Understanding rapid evolution using historical pest genomes

Angela McGaughran

Helicoverpa moths are an ideal group for studying the effects of insecticide resistance driving rapid evolution.

Dr Angela McGaughran is a post-doctoral fellow at CSIRO, visiting from the University of Melbourne.

Angela specialises in adaptation and population genomics, and has a particular interest in understanding the ways in which natural populations respond to environmental change.

Her work at CSIRO focuses on two Australian moth species:

  1. Helicoverpa armigera (cotton bollworm) - the most significant food and fibre crop pest in Asia, Europe, Africa, and Australasia, causing an excess of US$2 billion worth of damage annually.
  2. H. punctigera (native budworm) - an endemic Australian species without significant pest status.

Helicoverpa armigera and H. punctigera share many inherent 'pesty' characteristics that make them successful and highly adaptive species:

  • high migratory capacity
  • wide host plant range
  • high fecundity
  • ability to enter diapause to avoid adverse environmental conditions

However, there is a key difference - H. armigera has evolved resistance to all commonly used insecticides, while H. punctigera has never developed any resistance.

This makes them an ideal pair of species for studying the effects of insecticide resistance driving rapid evolution.

Populations can adapt to new environments in two distinct ways:

  1. They can wait for the appearance of an advantageous novel mutation, which will become quickly established in the population; or
  2. They can evolve immediately by co-opting standing (i.e. pre-existing) genetic variation. 

However, determining whether adaptive mutations pre-date environmental change is difficult. To discriminate between the two possibilities in natural populations requires samples that have not been exposed to the selection pressure, ie. insecticides.

Angela's research will address this by comparing DNA sequences from historical, insecticide-free pest genomes (using pinned specimens from the Australian National Insect Collection) to contemporary populations of H. armigera and H. punctigera that are currently exposed to insecticides.

Her work will examine the genetic make-up of a fast adaptive response to environmental change, providing a template for testing questions about the presence or absence of pre-adapted resistance genes, and for understanding the mechanisms behind successful pest status.

Angela did her PhD in New Zealand (Massey University), and her first post-doc in Germany (Max Planck Institute), where she examined adaptive responses among populations of springtails in Antarctica, and nematodes on La Réunion Island, respectively.

While based at CSIRO, Angela is keen to collaborate with others and to continue building her skills in computational and big data analysis.

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Molecular phylogeny of Helicoverpa from museum specimens

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