Gene duplication, mutation, or other processes can produce new genes and alleles and increase genetic variation. New genetic variation can be created within generations in a population, so a population with rapid reproduction rates will probably have high genetic variation.
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Gasoline, paint, radioactive waste, pesticides, mercury, lead oil, and battery acid.
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Mountain building and defrostation
Abiotic variables found in terrestrial ecosystems can include things like rain, wind, temperature, altitude, soil, pollution, nutrients, pH, types of soil, and sunlight. The boundaries of an individual abiotic factor can be just as unclear as the boundaries of an ecosystem.These are often referred to as abiotic factors. Abiotic factors are non-living elements found within an ecosystem. There are six abiotic factors that affect plant growth: air, water, space, temperature, light and soil (nutrients).The two most important abiotic factors affecting plant primary productivity in an ecosystem are temperature and moisture.
LEARNING OBJECTIVE[ edit ]
Identify the abiotic factors that affect plant growth
KEY POINTS[ edit ]
Primary production, on which almost all of life on earth is dependent, occurs through either photosynthesis or chemosynthesis.
Annual biomass production, used to estimate net primary productivity by plants in an area, is directly influenced by an environment's abiotic factors, which include temperature and moisture.
Warm and wet climates have the greatest amount of plant biomass because they offer conditions in which photosynthesis, plant growth, and the resulting net primary productivity are highest.
TERMS[ edit ]
biomass
the total mass of all living things within a specific area, habitat, etc.
eco-region
a region, smaller than an ecozone, that contains a distinct biodiversity of flora and fauna
chemosynthesis
the production of carbohydrates and other compounds using the oxidation of chemical nutrients as a source of energy rather than sunlight; it is limited to certain bacteria and fungi
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Over the ages the tendency of crop improvement efforts has been to select varieties with traits that give the highest return, largely by concentrating on genetic strains that combine the most desirable traits. The resulting homogeneity and uniformity can offer substantial advantages in both the quantity and quality of crop harvested, but this same genetic homogeneity can also reflect greater susceptibility or pathogens. Thus it appears the more that agricultural selection disturbs the natural balance in favor of variety uniformity over large areas, the more vulnerable such varieties are to losses from epidemics. The increased risks presented by genetic selection and the increased cultivation of only a few selected cultivars are easily perceived. Chapters 1 and 2 of this reports focus on crop vulnerability, because it is a broadly recognized problem. The issue of genetic vulnerability, however, is only one of several important problems affecting the management of global genetic resources.
