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Dr Andrea Waeschenbach

Image of Andrea Waeschenbach
  • Post-Doc Research Assistant - NSF PBI
  • Zoology department
  • Zoology Biomedical Parasitology Research
Natural History Museum
Cromwell Road
London
SW7 5BD

Biography

Qualifications

  • B. Sc. (Marine Biology), University of Wales, Swansea, U.K. 1999
  • Ph.D, University of Wales, Swansea, U.K. 2003

Employment history

  • NERC Postdoctoral Researcher, Natural History Museum, London, UK, 2007 – present
  • Postdoctoral Research Assistant, Natural History Museum, London, UK, 2006 – 07
  • Wellcome Trust Research Assistant, Natural History Museum, London, UK, 2005 – 06
  • NERC Postdoctoral Research Associate, Natural History Museum, London, UK, 2004 – 05

Bryozoa Research

External Links

Rates, patterns and divergence times among the Bryozoa: integrating fossil, molecular and morphological data

This NERC-funded project (NE/E015298/1) is in collaboration with Tim Littlewood, Paul Taylor (NHM) and 

Joanne Porter

(Heriot-Watt University, Edinburgh). We use molecular data from mitochondrial genomes, ribosomal RNA and nuclear protein coding genes, together with multiple calibration points from an extensive fossil record, to resolve some of the phylogenetic uncertainties in this group and to construct date-calibrated trees.

Underwater picture of cheilostome bryozoans

© Joanne Porter

  

 

  • The interrelationships of the three bryozoan classes and their position amongst the Metazoa

Data from mitochondrial genomes place the phylum Bryozoa as a monophyletic clade within the Lophotrochozoa (see below). The freshwater bryozoans (Class Phylactolaemata) are distinct from all other bryozoans in their morphology as well as in their life history, propagating by means of clonal resting stages (statoblasts). According to our data, this group forms the most basal taxon in the phylum. This suggests that the remaining bryozoan lineages, largely consisting of marine taxa, have evolved from an uncalcified freshwater ancestor.

Interrelationships of bryozoan classes and their position amongst the Lophotrochozoa

 

 

 

  • Larval strategy as a driving force in macroevolutionary processes
Brood chamber of the cyclostome bryozoan Hornera foliacea

Brood chamber of the cyclostome bryozoan Hornera foliacea, situated on the back of the colony. © Andrea Waeschenbach

 

The three classes of Bryozoa differ greatly in the way they reproduce and propagate.  The Phylactolaemata, which live exclusively in freshwater, largely propagate by asexually produced resting stages. The Cyclostomata are unique amongst bryozoans, in that they reproduce via polyembryony. Large brood chambers (see right) are formed by the colony, which accommodate clonal replication of embryos to produce numerous genetically identical offspring from a single sexually produced larva. Amongst the Gymnolaemata some species produce planktotrophic and others lecithotrophic larvae.  A subgroup of the Gymnolaemata, the Cheilostomata underwent an extensive radiation during the late Cretaceous, which is thought to have been triggered by the advent of brooding lecithotrophic larvae.  As a result, approximately 75% of today's bryozoans belong to the Cheilostomata. They are an extremely diverse group of >5000 species, exhibiting extensive morphological polymorphisms. The Cyclostomata, on the other hand, make up about 20% of all bryozoan species and are morphological less complex, compared to cheilostomes. The least diverse group, the Phylactolaemata, only contains ~85 species.

We investigate whether the type of reproductive strategy (asexual vs. polyembryony vs. planktotrophy vs. lecithotrophy) correlates with rates of speciation and rates of molecular and morphological change across the phylum.

 

The cyclostome bryozoan Hornea foliacea

Frontal view of the cyclostome bryozoan Hornera foliacea, showing zooids and pseudopores. © Andrea Waeschenbach

 

  • The interrelationships and origins of orders in the class Stenolaemata, a group for which morphological phylogeny-informative characters are sparse

A molecular phylogeny of the stenolaemate order Cyclostomata revealed several of the suborders and one family to be polyphyletic (see below).  Hence, convergent evolution has resulted in highly homoplasious morphological characters, which have prevented the construction of a robust phylogeny in the past. This discovery of polyphyly of well-studied fossil taxa raises uncertainties of temporal species range inference and the estimation of extinction rates. It highlights the importance of generating robust molecular phylogenetic frameworks prior to deriving evolutionary and geological hypotheses based on fossil taxa.

