First insight of genetic diversity, phylogeographic relationships, and population structure of marine sponge Chondrosia reniformis from the eastern and western Mediterranean coasts of Tunisia

Abstract

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Highly structured populations of deep-sea copepods associated with hydrothermal vents across the Southwest Pacific, despite contrasting life history traits

“…S . lauensis is distributed across the Lau Basin over a distance of 775 km and exhibited the highest haplotype diversity values and very low nucleotide diversity, a typical trait of well-mixed populations that have experienced a bottleneck followed by a sudden population expansion [ 78 ] and is therefore, unlikely to be caused by small, long-term effective population sizes given their densities. No phenotypic differences were encountered between any of the specimens examined in the S .…”

“…Firstly, Tajima's D [72], which calculates the difference between the mean number of pairwise differences and the number of segregating sites, and secondly, Fu's F s [73], which estimates the probability of observing a random sample with numbers of alleles equal to or smaller than the observed value, given the observed diversity and assumption that all the alleles are selectively neutral. These parameters in combination are affected by changes in population size, where negative values of both indicate an excess of low frequency polymorphisms (rare alleles), as expected from a recent population expansion or genetic hitchhiking, causing deviation from mutation-drift equilibrium [74][75][76][77][78]. Sum of Squared Deviations (SSD) and Harpending's raggedness index (rg) [79], are parameters that describe the mismatch distribution of pairwise nucleotide differences.…”

“…lauensis 1, 2, and 3, an unprecedented finding for a genus that is otherwise well distributed across vent sites and fields along MORs [19, 25,28,29]. S. lauensis is distributed across the Lau Basin over a distance of 775 km and exhibited the highest haplotype diversity values and very low nucleotide diversity, a typical trait of well-mixed populations that have experienced a bottleneck followed by a sudden population expansion [78] and is therefore, unlikely to be caused by small, long-term effective population sizes given their densities. No phenotypic differences were encountered between any of the specimens examined in the S. lauensis complex, indicative of recent allopatric speciation where morphological traits have yet to appear [90].…”

Polychaetes (Annelida) of Cyprus (Eastern Mediterranean Sea): An Updated and Annotated Checklist including New Distribution Records

“…In this context, the Eastern Mediterranean Sea is particularly interesting. On one hand, it is considered an area of genetic diversification [77,78], hosting unique lineages [79,80], and sometimes even distinct species [81,82]. On the other hand, the eastern sub-basin is affected by a strong pressure from invasive species, mostly arriving from the Red Sea through the Suez Canal.…”