title: Support for the evolutionary speed hypothesis from intraspecific population genetic data in the non-biting midge Chironomus riparius.
abstract: The evolutionary speed hypothesis (ESH) proposes a causal mechanism for the latitudinal diversity gradient. The central idea of the ESH is that warmer temperatures lead to shorter generation times and increased mutation rates. On an absolute time scale, both should lead to an acceleration of selection and drift. Based on the ESH, we developed predictions regarding the distribution of intraspecific genetic diversity: populations of ectothermic species with more generations per year owing to warmer ambient temperatures should be more differentiated from each other, accumulate more mutations and show evidence for increased mutation rates compared with populations in colder regions. We used the multivoltine insect species Chironomus riparius to test these predictions with cytochrome oxidase I (COI) sequence data and found that populations from warmer regions are indeed significantly more differentiated and have significantly more derived haplotypes than populations from colder regions. We also found a significant correlation of the annual mean temperature with the population mutation parameter θ that serves as a proxy for the per generation mutation rate under certain assumptions. This pattern could be corroborated with two nuclear loci. Overall, our results support the ESH and indicate that the thermal regime experienced may be crucially driving the evolution of ectotherms and may thus ultimately govern their speciation rate.
authors.affiliation: Molecular Ecology Group, Institute for Ecology, Evolution and Diversity, Goethe-University Frankfurt am Main, Hessen, Germany Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany ann-marie.oppold@senckenberg.de.
authors.forename: Ann-Marie
authors.identifier: http://orcid.org/0000-0003-2637-0766
authors.initials: AM
authors.lastname: Oppold
authors.affiliation: Departamento de Biologia and CESAM, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal Conservation Genetics Group, Senckenberg Research Institute, Gelnhausen, Hessen, Germany.
authors.forename: João A M
authors.initials: JA
authors.lastname: Pedrosa
authors.affiliation: Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany.
authors.forename: Miklós
authors.initials: M
authors.lastname: Bálint
authors.affiliation: Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany.
authors.forename: João B
authors.initials: JB
authors.lastname: Diogo
authors.affiliation: Institute of Biodiversity and Ecosystem research, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: Julia
authors.initials: J
authors.lastname: Ilkova
authors.affiliation: Departamento de Biologia and CESAM, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.
authors.forename: João L T
authors.initials: JL
authors.lastname: Pestana
authors.affiliation: Molecular Ecology Group, Institute for Ecology, Evolution and Diversity, Goethe-University Frankfurt am Main, Hessen, Germany Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Pfenninger
mesh_terms: D063147:Animal Distribution; D000818:Animals; D005075:Biological Evolution; D002683:Chironomidae / Q000235:genetics / Q000502:physiology*; D002980:Climate; D005060:Europe; D006239:Haplotypes; D013696:Temperature
keywords: intraspecific diversity; neutral evolution; population differentiation; speciation