Related Experiment Video
Updated: Jun 28, 2025
09:55
Examining Monosynaptic Connections in Drosophila Using Tetrodotoxin Resistant Sodium Channels
Published on: February 14, 2018
9.9K
HOST SWITCHING IN DICYEMIDS (PHYLUM DICYEMIDA)
Hiroaki Nakajima1, Ayako Fukui1, Kazutaka Suzuki1
1Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
The Journal of Parasitology
|April 17, 2024
Summary
Dicyemid parasites in cephalopods show complex evolutionary histories. Their speciation likely involves a mix of host switching and divergence within a single host species, challenging traditional classifications.
Area of Science:
- Marine Biology
- Parasitology
- Evolutionary Biology
- Invertebrate Zoology
Background:
- Dicyemids are common endosymbionts in cephalopods, exhibiting high host specificity.
- Phylogenetic congruence between hosts and parasites is expected due to co-speciation, but often disrupted by host switching.
- Understanding dicyemid evolution requires comparing their phylogeny with that of their cephalopod hosts.
Purpose of the Study:
- To investigate the evolutionary history and diversification mechanisms of dicyemids associated with cephalopod molluscs.
- To compare the phylogenies of dicyemids and their hosts to understand their co-evolutionary patterns.
- To evaluate the roles of host switching and intra-host speciation in dicyemid diversification.
Main Methods:
- Collection of dicyemid species from various octopodiform and decapodiform cephalopods in Japanese waters.
- Phylogenetic reconstruction using whole mitochondrial cytochrome c oxidase subunit 1 (COI) gene sequences from 37 dicyemid species.
- Analysis of phylogenetic trees to assess relationships among dicyemid genera and their divergence patterns.
Main Results:
- Phylogenetic analyses revealed 3 major clades within dicyemids, indicating that common genera like Dicyema and Dicyemennea are not monophyletic.
- Morphological classifications do not accurately reflect the phylogenetic relationships of these dicyemid genera.
- Evidence suggests dicyemid speciation can occur within a single host species, with potential host-switching events between or within cephalopod orders.
Conclusions:
- Dicyemid diversification is shaped by a combination of intra-host speciation and host switching, rather than solely co-speciation.
- The study highlights the limitations of morphological data in classifying dicyemids and underscores the importance of molecular phylogenetics.
- This research provides the first comprehensive evaluation of dicyemid diversification dynamics with a substantial number of species and genera.
Related Concept Videos
01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
4.6K
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
4.6K
01:05Mechanism of Ciliary Motion
3.7K
The ciliary structures were first seen in 1647 by Antonie Leeuwenhoek while observing the protozoans. In lower organisms, these appendages are responsible for cell movement, while in higher organisms, these appendages help in the movement of the extracellular fluids within the body cavities.
The cilia are made up of microtubules in a 9+2 arrangement, with nine microtubule doublet ring bundles, surrounding a pair of central singlet microtubule bundles. The doublet microtubule bundles are...
The cilia are made up of microtubules in a 9+2 arrangement, with nine microtubule doublet ring bundles, surrounding a pair of central singlet microtubule bundles. The doublet microtubule bundles are...
3.7K
01:24Diels–Alder Reaction: Characteristics of Dienophiles
6.1K
In a Diels–Alder reaction, the diene is usually an electron-rich system and acts as a nucleophile, whereas the dienophile is electron-deficient and functions as an electrophile. Much like the diene, the nature of the dienophile significantly impacts the outcome of the reaction.
Characteristics of Dienophiles
Generally, the best dienophiles are alkenes containing electron-withdrawing substituents such as carbonyl, nitrile, and nitro groups. The feasibility of a Diels–Alder reaction depends...
Characteristics of Dienophiles
Generally, the best dienophiles are alkenes containing electron-withdrawing substituents such as carbonyl, nitrile, and nitro groups. The feasibility of a Diels–Alder reaction depends...
6.1K
02:37Disubstituted Cyclohexanes: cis-trans Isomerism
11.9K
Depending upon the different spatial orientation of the substituents, the disubstituted cycloalkanes exhibit two types of stereoisomers. The cis isomers have the substituents on the same side of the ring, whereas the trans isomers have the substituents on the opposite sides. These stereoisomers exhibit different physical properties and cannot be interconverted without breaking the carbon-carbon bonds.
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
11.9K
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
10.1K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
10.1K
![[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12422.jpg&w=3840&q=75)
01:21[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
2.7K
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
2.7K