Nathan Rank

Sonoma State University

Evolution of host plant preference
Results and conclusions (Page 3 of 3)

Introduction

Species & Genes Sampled

Results & Conclusions

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See also research summary.

  • A robust tree indicated that Phratora is a monophyletic group and that morphologically similar species are especially closely related.
  • The use of host plant salicylates to produce a salicylaldehyde larval secretion evolved along the lineage leading to P. vitellinae.
  • Our reconstruction of host plant preference suggests that evolutionary history constrains host plant use but that radical changes in host plant use are possible after specialization.


Phylogenetic analysis

  • The topology of the tree remained identical, regardless of whether parsimony or maximum-likelihood methods were used.
  • Bootstrap values were very high for most nodes in the tree.
  • The phylogenetic tree showed that Phratora clearly is a monophyletic group.
  • Species that are morphologically similar tend to cluster together in the tree (e.g. the North American P. aklaviki and the European P. vulgatissima).
  • The willow-feeding P. polaris and birch-feeding P. polaris probably belong to different species.

 

Phylogenetic tree based on maximum parsimony analysis of the nucleotide sequence.

Host use reconstruction.

  • Closely related beetles tend to use related or chemically similar host plant species.
  • There was a trend towards increasing specialization in Phratora, because the basal species, P. vitellinae, had the broadest diet.
  • Specialized species are still capable of making a shift among host families (from willows in the Salicaceae to birch in the Betulaceae)
  • There was no evidence in favor of the Predation Hypothesis, because the species that uses host salicylates for its larval secretion, P. vitellinae, has the broadest diet breadth (see also pages on Natural enemies and herbivore host use).


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January 23, 1999 NER