Search results for "Study"
showing 10 items of 15483 documents
Pactola kuschelisp. nov. (Coleoptera: Curculionidae), a potential cause for the decline of the threatened New Caledonian conifer,Agathis montanade La…
2016
Agathis montana is a conifer endemic to New Caledonia and one of the most threatened (Critically Endangered) plant species of this area. The exact causes of its decline are still unknown. The authors describe the characteristics of A. montana, the history and methodology of population monitoring, and possible factors causing the decline and habitat degradation. In 2014, some twigs showing symptoms suggesting attack by wood-boring insects were collected. From these, imagines of an unknown weevil species belonging to the genus Pactola Pascoe (Eugnomini) were reared. The new species is described as Pactola kuscheli Mazur sp. nov. Colour photographs of the dorsal habitus, line drawings of taxon…
Lesser kestrel diet and agricultural intensification in the Mediterranean: An unexpected win-win solution?
2018
Abstract Farmland bird species have suffered dramatic declines in recent decades, especially in Mediterranean areas. The intensification of agricultural practices has led to reduced invertebrate prey, which represent the bulk of the diet of many farmland birds. In this study, we investigated the spatial and temporal variation in the diet of the lesser kestrel (Falco naumanni) during the breeding season, monitored over a five-year period between 2006 and 2013 in the Gela Plain (Sicily). Our aim was to understand whether, and to what extent, farming practices affected the reproductive outputs of this predominantly insectivore bird in order to find a profitable compromise between conservation …
Host range testing of Tamarixia dryi (Hymenoptera: Eulophidae) sourced from South Africa for classical biological control of Trioza erytreae (Hemipte…
2019
Abstract The African citrus psyllid, Trioza erytreae, vectors citrus greening or huanglongbing (HLB) disease. The psyllid has been reported from mainland Europe, where it is rapidly spreading from the northwest to the southwest of the Iberian Peninsula. In order to reduce its spread and population levels, a classical biological control program with the parasitoid Tamarixia dryi is under development in Spain. We evaluated the host specificity of T. dryi using 11 non-target psyllid (NTP) species, including five species of the genus Trioza. The psyllids were selected based on phylogenetic and ecological criteria. Tamarixia dryi exhibited a high host specificity. Females did not parasitize any …
Pulsed-resource dynamics increase the asymmetry of antagonistic coevolution between a predatory protist and a prey bacterium
2011
Temporal resource fluctuations could affect the strength of antagonistic coevolution through population dynamics and costs of adaptation. We studied this by coevolving the prey bacterium Serratia marcescens with the predatory protozoa Tetrahymena thermophila in constant and pulsed-resource environments for approximately 1300 prey generations. Consistent with arms race theory, the prey evolved to be more defended, whereas the predator evolved to be more efficient in consuming the bacteria. Coevolutionary adaptations were costly in terms of reduced prey growth in resource-limited conditions and less efficient predator growth on nonliving resource medium. However, no differences in mean coevol…
Adapted conservation measures are required to save the Iberian lynx in a changing climate
2013
The Iberian lynx ( Lynx pardinus ) has suffered severe population declines in the twentieth century and is now on the brink of extinction 1 . Climate change could further threaten the survival of the species 2 , but its forecast effects are being neglected in recovery plans 3,4 . Quantitative estimates of extinction risk under climate change have so far mostly relied on inferences from correlative projections of species’ habitat shifts 5 . Here we use ecological niche models coupled to metapopulation simulations with source–sink dynamics 6,7 to directly investi- gate the combined effects of climate change, prey availabil- ity and management intervention on the persistence of the Iberian lyn…
The influence of temperature model assumptions on the prognosis accuracy of extinction risk
2000
Abstract For a species whose abundance is well-known to correlate on the degree of heat different temperature model assumptions may affect the prognosis accuracy of persistence. Likewise, year-to-year autocorrelations in weather fluctuations are known to decrease extinction risk. Thus, we investigated the grey bush cricket Platycleis albopunctata . For this species is known that growth and reproduction is mainly influenced by temperature. We developed a stochastic individual based model for the bush cricket. This day–degree model described the demographic growth of the species that depends on temperature. Daily temperatures were generated by five different methods: (i) temperatures were seq…
Population variability in space and time.
2000
One of the most ubiquitous phenomena of all natural populations is their variability in numbers in space and time. However, there are notable differences among populations in the way the population size fluctuates. One of the major challenges in population and community ecology is to explain and understand this variety and to find possible underlying rules that might be modified from case-to-case. Population variability also has a spatial component because fluctuations are often synchronized over relatively large distances. Recently, this has led to growing interest in how 'internal' (density-dependent) processes interact with 'external' factors such as environmental variability.
The ecology of sexual conflict: Temperature variation in the social environment can drastically modulate male harm to females
2019
Sexual conflict is a fundamental driver of male/female adaptations, an engine of biodiversity and a crucial determinant of population viability. Sexual conflict frequently leads to behavioural adaptations that allow males to displace their rivals, but in doing so harm those same females they are competing to access, which can decrease population viability and facilitate extinction. We are far from understanding what factors modulate the intensity of sexual conflict and particularly the role of ecology in mediating underlying behavioural adaptations. In this study, we show that, in Drosophila melanogaster, variations in environmental temperature of ±4°C decrease male harm impact on female fi…
Punishment of polygyny
1999
We investigated the evolution of monogamy (one male, one female) and polygyny (one male, more than one female). In particular, we studied whether it is possible for a mutant polygynous mating strategy to invade a resident population of monogamous breeders and, alternatively, whether a mutant monogamy can invade resident polygyny. Our population obeys discrete-time Ricker dynamics. The role of males and females in the breeding system is incorporated via the harmonic birth function. The results of the invasability analysis are straightforward. Polygyny is an evolutionarily stable strategy mating system; this holds throughout the examined range of numbers of offspring produced per female. So t…
Genetic analysis of populations of brown trout (Salmo truttaL.) from the Romanian Carpathians
2019
The Carpathian Mountains are one of the most complex orogenetic areas of Europe, with unique fauna, including the brown trout (Salmo trutta). In this study we performed population genetic analysis of 12 differentS. truttapopulations using two types of molecular markers: nine microsatellites and mitochondrial D-loop sequences. The following working hypothesis was considered: the Romanian Carpathians and their surrounding lowlands can be key relief units based on which theS. truttagenetic diversity, spread, distribution, connectivity, relative isolation and genetic divergence can be at least partially explained. The phylogenetic analysis revealed that the majority of sequences were grouped in…