Vector-agent co-adaptation in arthropod transmitted disease
A. Sonia Olmeda, José-Luis Pérez, Félix Valcárcel
There are multiple and varied mechanisms by which some arthropods have adapted to parasitism. The absence of fossils has prevented us from dating the origin of this process, but we can say that the first ancestor of each animal species which we know today has been affected by ticks, which evolved in it and adapted intimately to its biological and ecological characteristics. In the process of co-evolution they learned to coexist, limiting the harm which they mutually infringed upon each other in an instable equilibrium which could be disturbed by any of their defensive barriers.
There is not only one origin by which multiple agents began to use vectors to pass form one invertebrate to another, and there are many organisms which chose the advantages offered by this living vehicle. Only those vector agents which were relatively innocuous for both invertebrate and vertebrate were able to perpetuate this form of transmission and co-evolution with them.
Domestication as well as the introduction of humans in environments of other species are the principal causes of equilibrium rupture and are also the reason why vector-borne diseases are considered emerging processes requiring worldwide attention. An ecological and evolutionary view could allow a better control of these diseases by achieving recovery of natural stability.