生物专业英语(5)

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• Species diversity consists of two components, species richness and species evenness. Species richness is a simple count of species, whereas species evenness quantifies how equal the abundances of the species are.
Baidu Nhomakorabea
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• "Biodiversity" is most commonly used to replace the more clearly defined and long established terms, species diversity and species richness. Biologists most often define biodiversity as the "totality of genes, species,
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Genetic diversity
• Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary.
and ecosystems of a region".
• An advantage of this definition is that it seems to describe most circumstances and presents a unified view of the traditional three levels at which biological variety has
• The effective number of species refers to the number of equally-abundant species needed to obtain the same mean proportional species abundance as that observed in the dataset of interest.
• Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions support fewer species.
been identified:
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Species diversity
• Species diversity is the effective number of different species that are represented in a collection of individuals.
Lesson Six
The Origin and Diversity of Life
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Biodiversity
• Biodiversity is the degree of variation of life forms within a given species, ecosystem, biome, or an entire planet.
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Ecosystem diversity
• Ecosystem diversity refers to the diversity of a place at the level of ecosystems.
• The term differs from biodiversity, which refers to variation in species rather than ecosystems.
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• Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of the success of
these individuals.
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Glossary
• Ecosystem diversity can also refer to the variety of ecosystems present in a biosphere, the variety of species and ecological processes that occur in different physical settings.