The developmental evolutionary biology, commonly abbreviated as evo-devo for its acronym in English, it is a novel field of evolutionary biology that integrates the branch of development in evolution. One of the most promising objectives of this discipline is to explain morphological diversity on earth.
The modern synthesis sought to integrate Darwin's theory of evolution by natural selection and the mechanisms of inheritance proposed by Mendel. However, he left out the possible role of development in evolutionary biology. Therefore, evo-devo arises from the lack of integration of development in the synthesis.
The development of molecular biology achieved the sequence of genomes and the visualization of genetic activity, allowing to fill that gap in evolutionary theory.
Thus, the discovery of the genes involved in these processes gave rise to the origin of evo-devo. Evolutionary developmental biologists are charged with comparing the genes that regulate developmental processes in a wide range of multicellular organisms..
One of the fundamental questions in evolutionary biology - and in biological sciences in general - is how the extraordinary biodiversity of the organisms that inhabit the planet today arose.
Different branches of biology, such as anatomy, paleontology, developmental biology, genetics and genomics provide information to find the answer to this question. However, within these disciplines, the development.
Organisms begin their life as a single cell and, through development processes, the formation of the structures that compose it occurs, call it head, legs, tails, among others..
Development is a central concept, since through this process all the genetic information contained in an organism is translated into the morphology that we observe. Thus, the discovery of the genetic bases of development has revealed how changes in this can be inherited, giving rise to evo-devo.
Evo-devo seeks to understand the mechanisms that have led to the evolution of development, in terms of:
- Development processes. For example, how a new cell or new tissue is responsible for novel morphologies in certain lineages
- Evolutionary processes. For example, which selective pressures promoted the evolution of these novel morphologies or structures.
Until the mid-1980s, most biologists assumed that diversity in forms had arisen thanks to significant changes in the genes that controlled the development of each lineage..
Biologists knew that a fly looked like a fly, and a mouse looked like a mouse, thanks to their genes. However, it was thought that the genes between such morphologically disparate organisms should reflect these abysmal differences at the gene level..
Studies in fruit fly mutants, Drosophila, led to the discovery of genes and gene products involved in insect development.
These pioneering works by Thomas Kaufman led to the discovery of genes Hox - those in charge of controlling the pattern of body structures and the identity of the segments in the anteroposterior axis. These genes work by regulating the transcription of other genes..
Thanks to comparative genomics, it can be concluded that these genes are present in almost all animals.
In other words, although metazoans differ greatly in morphology (think of a worm, a bat, and a whale), they share common developmental pathways. This discovery was shocking to biologists of the time and led to the proliferation of the science of evo-devo..
Thus, it was concluded that species with very different phenotypes have very few genetic differences and that genetic and cellular mechanisms are extremely similar throughout the tree of life..
Evo-devo has been characterized by the development of multiple research programs. Muller (2007) mentions four of them, although he warns that they overlap each other.
This type of study seeks to clarify the morphogenetic differences that distinguish primitive ontogeny from derived ones. The information can be complemented with what is found in the fossil record.
Following this line of thought, different patterns of morphological evolution can be characterized on large scales, such as the existence of heterochronies..
These are variations that occur in development, either in the time of appearance in the rate of formation of the trait.
This approach focuses on the evolution of the developmental genetic machinery. Among the techniques used is the cloning and visualization of the expression of genes involved in the regulation.
For example, the study of genes Hox and its evolution through processes such as mutation, duplication and divergence.
This program studies the interaction and the molecular, cellular and tissue level dynamics affect evolutionary changes. Studies developmental properties that are not contained in the organism's genome.
This approach allows corroborating that, although the same phenotype exists, it can be expressed differentially depending on environmental conditions..
This program focuses on the quantification, modeling and simulation of the evolution of development, including mathematical models for data analysis..
The emergence of evo-devo gave rise to the formation of other disciplines that sought to continue with the integration of different branches of biology in evolutionary theory, thus eco-evo-devo was born..
This new branch seeks the integration of the concepts of developmental symbiosis, developmental plasticity, genetic accommodation and construction of niches..
In general terms, developmental symbiosis states that organisms are built, in part, thanks to interactions with their environment and are persistent symbiotic relationships with microorganisms. For example, in various insects, the existence of symbiotic bacteria produces reproductive isolation.
There is no doubt that symbiosis has had an impressive impact on the evolution of organisms, from the origin of the eukaryotic cell to the origin of multicellularity itself..
Similarly, developmental plasticity consists of the ability of organisms to generate different phenotypes, depending on the environment. Under this concept, the environment is not exclusively a selective agent, without also shaping the phenotype.