatures. Recommendations for wild-population reinforcement programmes and for the management of the natural habitat of both endemics are discussed.