While the endosymbiont adapts to the host`s lifestyle, the endosymbiont changes radically. There is a drastic reduction in the size of its genome, as many genes are lost during the metabolic process, and DNA repair and recombination, while important genes involved in DNA transcription to RNA, protein translation and DNA/RNA replication are maintained. The decrease in genome size is due to the loss of protein coding genes and not to the reduction in the size of intergenic regions or the size of the open reading frame (ORF). Species that evolve naturally and contain smaller gene sizes may be responsible for an increased number of noticeable differences between them, resulting in changes in their rate of evolution. When insect-associated endosymbiotic bacteria are strictly transmitted to offspring by vertical genetic transmission, intracellular bacteria will overcome many obstacles during the process, resulting in a decrease in the actual size of the population compared to wild bacteria. The inability of endosymbiotic bacteria to reintegrate their wild-type phenotype through a recombination process is called the Muller ratchet phenomenon. Muller`s ratchet phenomenon, combined with less efficient population sizes, leads to an accumulation of harmful mutations in the non-essential genes of intracellular bacteria.  This may be due to the lack of selection mechanisms that predominate in the relatively “rich” host environment.  A radically new and sustainable economic model that confirms the possibility of developing a symbiotic relationship (positive reciprocal growth) between flourishing natural ecosystems and intense human activity in all economic areas A spectacular example of mandatory reciprocity is the relationship between Siboglinide tubular worms and symbiotic bacteria that live in hydrothermal schlots and cold sources of lezions.
The worm has no digestive tract and depends entirely on its internal symbiotes for feeding. Bacteria oxidize either hydrogen sulphide or methane provided by the host. These worms were discovered in the late 1980s in hydrothermal vents near the Galapagos Islands and have since been found in deep-water hydrothermal holes and cold lezques springs in all the world`s seas.  When assembled, innovations in three sectors of economic activity – those that use natural ecosystems, social and collaborative innovation and effective technology – enter into symbiotic relationships. Endosymbiosis is any symbiotic relationship in which one symbiote lives inside the tissues of the other, either inside the cells or extracellular.   Examples are different microbiomes: rhizobia, nitrogen bacteria that live in root tubers on legumes; actinomycetes, nitrogen bacteria such as Frankia, which live in tubers of earth roots; single-celled algae in reef corals; and bacterial endosymbions that provide essential nutrients to about 10% to 15% of insects. [Citation required] Ectosymbiosis is any symbiotic relationship in which the symbiote lives on the body surface of the host, including the inner surface of the digestive tract or the ducts of the exocrine glands.   Ectoparasites, such as lice, are examples. commensal ectosymbiontes such as thorns attached to the jaws of whales; and mutualistic ectosymbiote, like cleaner fish.