Diversity of Phylum Nematoda Quiz

Study Notes

Phylum Nematoda: A Diverse Group of Organisms

The Nematoda, also known as nematodes or roundworms, are a highly diverse group of organisms that have evolved to exploit a wide range of ecological niches. As the second most abundant multicellular organisms on Earth, nematodes account for approximately 80% of all individual animals. With estimates ranging from 100,000 to 1 million extant species, the phylum Nematoda is one of the most diverse groups in the animal kingdom.

Nematode Clades

Nematodes can be divided into three major clades based on small subunit ribosomal RNA (SSU rRNA) phylogenetics: Dorylaimia (clade I), Enoplia (clade II), and Chromadorea. Chromadorea can further be divided into Rhabditida, which includes Spirurina, Tylenchina, and Rhabditina. All major clades within the Nematoda include both free-living and parasitic species.

Parasitism and Nematode Evolution

Parasitism in Nematoda has arisen multiple times throughout their evolution, with all major clades including parasites. The transition from free-living to parasitic lifestyles has been a significant factor in the diversification of nematode species.

Nematode-Specific Protein Families

A transcriptomic analysis of the phylum Nematoda identified more than 2,600 different known protein domains, some of which had differential abundances between major taxonomic groups of nematodes and 4,228 nematode-specific protein families that probably underpin species- and higher-level taxonomic disparity. These nematode-specific families are particularly interesting as potential drug and vaccine targets.

Nematode Ecology and Habitats

Nematodes occupy a wide range of ecological niches, from free-living microbivores to human parasites. They exploit various habitats, including terrestrial, marine, and freshwater environments. Some nematodes, like Gordioidea and Nectonematoidea, are obligate parasites of terrestrial and marine arthropod hosts, while others, like Heligmosomoides polygyrus bakeri, are parasites of animals and humans.

Nematode Phylogenetics and Classification

Phylogenetic relationships within many lineages of the phylum Nematoda remain unresolved, despite numerous morphology-based and molecular analyses. The most widely accepted morphology-based classification divides Nematoda into Aphasmidia/Adenophorea and Phasmidia/Secernentea. However, molecular data, such as small subunit ribosomal RNA (SSU rRNA) sequences, have led to a more nuanced understanding of nematode phylogeny.

In conclusion, the phylum Nematoda is a highly diverse and successful group of organisms, with a wide range of ecological niches and numerous phylogenetic relationships. The field of nematode research continues to evolve, with new discoveries and analyses shedding light on the complex and fascinating world of these roundworms.

Description

Test your knowledge on the diverse group of organisms known as Nematoda, or nematodes, which occupy a wide range of ecological niches and include both free-living and parasitic species. Explore topics such as nematode clades, parasitism, protein families, ecology, habitats, phylogenetics, and classification within the phylum Nematoda.