GALAPAGOS - Cophylogeography of ecological replicates: the coevolution and biogeography of Galápagos mockingbirds and their ectoparasites

Galapagos is a two-year EU funded project (2009-2011, FP7, Marie Curie Actions) aiming to explore the co-evolutionary patterns between Galápagos mockingbirds and their louse and mite parasites. The project scientific tasks are as follows:

  1. Generate molecular and morphological data necessary to resolve the population genetic and phylogenetic history of the parasites infesting Galápagos mockingbirds.
  2. Compare and contrast the genetic structure and evolutionary history of the mockingbird louse and mites lineages.
  3. Identify the common evolutionary and biogeographic processes influencing the diversification of Galápagos mockingbird ectoparasites.

Nowadays there are four enedemic species of mockingbirds (Mimus spp) distributed on the Galápagos archipelago. They evolved from a common ancestor after colonising the Galápagos from the South American mainland several million years ago. 

The Galápagos mockingbirds played an important role in the early days of evolutionary research. Slight differences in the morphology between Galápagos mockingbirds, and their apparent similarity with South American mockingbirds were first recognised by Charles Darwin during his visit to the archipelago in 1835.This experience ultimately led Darwin to the idea that species evolve through the time and triggered his work on the evolutionary theory.

Three species of ectoparasites were selected for the project. These comprised two species of lice, an amblyceran Myrsidea nesomimi, an ischnoceran Brueelia galapagensis, and a yet to be taxonomically described mite, Analges sp.

Obtained data will help to understand how the unique fauna of the Galápagos islands was formed and how it changed through time. 

Description of the main results achieved so far:

  • The project is the first attempt to reconstruct the phylogeny of multiple lineages parasitizing a single host group within the Galápagos archipelago.
  • Phylogenies for two of the three parasite lineages are highly congruent with those published for the host and with the geologic age of the islands.
  • Possible explanations for the lack of congruence for the third parasite lineage include host switching and migration between the islands or recent demographic events (e.g. bottlenecks or a genetic sweep) resulting in reduced genetic variability of sampled genes.
  • Studied system provides a model for understanding the evolutionary forces affecting genetic character of populations colonizing new habitats.
  • Correlation between the genetic diversity of parasite populations and the size of inhabited islands suggests parasites are a valuable information resource for conservation efforts of the mockingbirds.

Implications for mockingbird conservation:

Populations of the four Galápagos mockingbird species have declined dramatically since they were first studied by Charles Darwin in 1835.

Particularly threatened are populations of the Floreana mocking bird (Nesomimus trifasciatus), a species which is now extinct on the Floreana island and only survives on two small satellite islets.

Because all parasites are directly affected by the condition of their host population,genetic data obtained for populations of parasites will provide useful information for planning measures to conserve and reintroduce mockingbird populations.

In particular, populations of Myrsidea louse parasites from Champion and Gardner by Floreana islands were found to be genetically distant, whilst their hosts and the other two parasite taxa from the two islands are genetically uniform. Unexpected divergence in Myrsidea populations may indicate recent gene flow to Champion form another island, most probably Santa Fe. Whether the gene flow in one of the parasites may have also affected the mockingbird populations will be tested in future research. 

Louse related publications:

Štefka, J., Hoeck, P.E.A., Keller, L.F., Smith, V.S. (under revision) A hitchhikers guide to the Galápagos: co-phylogeography of Galápagos mockingbirds and their parasites. BMC Evolutionary Biology.

Štefka, J., Hoeck. P.E.A., Keller, L.F., Smith, V.S. Size matters: a link between habitat size and genetic diversity in the populations of Galápagos mockingbirds and their parasites. In preparation for Biology Letters (to be submitted in July 2011).

Louse related published presentation abstracts:

Štefka, J., Smith, V.S. (2010) Hitchhikers’ guide to the Galápagos: Population structure and coevolution in lice and mites parasitizing Galápagos mockingbirds. 4th International Conference on Phthiraptera., Turkey, Urgup (June 13.-18., 2010). Turkiye Parazitol. Derg., 34(Suppl.1): 82.

Louse related presentations:

Štefka, J. (2010) Is host specificity the cause or the consequence of parasite diversification: lessons from the population genetics of lice and helminths. 14th Evolutionary Biology Meeting at Marseilles. Sept. 21 – 24, 2010, Marseilles, France.

Štefka, J., Smith, V.S. (2011) A hitchhikers guide to the Galápagos: Co-phylogeography of Galápagos mockingbirds and their parasites. Joint meetings of the American Society of Naturalists (ASN), the Society for the Study of Evolution (SSE), and the Society of Systematic Biologists (SSB). The University of Oklahoma, Norman, Oklahoma, USA. June 17 - 21, 2011.

Downloadable datasets and other files:

 Associated publications & presentations:

Králová-Hromadová, I., Bazsalovicsová, E., Štefka, J., Spakulová, M., Vávrová, S., Szemes, T., et al. (2011). Multiple origins of European populations of the giant liver fluke Fascioloides magna (Trematoda: Fasciolidae), a liver parasite of ruminants. International Journal for Parasitology, 41(3-4): 373-83. doi: 10.1016/j.ijpara.2010.10.010.

Bazsalovicsová, E., Králová-Hromadová, I., Štefka, J., Scholz, T., Hanzelová, V., Vávrová, S., Szemes, T., Kirk, R. (2011) Population study of Atractolytocestus huronensis (Cestoda: Caryophyllidea), an invasive parasite of common carp introduced to Europe: mitochondrial cox1 haplotypes and intragenomic ribosomal ITS2 variants. Parasitology Research, 109: 125-131. doi: 10.1007/s00436-010-2235-x.

Králová-Hromadová, I., Bazsalovicsová, E., Štefka, J., Scholz, T. Molecular characterization of Atractolytocestus sagittatus (Cestoda: Caryophyllidea), monozoic parasite of common carp, and its differentiation from Atractolytocestus huronensis. (in preparation for submission in July 2011)

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith