Morphological and genetic variation in the North Atlantic copepod,Centropages typicus

Abstract

This study describes phenotypic and genotypic variations in the planktonic copepod, Centropages typicus (Copepoda: Calanoida) that indicate differentiation between geographical samples. We found consistent differences in the morphology of the chela of the sexually modified fifth pereiopod (P5) of male C. typicus between samples from the Mediterranean, western North Atlantic and eastern North Atlantic. A 560 base pairs (bp) region of the C. typicus mitochondrial cytochrome c oxidase subunit I (COI) and a 462 bp fragment of the nuclear rDNA internal transcribed spacer (ITS) tandem array were analysed to determine whether these morphological variations reflect population genetic differentiation. Mitochondrial haplotype diversity was found to be high with 100 unique COI haplotypes among 116 individuals. Analysis of mtCOI variation suggested differentiation between the Mediterranean and Atlantic populations but no separation was detected within the Atlantic. Intragenomic variation in the ITS array suggested genetic differentiation between samples from the western North Atlantic and those from the eastern North Atlantic and Mediterranean. Breeding experiments would be required to elucidate the extent of genetic isolation between C. typicus from the different population centres.

New view of population genetics of zooplankton: RAD‐seq analysis reveals population structure of the North Atlantic planktonic copepod Centropages typicus

“…These results agree with the conclusions inferred from morphological characteristics by Castellani et al . (), but contradict the molecular results from the same study, which indicated lack of genetic structure across the entire distributional range of the species (Castellani et al . ).…”

“…(), but contradict the molecular results from the same study, which indicated lack of genetic structure across the entire distributional range of the species (Castellani et al . ). In contrast, our finding of significant genetic structure reflects the power and potential of next‐generation technologies to resolve highly sensitive and specific molecular genetic markers, such as RAD tags (Reitzel et al .…”

“…; Castellani et al . ). The expatriation of individuals to the open ocean and the limited connection between the two sides of the North Atlantic Ocean during the seasonal maximum of the species (Beaugrand et al .…”

“…Centropages typicus has shown apparent panmixia based on mitochondrial markers, while nuclear ribosomal data suggest some differentiation between the NE and the NW Atlantic shelf ecosystems (Castellani et al . ). These apparently contradictory results could be due to the different nature of these markers (e.g.…”

Population Genomics of Marine Zooplankton

“…data). Similarly, a study of the copepod, Centropages typicus, by Blanco-Bercial and Bucklin (2016) using 1,000s of genomic SNPs obtained by RAD-seq revealed evidence of population structure, in contrast to an earlier study based on mitochondrial gene sequences (Castellani et al 2012). …”