richard-merrillThe genetic basis of ecological differences between two sympatric Heliconius species

The sister species Heliconius cydno and Heliconius melpomene are sympatric across much of Central and northern South America. They differ in mimetic colour pattern, which both warns predators and attracts mates, as well as in habitat and host-plant use: In Panama, H.cydno mimics Heliconius sapho, is normally found in primary forest and oviposits on a range of Passiflora species; H. melpomene, on the other hand, mimics Heliconius erato, occurs in secondary forest and specialises on Passsiflora menispermifolia. Despite these differences the two butterflies are often seen flying together and will hybridise in nature, albeit at very low frequency.

Currently based at the Smithsonian Tropical Research Institute in Panama, my research will investigate the ecology and genetics of traits that keep these species separate. In particular, my work will focus on the genetic basis of male mate preferences that result in assortative mating. Because genetic architecture can influence both the effects of selection on associated loci and recombination understanding the genetics of such traits will shed light on the speciation of these two butterflies .  

Male mate preference is associated with forewing colour.

The probability of courting H. melpomene live females (a) and wing pattern models (b) by backcross hybrids to H. cydno that have the red forewing band (Bb, red squares) and those that do not (bb, white squares). Blacked-out males had their forewing colour pattern obscured in order to prevent self-matching. Dashed lines represent the probabilities of courting live H. melpomene females forH. melpomene (MP) and H. cydno (CP) males (from Merrill et al. 2011 Proc. Bio. Sci.).

      CV

  • 2011-present. Junior Research Fellow, King’s College, Cambridge
  • 2007-2011 PhD, Department of Zoology, University of Cambridge, UK (BBSRC funded)
  • 2005-2006 MSc in Biology (Integrative Biosciences), University of Oxford
  • 2001-2004 BSc (Hons), Biology, University College London

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Publications

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Merrill, R. M., Naisbit, R. E., Mallet, J. & Jiggins, C. D. Ecological and genetic factors influencing the transition between host-use strategies in sympatric Heliconius butterflies. Journal of Evolutionary Biology 26, 1959–1967 (2013).
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Merrill, R. M. et al. Disruptive ecological selection on a mating cue. Proc. R. Soc. B 279, 4907–13 (2012).
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Van Dijk, R. E. et al. Maternal effects in the highly communal sociable weaver may exacerbate brood reduction and prepare offspring for a competitive social environment. Oecologia (2012). doi:10.1007/s00442-012-2439-0
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Merrill, R. M. et al. Mate preference across the speciation continuum in a clade of mimetic butterflies. Evolution 65, 1489–1500 (2011).
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Merrill, R. M., Van Schooten, B., Scott, J. A. & Jiggins, C. D. Pervasive genetic associations between traits causing reproductive isolation in Heliconius butterflies. Proc Biol Sci 278, 511–518 (2011).
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Merrill, R. M. & Jiggins, C. D. Müllerian Mimicry: Sharing the Load Reduces the Legwork. Current Biology 19, R687–R689 (2009).
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Seddon, N., Merrill, R. M. & Tobias, J. A. Sexually selected traits predict patterns of species richness in a diverse clade of suboscine birds. Am. Nat. 171, 620–631 (2008).
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Merrill, R. M. et al. Combined effects of climate and biotic interactions on the elevational range of a phytophagous insect. J Anim Ecol 77, 145–55 (2008).