In today’s blog, let us explore phylogenetic relationships of the Octopoda comparing results from molecular data analyses with classification based on morphological features.
The Octopod phylogeny is complex and full of controversies. Research utilizing Molecular data did not support the Octopodidae as a monophyletic group (based on morphological features).(Carlin D.A et al, 2001)
Notable disparities were seen at the order of branching.(Fig.1 and 2) At the base, Argonauta branched off first in the MP tree. Argonauta grouped based on smaller mature male compared to mature female, hectocotylus remain coiled inside a pocket until use, and hectocotylus break off during mating. (Nesis, 1987), Whereas in the ML tree, a clade consisting of Argonauta and three members of subfamily octopodinae (O. tetricus, O. bimaculoides, and Hapalochlaena sp.) initially branched off from the others.Based on the various positioning of O. bimaculoides ,it’s evolutionary history is unconfirmed.
O. tetricus ;O. bimaculoides and Hapalochlaena were shown as sister taxa, in clade subfamily octopodinae .A sister taxon relationship based on shared trait of ink sac and two sucker rows. This was also supported by data from ML and MP trees.
In both tree,O. californicus was closely related to Benthoctopus sp. than O. bimaculoides, although O. californicus shared possession of ink sac and double sucker rows with O. bimaculoides. Benthoctopus sp. on the other hand possess double sucker row with no ink sac .(O’Shea S.1999)
MP tree was a significantly longer tree compared to the ML tree especially since branch lengths were constructed proportionally to the number of parsimony steps between nodes.(Carlin D.A et al, 2001)
REFERENCE
Carlin D.A et al (2001) A molecular phylogeny of the Octopoda (Mollusca: Cephalopoda) evaluated in light of morphological evidence. Molecular phylogenetics and evolution, ISSN: 1055-7903, Vol: 21, Issue: 3, Page: 388-97 .
Nesis, K. N. (1987). “Cephalopods of the World: Squids, Cuttlefishes, Octopuses, and Allies,” Tropical Fish Hobbyist Publ. Inc., Neptune City, NJ.
- O’Shea S. (1999) The Marine Fauna of New Zealand: Octopoda (Mollusca: Cephalopoda), National Institute of Water and Atmospheric Research (NIWA),page 114
FUN FACT
Paul an octopus predicted the results of eight matches in the 2010 World Cup, including the winner, Spain. Spain scored 1-0 in the final against Netherlands.
Source – http://www.bbc.com/news/10566287