Positive selection over the mitochondrial genome and its role in the diversification of gentoo penguins in response to adaptation in isolation.

Although mitochondrial DNA has been widely used in phylogeography, evidence has emerged that factors such as climate, food availability, and environmental pressures that produce high levels of stress can exert a strong influence on mitochondrial genomes, to the point of promoting the persistence of certain genotypes in order to compensate for the metabolic requirements of the local environment. As recently discovered, the gentoo penguins (Pygoscelis papua) comprise four highly divergent lineages across their distribution spanning the Antarctic and sub-Antarctic regions. Gentoo penguins therefore represent a suitable animal model to study adaptive processes across divergent environments. Based on 62 mitogenomes that we obtained from nine locations spanning all four gentoo penguin lineages, we demonstrated lineage-specific nucleotide substitutions for various genes, but only lineage-specific amino acid replacements for the ND1 and ND5 protein-coding genes. Purifying selection (dN/dS < 1) is the main driving force in the protein-coding genes that shape the diversity of mitogenomes in gentoo penguins. Positive selection (dN/dS > 1) was mostly present in codons of the Complex I (NADH genes), supported by two different codon-based methods at the ND1 and ND4 in the most divergent lineages, the eastern gentoo penguin from Crozet and Marion Islands and the southern gentoo penguin from Antarctica respectively. Additionally, ND5 and ATP6 were under selection in the branches of the phylogeny involving all gentoo penguins except the eastern lineage. Our study suggests that local adaptation of gentoo penguins has emerged as a response to environmental variability promoting the fixation of mitochondrial haplotypes in a non-random manner. Mitogenome adaptation is thus likely to have been associated with gentoo penguin diversification across the Southern Ocean and to have promoted their survival in extreme environments such as Antarctica. Such selective processes on the mitochondrial genome may also be responsible for the discordance detected between nuclear- and mitochondrial-based phylogenies of gentoo penguin lineages.

Contrasting phylogeographic pattern among Eudyptes penguins around the Southern Ocean.

Since at least the middle-Miocene, the Antarctic Polar Front (APF) and the Subtropical Front (STF) appear to have been the main drivers of diversification of marine biota in the Southern Ocean. However, highly migratory marine birds and mammals challenge this paradigm and the importance of oceanographic barriers. Eudyptes penguins range from the Antarctic Peninsula to subantarctic islands and some of the southernmost subtropical islands. Because of recent diversification, the number of species remains uncertain. Here we analyze two mtDNA (HVRI, COI) and two nuclear (ODC, AK1) markers from 13 locations of five putative Eudyptes species: rockhopper (E. filholi, E. chrysocome, and E. moseleyi), macaroni (E. chrysolophus) and royal penguins (E. schlegeli). Our results show a strong phylogeographic structure among rockhopper penguins from South America, subantarctic and subtropical islands supporting the recognition of three separated species of rockhopper penguins. Although genetic divergence was neither observed among macaroni penguins from the Antarctic Peninsula and sub-Antarctic islands nor between macaroni and royal penguins, population genetic analyses revealed population genetic structure in both cases. We suggest that the APF and STF can act as barriers for these species. While the geographic distance between colonies might play a role, their impact/incidence on gene flow may vary between species and colonies.

Comparative phylogeography of co-distributed Phrygilus species (Aves, Thraupidae) from the Central Andes.

The Neotropical ecoregion has been an important place of avian diversification where dispersal and allopatric events coupled with periods of active orogeny and climate change (Late Pliocene-Pleistocene) have shaped the biogeography of the region. In the Neotropics, avian population structure has been sculpted not only by geographical barriers, but also by non-allopatric factors such as natural selection and local adaptation. We analyzed the genetic variation of six co-distributed Phrygilus species from the Central Andes, based on mitochondrial and nuclear markers in conjunction with morphological differentiation. We examined if Phrygilus species share patterns of population structure and historical demography, and reviewed the intraspecific taxonomy in part of their geographic range. Our results showed different phylogeographic patterns between species, even among those belonging to the same phylogenetic clade. P. alaudinus, P. atriceps, and P. unicolor showed genetic differentiation mediated by allopatric mechanisms in response to specific geographic barriers; P. gayi showed sympatric lineages in northern Chile, while P. plebejus and P. fruticeti showed a single genetic group. We found no relationship between geographic range size and genetic structure. Additionally, a signature of expansion was found in three species related to the expansion of paleolakes in the Altiplano region and the drying phase of the Atacama Desert. Morphological analysis showed congruence with molecular data and intraspecific taxonomy in most species. While we detected genetic and phenotypic patterns that could be related to natural selection and local adaptation, our results indicate that allopatric events acted as a major factor in the population differentiation of Phrygilus species.

Cross-amplification of nonspecific microsatellites markers: a useful tool to study endangered/vulnerable species of southern Andes deer.

Thirty-nine microsatellite loci that are highly conserved in red deer, sika deer, reindeer, Soay sheep, and other artiodactyls were tested in two vulnerable and endangered Neotropical deer (pudu: Pudu puda and huemul: Hippocamelus bisulcus) with the aim of producing a standardized set of markers that can be used successfully in noninvasive samples from these species. We also compared these nonspecific loci against eight polymorphic loci that were recently developed for huemul to determine whether the nonspecific markers could reflect the huemul's genetic variation that was observed with the specific loci. We identified 10 suitable loci, six of which constitute a standardized set for the two species and can be used to identify them in the absence of phenotypic data. The expected heterozygosity per locus for the panel of six loci ranged from 0.461 to 0.889 (average 0.665), and the maximum probability of identity value was 6.9x10(-6) and 3.2x10(-4) in pudu and huemul, respectively. This set of loci has potential applications in evolutionary, ecological, forensic, and conservation studies in pudu and huemul.

Time variation of some selected topics in bioethical publications.

OBJECTIVE: To analyse the time variation of topics in bioethical publications as a proxy of the relative importance. METHODS: We searched the Medline database for bioethics publications using the words "ethics or bioethics", and for 360 specific topics publications, associating Medical Subject Heading topic descriptors to those words. We calculated the ratio of bioethics publications to the total publications of Medline, and the ratio of each topic publications to the total bioethics publications, for five-year intervals, from 1970 to 2004. We calculated the time variation of ratios, dividing the difference between the highest and lowest ratio of each topic by its highest ratio. Four topics were described, selected to illustrate different patterns of variation: "Induced Abortion", "Conflict of Interest", "Acquired Immunodeficiency Syndrome", "Medical Education." RESULTS: The ratio of bioethics publications to total Medline publications increased from 0.003 to 0.012. The variation of the topic's ratios was higher than 0.7 for 68% of the topics. The Induced Abortion ratios decreased from 0.12 to 0.02. Conflict of Interest ratios increased from zero to 0.07. The Acquired Immunodeficiency Syndrome ratios were nearly zero in the first three intervals, had a peak of 0.06 during 1985-9, followed by a decrease to 0.01. Medical Education ratios varied few, from 0.04 to 0.03. CONCLUSIONS: There was an increase of bioethical publications in the Medline database. The topics in bioethics literature have an important time variation. Some factors were suggested to explain this variation: current legal cases, resolution of the issue, saturation of a discussion and epidemiologic importance.