The evolution of invasiveness in garden ants.
It is unclear why some species become successful invaders whilst others fail, and whether invasive success depends on pre-adaptations already present in the native range or on characters evolving de-novo after introduction. Ants are among the worst invasive pests, with Lasius neglectus and its rapid spread through Europe and Asia as the most recent example of a pest ant that may become a global problem. Here, we present the first integrated study on behavior, morphology, population genetics, chemical recognition and parasite load of L. neglectus and its non-invasive sister species L. turcicus. We find that L. neglectus expresses the same supercolonial syndrome as other invasive ants, a social system that is characterized by mating without dispersal and large networks of cooperating nests rather than smaller mutually hostile colonies. We conclude that the invasive success of L. neglectus relies on a combination of parasite-release following introduction and pre-adaptations in mating system, body-size, queen number and recognition efficiency that evolved long before introduction. Our results challenge the notion that supercolonial organization is an inevitable consequence of low genetic variation for chemical recognition cues in small invasive founder populations. We infer that low variation and limited volatility in cuticular hydrocarbon profiles already existed in the native range in combination with low dispersal and a highly viscous population structure. Human transport to relatively disturbed urban areas thus became the decisive factor to induce parasite release, a well established general promoter of invasiveness in non-social animals and plants, but understudied in invasive social insects.
Cremer
Sylvia
S
Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark. sylvia.cremer@biologie.uni-regensburg.de
Ugelvig
Line V
LV
Drijfhout
Falko P
FP
Schlick-Steiner
Birgit C
BC
Steiner
Florian M
FM
Seifert
Bernhard
B
Hughes
David P
DP
Schulz
Andreas
A
Petersen
Klaus S
KS
Konrad
Heino
H
Stauffer
Christian
C
Kiran
Kadri
K
Espadaler
Xavier
X
d'Ettorre
Patrizia
P
Aktaç
Nihat
N
Eilenberg
Jørgen
J
Jones
Graeme R
GR
Nash
David R
DR
Pedersen
Jes S
JS
Boomsma
Jacobus J
JJ
D000374:Aggression; D000818:Animals; D001000:Ants / Q000737:chemistry / Q000235:genetics* / Q000382:microbiology / Q000469:parasitology; D001208:Asia; D052982:Beauveria / Q000302:isolation & purification; D001522:Behavior, Animal; D005075:Biological Evolution; D005060:Europe; D005828:Genetics, Population; D006838:Hydrocarbons / Q000032:analysis; D009425:Nesting Behavior; D011157:Population Dynamics; D020577:Wolbachia / Q000302:isolation & purification
D006838:Hydrocarbons