Gradual Distance Dispersal Shapes the Genetic Structure in an Alpine Grasshopper

Evaluating Causes of Current Genetic Gradients of Modern Humans of the Iberian Peninsula

The history of modern humans in the Iberian Peninsula includes a variety of population arrivals sometimes presenting admixture with resident populations. Genetic data from current Iberian populations revealed an overall east–west genetic gradient that some authors interpreted as a direct consequence of the Reconquista, where Catholic Kingdoms expanded their territories toward the south while displacing Muslims. However, this interpretation has not been formally evaluated. Here, we present a qualitative analysis of the causes of the current genetic gradient observed in the Iberian Peninsula using extensive spatially explicit computer simulations based on a variety of evolutionary scenarios. Our results indicate that the Neolithic range expansion clearly produces the orientation of the observed genetic gradient. Concerning the Reconquista (including political borders among Catholic Kingdoms and regions with different languages), if modeled upon a previous Neolithic expansion, it effectively favored the orientation of the observed genetic gradient and shows local isolation of certain regions (i.e., Basques and Galicia). Despite additional evolutionary scenarios could be evaluated to more accurately decipher the causes of the Iberian genetic gradient, here we show that this gradient has a more complex explanation than that previously hypothesized.

Historical migration and taxonomic entity of Korean endemic shrub Lespedeza maritima (Fabaceae) based on microsatellite loci

Various plant species are endemic to the Korean Peninsula, but their evolutionary divergence and establishment are poorly understood. One of these, Lespedeza maritima, has been proposed as either a hybrid (L. cyrtobotrya × L. maximowiczii) or a synonym of L. thunbergii. A distinct taxon, L. uekii, has been proposed for inland populations. We investigated genetic diversity and structure in L. maritima and related taxa to resolve this. Genotypes of L. maritima (n = 244, including L. uekii) were determined using 12 microsatellite loci, then compared with those of related species. Genetic diversity within L. maritima was estimated, and Bayesian clustering analysis was used to represent its genetic structure and that of related taxa. Its distribution during the last glacial maximum (LGM) was predicted using ecological niche modelling (ENM). Neighbour-joining (NJ) analysis and principal coordinate analysis (PCoA) were used to investigate relationships among species. Bayesian tree based on nuclear ribosomal internal transcribed spacers (nrITS) was also reconstructed to show relationships and divergence time among species. Morphological features were examined using flower characteristics. In result, expected heterozygosity (H _E) and allelic richness (A _R) within L. maritima were higher in southern than northern populations. Bayesian clustering analysis largely assigned populations to two clusters (K = 2) (south vs. north). The ENM showed that L. maritima occurred around the East China Sea and Korean Strait land bridge during the LGM. Compared with other Lespedeza species, L. maritima was assigned to an independent cluster (K = 2-5), supported by the NJ, PCoA, Bayesian tree and morphological examination results. Lespedeza maritima and L. uekii were clustered to one clade on Bayesian tree. Given results, current L. maritima populations derive from post-LGM colonization away from southern refugia. The type L. uekii, which grows inland, is thought synonym of L. maritima. In addition, L. maritima is considered a distinct species, compared with related taxa.

Historical migration and taxonomic entity of Korean endemic shrub Lespedeza maritima (Fabaceae) based on microsatellite loci

Various plant species are endemic to the Korean Peninsula, but their evolutionary divergence and establishment are poorly understood. One of these, Lespedeza maritima, has been proposed as either a hybrid (L. cyrtobotrya × L. maximowiczii) or a synonym of L. thunbergii. A distinct taxon, L. uekii, has been proposed for inland populations. We investigated genetic diversity and structure in L. maritima and related taxa to resolve this. Genotypes of L. maritima (n = 244, including L. uekii) were determined using 12 microsatellite loci, then compared with those of related species. Genetic diversity within L. maritima was estimated, and Bayesian clustering analysis was used to represent its genetic structure and that of related taxa. Its distribution during the last glacial maximum (LGM) was predicted using ecological niche modelling (ENM). Neighbour-joining (NJ) analysis and principal coordinate analysis (PCoA) were used to investigate relationships among species. Bayesian tree based on nuclear ribosomal internal transcribed spacers (nrITS) was also reconstructed to show relationships and divergence time among species. Morphological features were examined using flower characteristics. In result, expected heterozygosity (H _E) and allelic richness (A _R) within L. maritima were higher in southern than northern populations. Bayesian clustering analysis largely assigned populations to two clusters (K = 2) (south vs. north). The ENM showed that L. maritima occurred around the East China Sea and Korean Strait land bridge during the LGM. Compared with other Lespedeza species, L. maritima was assigned to an independent cluster (K = 2-5), supported by the NJ, PCoA, Bayesian tree and morphological examination results. Lespedeza maritima and L. uekii were clustered to one clade on Bayesian tree. Given results, current L. maritima populations derive from post-LGM colonization away from southern refugia. The type L. uekii, which grows inland, is thought synonym of L. maritima. In addition, L. maritima is considered a distinct species, compared with related taxa.

Selection for functional performance in the evolution of cuticle hardening mechanisms in insects

Calcified tissues have repeatedly evolved in many animal lineages and show a tremendous diversity of forms and functions. The cuticle of many insects is enriched with elements other than Calcium, a strategy of hardening that is taxonomically widespread but apparently poorly variable among clades. Here, we investigate the evolutionary potential of the enrichment with metals in insect cuticle at different biological levels. We combined experimental evidence of Zinc content variation in the mandibles of a target species (Chorthippus cazurroi [Bolívar]) with phylogenetic comparative analyses among grasshopper species. We found that mandibular Zinc content was repeatable among related individuals and was associated with an indicator of fitness, so there was potential for adaptive variation. Among species, Zinc enrichment evolved as a consequence of environmental and dietary influences on the physical function of the jaw (cutting and chewing), suggesting a role of natural selection in environmental fit. However, there were also important within and transgenerational environmental sources of similarity among individuals. These environmental influences, along with the tight relationship with biomechanics, may limit the potential for diversification of this hardening mechanism. This work provides novel insights into the diversification of biological structures and the link between evolutionary capacity and intra- and interspecific variation.