Cryptic species and genetic structure in Didemnum granulatum Tokioka, 1954 (Tunicata: Ascidiacea) from the southern Brazilian coast

Bouzon, J. L.; Vargas, Sarah M.; Neto, João Favero; Stoco, Patrícia Hermes; Brandini, Frederico Pereira

doi:10.1590/1519-6984.00213

Cited by 5 publications

(2 citation statements)

References 29 publications

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“…Genetic analyses using the mitochondrial COI gene and ribosomal 18S rRNA gene revealed the presence of two distinct genetic lineages within the investigated D. bermudensis colonies. We detected an interclade divergence of 20.5% based on the COI gene, well above or comparable to the COI divergence values reported for other cryptic colonial species (Bock et al., 2012; Bouzon et al., 2014; López‐Legentil & Turon, 2006; Pérez‐Portela et al., 2013; Pérez‐Portela & Turon, 2008; Tarjuelo et al., 2004), and between congeneric species of Chordata (Hebert et al., 2003). When we further investigated the association between genetic identity and colour variation, a distinct pattern emerged, with lighter tunics and darker zooid openings (colour morphs 4 and 5) corresponding to Lineage A and darker tunics with lighter zooid openings (colour morphs 1, 2 and 3) corresponding to Lineage B.…”

Section: Discussionsupporting

confidence: 85%

“…No other morphological differences were observed between either the adults or the larvae of the two lineages. However, previous studies investigating cryptic or early speciation in ascidians have similarly detected genetic differences among colour morphs and the absence of other distinguishing morphological characters between these taxa (Bouzona et al, 2014; López‐Legentil & Turon, 2005, 2006; Tarjuelo et al., 2004).…”

Section: Discussionmentioning

confidence: 92%

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Cryptic genetic lineages of a colonial ascidian host distinct microbiomes

et al. 2021

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Colour variation in marine invertebrates is typically attributed to intraspecific variability; however, the use of molecular tools to investigate its genetic basis has uncovered many instances of cryptic speciation. The colonial ascidian Distaplia bermudensis occurs in a wide array of colour morphs, ranging from all white to a dark blue tunic with yellow siphon apertures; yet careful observations of zooid and larval morphologies have not revealed any consistent difference among these colour morphs. In this study, we sampled the 5 main colour morph groupings of D. bermudensis from Wilmington, North Carolina (USA) and sequenced fragments of the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear 18S rRNA genes. Analyses of both genes revealed the presence of two distinct genetic lineages that corresponded to unique colour morphology groupings. We further characterized symbiotic microbial communities for four samples from each lineage by high‐throughput sequencing of partial 16S rRNA genes. Each genetic lineage also harboured unique symbiont communities that differed significantly in diversity and structure. Thus, the two genetic lineages detected herein corresponded to unique colour morphs and microbial communities, indicating that two distinct species coexist under the same scientific name. Further, our study reports the utility of symbiont profiling in resolving the taxonomic status of phenotypically variable ascidian species.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 92%

Cryptic genetic lineages of a colonial ascidian host distinct microbiomes

et al. 2021

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Identification of four Indian ascidians based on COI gene sequences

Jaffarali¹,

Akram²,

Arshan³

2016

Mitochondrial DNA Part A

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DNA barcoding involving the sequencing of a short mitochondrial DNA segment, cytochrome c oxidase subunit 1 (COI) gene, is a specialized technique for the identification of species even at the early embryonic and larval stages, which is quite difficult in morphology-based taxonomy. Ascidians are sessile invertebrate chordates possessing numerous biochemical as well as pharmacological activities. In this study, a total of 36 ascidian samples belonging to the family Didemnidae were sequenced for a 650 bp region of the mitochondrial COI gene. All the species were represented by multiple specimens. The barcode sequences showed no stop-codons and indels in the alignments. The aligned sequences were submitted in Barcode submission tool, NCBI, and the accession numbers were obtained. The minimum intraspecific distance was found to be 0.00% and the maximum was 2.23%. Mean Kimura 2-parameter (K2P) distances within-species, genus, and family were 0.88, 5.98, and 20.03%, respectively. The mean interspecific distance is more than the mean intraspecific divergence, which indicates efficiency of DNA barcoding for identification of ascidians.

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Speciation across the Tree of Life

et al. 2021

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Much of what we know about speciation comes from detailed studies of well‐known model systems. Although there have been several important syntheses on speciation, few (if any) have explicitly compared speciation among major groups across the Tree of Life. Here, we synthesize and compare what is known about key aspects of speciation across taxa, including bacteria, protists, fungi, plants, and major animal groups. We focus on three main questions. Is allopatric speciation predominant across groups? How common is ecological divergence of sister species (a requirement for ecological speciation), and on what niche axes do species diverge in each group? What are the reproductive isolating barriers in each group? Our review suggests the following patterns. (i) Based on our survey and projected species numbers, the most frequent speciation process across the Tree of Life may be co‐speciation between endosymbiotic bacteria and their insect hosts. (ii) Allopatric speciation appears to be present in all major groups, and may be the most common mode in both animals and plants, based on non‐overlapping ranges of sister species. (iii) Full sympatry of sister species is also widespread, and may be more common in fungi than allopatry. (iv) Full sympatry of sister species is more common in some marine animals than in terrestrial and freshwater ones. (v) Ecological divergence of sister species is widespread in all groups, including ~70% of surveyed species pairs of plants and insects. (vi) Major axes of ecological divergence involve species interactions (e.g. host‐switching) and habitat divergence. (vii) Prezygotic isolation appears to be generally more widespread and important than postzygotic isolation. (viii) Rates of diversification (and presumably speciation) are strikingly different across groups, with the fastest rates in plants, and successively slower rates in animals, fungi, and protists, with the slowest rates in prokaryotes. Overall, our study represents an initial step towards understanding general patterns in speciation across all organisms.

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Cryptic species and genetic structure in Didemnum granulatum Tokioka, 1954 (Tunicata: Ascidiacea) from the southern Brazilian coast

Cited by 5 publications

References 29 publications

Cryptic genetic lineages of a colonial ascidian host distinct microbiomes

Cryptic genetic lineages of a colonial ascidian host distinct microbiomes

Identification of four Indian ascidians based on COI gene sequences

Speciation across the Tree of Life

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