A science study reveals mites and ticks represent one evolutionary lineage only
Mites and ticks represent only one evolutionary lineage -and not two, which was thought so far- according to a new article published in Nature Communications. The first author of the article is Jesús Lozano, from the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio).
These findings, which provide a new view on biodiversity over biological evolution, are based on the largest genomic study to rebuild the evolutionary history of chelicerates, a group of more than 110.000 arthropods including spiders, scorpions, mites and ticks. Other experts from the University of Bristol and the Museum of Natural History of London (United Kingdom), and the National University of Ireland took part in the study.
Mites and ticks represent only one evolutionary lineage -and not two, which was thought so far- according to a new article published in Nature Communications. The first author of the article is Jesús Lozano, from the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio).
These findings, which provide a new view on biodiversity over biological evolution, are based on the largest genomic study to rebuild the evolutionary history of chelicerates, a group of more than 110.000 arthropods including spiders, scorpions, mites and ticks. Other experts from the University of Bristol and the Museum of Natural History of London (United Kingdom), and the National University of Ireland took part in the study.
An evolutionary history with more than 500 million years
Arthropods are a highly diversified taxonomic group of invertebrates with articulated legs which are now the biggest part of the animal biodiversity. This is an old biological taxon -there are fossils from the Cambrian Period- and its evolutionary history is believed to be older than 500 million years.
Among other general traits, these bilateral symmetric bodies with a segmented body, have an exoskeleton -formed by proteins and chitin- with articulated pieces, appendixes and sensory organs. With a global distribution in several ecosystems -from oceanic crusts to the troposphere- some specimens can pollinize (bees, butterflies) or can have commercial interest (shrimps, crabs) while others can bring diseases (mites, mosquitoes, louses, ticks). To understand their biological success -a wide range of species in different environments- is determining to understand the evolutionary history and genetic parentage with different groups of arthropods.
Mites and ticks: closer than what was thought
Mites and ticks share many anatomical similarities “and that suggests they formed a natural evolutionary group, which has been called Acari. However, not all anatomists share this opinion, and genomic data had never supported this idea”, notes the expert Greg Edgecombe, from the Natural History Museum of London.
In the new study, the scientific team studied ten species of mites and eleven species of ticks -almost equivalent- that form the most complete biological sample analysed so far at a genomic scale in these groups. “Regardless of the method we use, our results merge into a same conclusion: mites and ticks create a natural group”, notes the expert Jesús Lozano, member of the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB and also researcher at the University of Bristol.
A new phylogenetic tree for chelicerate arthropods
The article in Nature Communications provides a new evolutionary view on spiders, a zoological group with more than 48,000 described species which were thought to have the chelicerate lineage with the largest biodiversity on Earth. Davide Pisani, lecturer at the University of Bristol and co-author of the study says that “there are more than 42,000 mites and 12,000 ticks described now. If these two groups form an only evolutionary group -and not two different ones, like it was believed so far- we should consider the Acari group larger than the spidersʼ”.
According to Jesús Lozano, “we could prove the group of arachnids colonized the Earth once and not several ways, like previous studies had suggested. Therefore, evolutionary trees such as the ones in this study bring determining data to understand the processes of genomic changes”.
“This new view of the phylogenetic tree in chelicerates is of great interest in the field of compared applied genomics to treat issues that are relevant in biomedicine and agriculture, such as identification of genomic changes that allowed the evolution of parasite ticks that feed from blood from ancestors that did not”, concludes Lozano.
Further information
Jesús Lozano-Fernández, Alastair R. Tanner, Mattia Giacomelli, Robert Carton, Jakob Vinther, Gregory D. Edgecombe y Davide Pisani. «Increasing species sampling in chelicerate genomic-scale datasets provides support for monophyly of Acari and Arachnida». Nature Communications, May 2019. Doi: https://doi.org/10.1038/s41467-019-10244-7