517 research outputs found
Toward a new generation of effective problem solvers and project-oriented applied ecologists
Abstract. In an era of environmental crises, conservation and management strategies
need a new generation of applied ecologists. Here, we stimulate the
next-generation applied ecologists to acquire a pragmatic mentality of
problems solvers in real contexts, using the wide arsenal of concepts,
approaches and techniques available in the project management (PM) arena using a
road map based on the main steps of conservation project cycle. The
acquisition of the conceptual and operational framework of PM can allow the
next-generation applied ecologists to take on a more important role in
nature conservation strategies: from data samplers, analyzers and
interpreters to suppliers of solutions and decisions driving changes in
species' targets inhabiting real contexts. Since the high number of applied
ecologists, this change in approach (from analytical to operational) could
make the difference in conservation science. We also provided, as a
conceptual framework, a set of suggestions and approaches useful to
facilitate this change
Better in the dark: two Mediterranean amphibians synchronize reproduction with moonlit nights
In Amphibians, both positive and negative correlations between activity and
full moon phase have been observed. In this study, we present data for two
anuran species (<i>Hyla intermedia</i> and <i>Rana dalmatina</i>)
studied in a hilly Mediterranean area of central
Italy. We analysed, in a two-year survey, the relationships between the
number of egg clutches laid each night and the moon phases by means of
circular statistics. Moreover, the studied species exhibited clear
oviposition site selection behaviour influenced, at least in <i>H. intermedia</i>, by moon
phases. We observed the occurrence of an avoidance effect by amphibians for
oviposition and specific egg-laying behaviour during moon phases around the
full moon. This apparent lunar phobia was evident in both species when
yearly data were pooled. On the other hand, while this pattern continued to
be also evident in <i>H. intermedia</i> when single years were considered,
in <i>R. dalmatina</i> it stood just in
one year of study. Nonetheless, during cloudy nights, when moonlight
arriving on the ground was low, the frogs' behaviour was similar to that
observed in new moon phases. We interpreted the observed pattern as an
anti-predatory strategy. Overall, comparisons between our own study and
previous research suggest that there was insufficient evidence to establish
any unequivocal patterns and that further research in this regard is needed
The ecological distribution of monitor lizards (Reptilia, Varanidaej in Nigeria
The ecological distribulion of three varanid lizards (Varanus exanthematicus, K niloticus niloticus, and V. niloticus ornatusj in Nigeria is studied in the present paper, from both literature records and long-term field ecological research. V. exanthematicus is present only in central and northern Nigeria, where it seerns to be widespread and locally cornrnon in the Guinea savanna vegetation zone, but rnay be found in several spots in the Sudan savanna and even in the Sahel savanna. V. n. ornatus is confined to the extreme south of the country, ¡.e. in the coastal mangrove and deltaic swamp rainforest habita%, and also in the moist lowland rainforest. The distribution of V. n. niloticus remains controversial. It is widespread in the Sudan savanna and in the Guinea savanna, but appears only rarely in the derived savanna and rnoist lowland forest vegetation zones. Despite a few old literature records, it seerns to be absent frorn the rainforest blocks of southern Nigeria. Annual precipitation regimes seem to condition greatly the general distribution patterns of the Nigerian varanids, which are quite generalist in terms of habitat preferences within each rnajor climatic-vegetation zone.
Key words: Varanidae, Distribution, Ecology, Nigeria.The ecological distribulion of three varanid lizards (Varanus exanthematicus, K niloticus niloticus, and V. niloticus ornatusj in Nigeria is studied in the present paper, from both literature records and long-term field ecological research. V. exanthematicus is present only in central and northern Nigeria, where it seerns to be widespread and locally cornrnon in the Guinea savanna vegetation zone, but rnay be found in several spots in the Sudan savanna and even in the Sahel savanna. V. n. ornatus is confined to the extreme south of the country, ¡.e. in the coastal mangrove and deltaic swamp rainforest habita%, and also in the moist lowland rainforest. The distribution of V. n. niloticus remains controversial. It is widespread in the Sudan savanna and in the Guinea savanna, but appears only rarely in the derived savanna and rnoist lowland forest vegetation zones. Despite a few old literature records, it seerns to be absent frorn the rainforest blocks of southern Nigeria. Annual precipitation regimes seem to condition greatly the general distribution patterns of the Nigerian varanids, which are quite generalist in terms of habitat preferences within each rnajor climatic-vegetation zone.
