Macroecological trend of increasing values of intraspecific genetic diversity and population structure from temperate to tropical streams

Abstract

Aim Assuming genetic variants are selectively neutral, estimates of intraspecific genetic diversity and population structure should increase simultaneously in parallel to coalescent time, population size and gene flow. However, other processes, such as genetic drift associated with demographic fluctuations, might cause a loss of genetic diversity while not affecting population structure. In this study, we assess large‐scale patterns of estimates of intraspecific genetic variation across species to determine the roles of dispersal, biogeography, divergence time and demographic fluctuations in decoupling genetic diversity and population structure. Location Pristine first‐order streams distributed in seven regions from Neotropical to boreal climate, covering a gradient of habitat persistence through major biogeographical changes (e.g., Pleistocene glaciations). Time period 2008–2010. Major taxa studied Freshwater insect lineages that differ in dispersal propensity. Methods Intraspecific nucleotide diversity (π) and population structure (ΦST) were estimated for 33 species using 2,128 sequences of the cox1 gene. The correlation between π and ΦST was tested using linear regression models. The geographical distribution of haplotypes was represented in networks. Phylogenetic trees were time calibrated to determine divergence time. Results At a global scale, a positive relationship between π and ΦST was found. Neotropical species showed the highest values of π and ΦST, probably owing to historical environmental stability. Across Europe, the low estimates of π and the wide array of ΦST values and haplotype networks found across species, lineages and latitude were contrary to the biogeographical and dispersal paradigms. Main conclusions Beyond the macroecological trend found, genetic trajectories of co‐distributed temperate species were disassociated from their functional traits and probably caused by persistent demographic fluctuations associated with local‐scale habitat instability. Overall, the idiosyncratic relationship between π and ΦST across species prevents the establishment of conclusive global patterns and questions the phylogeographical patterns established when studying a reduced number of co‐distributed species.

Spatial Genetic Structure of Prunus mongolica in Arid Northwestern China Based on RAD Sequencing Data

“…Thus, the southern populations could have persisted in their distribution ranges and harbored high levels of genetic diversity during the process of paleoclimatic change. This hypothesis was also supported by a few of species [31,32] that habitat stability was positively associated with population genetic diversity. However, the low levels of genetic diversity for northern populations were not the result of founder effects following interglacial recolonizations [33].…”

Multiple Doris “kerguelenensis” (Nudibranchia) species span the Antarctic Polar Front

“…Due to the regions glacial history, this expansion is indicative of a bottleneck or a founder event; however, alternative hypotheses include populations expanding after a selective sweep, and/or purifying selection. As a result, the mitochondrial genetic diversity seen here may not exclusively reflect the demographic history of these tested populations and instead reflect time since a selective sweep (Bazin et al, 2006 ; Ellegren & Galtier, 2016 ; Salinas‐Ivanenko & Múrria, 2021 ). Within this dataset, high levels of haplotypic diversity are indicated through the generally parochial networks and associated diversity and demographic indices.…”

“…TA B L E 4Pairwise Φ ST distances (below diagonal) based on mitochondrial sequence data for 355 samples from species 24 within the Doris "kerguelenensis" species complex. n the demographic history of these tested populations and instead reflect time since a selective sweep(Bazin et al, 2006;Ellegren & Galtier, 2016;Salinas-Ivanenko & Múrria, 2021). Within this data-set, high levels of haplotypic diversity are indicated through the generally parochial networks and associated diversity and demographic indices.…”

Global determinants of insect mitochondrial genetic diversity

“…Our finding of lower genetic diversity in areas that were glaciated or tundra during the LGM is consistent with a gradient of lower haplotype richness in recently unglaciated areas found in European butterflies 30 based on the same COI data from BOLD used here. Similarly, aquatic insect species have lower intraspecific genetic diversities in recently unglaciated areas of Europe compared to Neotropical areas 32 .…”