If the temperature difference between summer and winter increases, long hair for animals being active during the winter or short hair for animals being active during the summer is advantageous.
disruptive selection A process of natural selection that favors individuals at both extremes of a phenotypic range. PICTURE
distal tubule The section of the renal tubule where tubular secretion occurs.
In some circumstances, individuals at both extremes of a range of phenotypes are favored over those in the middle. This is called disruptive selection.
An example: ...
Disruptive selection: Selection against the middle range of variation causing an increase in the frequency of a trait showing the extreme ranges of its variation. Disruptive selection might cause one species to evolve into two.
In disruptive selection, selection pressures act against individuals in the middle of the trait distribution. The result is a bimodal, or two-peaked, curve in which the two extremes of the curve create their own smaller curves.
2 ~ on Drosophila melanogaster
Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females. They applied selection on this population for flies with the highest and lowest numbers of sternoplural chaetae (hairs).
~----natural selection that favors individuals with either extreme variations of a trait tends to eliminate intermediate phenotype.
~ is kind of those 2 ideas merged, where instead of favoring one extreme or the other or favoring the middle instead you disfavor the middle and give the advantage to either end and so you'll tend to see what sometimes is a bimodal curve where you'll have a fair number who are ...
~: A third possibility is that the organisms with traits at the extremes of the population distribution actually have a reproductive advantage over those nearer the mean.
~ - competition favoring fishes at either extreme of body size and mouth size over those nearer the mean - coupled with:
assortative mating - each size preferred mates like it - favored a divergence into two subpopulations exploiting different food in different parts of the lake.
~ a type of natural selection in which the environment favours forms at the extremes of the range of phenotypic variation.
Diversity a measure of the number of different species present in a particular habitat.
DNA a molecule that forms the genetic material of all living organisms.
~ Natural selection that occurs when individuals of the most common phenotypes are at a disadvantage; produces contrasting subpopulations.
dissociation The breaking up of a molecule into ions when placed in water or other solvents.
~ occurs when environmental conditions favor individuals at both extremes of the phenotypic range over those with intermediate phenotypes.
For example, two distinct bill types are present in Cameroon's black-bellied seedcrackers.
"Speciation via disruptive selection on habitat preference: experimental evidence". The American Naturalist 131: 911-917.
^ Dodd, D.M.B. (1989) "Reproductive isolation as a consequence of adaptive divergence in Drosophila pseudoobscura." Evolution 43:1308-1311.
^ Kirkpatrick, M.
In ~, two extreme phenotypes are favored in the population, while the intermediate phenotype is driven towards elimination.
See also: What is the meaning of Selection, Natural selection, Species, Population, Evolution?