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Published on: February 11, 2020
High genetic load in an old isolated butterfly population
Anniina L K Mattila1, Anne Duplouy, Malla Kirjokangas
1Metapopulation Research Group, Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland. anniina.mattila@helsinki.fi
Small island populations of Glanville fritillary butterflies (Melitaea cinxia) show high genetic load due to accumulated mutations. This genetic burden threatens their survival in fragmented landscapes.
Area of Science:
- Evolutionary Biology
- Conservation Genetics
- Population Genetics
Background:
- Small, isolated populations face unique evolutionary pressures.
- The Glanville fritillary butterfly (Melitaea cinxia) on Pikku Tytärsaari (PT) island has been isolated for over 75 years.
- Understanding genetic load is crucial for assessing extinction risk in endangered populations.
Purpose of the Study:
- To investigate inbreeding depression and genetic load in an isolated Glanville fritillary butterfly population.
- To compare genetic load and diversity with mainland populations.
- To assess the impact of genetic load on various fitness-related traits.
Main Methods:
- Studied 58 traits including behavior, development, morphology, and metabolism.
- Compared the isolated PT population with reference populations from the Åland Islands and Estonia.
- Analyzed microsatellite markers to assess genetic diversity.
- Conducted crosses to observe heterosis effects on egg viability and metabolic rate.
Main Results:
- The PT population exhibited high genetic load in traits like adult weight (L=0.12), flight metabolic rate (L=0.53), egg viability (L=0.37), and lifetime egg production (L=0.70).
- Reduced genetic diversity and immediate heterosis in crosses indicated fixation of deleterious recessive mutations.
- No significant inbreeding depression was observed after one generation of full-sib mating.
- Elevated resting metabolic rate in males correlated with shorter lifespans (L=0.25).
Conclusions:
- The isolated PT population demonstrates significant genetic load, consistent with mutation accumulation models for small populations.
- High genetic load makes this population vulnerable to extinction, highlighting risks in fragmented landscapes.
- Conservation efforts may need to address genetic rescue strategies for such isolated populations.
Related Concept Videos
Mutation, Gene Flow, and Genetic Drift
Frequency-dependent Selection
Genetic Drift
Gene Flow
Hardy-Weinberg Principle
Conservation of Small Populations

