| 1. |
- Lundgren, Magnus, 1975-
(author)
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Archaeal Chromosome
- 2008
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In: Encyclopedia of Life Sciences. - Chichester, England : John Wiley & Sons. - 0470664789 - 9780470015902
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Book chapter (peer-reviewed)abstract
- The Archaea is one of the three domains of life, and the least known. Sequencing ofmany archaeal chromosomes has shown that archaea display many eukaryotic features,despite sharing their appearance and range of genome size with bacteria. Chromatinorganization, replication and transcription are similar to eukaryotes while operonorganization and transcription regulation are similar to bacteria.
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| 2. |
- Backström, Niclas
(author)
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Adaptive evolution in passerine birds
- 2014
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In: Encyclopedia of Life Sciences. - : Wiley. - 1476-9506. - 9780470015902
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Journal article (other academic/artistic)abstract
- Adaptive evolution is the process whereby mutations that provide the carrier with a selective advantage increase in frequency in a population via the process of natural selection. Passerines are widespread, common and long-term targets for field study and they demonstrate a copious diversity in physiological and morphological adaptations to varying habitats, for example, beak size and wing shape, and they are, therefore, an important study system to understand adaptive evolution. Recent technological advancements have made it easier to investigate the mechanistic and evolutionary underpinnings of adaptive evolution by allowing genome sequence data to be generated in almost any species of interest. However, it is important to assess the contribution of neutral forces like demographic events and GC-biased gene conversion before concluding that selection has shaped the patterns observed in genomic data. Initial analyses in passerines have identified candidate genes that might be involved in, for example, song learning, beak morphology, disease resistance, high-altitude adaptation and exploratory behavior, but functional verifications are needed to establish a causative relationship between the identified genes and the traits. Key Concepts:Key Concepts: * Passerines are widespread, generally common and easy targets for field study and they demonstrate a copious diversity in physiological and morphological adaptations to varying habitats and they have, therefore, played an important role in previous studies concerning behaviour, ecology and evolution. * A full understanding of passerine adaptations requires an integrative approach aiming at identifying and characterising both proximate (mechanistic) and ultimate (evolutionary) underpinnings to adaptive traits. * The recent advancements in molecular techniques allows for using both comparative genomics, expression profiling, candidate gene approaches and classical association and QTL mapping strategies to identify the genetic basis of adaptive traits in passerines. * Groundwork studies of ecological genetics and genomics using comparative approaches, expression profiling and candidate genes are now accumulating and in a handful of cases we have an idea about the genetic basis of adaptive traits related to, for example, dietary specialisation, learning, exploratory behaviour, immune response and high-altitude adaptations in passerines. * Demographic history and other neutral processes, for example, GC-biased gene conversion (gcBGC), may mimic signals of selection and it is important to verify findings of adaptive evolution using independent methods.
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| 3. |
- Bellini, Catherine
(author)
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Adventious roots
- 2014
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In: eLS. - Chichester : John Wiley & Sons. - 9780470015902
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Book chapter (pop. science, debate, etc.)abstract
- The root system of a plant is composed of the primary, lateral and adventitious roots (ARs). Lateral roots always develop from roots, whereas ARs form from stem or leaf‐derived cells. AR formation is part of the normal development of the plant and occurs naturally, like in most monocotyledonous for which they constitute the main root system or in many dicotyledonous species that propagate vegetatively. Adventitious rooting is an essential step for vegetative propagation of economically important horticultural and woody species as it allows clonal propagation and rapid fixation of superior genotypes prior to their introduction into production or breeding programmes. Development of ARs is a complex process that is affected by multiple endogenous and environmental factors, including phytohormones; light; nutritional status; associated stress responses, such as wounding; and genetic characteristics.
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| 4. |
- Birkhofer, Klaus, et al.
(author)
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Environmental Impacts of Organic Farming
- 2016
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In: eLS. - : Wiley. - 9780470015902 ; , s. 1-7
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Book chapter (other academic/artistic)abstract
- Organic agriculture is a production system that aims at sustaining healthy soils, ecosystems and people by prohibiting the application of synthetic pesticides and fertilisers in crop production and by emphasising animal welfare in livestock breeding. This article shows that organic agriculture is characterised by higher soil quality and reduced nutrient or pesticide leaching compared to nonorganic agriculture, but that positive effects on biological control services or emission of greenhouse gases are less evident. Yield gaps between organic and nonorganic agriculture are on average 20%, but vary between crops and regions. Given the environmental risks that are associated with intensive, nonorganic agriculture, farming practices should be modified to decrease risks. Organic agriculture can be a more environmentally friendly alternative, but individual farming practices need improvement to meet the demands of a growing human population. Further growth of the organic farming sector will contribute to reduce the negative environmental impact of agriculture.
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| 5. |
- Cherif, Mehdi
(author)
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Stoichiometry and Population Growth in Osmotrophs and Non‐Osmotrophs
- 2016
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In: eLS. - : John Wiley & Sons. - 9780470015902 ; , s. 1-6
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Book chapter (peer-reviewed)abstract
- Growth is a process fundamental to life. It implies an increase in not only energy and information but also matter content. Recent advances in ecology have demonstrated that the elemental composition of organisms – their stoichiometry – is inextricably linked to their growth rate. Unbalances between the demands of elements for growth and their relative availabilities often result in elemental limitation. Also, different cellular components have different elemental compositions, and thus changes in allocation between uptake and assembly machineries affect both growth rate and elemental composition at the organismal level. Osmotrophs (including autotrophs) acquire essential elements through a vast set of separate molecules, resulting in more flexible stoichiometries compared to non-osmotrophs that ingest their preys in one package. Relationships between elemental composition and growth rate should be considered differently for individuals and for populations, as processes and mechanisms differ between the two scales, and more generally among the various biological scales.
