Effects of natural and artificial barriers on the genetic diversity of game species: a review.

Barriers are various natural or artificial borders that fragment the landscape. They reduce the habitat, block pathways and separate the populations into smaller segments. A natural barrier may be a sierra, a valley, a river, a sea, the distance between optimal habitats etc. Human-related barriers are the roads, fences and cities. The following hypothesis was tested: the barrier-effect’s strength depends on the barrier itself as well as on the size, migratory behavior and other properties of the affected species. This review was written with the focus on the species size, the barrier type and the effect’s strength in the case of multiple species and barriers. The results are mostly in agreement with this hypothesis, but it is revealed that the evaluation is not fully standardized yet. Wright’s Fst value is an exact number, but researchers have handled it differently. In some cases they were more permissive and ascribed less impact (mostly in the case of low Fst values). On the other hand, there are authors who valorized the low Fst values because of the possible cascade effect caused by genetic division and changing behaviour. This review describes the possible effects of barriers, but every species and habitat is unique, therefore the method described should not be regarded as 100% accurate. With this comparing technique the effects may be predicted more precisely prior to carrying out the impact studies, thus the additional costs and the impact on the actual species will be easier to estimate.

Division of labor during biofilm matrix production

SummaryOrganisms as simple as bacteria can engage in complex collective actions, such as group motility and fruiting body formation. Some of these actions involve a division of labor, where phenotypically specialized clonal subpopulations, or genetically distinct lineages cooperate with each other by performing complementary tasks. Here, we combine experimental and computational approaches to investigate potential benefits arising from division of labor during biofilm matrix production. We show that both phenotypic and genetic strategies for a division of labor can promote collective biofilm formation in the soil bacteriumBacillus subtilis. In this species, biofilm matrix consists of two major components; EPS and TasA. We observed that clonal groups ofB. subtilisphenotypically segregate into three subpopulations composed of matrix non-producers, EPS-producers, and generalists, which produce both EPS and TasA. This incomplete phenotypic specialization was outperformed by a genetic division of labor, where two mutants, engineered as specialists, complemented each other by exchanging EPS and TasA. The relative fitness of the two mutants displayed a negative frequency dependence bothin vitroand on plant roots, with strain frequency reaching a stable equilibrium at 30% TasA-producers, corresponding exactly to the population composition where group productivity is maximized. Using individual-based modelling, we show that asymmetries in strain ratio can arise due to differences in the relative benefits that matrix compounds generate for the collective; and that genetic division of labor can be favored when it breaks metabolic constraints associated with the simultaneous production of two matrix components.Highlights- matrix components EPS and TasA are costly public goods inB. subtilisbiofilms- genetic division of labor using Δepsand ΔtasAfosters maximal biofilm productivity- Δepsand ΔtasAcooperation is evolutionary stable in laboratory and ecological systems- costly metabolic coupling of public goods favors genetic division of labor

A hybrid zone defined by allozymes and ventral colour in Geocrinia rosea (Anura:Myobatrachidae)

The frog Geocrinia rosea is highly genetically subdivided with a major genetic division between northern and southern populations. Previous research did not sample a region spanning 12 km between these two populations. We report the distribution of G. rosea in the unsampled area and identify a geographically restricted hybrid zone. Boundaries of genetic groups were defined using two allozyme loci in 13 populations and ventral colouration. G. rosea was not continuously distributed in the area of parapatry. At the only point where the northern and southern groups met, there was a single hybrid population with genotypes demonstrating substantial interbreeding. Colour patterns implied a slightly broader hybrid zone, with four populations showing ventral colour introgression. Northern populations tended to have pink bellies whereas southern populations generally had orange bellies. We conclude that the two groups have diverged in allopatry and have formed a very narrow hybrid zone after range expansion. The magnitude of allozyme divergence between the four currently recognised species in the G. rosea complex is similar to the divergence between northern and southern G. rosea and is much greater than the divergence between other intraspecific groups. Taxonomic revision may therefore be warranted.