Animals are distributed all over the planet and, although some regions tend to be more diverse than others, even in the harshest habitats animal life is present. In order to live in certain environments, the different species have managed to develop adaptations and internal processes that allow them to live in habitats with particular characteristics. In this article on our site, we want to present information about one of those ways that different animals use to cope with harsh environmental conditions, diapause. We invite you to continue reading to learn all about diapause in animals, what it is and examples of animals that perform it.
What is diapause?
Some animals that live in places with extremely cold winters enter a state of torpor known as hibernation. Others, in dry and hot conditions, go through a state called aestivation. In any of the cases, these are processes that generate certain changes at the level of behavior and physiology that seek to ensure the survival of the animal.
Insects develop a process known as diapause, which is temporary and is intended to cope with adverse environmental conditions that can counteract development and reproduction of the animal. In this sense, diapause is a state in which development is suppressed or profoundly reduced and, therefore, any metabolic activity where a series of processes are involved physiological and behavioral changes towards inactivity, which promote resistance to an unfavorable habitat for some species.
Diapause is a strategy that allows insects to regulate their active period of life with the most favorable environmental conditions and power thus reproduce even in these places. The process, although it is linked to environmental conditions, is regulated by the genetic component through hormones. This state of inactivity can occur at any stage or phase of the insect, however, it is quite common to occur when it is in the pupal stage.
Environmental factors that induce diapause in insects are:
- Temperature
- Photoperiod
- Humidity
- Foods
- Population
However, insects are not the only animals that carry out diapause to guarantee their survival. Some mammals also develop a type of diapause that we will see later.
How long is the diapause?
The factors mentioned above are involved both in the time and in the intensity of the changes that occur in the insect, however, diapause begins before the adverse changes begin, so that these animals they predict unfavorable conditions, which allows them to survive, for example, before the arrival of winter. On the other hand, the process does not necessarily end when the extreme factors end.
Given the different environmental conditions that habitats present, the diapause process can vary from short times, such as a few weeks, to even months in the face of larger seasonal situations.
Stages of diapause
The issue of the phases or stages of diapause has been controversial, however, it has been proposed that it has three main moments, which are: pre-diapause, diapause and post-diapause In addition, it has been suggested [1] also the following phases more specifics:
- Induction
- Preparation
- Initiation
- Maintenance
- Termination
- Post-diapause quiescence
Difference between diapause and quiescence
The difference between diapause and quiescence is that, in the former, as we have mentioned, there is a considerable arrest or decrease in all the processes of the insect that imply physiological changes. The quiescence consists of a period of rest where the metabolism is still slowed down, but the animal can moveif you wish and activate to take advantage of favorable conditions. The latter does not have the level of regulation, genetic and environmental control as the former.
Types of diapause
There are two types of diapause, one mandatory and the other optional, and it is estimated that this has to do with the environment where the species has evolved.
- Obligatory diapause: Insects have no choice but to enter this process at some stage of their life.
- Facultative diapause: insects will start this process only when environmental conditions become adverse.
On the other hand, although diapause is more common in insects, it is important to mention that, in some mammals, such as kangaroos, a process called embryonic diapause occurs. These animals are marsupials, that is, they have a bag or marsupium, where an embryo after birth, barely developed, will enter and culminate its growth. In this way, after between 28 and 33 days of gestation, a calf will be born that will instinctively move to the marsupial bag and immediately the female can become pregnant again. However, with the presence of an infant attached to her breast, gestational development stops, and embryonic diapause occurs, which can last about 235 days, enough time for the infant to grow properly. Once the young leave the bag, the growth of the embryo in the uterus is reactivated to be born about a month later.
However, this also happens in other mammals that are not marsupials, such as the roe deer, since the female has the ability to leave her fertilized ovules in a state latent so that they can develop and be born later, when the conditions are the most suitable. Without a doubt, it is a reproductive strategy designed to guarantee the survival of the species. In this specific case, the female enters heat only once a year and for a very short period of time. Through embryonic diapause, all births occur at the same time of year.
Examples of diapause
Within the group of insects, there are different frequencies in which diapause occurs depending on the stage of the individual. Thus, for example, in beetles, it is the adults who go through the process to a greater extent, and this happens to more individuals in the summer than in the winter. On the other hand, in Lepidoptera, in winter, it is in the pupal stage that diapause occurs the most, although in the larval stage it also occurs in an important proportion, but less than the previous ones. Similarly in Diptera, it is in the pupal stage when they go through this time of inactivity, occurring in similar proportions in summer and winter.
Some specific examples of diapause in insects are found in the following species:
- Beetle (Lagria hirta)
- Mouse fly (Cuterebra fontinella)
- Monarch butterfly (Danaus plexippus)
- Codling moth (Cydia pomonella)
- Turnip root fly (Delia floralis)
- Wheat midge (Sitodiplosis mosellana)
- Flesh fly (Sarcophagus crassipalpis)
- Tobacco hawk moth (Sarcophagus crassipalpis)
- Fly of the family Drosophilidae (Chymomyza costata)
- Southwestern Corn Borer (Diatraea grandiosella)
Since insects are not the only animals that carry out diapause, although they do constitute the vast majority, other examples are the following:
- Roe deer (Capreolus capreolus)
- Southern Long-nosed Armadillo (Hybrid Dasypus)
- Red Kangaroo (Macropus rufus)
- Antelope kangaroo (Macropus antilopinus)
