Mechanisms underlying competitive interactions are important in understanding the structure of planktonic communities, particularly the coexistence of similar species. Here we present experimental results of exploitative competition among three sympatric sibling species of the Brachionus plicatilis complex for two differently-sized species of food microalgae. These three rotifer species are to ...

Realistic studies of plumage color need to consider that many birds can see near-UV light, which normal humans cannot perceive. Although previous investigations have revealed that UV-based plumage reflectance is an important component of various intraspecific social signals, the contribution of UV signals to inter-specific divergence and speciation in birds remains largely unexplored. I describ...

Considerable enzyme variation that is genetically controlled exists within and between natural populations of Drosophila. Our studies of two groups of sibling species show that allozyme differences can be used as species-diagnostic characters. A locus is defined as diagnostic if an individual can be correctly assigned to one of two species with a probability of 99% or higher. Between 15 and 32%...

The aim of the present study is to establish a common RAPD marker for P. jenningsi using a series of Ro primers and to investigate if strains originating from distant and isolated localities (Japan, China, India, Saudi Arabia) have isolated gene pools and represent distinct species. An analysis of dendrograms constructed on the basis of RAPD-PCR fingerprints with four primers (Ro 460-04, 460-06...

Models are formulated for the population dynamics of a monoecious or dioecious species with an all-female parthenogenetic sibling species which is also gynogenetic. Continuous, deterministic reproduction and mortality, a stationary age distribution, random mating, and limited sexual competence for all individuals are posited. It is also supposed that in the dioecious case males do not distingui...

This article investigates the phenomenon of interindividual rivalry and its consequences for motivation and task performance. Two studies of adults from the general population found that rivalry, as compared to nonrival competition, was associated with increased motivation and performance, controlling for tangible stakes, dislike, and other factors. Then, a large-scale archival study of long-di...

Temperature dependent larval pupation site preference in Drosophila. – Vandal N.B., Shivanna N. – The pupation site preferences (PSP) in sibling, sympatric and closely related species of Drosophila belonging to different groups were studied at different temperatures. The study has revealed that the pupation site choice varies significantly at extreme temperatures compared to the control one. Di...

On the basis of karyologically identified individuals of the common vole Microtus arvalis and the sibling vole Microtus rossiaemeridionalis from Europe and the Asiatic part of Turkey, a canonical craniometric classification function for the differentiation of these sibling species was worked out. The function is sex-independent and includes four craniometric parameters measured in millimeters (...