As dormancy (from the Latin dormire = sleep ) all forms of developmental delay in animals are called. These are partly due to external factors, but they can also be controlled genetically and hormonally. Dormanzphasen above all ensure the survival of animals and plants under unfavorable environmental conditions.
The main features of dormancy include a greatly reduced metabolism and increased resistance. The dormancy can occur in all phases of development and external conditions vary in length even within the same species dependent, as for example observed in dormancy.
- 2.1 Consecutive dormancy 2.1.1 quiescence
- 2.1.2 Oligopause
- 2.2.1 Para break
- 2.2.2 Eudiapause
Dormancy in botany
The term dormancy the seed dormancy is referred to in botany, which is to prevent premature germination in seeds under unfavorable conditions or even to the mother plant. This dormancy can be called by treating the seeds, stratification, to be cut short.
As dormancy but also the dormancy of plants is called: flowers or lateral shoot buds may remain in a resting phase for a long time due to external influences or hormonally controlled. Especially pronounced is in many plant species the bud dormancy of side shoots, which is mediated by the main stem or main stem and also known as apical dominance. If you remove the main engines, the dormancy of side shoots is refracted by and they start to grow out.
Another example of dormancy in the plant kingdom are the rest of many sympodial orchids that grow in adaptation to the respective regional cold and / or drought periods. The two pictures above show the common case two Dormanzmuster.
Dormancy in zoology
The dormancy is a survival strategy that is implemented mainly by cold-blooded ( poikilothermic ) animals. You can not only affect the whole organism, but only the gonads. For eggs or embryos is the dormancy of the mothers, usually triggered by parasitoids on the hosts. The term diapause is often used interchangeably, but always includes an endogenous component that switches the metabolism ( diapause in the broad sense ), as opposed to purely exogenously influenced quiescence.
There are two main forms of dormancy, with the trend of consecutive to prospective dormancy goes. Furthermore there is a tendency to limit the dormancy to a developmental stage.
In this form, the change of the external factors plays a significant role. The development curve follows the change in the decisive external factor and eventually can lead to developmental arrest at sub-optimal environmental conditions. Dormancy -inducing factor is that at the same time, terminates the dormancy again. As external factors occur here: temperature, food, moisture, and photoperiod. The Consecutive dormancy is divided into quiescence and Oligopause, the latter i for diapause w. P belongs.
In quiescence dormancy occurs immediately at the start of disfavor and is also terminated after completion of the unfavorable immediately. It can occur at any stage of development. The hibernation can be regarded as the same warm thermal quiescence ( homoiothermen ) animals.
When Oligopause dormancy occurs gradually after initiation of disfavor and after accumulation of the stimulus. It is almost " checked " if the disfavour will persist long term or a short-term environmental variation is present. This is followed by a change of physiology. The Oligopause is also gradually stopped after a decumulation of the stimulus. After the stage at which employs the Oligopause, three types are distinguished:
The hibernation is the thermal Oligopause the homoiothermen animals.
In this form the time of dormancy is genetically determined and is positioned so that the evolutionary change starts before a mostly seasonal change of an external factor is in an unfavorable area, looking quasi advance. Dormancy is coupled to a particular stage of development. This dormancy also has two forms, both for the diapause w i. S. include:
While in the other Dormanzformen development during unfavorable environmental conditions come to a standstill here a developmental stage is set to further development during unfavorable and needs this even. Therefore, the para break is mandatory and occurs upon reaching the particular stage. Termination occurs only after reaching the next stage by an external factor. As factors act here mainly the temperature or photoperiod.
Since all individuals in a population para pause at the same stage and are released by the same external factor only once during the year of dormancy, the development of this population is synchronous and there is only one generation per year ( Monovoltinismus ).
This is the diapause in the narrow sense Dormanzauslösender factor in the Eudiapause only the photoperiod, as it is in contrast to the other external factors astronomically accurate and thus always reliable. The critical photoperiod is the ratio of light-to dark hours, in which half of a population begins to diapausieren, and changed with increasing latitude. The signal for triggering the Eudiapause must be made in the preceding stages. If it fails, learns the intended stage a nondiapausäre development. Therefore, the Eudiapause is optional. Of terminating external factor is the temperature: an obligate, long cold spell. If the Eudiapause be completed, although involve adverse environmental conditions, follows quiescence.
The optional nature of Eudiapause is a kind of the possibility of more than one generation per year to bring forth (potential Polyvoltinismus ). For example, the Map Butterfly Butterfly Araschnia levana to two generations per year, of which performs a one nondiapausäre development and other Eudiapause. This also leads to different phenotypes between the two generations ( Saisondiphänismus ) of this Article