Key words: Varanidae, Distribution, Ecology, Nigeria.The ecological distribulion of three varanid lizards (Varanus exanthematicus, K niloticus niloticus, and V. niloticus ornatusj in Nigeria is studied in the present paper, from both literature records and long-term field ecological research. V. exanthematicus is present only in central and northern Nigeria, where it seerns to be widespread and locally cornrnon in the Guinea savanna vegetation zone, but rnay be found in several spots in the Sudan savanna and even in the Sahel savanna. V. n. ornatus is confined to the extreme south of the country, ¡.e. in the coastal mangrove and deltaic swamp rainforest habita%, and also in the moist lowland rainforest. The distribution of V. n. niloticus remains controversial. It is widespread in the Sudan savanna and in the Guinea savanna, but appears only rarely in the derived savanna and rnoist lowland forest vegetation zones. Despite a few old literature records, it seerns to be absent frorn the rainforest blocks of southern Nigeria. Annual precipitation regimes seem to condition greatly the general distribution patterns of the Nigerian varanids, which are quite generalist in terms of habitat preferences within each rnajor climatic-vegetation zone.
Key words: Varanidae, Distribution, Ecology, Nigeria
“Heaven” of Data Deficient Species: The Conservation Status of the Endemic Amphibian Fauna of Vietnam
Predicting the true status of Data Deficient (DD) species is a prominent theme in recent conservation biology, but there still is much debate regarding the conservation approach that should be used for DD taxa and no definitive conclusions are yet available. We review and analyse the current data available on the conservation status of amphibians in Vietnam, with an emphasis on the DD species. We also compare Vietnamese DD frequency of occurrence with other regions of the world, examine the extent of the range of taxa divided by Red List status, and explore the protection attributes of the taxa based on their inclusion within protected areas of Vietnam. We documented that the analysis of amphibians in Southeast Asia, and especially in Vietnam, substantially agrees with patterns highlighted by previous global research, and confirms the risk that several DD species may silently go extinct without their actual risk ever being recognized. Importantly, our study showed that fine-scale analyses are essential to highlight the potential drivers of extinction risk for the DD species of amphibians. A crucial next step for conservation policies in Vietnam (and in surrounding countries) is developing and implementing species-specific studies targeted at addressing each species’ drivers of extinction and determining science-based strategies for minimizing their extinction risk
Body size, sexual size dimorphism and reproduction in different colour morphs in a population of Western Whip snakes, Coluber viridiflavus
Plusieurs des principales hypothèses sur le rôle écologique du mélanisme dans les populations de serpents sont testées et discutées dans une étude d'une population de la Couleuvre verte et jaune (Coluber viridiflavus) dans le
centre des Apennins (vallée de Sagittario, Abruzze, Italie centrale). Dans cette population, les adultes sont soit de coloration normale verte et jaune, soit mélaniques. La morphe mélanique semblerait plus commune chez les femelles que chez les mâles mais la différence n'est pas
statistiquement significative. Les individus mélaniques, tant mâles que femelles, atteignent une taille supérieure à celles des individus de coloration normale et leur condition physique, en termes de poids, s'avère meilleure. Ces résultats morphométriques confirment des observations
antérieures sur d'autres serpents, p. ex. Vipera berus. En raison de leur plus grande taille, les femelles noires sembleraient produire un peu plus d'oeufs que les vertes et jaunes (x = 7,6 + 1,52 contre 6,6 + 1,72 oeufs par femelle et par an, toutefois différence non significative mais
petit échantillon). De plus, une plus forte proportion (83,3 contre 56,2 %) de femelles noires étaient gravides en juin, suggérant que les individus mélaniques se reproduiraient plus souvent que les individus de coloration normale. Dans l'ensemble, les résultats de cette étude de C.
