Author: Ljiljana Mihajlovic

Introduction The pace of the evolutionary change depends on the existence of genetic variation, population size and intensity of the selection. While environmental change very often exceeds the rate of evolution for many species, killifish (Fundulus heteroclitus), living in U.S Atlantic coast estuaries turn out to be remarkably resilient. They have adapted to survive levels of toxic industrial pollutants, tolerating concentrations up to 8000 times higher than sensitive fish.  In this interesting study, Reid et al. use population genomic and transcriptomic analyses to reveal complex genetic basis of rapid adaptation in killifish to dramatic, human-induced, environmental change. Results Four pairs of sensitive and tolerant populations were compared. Based on comparative trancriptomics and analysis of 384 whole genome sequences few candidate regions are identified to underlay tolerance to complex mixtures of polycyclic and halogenated aromatic hydrocarbons. Interestingly, they are shared among four tolerant populations and are highly ranked. This suggests that the most important targets of selection have evolved in parallel across polluted sites. Within shared outliers are genes involved in aryl hydrocarbon receptor (AHR) signalling pathway. Role of this pathway is to mediate toxicity. Experiments showed that tolerant populations exhibit reduced inducibility of AHR regulated genes while sensitive populations showed …

Introduction Novel traits play a key role in evolution by facilitating the access to new ecological niches. Novelty is often recognized at a phenotypic level and usually related to gain of new function. But can nature innovate through the loss of the function? Wing reduction and loss of flight in birds occurred several times in evolutionary history. It is found among 26 families of birds. However, it is difficult to determine genetic basis underlying this change. In this interesting study Burga et al.  are using flightless Galapagos cormorant (Phalacrocorax harrisi) as an interesting model to study evolution of recent loss of flight. Namely, P.harrisi diverged from its flighted relatives within the past 2 million years and represents the only flightless cormorant among 40 existing species. The entire population (approximately 1500 individuals) is distributed along the coastlines of Isabela and Fernandina islands in the Galapagos archipelago. There are two evolutionary paths that could possibly explain the loss of flight. Flightlessness could be positively selected if it helps birds to develop alternative ability to escape from predators and to survive (like swimming). Alternatively, if flying was not essential for surviving (no need to escape from predators) the mutations that obstruct flight might …