You may have already come into contact with this concept: “adaptive radiation”, Widely used in evolutionary biology. Adaptive radiation, as the name suggests, is an adaptive biological process in which certain species can fill an ecological niche very quickly.
This phenomenon of domination of the territory of certain species is called “speciation” and is part of an evolutionary process, because mutations and aspects of natural selection are involved.
In this article, we will see in detail what these concepts consist of; ecological niche, mutation and natural selection, fundamental concepts to understand what adaptive radiation is. And finally we will know what adaptive radiation is, what are its causes and origins, the characteristics that determine if we are in an adaptive radiation situation, the types of adaptive radiation and some examples.
What is adaptive radiation?
As we presented above, adaptive radiation arises from an adaptive issue of species. It is very common for this phenomenon to appear in an ecosystem where a new species is introduced, or when there are already species in this ecosystem that manage to survive in this environment that they have not yet reached.
In this process, the appearance of genetic mutations is necessary. A genetic mutation is a modification of the genetic material which makes possible a phenotypic change, that is to say in the expression of this characteristic in the organism of this animal. These mutations can give them characteristics favorable to their survival, or even negative.
Therefore, it is normal that if this (random) mutation which occurs in the animal gives it capacities which allow it to adapt better to the environment, this group of animals with this mutation survive longer and pass this mutation on to their offspring, And that those who do not adapt (without the mutation) end up disappearing.
Hence the concept of natural selection; Darwin, the scientist who postulated this concept, defined that natural selection states that the conditions of an environment or an ecosystem favor or hinder, that is to say, select, the reproduction of living organisms according to their characteristics.
In other words, if in a giraffe ecosystem where the trees with food are very tall, and in this way only have access to food for the giraffes with very long necks, those that have in their genetic material a mutation that gives them a longer neck, they will survive longer because they will feed more and not starve.
And so, when these giraffes do not die, they will be able to have offspring, and it is very likely that their offspring will inherit this mutation. Gradually, giraffes that have no characteristics to eat and do not starve will die and of course will not be able to transmit their genetic material. These species then fill what are called ecological niches., Which are understood as the functions performed by species within an ecosystem.
Characteristics of this biological phenomenon
There are a number of characteristics that allow us to define an adaptive radiation process, they are as follows.
1. A common ancestor
One of the main characteristics of adaptive radiation is that all derived species have a single common ancestor.
2. Phenotype-environment correlation
The existence of a correlation between the phenotype (the characteristics that are manifested in the organism) and the environment is essential to speak of adaptive adaptation. In other words, there is a significant relationship between the morphological and physiological characteristics of the organism and this environment.
3. Utility character
In other words, that is to say that the morphological and physiological characteristics of the organism are adapted to the needs of the environment. In other words, these characteristics are useful to the animal for its survival.
4. Speed in the process
This speciation is a response to the need to adapt to the environment and to be a rapid process.
Types of adaptive radiation
There are basically three types of adaptive radiation.
1. General adaptation
This type of adaptive radiation occurs when a species that develops a radically new characteristic or skill that can lead to the invasion of new parts of that environment. An example of this would be the flight of certain species of birds which facilitates the arrival of these latter towards other spaces.
2. Environmental change
In that case, a species that has the ability to survive in a radically changed environmentComparing others that do not have this ability, it is very likely that it will diversify into new species, covering other ecological niches.
An example of adaptive radiation in response to environmental changes would be the rapid expansion and development of mammals with the previous extinction of dinosaurs.
This type of adaptive radiation focuses on the archipelagos, which would be isolated ecosystems such as islands or mountainous areas.
These can be colonized by new species which, once established, go through a process of rapid evolution in which they diversify. The clearest example would be Darwin’s finches which we will see below.
Examples of adaptive radiation
Real and documented examples of adaptive radiation are now believed to be Darwin’s Finches of the Galapagos Islands. Darwin’s finches were birds that developed and reproduced from a single species of finches. who came to these islands at some point.
In this case, there was a diversity of woodpeckers in the different finch species. These finches were from the same ancestral species, but had been adapted to different feeding modes, hence their beak-shaped varieties.
Other documented cases of adaptive radiation would, for example human introduction of predatory mammals into parts of Australia, With the survival and expansion of these, or the development of dipnose (fish with lungs) over a period of time that took place about 300 million years ago.
In all of these cases, there are certain common factors that call them examples of adaptive radiation: genetic mutations that lead to phenotypic changes, better adaptation to the environment than other species in the same ecosystem, and finally rapid colonization. of this species in this ecological niche. .
- Carranza, J. (2016). Adaptive ethology: behavior as a product of natural selection. UCOPress, Editorial University of Córdoba, 1st edition.
- Gould Stephen, J. (2004). The structure of the theory of evolution. TusQuets editors.
- Pincheira-Donoso, D. (2012). Selection and adaptive evolution: theoretical and empirical foundations from the point of view of lizards. UC editions.