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| 6. |
- Guschanski, Katerina, Dr. 1978-
(author)
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Recent Loss of Genetic Diversity in Eastern Gorillas
- 2020
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In: eLS. - : Wiley-Blackwell. - 9780470015902
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Book chapter (other academic/artistic)abstract
- Many primate populations are declining as a result of human activities. Eastern gorillas are the most affected of all great apes. Understanding the genomic consequences of rapid declines is important for assessing conservation needs. Genomic analyses of museum specimens that predate the most recent changes allow for quantification of the genomic effects of population declines and extinctions. Grauer's gorillas, one of the two Eastern gorilla subspecies, have declined by almost 80% in the last two decades. Comparisons of genomic changes over the last 100 years revealed severe reduction in genetic diversity and increase in inbreeding and frequency of deleterious mutations. The other subspecies, the Mountain gorilla, has experienced little genomic change, possibly as a result of both long‐term evolutionary history and recent conservation efforts over the last 60 years. There is thus hope for the critically endangered species if appropriate conservation actions are taken.
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| 7. |
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| 8. |
- Kawakami, Takeshi, et al.
(author)
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Hybrid Zones
- 2012
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In: eLS. - : John Wiley & Sons. - 9780470015902
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Book chapter (peer-reviewed)
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| 9. |
- McWatters, Harriet G, et al.
(author)
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Plant Circadian Rhythms
- 2007
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In: eLS. - Chichester : John Wiley & Sons. - 9780470015902
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Book chapter (other academic/artistic)abstract
- Circadian clocks are found in most eukaryotic organisms. By allowing anticipation of daily and seasonal changes they enable coordination of metabolism and life cycle with the natural rhythms of the environment. Plant circadian rhythms are generated by a series of interlocking feedback loops of ribonucleic acid (RNA) and protein expression that respond to environmental cycles of light and temperature. They control essential processes in the plant’s development, such as the transition to flowering or growth cessation.
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| 10. |
- Oksanen, Lauri, et al.
(author)
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Vertebrate Herbivory and Its Ecosystem Consequences
- 2009
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In: Encyclopedia of Life Sciences. - Chichester : John Wiley & Sons, Inc.. - 9780470015902
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Book chapter (other academic/artistic)abstract
- Herbivory is a process where animals obtain energy and nutrients from vegetative plant parts (leaves, stems, etc.). Herbivory is called grazing, browsing or folivory, depending on the size of the herbivore and the type of plant tissue consumed. The consumption is actually performed by microbes in the digestive system. The role of the animal is to prepare the material and to provide a good environment for the microbes. This requires specializations, making herbivores a distinct animal group. This article focuses on consequences of herbivory by vertebrates. Vertebrate herbivory can change forests to heathlands or grasslands and influence the composition and species richness of the herbaceous vegetation.
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| 11. |
- Rundlöf, Maj, et al.
(author)
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Effects of Organic Farming on Biodiversity
- 2016
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In: eLS. - : Wiley. - 9780470015902 ; , s. 1-7
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Book chapter (other academic/artistic)abstract
- Changes in farming practices over the past century have had negative influence on farmland biodiversity. Organic farming excludes most agrochemicals, such as inorganic fertilisers and synthetic pesticides, and can be an alternative to conventional farming. A recent meta-analysis indicates that there is on average 30% higher species richness on organically managed farmland compared to conventionally managed farmland. There are, however, large variation between organism groups, with a positive influence on plants and pollinators and possibly predators and birds, but less influence on and insufficient knowledge for other groups. Using more formal experimental design, focusing on understudied organism groups and aspects of biodiversity, such as genetic and ecosystem diversity, and evaluating effects on rare species would advance our knowledge. The yield reduction under organic farming, resulting in more land needed to produce the same amount, could offset some of the biodiversity benefits of organic farming. Agricultural landscapes are both used to produce food and other agricultural products and as habitat for farmland biodiversity.Agricultural intensification, with increased use of agrochemical, mechanisation, crop breeding and conversion of land, is a threat to biodiversity.Organic farming is aimed at ecosystem management and reduction of agrochemical use.Organic farming results in around 30% higher biodiversity compared to conventional farming.The effects of organic farming vary between organism groups owing to their ecological traits.The effect of organic farming on biodiversity can be modified by landscape heterogeneity, land use intensity and time since conversion to organic farming.There are remaining gaps in the knowledge about how to combine agricultural production and biodiversity conservation.
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| 12. |
- van Bezooijen, Rutger Leo, et al.
(author)
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Bone morphogenetic proteins and their receptors
- 2006
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In: Encyclopedia of Life Sciences. - Chichester : John Wiley & Sons, Ltd.. - 9780470015902
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Book chapter (peer-reviewed)abstract
- Bone morphogenetic proteins (BMPs) are important cell–cell signalling molecules that were first identified by their ability to induce cartilage and bone, and subsequently were shown to be multifunctional proteins. BMPs transmit their signals from membrane to nucleus through distinct combinations of type I and type II serine/threonine kinase receptors and their intracellular effectors known as Smad proteins. Transcription of target genes is regulated in a complex manner in which interactions with other signalling components and pathways define the final response.
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