viridiflavus corroborent les hypothèses générales sur le rôle écologique du mélanisme
Broad geographic, taxonomic and ecological patterns of interpopulation variation in the dietary habits of snakes
Because of their unique morphological and ecological characteristics (i.e. being obligate carnivorous, solitary, and ingesting their prey whole), snakes are expected to show unusual dietary patterns compared to other ectothermic vertebrates, and the best way to explore this is to analyse the snake dietary patterns globally. Here I review and analyse the peer-reviewed snake diet literature available in order to explore whether there are broad patterns in the interpopulation variability of diet composition in these unique ectothermic predators. I collated data for 181 independent populations belonging to 58 species of snakes from some of the main families (1 Boidae, 2 Pythonidae, 27 Colubridae, 10 Elapidae, and 18 Viperidae) and from all the continents (4 from South and Central America, 13 from North America, 12 from Europe, 18 from Africa, 4 from Asia, and 7 from Australia). All these populations satisfied some precise criteria of inclusion, and were therefore re-analysed in a comparative perspective. I classified each literature entry according to 1) snake species, 2) snake family, 3) geographic position (continent) of the study areas, 4) climatic region (temperate versus tropical), 5) guild (if the species is aquatic, terrestrial, or arboreal), 6) hunting strategy (sit-and-wait versus active forager), and 7) venom (if the species is venomous or not). All these seven factors were analysed by GLM procedures to evaluate their effects on the interpopulation diet variation within snake species, that was assessed by using a univariate similarity index. The various taxonomical categories of snake prey were grouped according to two different levels of taxonomic affinity: a) general affinity, e.g. frogs and toads, salamanders, lizards, birds, etc., and b) close affinity, by grouping prey types belonging to a same genus. My study revealed that, within-species snake populations showed a very low variability in terms of diet composition. As for the general affinity criterion, there was no single factor that produced a significant effect on the interpopulation diet variation but, with regard to the interaction terms between factors, significant effects were determined by 1) continent &times; climatic region (with Asian, African and South-American tropical populations having significantly lesser similarity values), 2) continent &times; hunting strategy (diets being less diverse in ambush predators in Africa, Asia and South America), and 3) climatic region &times; guild (with arboreal tropical snakes showing less interpopulation similarity). As for the close affinity criterion, there was also no effect of single factors on interpopulation diet variability, but the interaction term hunting strategy &times; venom was significant, with sit-and-wait venomous species being less variable in their diet composition. Snake family was completely un-influent in determining any effect on snake interpopulation diet variation. The broad reasons that may explain these generalized patterns are discussed
The ecological role of color polymorphism in male adders, Vipera berus: testing the hypotheses
Le succès reproducteur des mâles adultes de Vipère péliade Vipera berus serait, selon une hypothèse très à la mode, plus élevé que celui des mâles à coloration cryptique, du fait des meilleures conditions de température dont
bénéficient les individus mélaniques qui leur permettraient une croissance plus rapide et un poids adulte supérieur à celui des vipères normales. Cette croissance accélérée et ce poids plus élevé seraient d'une grande importance lors des combats ritualisés que se livrent les mâles à l'époque
de la reproduction, les mâles les plus grands et les plus lourds l'emportant généralement lors de ces combat
Estrategia vital y distribución ecológica de camaleones (Reptilia, Chamaeleonidae) de los bosques húmedos de Nígeria: implicaciones en la conservación
Five species of chameleons were observed in the continuous forest zone of southern Nigeria: Chamaeleo gracilis gracilis Hallowell, 1842, Chamaeleo owenii Gray, 1831, Chamaeleo cristatus Stutchbury, 1837, Chamaeleo wiedersheimi Nieden, 1910, and Rhampholeon spectrum (Bucholz 1874). Many original locality records are presented for each species. One species is apparently rare and confined to montane habitats (C. wiedersheimi), another species is relatively common and its habitat is generalist (C. gracilis), and the other three species are vulnerable and limited to specific micro–habitats. Female R. spectrum had clutch sizes of two eggs each and exhibited a prolonged reproductive season with oviposition likely occurring during the late phase of the dry season. Females of both C. cristatus (clutch sizes: 11–14 eggs) and C. owenii (clutch sizes: 15–19 eggs) have a shorter reproductive season with oviposition occurring most probably at the interphase between the end of the wet season and the onset of the dry season, and female C. gracilis (clutch sizes: 14–23 eggs) appeared to exhibit two distinct oviposition periods (one at the interphase between the end of the wet season and the onset of the dry season, and one at the peak phase of the dry season). Diets of four sympatric species of chameleons consisted almost exclusively of arthropods. There were significant inter–group differences at either intra–specific level (with the females of the two best studied species, i.e. R. spectrum and C. gracilis, having a wider food niche breadth than males) or inter–specific level (with a continuum of dietary specialization from the less generalist (C. cristatus) to the more generalist (C. gracilis). However, “thread–trailing” experiments indicated that activity patterns of Nigerian chameleons were relatively similar among species. The overall abundance of chameleons (as estimated from the number of specimens observed in the time unit of field effort) was relatively similar in three contrasted habitat types, but lizards were more abundant in the mature secondary forest. When greatly altered by massive logging activity, the overall abundance of chameleons in the mature secondary forest habitat declined only slightly, whereas the species diversity declined drastically. This was an effect of (i) the simultaneous extinction of three of the four species originally present