Biomedical subjects

Lilach Hadany

Publications and source records attributed to Lilach Hadany.

4 recordsLinked to original sources

PubMed2006

Why is stress so deadly? An evolutionary perspective.

The reaction of the body to prolonged stress has many harmful effects. Classical theory assumes that stress responses have evolved due to their short-term selective advantages ('flight or fight'), and despite their adverse long-term effects. In contrast, we demonstrate that the adverse effects of stress responses may have a selective advantage. Using an analytical model we show that a gene that causes the early death of a relatively unfit individual can increase in frequency in a structured population even if it has no positive effect on that individual. This result offers a new perspective on the relations between stress factors, stress responses and stress-related diseases.

Cultural Evolution↗

PubMed2005

The evolution of plastic recombination.

Empirical data suggest that recombination rates may change in response to stress. To study the evolution of plastic recombination, we develop a modifier model using the same theoretical framework used to study conventional (nonplastic) modifiers, thus allowing direct comparison. We examine the evolution of plastic recombination in both haploid and diploid systems. In haploids, a plastic modifier spreads by forming associations with selectively favored alleles. Relative to nonplastic effects, selection on the plastic effects of a modifier is both much stronger and less sensitive to the specifics of the selection regime (e.g., epistasis). In contrast, the evolution of plastic recombination in diploids is much more restricted. Selection on plasticity requires the ability to detect DNA damage or cis-trans effects as may occur through maternal effects on fitness.

Evolution, Molecular↗

PubMed2003

Adaptive peak shifts in a heterogenous environment.

The problem of moving from one coadapted gene complex to a better one can be divided into two steps: first the advantageous combination has to appear and then it has to take over the population. Selection can have contrasting effects on the two stages. When selection is weak intermediate forms are frequent, and the advantageous combination appears easily. Spreading of that advantageous combination, on the other hand, tends to be hard, as recombination acts to break it. The opposite is true when selection is strong. Spreading is easier, but if selection is also strong against the intermediate forms, the appearance of the beneficial combination becomes an extremely rare event. This inherent contrast in the optimal conditions for the two stages raises the possibility that proximity of areas differing in the intensity of selection may significantly shorten the expected waiting time for a peak shift. We studied this phenomenon in a haploid two-locus diallelic model of two neighboring subpopulations. Our results show that limited migration between the two areas might shorten the waiting time for a peak shift by orders of magnitude in comparison with either complete isolation or complete mixing. Implications for peripheral evolution and speciation are discussed.

Adaptation, Biological↗

PubMed2003

On the evolutionary advantage of fitness-associated recombination.

The adaptive value of recombination remains something of a puzzle. One of the basic problems is that recombination not only creates new and advantageous genetic combinations, but also breaks down existing good ones. A negative correlation between the fitness of an individual and its recombination rate would result in prolonged integrity of fitter genetic combinations while enabling less fit ones to produce new combinations. Such a correlation could be mediated by various factors, including stress responses, age, or direct DNA damage. For haploid population models, we show that an allele for such fitness-associated recombination (FAR) can spread both in asexual populations and in populations reproducing sexually at any uniform recombination rate. FAR also carries an advantage for the population as a whole, resulting in a higher average fitness at mutation-selection balance. These results are demonstrated in populations adapting to new environments as well as in well-adapted populations coping with deleterious mutations. Current experimental results providing evidence for the existence of FAR in nature are discussed.

Adaptation, Physiological↗