Negative selection (artificial selection)
Encyclopedia
In artificial selection
, negative selection is where negative, rather than positive, traits of a species are selected for evolutionary continuance. It is generally not desirable, but may be caused by man-made conditions such as bad management
, or like when human
s eat the best plants or animals they have, leading to worse and worse stock; for example, it occurred frequently in primitive beekeeping
. Another more recent example are regulations on fish and deer, where fish below a certain desired size will be set free, and deer suffering small antlers would less likely to be hunted, leading to undersized fish and small-antlered deer populations; the same case applies to the elephant's tusks.
Some proponents of Social Darwinism
and eugenics
argue that medicine
and other technological
, societal
, and cultural
practices cause negative selection in humans, better known as dysgenics
. According to them, human manifests more and more negative traits.
In the case of microbiology
and molecular biology
, negative selection is used to screen
for microorganisms that fail to possess a certain phenotype. An example of this is through replica plating
.
(Chilean abalone) and Loxechinus albus
(Chilean sea urchin) have been exposed to over-extraction during a long time. Populations have shrunk and a recent study shows that extraction is making an artificial selection to eliminate faster-growing individuals. The same study also showed that populations in Chile are relatively homogeneous with low genetic variability
.
Artificial selection
Artificial selection describes intentional breeding for certain traits, or combination of traits. The term was utilized by Charles Darwin in contrast to natural selection, in which the differential reproduction of organisms with certain traits is attributed to improved survival or reproductive...
, negative selection is where negative, rather than positive, traits of a species are selected for evolutionary continuance. It is generally not desirable, but may be caused by man-made conditions such as bad management
Management
Management in all business and organizational activities is the act of getting people together to accomplish desired goals and objectives using available resources efficiently and effectively...
, or like when human
Human
Humans are the only living species in the Homo genus...
s eat the best plants or animals they have, leading to worse and worse stock; for example, it occurred frequently in primitive beekeeping
Beekeeping
Beekeeping is the maintenance of honey bee colonies, commonly in hives, by humans. A beekeeper keeps bees in order to collect honey and other products of the hive , to pollinate crops, or to produce bees for sale to other beekeepers...
. Another more recent example are regulations on fish and deer, where fish below a certain desired size will be set free, and deer suffering small antlers would less likely to be hunted, leading to undersized fish and small-antlered deer populations; the same case applies to the elephant's tusks.
Some proponents of Social Darwinism
Social Darwinism
Social Darwinism is a term commonly used for theories of society that emerged in England and the United States in the 1870s, seeking to apply the principles of Darwinian evolution to sociology and politics...
and eugenics
Eugenics
Eugenics is the "applied science or the bio-social movement which advocates the use of practices aimed at improving the genetic composition of a population", usually referring to human populations. The origins of the concept of eugenics began with certain interpretations of Mendelian inheritance,...
argue that medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
and other technological
Technology
Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...
, societal
Society
A society, or a human society, is a group of people related to each other through persistent relations, or a large social grouping sharing the same geographical or virtual territory, subject to the same political authority and dominant cultural expectations...
, and cultural
Culture
Culture is a term that has many different inter-related meanings. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions...
practices cause negative selection in humans, better known as dysgenics
Dysgenics
Dysgenics is the study of factors producing the accumulation and perpetuation of defective or disadvantageous genes and traits in offspring of a particular population or species. Dysgenic mutations have been studied in animals such as the mouse and the fruit fly...
. According to them, human manifests more and more negative traits.
In the case of microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
and molecular biology
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...
, negative selection is used to screen
Genetic screen
A genetic screen is a procedure or test to identify and select individuals who possess a phenotype of interest. A genetic screen for new genes is often referred to as forward genetics as opposed to reverse genetics, the term for identifying mutant alleles in genes that are already known...
for microorganisms that fail to possess a certain phenotype. An example of this is through replica plating
Replica plating
In molecular biology and microbiology, replica plating is a technique in which one or more secondary Petri plates containing different solid selective growth media are inoculated with the same colonies of microorganisms from a primary plate , reproducing the original spatial...
.
Examples
The shellfishes Concholepas concholepasConcholepas concholepas
Concholepas concholepas, common names the Chilean abalone, loco or pata de burro and chanque , is a species of large edible sea snail, a marine gastropod mollusk. Despite the superficial resemblance, C...
(Chilean abalone) and Loxechinus albus
Loxechinus albus
Loxechinus albus or Chilean sea urchin is an echinoderm of the family Parechinidae, native to the coasts of Chile and Peru. It is found shallowly buried in fine sand, and muddy sand, beaches at and below low tide level.-Description:...
(Chilean sea urchin) have been exposed to over-extraction during a long time. Populations have shrunk and a recent study shows that extraction is making an artificial selection to eliminate faster-growing individuals. The same study also showed that populations in Chile are relatively homogeneous with low genetic variability
Genetic variability
Genetic variability is a measure of the tendency of individual genotypes in a population to vary from one another. Variability is different from genetic diversity, which is the amount of variation seen in a particular population. The variability of a trait describes how much that trait tends to...
.