title: Amino acid transporter expansions associated with the evolution of obligate endosymbiosis in sap-feeding insects (Hemiptera: sternorrhyncha).
abstract: BACKGROUND
  Mutualistic obligate endosymbioses shape the evolution of endosymbiont genomes, but their impact on host genomes remains unclear. Insects of the sub-order Sternorrhyncha (Hemiptera) depend on bacterial endosymbionts for essential amino acids present at low abundances in their phloem-based diet. This obligate dependency has been proposed to explain why multiple amino acid transporter genes are maintained in the genomes of the insect hosts. We implemented phylogenetic comparative methods to test whether amino acid transporters have proliferated in sternorrhynchan genomes at rates grater than expected by chance.
  
  
  RESULTS
  By applying a series of methods to reconcile gene and species trees, inferring the size of gene families in ancestral lineages, and simulating the null process of birth and death in multi-gene families, we uncovered a 10-fold increase in duplication rate in the AAAP family of amino acid transporters within Sternorrhyncha. This gene family expansion was unmatched in other closely related clades lacking endosymbionts that provide essential amino acids.
  
  
  CONCLUSIONS
  Our findings support the influence of obligate endosymbioses on host genome evolution by both inferring significant expansions of gene families involved in symbiotic interactions, and discovering increases in the rate of duplication associated with multiple emergences of obligate symbiosis in Sternorrhyncha.
authors.affiliation: Department of Ecology and Evolution, State University of New York at Stony Brook, Stony Brook, NY, 11794, USA. romain.a.dahan@gmail.com.|Department of Biology, University of Rochester, Rochester, NY, 14627, USA. romain.a.dahan@gmail.com.
authors.forename: Romain A
authors.initials: RA
authors.lastname: Dahan
authors.affiliation: Department of Biology, University of Miami, Coral Gables, FL, 33146, USA. rduncan@bio.miami.edu.
authors.forename: Rebecca P
authors.initials: RP
authors.lastname: Duncan
authors.affiliation: Department of Biology, University of Miami, Coral Gables, FL, 33146, USA. acwilson@bio.miami.edu.
authors.forename: Alex C C
authors.initials: AC
authors.lastname: Wilson
authors.affiliation: Department of Ecology and Evolution, State University of New York at Stony Brook, Stony Brook, NY, 11794, USA. Liliana.Davalos-Alvarez@stonybrook.edu.|Consortium for Inter-Disciplinary Environmental Research (CIDER), State University of New York at Stony Brook, Stony Brook, NY, 11794, USA. Liliana.Davalos-Alvarez@stonybrook.edu.
authors.forename: Liliana M
authors.initials: LM
authors.lastname: Dávalos
mesh_terms: D000465:Algorithms; D026905:Amino Acid Transport Systems / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D005075:Biological Evolution; D006430:Hemiptera / Q000145:classification* / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D013559:Symbiosis
chemical_list: D026905:Amino Acid Transport Systems; D019476:Insect Proteins