Bamboozled! Systematic studies of the Keratoisididae (Octocorallia: Scleralcyonacea)
Date
2023-11-15Embargo Date
2024-11-15
Author
Morrissey, Declan
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Abstract
Deep-sea corals are globally distributed and form a three-dimensional
habitat on the benthos which hosts a diverse invertebrate community.
Despite this importance, a global lack of taxonomic expertise and low resolution single-gene barcodes has meant they are rarely identified to
species level. Bamboo corals, specifically referring to those in the family
Keratoisididae, are an exclusively deep-sea group of octocorals that are
particularly taxonomically challenging due to the historic use of labile
traits as diagnostic characters for genera. This has led to polyphyly
within the family, and large amounts of undescribed biodiversity.
Chapter 2 uses an integrative taxonomic approach to provide an upper
and lower estimate to the number of species of calcaxonian octocorals
present along the Irish margin. I found between 14 – 27 species of
Keratoisididae, 6 – 7 species of Primnoidae, and 4 – 5 species of
Chrysogorgiidae. The phylogenetic relationships among the different
groups within Keratoisididae were unresolved despite using a ~3000 bp
portion of the mitogenome.
Chapter 3 further interrogates the phylogenomic relationships of
Keratoisididae. Using hundreds of nuclear markers, generated using
target-capture techniques, deep evolutionary nodes within the
phylogeny of keratoisidids were resolved. The phylogeny found a deep
split in the family forming two distinct clades. Furthermore, there is
evidence that some keratoisidid groups are polyphyletic. This phylogeny
is the first to use such high genomic resolution and is incongruent with
previous phylogenies created using multiple gene regions from the
mitogenome.
Chapter 4 further compares phylogenies generated from full
mitochondrial genomes with that from hundreds of nuclear markers and
discovers mitonuclear discordance within the keratoisidids.
Furthermore, by investigating the characteristics and genomic diversity
within the keratoisidid mitogenome, three unknown Open Reading
Frames were discovered in the space between cob and nad6.