Laboratory experimental evolution provides a window into the details of the evolutionary process. To investigate the consequences of long-term adaptation, we evolved 205 S. cerevisiae populations (124 haploid and 81 diploid) for ∼10,000 generations in three environments. We measured the dynamics of fitness changes over time, finding repeatable patterns of declining adaptability. Sequencing revealed that this phenotypic adaptation is coupled with a steady accumulation of mutations, widespread genetic parallelism, and historical contingency. In contrast to long-term evolution in E. coli, we do not observe long-term coexistence or populations with highly elevated mutation rates. We find that evolution in diploid populations involves both fixation of heterozygous mutations and frequent loss-of-heterozygosity events. Together, these results help distinguish aspects of evolutionary dynamics that are likely to be general features of adaptation across many systems from those that are specific to individual organisms and environmental conditions.

Seawater that has been altered by reaction with basaltic basement has been sampled from Deep Sea Drilling Project Hole 504B, located on 5.9-m.y.-old crust on the southern flank of the Costa Rica Rift. Fourteen water samples have been collected on Legs 69, 70, and 83, both before and after renewed drilling on the latter two legs, at temperatures from 69 to 133°C and pressures from 390 to 425 bars.The water sampled prior to renewed drilling on Leg 83 had occupied the hole for nearly 2 yr. since it was last flushed with surface seawater at the end of Leg 70. Despite some contamination by seawater during sampling, the composition of two of these waters has been determined by using nitrate as a tag for the contaminant. Both the 80 and 115°C waters have seawater chlorinity, but have lost considerable Mg, Na, K, sulfate, and 0 2 , and have gained Ca, alkalinity, Si, NH 3 and H 2 S. The loss of sulfate is due to anhydrite precipitation, as indicated by the δ 34 S value of the remaining dissolved sulfate. The 87 Sr/ 86 Sr ratio has been lowered to 0.7086 for the 80°C water and 0.7078 for the 115°C water, whereas the Sr concentration is nearly unchanged. The changes in major element composition relative to seawater are also larger for the 115°C water, indicating that the basement formation water at this site probably varies in composition with depth. Based on their direction relative to seawater, the compositional changes for the 80 and 115°C waters do not complement the changes inferred for the altered rocks from Hole 504B, suggesting that the bulk composition of the altered rocks, like their mineralogy, is largely unrelated to the present thermal and alteration regime in the hole.The exact nature of the reacted seawaters cannot be determined yet, however. During its 2 yr. residence in the hole, the surface seawater remaining at the end of Leg 70 would have reacted with the wall rocks and exchanged with their interstitial formation waters by diffusion and possibly convection. How far these processes have proceeded is not yet certain, although calculations suggest that diffusion alone could have largely exchanged the surface seawater for interstitial water. The δ 18 θ of the samples is indistinguishable from seawater, however, and the Δ 14 C of the 80°C sample is similar to that of ocean bottom water. Although the interpretation of these species is ambiguous, that of tritium should not be. Tritium analyses, which are in progress, should clarify the nature of the reacted seawaters obtained from the hole.

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Cartilage excision alone has been demonstrated to be an effective technique in the treatment of chondrodermatitis nodularis (CDN), and in the short term is associated with an 80% cure rate. The objective of this study was to demonstrate that long-term disease control could be achieved using this surgical technique. Set in three hospital dermatology departments, 94 patients with CDN affecting the helix and antihelix were contacted by postal questionnaire at least 6 months after surgery. Replies were received from 77; 11 patients had died and six could not be traced. The main outcome measure was the identification of those patients in remission and those with disease recurrence. Sixty-two helix lesions were followed up for a mean of 52 months (range 8-99). There was recurrence in 10 patients (all men; 16%). Twenty antihelix lesions were followed up for a mean of 55 months (range 8-93). There was recurrence in five patients (all women; 25%). In conclusion, this study confirms that only cartilage needs to be excised for the long-term effective treatment of CDN. The only relevant aetiological factor identified was that all except one patient slept on the same side as the CDN. We believe that pressure on the ear during sleep causes CDN. This is most evident on the most protuberant part of the ear.

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