Signs of selection in the stomach

Helicobacter pylori, a globally distributed gastric bacterium, is genetically highly adaptable. Microbiologists at LMU have now characterized its population structure in individual patients, demonstrating an important role ...

Climate change has long-term impact on species adaptability

Historic climate change events can have a lasting impact on the genetic diversity of a species, reveals a new study published in Current Biology. This unexpected finding emerged from an analysis of the alpine marmot's genome.

The global invasion routes of the red swamp crayfish

Spanish National Research Council (CSIC) researchers have reconstructed the invasion routes followed by the red swamp crayfish during its human-driven expansion based on the analysis of a mitochondrial gene (COI), which was ...

Global warming hits sea creatures hardest

Global warming has caused twice as many ocean-dwelling species as land-dwelling species to disappear from their habitats, a unique Rutgers-led study found.

Bacteria reveal strong individuality when navigating a maze

Researchers from ETH Zurich demonstrate that genetically identical cells exhibit differing responses in their motility towards chemical attractants. Average values hide the full picture when it comes to describing the behavior ...

Origin of the saffron crocus traced back to Greece

The origin of C. sativus has long been the subject of speculation and research, as this knowledge would enable breeders to introduce genetic diversity into the otherwise genetically uniform plant species. Two new studies ...

Duckweed: The low-down on a tiny plant

Duckweeds are a treat for many aquatic animals like ducks and snails, but for pond owners, they're sometimes a thorn in the side. The tiny and fast-growing plants are of great interest to researchers, not at least because ...

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Genetic diversity

Genetic diversity is a level of biodiversity that 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.

The academic field of population genetics includes several hypotheses and theories regarding genetic diversity. The neutral theory of evolution proposes that diversity is the result of the accumulation of neutral substitutions. Diversifying selection is the hypothesis that two subpopulations of a species live in different environments that select for different alleles at a particular locus. This may occur, for instance, if a species has a large range relative to the mobility of individuals within it. Frequency-dependent selection is the hypothesis that as alleles become more common, they become less fit. This is often invoked in host-pathogen interactions, where a high frequency of a defensive allele among the host means that it is more likely that a pathogen will spread if it is able to overcome that allele.

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