Restricted gene flow between two social forms in the ant Formica truncorum

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Population Genetics

Background:

• Formica truncorum ants exhibit distinct social structures: M-type (single queen, independent nest founding) and P-type (multiple queens, dependent nest founding, colonial networks).
• These social types coexist as sympatric populations within a single locality, raising questions about their genetic distinctiveness.

Purpose of the Study:

• To investigate the genetic differentiation and gene flow between the M-type and P-type social forms of Formica truncorum.
• To understand the implications of genetic exchange on social evolution and reproductive strategies within these ant populations.

Main Methods:

• Analysis of genetic differentiation using nuclear and mitochondrial DNA markers.
• Mitochondrial haplotype analysis to assess female gene flow.
• Nuclear DNA analysis to evaluate male gene flow and population structure.
• Assignment analysis to infer individual origins and gene flow patterns.

Main Results:

• Significant genetic differentiation was found between the M-type and P-type populations.
• Absence of shared mitochondrial haplotypes indicates no female gene flow between the social forms.
• Weak male gene flow was detected, with some evidence of P-type males mating with M-type females.
• Assignment analysis confirmed limited but detectable gene flow, particularly from P-type males to M-type females.

Conclusions:

• Restricted gene flow, especially among females, contributes to the genetic distinctiveness of the two social forms.
• Inferred gene flow from P-type to M-type populations may lead to suboptimal sex ratios in M-type colonies.
• Further research in additional localities is needed to generalize these findings on social evolution and gene flow.