Abstract
BackgroundCopepods are key components of aquatic ecosystems and can help regulate the global carbon cycle. Much attention has been paid to the species diversity of copepods worldwide, but the phylogeography and genetic diversity of copepods in Nigeria is unexplored.ResultsUsing a mitochondrial cytochrome c oxidase subunit I marker, we preformed phylogenetic and phylogeographic analyses for Cyclopidae copepods in Southeast Nigeria. A high species diversity of Cyclopidae in Nigeria: 5 species of Tropocyclops, 5 species of Mesocyclops and 2 species of Thermocyclops from Cyclopidae were identified in 15 populations. Moreover, we detected 18 unique haplotypes, which fell into two distinct clades. Pairwise genetic distances (uncorrected p-distances) among the species of Cyclopidae ranged from 0.05 to 0.257. Several species co-existed in the same lake, and some haplotypes were shared among different geographic populations, suggesting a dispersal of Cyclopidae in our sampling region. Finally, we found that the population genetic diversity for each species of Cyclopidae was low in Nigeria.ConclusionsOur findings explored the species diversity and distribution of copepods within the family Cyclopidae for 15 Nigerian freshwater ecosystems: a high species diversity of Cyclopidae copepods was detected over a small geographic sampling range. Results from this study contribute to a better understanding of copepod diversity of Nigerian freshwater ecosystems.
Highlights
Copepods are key components of aquatic ecosystems and can help regulate the global carbon cycle
We investigated the phylogeography of Cyclopidae in Nigeria
Species and c oxidase subunit I (COI) genetic diversity One to 9 specimens of Cyclopidae were sequenced per location, and a total of 88 Cyclopidae COI sequences were successfully obtained from 15 freshwater lakes around Southeast Nigeria, of which 18 unique haplotypes were detected (Tables 1 and 2)
Summary
Copepods are key components of aquatic ecosystems and can help regulate the global carbon cycle. Copepods are one of the most taxonomically diverse groups of crustaceans, containing approximately 14,000 described species globally [1]. Much attention has been paid to the bio-diversity of copepods in aquatic ecosystems [12, 13]. A few regional biogeographic studies have been conducted on copepods based on morphological species identification [17]. Based on the morphology, a previous study showed the occurrence of the genera Mesocyclops Sars, 1914 and Thermocyclops Kiefer, 1927 in Nigerian freshwater ecosystems: six Mesocyclops species and three Thermocyclops species were identified [18]. The identification of different species of copepods solely based on morphology has technical limitations [19], as cryptic species are often detected. More discerning methods such as DNA barcoding are needed to investigate copepod taxonomy, especially to recognize morphologically cryptic genetic lineages [20]
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