PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 12167749

Ultimate divers.

Lewis Halsey
View original source ↗Export metadata ↓

Abstract

An extraordinary variety of mammals, birds, amphibians and reptiles are adapted to life in the oceans. Many of them spend their entire lives there without being able to breathe underwater. But just how do they exploit this hostile environment?

Explore related subjects

Adaptation, PhysiologicalAnimalsBiological EvolutionBirdsDivingHumansOceans and SeasRespirationWhalesJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Lewis Halsey. 2002. Ultimate divers.. https://pubmed.ncbi.nlm.nih.gov/12167749/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2025

Genome sequencing and population genetics provide insights into local adaptation of Opisthopappus species on cliff environments of Taihang Mountains.

Local adaptation represents a pivotal theme in evolutionary biology. The Opisthopappus genus, comprising Opisthopappus longilobus and O. taihangensis, thrives on the cliffs of the Taihang Mountains. During their evolutionary history, two species are hypothesized to have locally adapted to their cliff habitats. In the present study, we employed a combined approach of whole-genome sequencing of O. taihangensis and population genomic analysis from both species to gain deeper insights into their patterns of local adaptation. Our results revealed that the expansive genome of O. taihangensis (3010.18 Mb), a consequence of a whole-genome duplication (WGD) event, coupled with a high proportion of repetitive sequences (82.70%), was postulated as one of its adaptive strategies. A clear differentiation between O. taihangensis and O. longilobus was observed, with the two species diverging approximately 17.57 million years ago (Mya), with O. longilobus serving as the ancestor. Since their divergence, limited gene flow was observed between the two species. Post-divergence, the effective population sizes of both species expanded, yet underwent a dramatic reduction at approximately 0.07 Mya. Furthermore, a total of 798 adaptive genes were identified, of which 207 overlapped with expanded genes, and eight genes were found to be under positive selection. These genes primarily regulated the growth and development of both species via pathways such as oxidation-reduction and ubiquitin-proteasome, enabling them to withstand climate changes. These findings provide profound insights into the local adaptation of Opisthopappus species to the cliff environments and offer valuable clues for further exploring the local adaptation among various cliff-dwelling organisms.

Adaptation, Physiological↗
PubMed2015

Variation in Drosophila melanogaster central metabolic genes appears driven by natural selection both within and between populations.

In this report, we examine the hypothesis that the drivers of latitudinal selection observed in the eastern US Drosophila melanogaster populations are reiterated within seasons in a temperate orchard population in Pennsylvania, USA. Specifically, we ask whether alleles that are apparently favoured in northern populations are also favoured early in the spring, and decrease in frequency from the spring to autumn with the population expansion. We use SNP data collected for 46 metabolic genes and 128 SNPs representing the central metabolic pathway and examine for the aggregate SNP allele frequencies whether the association of allele change with latitude and that with increasing days of spring-autumn season are reversed. Testing by random permutation, we observe a highly significant negative correlation between these associations that is consistent with this expectation. This correlation is stronger when we confine our analysis to only those alleles that show significant latitudinal changes. This pattern is not caused by association with chromosomal inversions. When data are resampled using SNPs for amino acid change the relationship is not significant but is supported when SNPs associated with cis-expression are only considered. Our results suggest that climate factors driving latitudinal molecular variation in a metabolic pathway are related to those operating on a seasonal level within populations.

Adaptation, Physiological↗
PubMed2003

Survival, growth, and inactivation of acid-stressed Shigella flexneri as affected by pH and temperature.

A study was done to determine the survival, growth, and inactivation characteristics of unadapted, acid-adapted, and acid-shocked Shigella flexneri 2a cells as affected by pH and temperature. The pathogen was grown at 37 degrees C for 18 h in tryptic soy broth containing no glucose (TSBNG) (unadapted cells) and TSBNG supplemented with 1% glucose (TSBG) (acid-adapted cells). Cells grown in TSBNG were acid-shocked by adjusting 18-h cultures to pH 4.5+/-0.05 with lactic acid. All three cell types were separately inoculated into tryptic soy broth (6.6-7.0 log(10) cfu/ml) containing 0.25% glucose (TSB) acidified to pH 3.5-5.5 with lactic acid and incubated at 4, 12, 21, 30, and 48 degrees C for up to 144 h. Overall, inactivation of S. flexneri cells at low pH was enhanced with an increase in incubation temperature. All three types of cells survived for 144 h at 4 degrees C in TSB acidified to pH 3.5, compared to < 24 h at 30 degrees C and 2 h at 48 degrees C. The population of all three cell types increased significantly (alpha = 0.05) within 24 h when cells were incubated at 12, 21, or 30 degrees C in TSB at pH 5.0, 5.5, or 7.3. Prior exposure of the S. flexneri to an acidic environment (acid-adapted or acid-shocked cells) resulted in increased resistance to extreme acid and temperature conditions. Acid-adapted cells decreased by approximately 2.5 log(10) cfu/ml when incubated at 4 degrees C for 144 h, compared to a 6-log(10) reduction in control (unadapted) cells. When cells were exposed to low pH (3.5-4.5) and high temperature (48 degrees C), significantly higher (alpha = 0.05) populations were recovered on tryptic soy agar (TSA) than on TSA supplemented with 4% NaCl (TSAS), indicating that a portion of S. flexneri cells were injured. Results show that the ability of S. flexneri to survive and grow at a given pH is influenced by previous exposure to acidic environments and by incubation temperature.

Adaptation, Physiological↗