نتایج جستجو برای: genetic erosion

تعداد نتایج: 644003  

2016
Tyler D. Hether

Details of the processes that generate biological diversity have long been of interest to evolutionary biologists. A common theme in nature is diversification via divergent selection with gene flow. Empirical studies on this topic find variable genetic di↵erentiation throughout the genome, that genetic di↵erentiation is non-randomly distributed, and that loci of adaptive significance are often ...

2012
R Bijlsma Volker Loeschcke

Biodiversity is increasingly subjected to human-induced changes of the environment. To persist, populations continually have to adapt to these often stressful changes including pollution and climate change. Genetic erosion in small populations, owing to fragmentation of natural habitats, is expected to obstruct such adaptive responses: (i) genetic drift will cause a decrease in the level of ada...

پایان نامه :وزارت بهداشت، درمان و آموزش پزشکی - دانشگاه علوم پزشکی و خدمات بهداشتی درمانی استان فارس - دانشکده دندانپزشکی 1381

چکیده ندارد.

2010
Kristin L Mercer Hugo R Perales

Landraces cultivated in centers of crop diversity result from past and contemporary patterns of natural and farmer-mediated evolutionary forces. Successful in situ conservation of crop genetic resources depends on continuity of these evolutionary processes. Climate change is projected to affect agricultural production, yet analyses of impacts on in situ conservation of crop genetic diversity an...

1996
Y. A. EL-KASSABY

during the fragmented phases of the tree-improvement delivery system are reviewed. The impacts of intentional and unintentional directional selection during phenotypic selection, seed production (with its associated reproductive-phenology asynchrony, fecundity differential and varying propensity to inbreeding), seed processing and storage, and seedling production are evaluated. In general, gene...

F. Nuez J. Cebolla-Cornejo S. Soler

Ever since the arrival of the tomato to Spain in the 16th century, great diversification of the crop has taken place, giving rise to a rich collection of varietal types. The ‘Comunidad Valenciana’, with its deep-rooted agricultural tradition, is one of the Spanish regions with the greatest diversity in traditional tomato varieties, characterised by their local adaptation and high fruit quality....

Ornamental geophytes (ornamental flower bulbs) are international and national heritage considering their contribution to people's life quality around the world. Iranian habitats support about 8000 species of flowering plants (belonging to 167 families and 100 genera) of which almost 1700 are endemic. Iran is a rich country in terms of distribution of bulbous plants. More than 200 species of bul...

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