What is meant by the phrase "the criteria of the form"?Before this serious conversation reminded anecdote.
villagers ran to his neighbor, and the watermelon cut in half, cockroaches inside of it sticks and watermelon halves with cockroaches clamps.Surprised doctor, asks his neighbor what it was doing.
same with a sly smile he says that this process is called selection."That scratches watermelon with cockroaches get a new variety.Cut the watermelon, beat piece on the table, and the seeds-so cockroaches do Watermelon and run out and hide in the cracks! »
Really funny!And all because the villagers are likely absolutely did not understand that there are certain criteria for the type of biological organisms.You can not make a selection, not only between insects and plants belonging to different realms of biology, but even between the pumpkin and watermelon, because these plants belong to different departments, classes, families, not to mention the views.
determination of the type of organism or individuals is based on a number of signs.Alternatively, these features can be called criteria.This word comes from the Greek "Criterion", which means - "the means to judge."
To distinguish organisms most often used type of criteria, highlighting the morphological, physiological, biochemical, genetic and geographic.
criteria species - a taxonomic characteristics typical of this type, but absent in others.They are still in some cases referred to as diagnostic."Species radical" named NIVavilov set of features that allows you to put a reliable inter-service delimiter.
criteria are divided into basic type, which are used for the majority of species, and more suitable for determination by no means all.The genetic test is based on the fact that the main feature of a certain circle of individuals is a different number, size and shape of the chromosomes.This fact makes it extremely difficult process of meiosis.
As a result, the gene exchange between different species is rare, ensuring the autonomy of the genetic species.Because of this diversity is preserved flora and fauna on earth.
But the genetic test species is not universal.For example, the hybridization of plants spread very widely in the world.Suffice it to recall the wonderful experiences on the selection of the greatest scientist - Michurin the botanist to understand that among the plants derive interspecific hybrids is quite real.
Pear apples, blackberries, raspberries, strawberries beardless and many other interesting species of garden plants.Also of note is the extreme ease of selection rozovotsvetnyh and other cultivated plants and garden flowers.
However, animal hybrids are extremely rare.If mating between members of different species of fauna still going on, and the offspring is born, it is very often no longer able to reproduce.Examples of this are the asses and mules.
But among canine known options such as the origin of the hybrids, where the starting material were wolves and dogs - representatives of different species, and in some cases even the dogs and foxes.And received successfully bred offspring, perpetuating the new form received genetic features.Because of this ability to canines were successfully derived a lot of very different breeds of dogs - their variety is simply amazing!
environmental criteria based on the kind of special relationship with the environment.For example, organisms with biotic constraints (parasitic species, disease vectors, commensals, symbionts) are characterized by confinement to a particular host.It is noted that sibling species, formerly known as "mosquito anopheles" different food base.Some of them are confined to mammals, while others - for the birds, and others - to the reptiles;some are carriers of malaria, and for others it is not typical.
«ecological niche" - habitat - for animals is often called "adaptive zone".For the "ecological niche as" plant is also called "Edafe phytocoenotic area."
However, different individuals of the same species sometimes occupy different ecological niches, forming ecotypes.Pine, for example, has ecotypes that inhabit the swamp (bog pine), dunes and pine forest areas.
Assuming full education of offspring by mating ecotypes together may form a single genetic system called ekovidom.