 

Using additional data, this phylogeny is being date-calibrated to provide an age estimate for the most common recent ancestor of the Cyclostomata. This is intended to test whether they are a truly monophyletic group, having originated ~ 150 Ma, or whether some suborders are, in fact, representatives of lineages that are thought to have gone extinct during the Triassic, which would push this node as far back as ~480 Ma.

Phylogeny of cyclostome bryozoans

Phylogeny of cyclostome bryozoans based on ssr+lsrDNA (Waeschenbach et al. 2009)

Novel markers from complete mitochondrial genomes for populations genetics and cryptic species detection in the bryozoan Celleporella hyalina.

As part of this collaborative project with Roger Hughes (University of Bangor) and Joanne Porter (Heriot-Watt University Edinburgh), who had been awarded funding for this work from the Centre for Integrated Research in the Rural Environment (CIRRE), I'm sequencing two mitochondrial genomes of the cheilostome bryozoan Celleporella hyalina, a supposedly cosmopolitan species, which is expected to be a complex of several cryptic species. Molecular markers will be developed from the mitochondrial data to tackle this issue, as well as to construct a wider-context phylogeny of the family Hippothooidae.

Helminth Research

Previous research with Tim Littlewood at the NHM focussed on molecular phylogenetics of platyhelminths and nematodes. Some of the projects I have been involved with are listed below:

Ordinal level tapeworm phylogeny

SEM image of Rhinebothrium sp.

The anterior attachment organ of the tapeworm Rhinebothrium sp. © Claire Healy

 

Complete small and large nuclear ribosomal DNA (18S, 28S) was sequenced from representatives across all tapeworm orders in order to provide a comprehensive phylogenetic framework for this group. The interrelationships for most lineages could be resolved, although ambiguity remained amongst the basal lineages (Waeschenbach et al. 2007). We subsequently sequenced 4kb of mitochondrial data for the same taxa, attempting to resolve the basal part of the tree.

Phylogeny of trypanorhynch tapeworms

In a collaboration led by 

Harry Palm (Heinrich-Heine-Universität Düsseldorf), we produced a comprehensive molecular phylogeny of trypanorhynch tapeworms. This study revealed morphological characters, used for traditional taxonomy, to be highly homoplasious (Palm et al. 2009).

 

Mating behaviour, sexual conflict and the
evolution of sperm design in the flatworm
Macrostomum

A study, led by 

Lukas Schärer (Universität Basel), on the free-living, hermaphroditic flatworm Macrostomum, showed differences in sperm morphology to be linked to mating behaviour and sexual conflict. In a reciprocal mating system, sperm have a highly complex morphology, adapted to the shape and structure of the female sperm receiving organ, to prevent sperm rejection. Whereas in the hypodermic impregnation system, sperm morphology is much simpler. By placing these observations into a phylogenetic framework, we found hypodermic impregnation to have evolved independently, at least twice, probably as a result of male strategy to by-pass female control.
The nematode Toxocara

The nematode Toxocara is commonly found in the intestine of cats and dogs and is the causative agent of toxocariasis in humans. Ocular larval migrans can, in severe cases, lead to blindness. © www.petcaregt.com/blog/
cat-worm.html

 

Nematode mitochondrial genomes

In a collaboration led by 

Robin Gasser

 and Aaron Jex (University of Melbourne), we sequenced several mt genomes of nematodes (Jex et al. 2009, 2008; Jex & Waeschenbach et al. 2008). The resultant data is used to provide phylogenetic estimates for this group and to develop novel molecular markers for diagnostics and population genetics.

Mitogenomics of Platyhelminthes

In addition to the published mt genomes of tapeworms and monogeneans, we sequenced the mt genomes of three free-living turbellarians and two basal tapeworm lineages.  This comprehensive dataset is expected to provide a well-supported phylogeny of Platyhelminthes.

Other projects

  • Resolving the molecular phylogeny for the genus Pedibothrium and reconstructing its evolution in orectolobiform sharks (led by collaborator Janine Caira, University of Connecticut).
  • Molecular phylogeny of tetraphyllidean tapeworms (led by collaborator Janine Caira, University of Connecticut).

Publications

2012

Waeschenbach A, Webster, BL, Littlewood, DTJ (2012) Adding resolution to ordinal level relationships of tapeworms (Platyhelminthes: Cestoda) with large fragments of mtDNA, Molecular Phylogenetics and Evolution, in press.

