Search results for "competition."

Characterisation of four species of the genus Kluyveromyces by mitochondrial DNA restriction analysis

1997

Summary In the present work, we determine the relationships at the within-species level among strains of Kluyveromyces dobzhanskii, K. lactis, K. marxianus, and K. thermotolerans, through the restriction analysis of their mtDNAs. The three first species showed a high level of intraspecific mtDNA divergence, this polymorphism is correlated to the varieties or species defined according to the original taxonomy of the genus, which is in concordance with that shown by other phenotypic or genotypic markers codified for by the nuclear genome. In these species, the analysis of the relationships among strains based on mtDNA restriction data agrees with previous classifications based on morphologica…

Adventitious bud formation on isolated leaves and its significance for mutation breeding

1968

Since a mutation is a unicellular event, irradiation of a multicellular meristem results in the so-called diplontic selection. This competition between the mutated cell and the surrounding non-mutated cells is often lost by the mutated cell, causing a low frequency of mutated plants and a narrow mutation spectrum. When a mutated cell survives, chimeras are automatically formed because most apices consist of a number of fairly independent groups of cell layers. Such an undesirable situation can be improved by growing complete plants from only one cell, resulting in a high frequency of solid, non-chimeral mutants and a wide mutation spectrum. Many plant species can be stimulated to form adven…

Inbreeding depression in intraspecific metabolic scaling

2013

Metabolic scaling (i.e., the relationship between the size and metabolic rate of organisms) has been suggested to explain a large variety of biological patterns from individual growth to species diversity. However, considerable disagreement remains regarding the underlying causes of metabolic scaling patterns, and what these patterns are. As in all biology, understanding metabolic scaling will require understanding its evolution by natural selection. We searched for evidence of natural selection on metabolic scaling indirectly by manipulating the genetic quality of male and female Drosophila montana flies with induced mutations and inbreeding, building on the notion that mutations and inbre…

Inter- and intraspecific chromosome pattern variation in the yeast genusKluyveromyces

1998

The analysis of the electrophoretic chromosome patterns of the species of the genus Kluyveromyces, reveals a high polymorphism in size, number and intensity of bands. DiVerent sets of electrophoresis running conditions were used to establish species-specific patterns and also to detect intraspecific variation. According to their karyotypes, the species of this genus can be divided into two major groups. The first group includes the species K. africanus, K. bacillisporus, K. delphensis, K. lodderae, K. phaY, K. polysporus and K. yarrowii, composing the so-called ‘Saccharomyces cerevisiae-like’ group, because their karyotypes resemble that of the species S. cerevisiae. The second group compri…

2015

Competition over access to reproductive opportunities can lead males to harm females. However, recent work has shown that, in Drosophila melanogaster, male competition and male harm of females are both reduced under conditions simulating male-specific population viscosity (i.e., in groups where males are related and reared with each other as larvae). Here, we seek to replicate these findings and investigate whether male population viscosity can have repercussions for the fitness of offspring in the next generation. We show that groups of unrelated-unfamiliar (i.e., unrelated individuals raised apart) males fight more intensely than groups of related-familiar males (i.e., full siblings raise…

A hierarchical analysis of genetic structure and variability in patchily distributed coexisting Chiastocheta species (Diptera:Anthomyiidae)

1996

The pattern of genetic variation in four coexisting fly species of the genus Chiastocheta was studied by allozyme electrophoresis. The fly species are confined to patches of one plant, Trollius europaeus, and thus experience very similar habitat fluctuations. Collection sites were chosen in a hierarchical fashion and F-statistics were estimated at three levels: intraregion, inter-region and total population. Population characteristic genetic parameters were compared within and among species and were related to the hierarchical level. The species were used as replicate experiments for inference of habitat history, and the hierarchical levels were used as inference for specific gene flow patt…

Differential competitive ability between sexes in the dioecious Antennaria dioica (Asteraceae)

2012

† Background and Aims Differences in competitive ability between the sexes of dioecious plants are expected as a result of allocation trade-offs associated with sex-differential reproductive costs. However, the available data on competitive ability in dioecious plants are scarce and contradictory. In this study sexual competition was eval- uated using the dioecious plant Antennaria dioica in a common garden transplantation experiment. † Methods Male and female plants were grown for 3 years either in isolation, or in competition with a plant of the same sex or the opposite sex. Flowering phenology, sexual and asexual reproduction, plant growth, nutrient content and arbuscular mycorrhizal col…

Interactions among bacterial strains and fluke genotypes shape virulence of co-infection.

2015

Most studies of virulence of infection focus on pairwise host–parasite interactions. However, hosts are almost universally co-infected by several parasite strains and/or genotypes of the same or different species. While theory predicts that co-infection favours more virulent parasite genotypes through intensified competition for host resources, knowledge of the effects of genotype by genotype (G × G) interactions between unrelated parasite species on virulence of co-infection is limited. Here, we tested such a relationship by challenging rainbow trout with replicated bacterial strains and fluke genotypes both singly and in all possible pairwise combinations. We found that virulence (host mo…

Geographies of Cyberspace: Internet, Community, Space, and Place

2017

This chapter “Geographies of Cyberspace” discusses the term “cyberspace” in relation to the concepts of “space”, “place”, and “community” by reviewing the academic literature from human geography, sociology, and cultural anthropology. It forms the basis for the development of a phenomenological perspective on cyberspace. Instead of presenting all possible approaches towards cyberspace, this chapter discusses only those concepts that focus on the connections between on- and offline life. It proposes that cyberspace not only includes spatial and territorial metaphors , as several human geographers have pointed out, but that it is also characterised by complex geographies, which have to be exp…

Femininity and the Salon

2020

This chapter concerns Salon Culture and its role as a distributor of philosophy at the beginning of the nineteenth century, marking the importance of the mostly unacknowledged contribution by female thinkers. The salon presents the space between private and profession in which the participants could try out new roles and change old ones. Thus, the establishment of sentimental circles such as the Tugendbund around Henriette Herz, the extensive net of communication and representation established by Rahel Varnhagen, the opportunity to publish under either pseudonyms or hidden behind a male editorship used by writers such as Dorothea Schlegel may all count as first attempts to form a role as sa…