Search results for "ecological relations"
showing 7 items of 7 documents
2016
By altering or eliminating delicate ecological relationships, non-indigenous species are con- sidered a major threat to biodiversity, as well as a driver of environmental change. Global cli- mate change affects ecosystems and ecological communities, leading to changes in the phenology, geographic ranges, or population abundance of several species. Thus, predicting the impacts of global climate change on the current and future distribution of invasive species is an important subject in macroecological studies. The African clawed frog (Xenopus laevis), native to South Africa, possesses a strong invasion potential and populations have become established in numerous countries across four contin…
The irreducible uncertainty of the demography–environment interaction in ecology
2002
The interpretation of ecological data has been greatly improved by bridging the gap between ecological and statistical models. The major challenge is to separate competing hypotheses concerning demography, or other ecological relationships, and environmental variability (noise). In this paper we demonstrate that this may be an arduous, if not impossible, task. It is the lack of adequate ecological theory, rather than statistical sophistication, which leads to this problem. A reconstruction of underlying ecological processes can only be done if we are certain of either the demographic or the noise model, which is something that can only be achieved by an improved theory of stochastic ecologi…
Notes on the karyology, genetics and ecology of Genista sect. Voglera in Sicily
2012
To investigate the biosystematic and genetic relationships among Sicilian species of Genista sect. Voglera, four populations of three species, Genista aristata C. Presl, Genista cupanii Guss., and Genista madoniensis Raimondo, have been studied. Genista madoniensis is tetraploid, with a chromosome number of 2n = 48, as are the other two species. An isozyme study showed that G. madoniensis is taxonomically closer to G. aristata than to G. cupanii, the latter possessing four unique alleles. The results are discussed in the context of the ecological characteristics of each species.
Symbionts and Pathogens: What is the Difference?
2011
The ecological relationships that organisms establish with others can be considered as broad and diverse as the forms of life that inhabit and interact in our planet. Those interactions can be considered as a continuum spectrum, ranging from beneficial to detrimental outcomes. However, this picture has revealed as more complex and dynamic than previously thought, involving not only factors that affect the two or more members that interact, but also external forces, with chance playing a crucial role in this interplay. Thus, defining a particular symbiont as mutualist or pathogen in an exclusive way, based on simple rules of classification is increasingly challenging if not unfeasible, since…
Hypericum scruglii sp. nov. (Guttiferae) from Sardinia
2010
A new species of Hypericum (Guttiferae) from Sardinia, H. scruglii, is described and illustrated. It occurs on damp soil, near springs or streams with freshwater, where it grows with numerous hygrophytes. This diploid species (2n � 16) belongs to the sect. Adenosepalum and is closely related to H. tomentosum, a species widespread in the west Mediterranean region. During field investigations in Sardinia, very peculiar populations of Hypericum L. were found occuring on damp soils and limited to calcareous substrates. These plants showed a close morphological and ecological relationship with H. tomentosum L., a species belonging to sect. Adenosepalum Spach. As emphasized by Robson (1996), the …
Recent applications of point process methods in forestry statistics
2000
Forestry statistics is an important field of applied statistics with a long tradition. Many forestry problems can be solved by means of point processes or marked point processes. There, the "points" are tree locations and the "marks" are tree characteristics such as diameter at breast height or degree of damage by environmental factors. Point pro- cess characteristics are valuable tools for exploratory data analysis in forestry, for describing the variability of forest stands and for under- standing and quantifying ecological relationships. Models of point pro- cesses are also an important basis of modern single-tree modeling, that gives simulation tools for the investigation of forest stru…