Waeschenbach A, Taylor PD, Littlewood DTJ (2012) A molecular phylogeny of bryozoans, Molecular Phylogenetics and Evolution, 62:718-735.

2011

Schärer L, Littlewood DTJ, Waeschenbach A, Yoshida W & Vizoso D (2011) Mating behaviour and the evolution of sperm design, Proceedings of the National Academy of Sciences, 108:1490-1495. doi:10.1073/pnas.1013892108

Taylor PD, Waeschenbach A, Florence W (2011) Phylogenetic position and systematics of the bryozoan Tennysonia: further evidence for convergence and plasticity in skeletal morphology among cyclostome bryozoans, Zootaxa, 3010:58-68.

 

2009

Bray RA, Waeschenbach A, Cribb TH, Weedall G, Dyal P, Littlewood DTJ (2009) The phylogeny of the Lepocreadioidea (Platyhelminthes: Digenea) inferred from nuclear and mitochondrial genes: implications for their systematics and evolution, Acta Parasitologica, 54:310-329. doi:10.2478/s11686-009-0045-z

Waeschenbach A, Cox CC, Littlewood DTJ, Porter JS & Taylor PD (2009) The first molecular estimate of cyclostome bryozoan phylogeny confirms extensive homoplasy among skeletal characters used in traditional taxonomy, Molecular Phylogenetics and Evolution, 52:241-251. doi:10.1016/j.ympev.2009.02.002

Palm HW, Waeschenbach A, Olson PD & Littlewood DTJ (2009) Molecular phylogeny and evolution of the Trypanorhyncha Diesing, 1863 (Platyhelminthes: Cestoda), Molecular Phylogenetics and Evolution, 52:351-367. doi:10.1016/j.ympev.2009.01.019

Jex AR, Waeschenbach A, Hu M, van Wyk J, Beveridge I, Littlewood DTJ & Gasser RB (2009) The mitochondrial genomes of Ancylostoma caninum and Bunostomum phlebotomum – two hookworms of animal health and zoonotic importance, BMC Genomics, 10:79. PDF PDF (448.8 KB)

 

2008

Jex AR, Waeschenbach A (joint 1st authorship), Littlewood DTJ, Hu M, Gasser RB (2008) The mitochondrial genome of Toxocara canis, PLoS Neglected Tropical Diseases, 2:e273. PDF PDF (604.8 KB)

 

Jex AR, Hu M, Littlewood DTJ, Waeschenbach A, Gasser RB (2008) Using 454 technology for long-PCR based sequencing of the complete mitochondrial genome from single Haemonchus contortus (Nematoda), BMC Genomics, 9:11. PDF PDF (957.6 KB)

 

Littlewood DTJ, Waeschenbach A, Nikolov PN (2008) In search of mitochondrial markers for resolving the phylogeny of cyclophyllidean tapeworms (Platyhelminthes, Cestoda) – a test study with Davaineidae, Acta Parasitologica, 53:133-144. doi:10.2478/s11686-008-0029-4

2007

Bray RA, Cribb TH, Waeschenbach A & Littlewood DTJ (2007) A new species of Stephanostomum Looss, 1899 (Digenea, Acanthocolpidae) with a bizarre oral sucker: S. adlardi sp. nov. from the common coral trout Plectropomus leopardus (Lacepède, 1802) (Perciformes, Serranidae) from Lizard Island, Great Barrier Reef, Acta Parasitologica, 53:206-212. doi:10.2478/s11686-007-0025-0

Palm HW, Waeschenbach A, Littlewood DTJ (2007) Genetic diversity in the trypanorhynch cestode Tentacularia coryphaenae Bosc, 1797: evidence for a cosmopolitan distribution and low host specificity in the teleost intermediate host, Parasitology Research, 101:153-159. doi:10.1007/s00436-006-0435-1

Waeschenbach A, Webster BL, Bray RA, Littlewood DTJ (2007) Added resolution among ordinal level relationships of tapeworms (Platyhelminthes: Cestoda) with complete small and large subunit nuclear ribosomal RNA genes, Molecular Phylogenetics and Evolution, 45:311-325. doi:10.1016/j.ympev.2007.03.019

2006

Waeschenbach A, Telford MJ, Porter JS & Littlewood DTJ (2006) The complete mitochondrial genome of Flustrellidra hispida and the phylogenetic position of Bryozoa among the Metazoa, Molecular Phylogenetics and Evolution, 40:195-207. doi:10.1016/j.ympev.2006.03.007

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