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Ecological Work (ecological + work)

Distribution by Scientific Domains
Life Sciences100%
Distribution within Life Sciences
Ecology & Organismal Biology50%

Selected Abstracts

Competition and character displacement in two species of scincid lizards

ECOLOGY LETTERS, Issue 3 2002
Jane Melville
Abstract The role of competition in habitat occupation and character displacement is investigated in two species of alpine lizards (Niveoscincus microlepidotus and N. greeni), using both controlled competition experiments and field-based ecological work. Competition experiments demonstrate that interspecific aggression occurs between these closely related species, with the larger and more aggressive N. greeni being socially dominant. When these species occur in sympatry, N. microlepidotus was found to shift its habitat occupation to the heathlands, which provide less thermal opportunities. In addition, a reduction in body size occurred in both adult and neonatal N. microlepidotus at sympatric field sites. Differences in body size between N. microlepidotus and N. greeni in sympatry were significantly greater than in allopatry, indicating that character displacement is occurring. Results, combined with previous molecular and biogeographical data, suggest that there is a trend towards a reduction in body size and a restriction in habitat occupation in N. microlepidotus in the north-east periphery of its distribution, which is shaped by competition with N. greeni. [source]

Phylogeographic analysis of a recent radiation of Enallagma damselflies (Odonata: Coenagrionidae)

MOLECULAR ECOLOGY, Issue 10 2002
J. Turgeon
Abstract A phylogenetic hypothesis revealed two recent radiations among species of Enallagma damselflies, and extensive ecological work suggests that both adaptive and nonadaptive processes are involved in these radiations. We analysed the geographical pattern of genetic variability at 868 bp of mitochondrial DNA (mtDNA) among 283 individuals of 5 species displaying little ecological differentiation to identify the ancestral lineage, support their independent evolutionary trajectories and identify historical events and the underlying mechanism for one of these radiations. Nested clade analysis results clearly support a past event of range fragmentation in E. hageni. These Atlantic and Continental hageni races experienced distinct dispersal histories and still maintain nearly nonoverlapping ranges All four other species derive from the Continental hageni. Whereas three species endemic to the Atlantic coastal plain show little genetic variation, E. ebrium shared several haplotypes with the Continental hageni. Contrasting levels of genetic differentiation between E. hageni and E. ebrium in geographical areas associated with distinct events of E. hageni's recent history support the recent origin of this species. Altogether, our results are compatible with a process of radiation via divergence in mate recognition systems within the Continental hageni race following secondary contacts between putative refugial races. [source]

Isolation of polymorphic microsatellite loci in the net-spinning caddisfly, Polycentropus flavomaculatus (Polycentropodidae)

MOLECULAR ECOLOGY RESOURCES, Issue 4 2002
Deborah A. Dawson
Abstract We have isolated eight polymorphic loci for the caddisfly, Polycentropus flavomaculatus. The application of these markers will allow us to define the genetic population structure of this species and, with complementary ecological work, will enable quantification of its dispersal ability and colonization potential. [source]

Is life-history buffering or lability adaptive in stochastic environments?

OIKOS, Issue 7 2009
David N. Koons
It is commonly thought that temporal fluctuations in demographic parameters should be selected against because of the deleterious impacts variation can have on fitness. A critical underpinning of this prediction is the assumption that changes in environmental conditions map linearly into changes in demographic parameters over time. We detail why this assumption may often break down and why selection should not always favor buffering of demographic parameters against environmental stochasticity. To the contrary, nonlinear relationships between the environment and demographic performance can produce asymmetric temporal variation in demographic parameters that actually enhances fitness. We extend this result to structured populations using simulation and show that ,demographic lability' rather than ,buffering' may be adaptive, particularly in organisms with low juvenile or adult survival. Finally, we review previous ecological work, and indicate cases where ,demographic lability' may be adaptive, then conclude by identifying research that is needed to develop a theory of life-history evolution that encompasses both demographic buffering and lability. [source]