title: Genomic divergence and lack of introgressive hybridization between two 13-year periodical cicadas support life cycle switching in the face of climate change.
abstract: Life history evolution spurred by post-Pleistocene climatic change is hypothesized to be responsible for the present diversity in periodical cicadas (Magicicada), but the mechanism of life cycle change has been controversial. To understand the divergence process of 13-year and 17-year cicada life cycles, we studied genetic relationships between two synchronously emerging, parapatric 13-year periodical cicada species in the Decim group, Magicicada tredecim and M. neotredecim. The latter was hypothesized to be of hybrid origin or to have switched from a 17-year cycle via developmental plasticity. Phylogenetic analysis using restriction-site-associated DNA sequences for all Decim species and broods revealed that the 13-year M. tredecim lineage is genomically distinct from 17-year Magicicada septendecim but that 13-year M. neotredecim is not. We detected no significant introgression between M. tredecim and M. neotredecim/M. septendecim thus refuting the hypothesis that M. neotredecim are products of hybridization between M. tredecim and M. septendecim. Further, we found that introgressive hybridization is very rare or absent in the contact zone between the two 13-year species evidenced by segregation patterns in single nucleotide polymorphisms, mitochondrial lineage identity and head width and abdominal sternite colour phenotypes. Our study demonstrates that the two 13-year Decim species are of independent origin and nearly completely reproductively isolated. Combining our data with increasing observations of occasional life cycle change in part of a cohort (e.g. 4-year acceleration of emergence in 17-year species), we suggest a pivotal role for developmental plasticity in Magicicada life cycle evolution.
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Koyama
authors.affiliation: Graduate School of Science and Technology, Shizuoka University, Hamamatsu, 432-8561, Japan.|Department of International Health, Institute of Tropical Medicine, Nagasaki University, Nagasaki, 852-8523, Japan.
authors.forename: Hiromu
authors.initials: H
authors.lastname: Ito
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan.
authors.forename: Tomochika
authors.initials: T
authors.lastname: Fujisawa
authors.affiliation: Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, 036-8561, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Graduate School of Science and Technology, Shizuoka University, Hamamatsu, 432-8561, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kakishima
authors.affiliation: College of Integrative Sciences, Wesleyan University, Middletown, CT, 06459, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Cooley
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06268-3043, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Simon
authors.affiliation: Graduate School of Science and Technology, Shizuoka University, Hamamatsu, 432-8561, Japan.|Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY, 13210, USA.|Marine Biosystems Research Center, Chiba University, Uchiura, Kamogawa, Chiba, 299-5502, Japan.
authors.forename: Jin
authors.initials: J
authors.lastname: Yoshimura
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan. sota@terra.zool.kyoto-u.ac.jp.
authors.forename: Teiji
authors.initials: T
authors.lastname: Sota
mesh_terms: D000818:Animals; D005075:Biological Evolution; D057231:Climate Change; D004272:DNA, Mitochondrial / Q000235:genetics; D023281:Genomics; D006430:Hemiptera / Q000145:classification / Q000235:genetics*; D006824:Hybridization, Genetic; D008018:Life Cycle Stages; D010641:Phenotype; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide
chemical_list: D004272:DNA, Mitochondrial
keywords: contact zone; developmental plasticity; gene flow; reproductive isolation; restriction-site-associated DNA sequences; single nucleotide polymorphism