Comparative Analysis of Japanese Three-Spined Stickleback Clades Reveals the Pacific Ocean Lineage Has Adapted to Freshwater Environments while the Japan Sea Has Not

Divergent selection and adaptive divergence can increase phenotypic diversification amongst populations and lineages. Yet adaptive divergence between different environments, habitats or niches does not occur in all lineages. For example, the colonization of freshwater environments by ancestral marine species has triggered adaptive radiation and phenotypic diversification in some taxa but not in others. Studying closely related lineages differing in their ability to diversify is an excellent means of understanding the factors promoting and constraining adaptive evolution. A well-known example of the evolution of increased phenotypic diversification following freshwater colonization is the three-spined stickleback. Two closely related stickleback lineages, the Pacific Ocean and the Japan Sea occur in Japan. However, Japanese freshwater stickleback populations are derived from the Pacific Ocean lineage only, suggesting the Japan Sea lineage is unable to colonize freshwater. Using stable isotope data and trophic morphology, we first show higher rates of phenotypic and ecological diversification between marine and freshwater populations within the Pacific Ocean lineage, confirming adaptive divergence has occurred between the two lineages and within the Pacific Ocean lineage but not in the Japan Sea lineage. We further identified consistent divergence in diet and foraging behaviour between marine forms from each lineage, confirming Pacific Ocean marine sticklebacks, from which all Japanese freshwater populations are derived, are better adapted to freshwater environments than Japan Sea sticklebacks. We suggest adaptive divergence between ancestral marine populations may have played a role in constraining phenotypic diversification and adaptive evolution in Japanese sticklebacks.     

Has the prehistoric ice-man contributed to the preservation of living fungal spores?

Abstract There are arguments against the conclusion drawn by Haselwandter and Ebner that fungal spores have survived for some 5300 years on hay padding in the leather boots of frozen body discovered in the Austrian Alps. According to cryobiological experience, long-term survival of fungal spores is very unlikely at temperatures fluctuating between zero and −40°C. It is quite possible that living spores of these common species have recently reached this substratum.