10.5061/DRYAD.NH31F
Laumer, Christopher E.
Harvard University
Giribet, Gonzalo
Harvard University
Data from: Inclusive taxon sampling suggests a single, stepwise origin of
ectolecithality in Platyhelminthes
Dryad
dataset
2014
Recent
Euneoophora
Platyhelminthes
implied weighting
Gnosonesimida
Lecithoepitheliata
Neoophora
heterotachy
mixture model
Prorhynchida
2014-02-10T14:56:28Z
2014-02-10T14:56:28Z
en
https://doi.org/10.1111/bij.12236
52571374 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Ectolecithality is a form of oogenesis unique within Metazoa but common in
Platyhelminthes, in which nearly-yolkless oocytes and tightly associated
yolk cells are deposited together in egg capsules. Despite profound
impacts on the embryogenesis and morphology of its beneficiaries, the
origins of this developmental phenomenon remain obscure. Traditionally,
all ectolecithal flatworms were grouped in a clade called Neoophora.
However, there are also morphological arguments for multiple origins of
ectolecithality, and Neoophora has to date seen little support from
molecular phylogenetic research, largely due to gaps in taxon sampling.
Accordingly, we present a molecular phylogeny focused on resolving the
deepest divergences among the free-living Platyhelminthes. Species were
chosen to completely span the diversity of all major endo- and
ectolecithal clades, including several aberrant species of uncertain
systematic affinity, and additionally a thorough sampling of the
“lecithoepitheliate” higher taxa Prorhynchida and Gnosonesimida,
respectively under- and unrepresented in phylogenies to date. Our analyses
validate the monophyly of all classical higher platyhelminth taxa, and
also resolve a clade possessing distinct yolk-cell and oocyte generating
organs (which we name Euneoophora new taxon). Furthermore, implied-weights
parsimony and Bayesian mixture model analyses suggest common ancestry of
this clade with the lecithoepitheliates, implying that these taxa may
retain a primitive form of ectolecithality. This topology thus
corroborates the classical hypothesis of homology between yolk cells and
oocytes in all Neoophora, and should serve to guide future evolutionary
research on this unique developmental innovation in Platyhelminthes.
BiolJLinnSoc_DryadNexus files for all alignments used in this study (by
gene and concatenated, raw and sequence-masked). Newick-formatted trees
with nodal resampling support values for implied-weights and unweighted
parsimony analyses, maximum likelihood analyses, and representative
BayesPhylogenies chains for both Matrix A and Matrix B.
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