Origin and evolution of the parasitic cyclopoid copepods

Area of Science:

• Zoology
• Evolutionary Biology
• Parasitology

Background:

• Six of ten Cyclopoida families exhibit parasitic lifestyles.
• These parasitic families are found on marine invertebrates, freshwater gastropods, and fishes.

Purpose of the Study:

• To investigate the evolutionary history of parasitism within the order Cyclopoida.
• To determine the number of independent evolutionary events leading to parasitism in this group.

Main Methods:

• A cladistic analysis was performed on the 10 recognized families of Cyclopoida.
• The analysis aimed to reconstruct the phylogenetic relationships and identify the origins of parasitic lineages.

Main Results:

• The study indicates that parasitism evolved independently on two separate occasions in Cyclopoida history.
• The first event involved marine ancestors colonizing ascidians, leading to Archinotodelphyidae and Notodelphyidae, and later Mantridae in bivalves.
• The second event originated from a sister group to ancestral cyclopoids, resulting in marine ascidian parasites and freshwater parasites (Lernaeidae on fish, Ozmanidae on gastropods).

Conclusions:

• Parasitism in Cyclopoida is a polyphyletic trait, having arisen twice through distinct evolutionary pathways.
• Understanding these independent origins provides insights into the adaptive radiation of copepods into parasitic niches.