in the forest plot, and of (ii) the rapid increase in abundance of a single species (C. gracilis) as a response to habitat alteration. The conservation implications of all these data are also discussed.Se observaron cinco especies de camaleones en la zona de bosque ininterrumpido del sur de Nigeria: Chamaeleo gracilis gracilis Hallowell, 1842, Chamaeleo owenii Gray, 1831, Chamaeleo cristatus Stutchbury, 1837, Chamaeleo wiedersheimi Nieden, 1910 y Rhampholeon spectrum (Bucholz 1874). Se presentan muchos registros de localidad originales para todas las especies. Una especie es aparentemente rara y está confinada a los hábitats montañosos (C. wiedersheimi), otra especie es relativamente común y generalista en cuanto al hábitat (C. gracilis), y las otras tres especies son vulnerables y están limitadas a microhábitats específicos. El tamaño de cada puesta de la hembra de R. spectrum fue de dos huevos, mostrando una prolongada estación reproductora con oviposición durante la última fase de la estación húmeda. Las hembras de C. cristatus (tamaño de puesta: 11–14 huevos) y C. owenii (tamaño de puesta: 15–19 huevos) tienen una estación reproductora más corta y la oviposición se da con mayor probabilidad en la interfase entre el final de la estación húmeda y el inicio de la estación seca, y la hembra de C. gracilis (tamaño de puesta: 14–23 huevos) presenta dos periodos distintos de oviposición (uno en la interfase entre el final de la estación húmeda y el inicio de la estación seca y el otro durante el período más seco de la estación seca). Las dietas de cuatro especies simpátricas de camaleones consistían prácticamente de forma exclusiva en artrópodos. Había diferencias significativas dentro del grupo tanto a nivel intraespecífico (con las hembras de las dos especies mejor estudiadas, es decir R. spectrum y C. gracilis, con un extenso nicho alimentario más amplio que los machos) o interespecíficas (con una continua especialización alimentaria desde los menos generalistas (C. cristatus) a los más generalistas (C. gracilis). Sin embargo los experimentos “thread–trailing” indican que los patrones de actividad de los camaleones de Nigeria eran relativamente similares entre especies. La abundancia de camaleones (estimada a partir de el número de especímenes observado en la unidad de tiempo de esfuerzo de campo) era relativamente similar en tres tipos de hábitats contrastados, pero el bosque secundario maduro fue el hábitat donde los lagartos fueron más abundantes. En cuanto al hábitat del bosque secundario, cuando estaba fuertemente alterado por una fuerte explotación forestal, la abundancia de camaleones disminuía sólo ligeramente, mientras que la diversidad de especies disminuía de forma drástica. Esto era debido a: (i) la extinción simultánea de tres de las cuatro especies originalmente presentadas en el bosque, y (ii) el rápido incremento en abundancia de una única especie (C. gracilis) como respuesta a una alteración del hábitat. Se discuten las implicaciones de estos datos sobre la conservación
Assessing environmental requirements effects on forest fragmentation sensitivity in two arboreal rodents
The study of the effect of habitat fragmentation on species that inhabit residual patches requires the investigation of the relationship existing between species distribution and landscape components. To understand which components of landscape mosaics are more influential for species’ persistence, we compared the distribution of two arboreal rodents proved to be sensitive to habitat fragmentation, the
hazel dormouse Muscardinus avellanarius and the red squirrel Sciurus vulgaris. Their occurrence in residual oak woods in central Italy was studied with nest-boxes and hair-tubes, developing a new method for hair analysis. Their distributions were analysed considering patch, matrix composition and configuration, and landscape vegetation variables. The two species showed a different degree of plasticity, with the squirrel being significantly more specialised at the landscape scale. The comparison of the two distribution patterns highlighted the influence of different ecological constraints and the existence of different strategies to cope with fragmentation. Patch size and patch attributes were generally weaker determinants of occurrence, compared to landscape metrics. The squirrel presence was significantly influenced by the presence of shared perimeter between hedgerows and woods and by the lack of isolation of the
residual patches, suggesting the use of several fragments to compensate the low habitat quality. Conversely the hazel dormouse seemed to be more affected by the internal management of the woods, and in particular by the mean DBH. Our results highlight how the recognition of the extrinsic constraints and the influence of multi-scale habitat selection may help guiding land use management, to ensure species conservation in profoundly exploited landscapes
Helminth community structure and diet of three Afrotropical anuran species: a test of the interactive-versus-isolationist parasite communities hypothesis
The interactive-versus-isolationist hypothesis predicts that parasite communities should be depauperated and weakly structured by interspecific competition in amphibians. A parasitological survey was carried out to test this hypothesis using three anuran species from Nigeria, tropical Africa (one Bufonidae; two Ranidae). High values of parasite infection parameters were found in all three species, which were infected by nematodes, cestodes and trematodes. Nonetheless, the parasite communities of the three anurans were very depauperated in terms of number of species (4 to 6). Interspecific competition was irrelevant in all species, as revealed by null models and Monte Carlo permutations. Cluster analyses revealed that, in terms of parasite community composition, the two Ranidae were similar, whereas the Bufonidae was more different. However, when prevalence, intensity, and abundance of parasites are combined into a multivariate analysis, each anuran species was clearly spaced apart from the others, thus revealing considerable species-specific differences in terms of their parasite communities. All anurans were generalists and probably opportunistic in terms of dietary habits, and showed no evidence of interspecific competition for food. Overall, our data are widely consistent with expectations driven from the interactive-versus-isolationist parasite communities hypothesis
- …