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Stepping‐stone expansion and habitat loss explain a peculiar genetic structure and distribution of a forest insect
Author(s) -
CasselLundhagen Anna,
Ronnås Cecilia,
Battisti Andrea,
Wallén Johan,
Larsson Stig
Publication year - 2013
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.12313
Subject(s) - biology , biological dispersal , range (aeronautics) , gene flow , ecology , genetic structure , genetic diversity , isolation by distance , genetic divergence , species distribution , biogeography , evolutionary biology , habitat , genetic variation , population , genetics , gene , materials science , demography , sociology , composite material
Abstract It is challenging to unravel the history of organisms with highly scattered populations. Such species may have fragmented distributions because extant populations are remnants of a previously more continuous range, or because the species has narrow habitat requirements in combination with good dispersal capacity (naturally or vector borne). The northern pine processionary moth T haumetopoea pinivora has a scattered distribution with fragmented populations in two separate regions, northern and south‐western E urope. The aims of this study were to explore the glacial and postglacial history of T . pinivora , and add to the understanding of its current distribution and level of contemporary gene flow. We surveyed published records of its occurrence and analysed individuals from a representative subset of populations across the range. A 633 bp long fragment of the mt DNA COI gene was sequenced and nine polymorphic microsatellite loci were genotyped. Only nine nucleotide sites were polymorphic in the COI gene and 90% of the individuals from across its whole range shared the same haplotype. The microsatellite diversity gradually declined towards the north, and unique alleles were found in only three of the northern and three of southern sites. Genetic structuring did not indicate complete isolation among regions, but an increase of genetic isolation by geographic distance. Approximate B ayesian model choice suggested recent divergence during the postglacial period, but glacial refugia remain unidentified. The progressive reduction of suitable habitats is suggested to explain the genetic structure of the populations and we suggest that T . pinivora is a cold‐tolerant relict species, with situation‐dependent dispersal.