Ignorance can be evolutionarily beneficial

Information is increasingly being viewed as a resource used by organisms to increase their fitness. Indeed, it has been formally shown that there is a sensible way to assign a reproductive value to information and it is non-negative. However, all of this work assumed that information collection is cost-free. Here, we account for such a cost and provide conditions for when the reproductive value of information will be negative. In these instances, counter-intuitively, it is in the interest of the organism to remain ignorant. We link our results to empirical studies where Bayesian behaviour appears to break down in complex environments and provide an alternative explanation of lowered arousal thresholds in the evolution of sleep.Comment: 5 pages, submitte

Weak universality in sensory tradeoffs

For many organisms, the number of sensory neurons is largely determined during development, before strong environmental cues are present. This is despite the fact that environments can fluctuate drastically both from generation to generation and within an organism's lifetime. How can organisms get by by hard-coding the number of sensory neurons? We approach this question using rate-distortion theory. A combination of simulation and theory suggests that when environments are large, the rate-distortion function---a proxy for material costs, timing delays, and energy requirements---depends only on coarse-grained environmental statistics that are expected to change on evolutionary, rather than ontogenetic, timescales

Measuring microsatellite conservation in mammalian evolution with a phylogenetic birth-death model.

Microsatellites make up ∼3% of the human genome, and there is increasing evidence that some microsatellites can have important functions and can be conserved by selection. To investigate this conservation, we performed a genome-wide analysis of human microsatellites and measured their conservation using a binary character birth--death model on a mammalian phylogeny. Using a maximum likelihood method to estimate birth and death rates for different types of microsatellites, we show that the rates at which microsatellites are gained and lost in mammals depend on their sequence composition, length, and position in the genome. Additionally, we use a mixture model to account for unequal death rates among microsatellites across the human genome. We use this model to assign a probability-based conservation score to each microsatellite. We found that microsatellites near the transcription start sites of genes are often highly conserved, and that distance from a microsatellite to the nearest transcription start site is a good predictor of the microsatellite conservation score. An analysis of gene ontology terms for genes that contain microsatellites near their transcription start site reveals that regulatory genes involved in growth and development are highly enriched with conserved microsatellites

On the fitness of informative cues in complex environments

To be able to deal with uncertainty is of primary importance to all organisms. When cues provide information about the state of the environment, organisms can use them to respond flexibly. Thus information can provide fitness advantages. Without environmental cues, an organism can reduce the risks of environmental uncertainty by hedging its bets across different scenarios. Risk mitigation is then possible by adopting a life-history of bet-hedging, either randomly switching between phenotypes (diversifying bet-hedging) or adopting intermediate phenotypes (conservative bet-hedging). Hence, understanding patterns of bet-hedging is necessary in order to quantify the fitness benefit of environmental cues, since it provides a baseline fitness in the absence of informative cues. Quantifying fitness benefits in terms of mutual information reveals deep connections between Darwinian evolution and information theory. However, physiological constraints or complex ecological scenarios often lead to the number of environmental states to exceed that of potential phenotypes, or a single intermediate phenotype is adopted, as in the case of conservative bet-hedging. Incorporating these biological complexities, we generalise the relationship between information theory and Darwinian fitness. Sophisticated bet-hedging strategies combining diversifying and conservative bet-hedging - can then evolve. We show that, counterintuitively, environmental complexity can reduce, rather than increase, the number of phenotypes that an organism can adopt. In conclusion, we develop an information-theoretic extensible approach for investigating and quantifying fitness in ecological studies