Contrasting quantitative traits and neutral genetic markers for genetic resource assessment of Mesoamerican Cedrela odorata

We compared within-population variability and degree of population differentiation for neutral genetic markers (RAPDS) and eight quantitative traits in Central American populations of the endangered tree, Cedrela odorata. Whilst population genetic diversity for neutral markers (Shannon index) and quantitative traits (heritability, coefficient of additive genetic variation) were uncorrelated, both marker types revealed strong differentiation between populations from the Atlantic coast of Costa Rica and the rest of the species' distribution. The degree of interpopulation differentiation was higher for RAPD markers (F-ST 0.67 for the sampled Mesoamerican range) than for quantitative traits (Q(ST) = 0.30). Hence, the divergence in quantitative traits was lower than could have been achieved by genetic drift alone, suggesting that balancing selection for similar phenotypes in different populations of this species. Nevertheless, a comparison of pair-wise estimates of population differentiation in neutral genetic markers and quantitative traits revealed a strong positive correlation (r = 0.66) suggesting that, for C. odorata, neutral marker divergence could be used as a surrogate for adaptive gene divergence for conservation planning. The utility of this finding and suggested further work are discussed.

Late Quaternary uplift and subsidence of the west coast of Tanna, south Vanuatu, southwest Pacific: U-Th ages of raised coral reefs in the Median Sedimentary Basin

Twelve Late Quaternary TIMS U-Th ages are reported here from 10 coral samples collected in situ from five transgressive coral/algal raised reefs (height: max. 113 m, min. 8 m) and two raised lagoonal deposits (height: max. 18 m, min. 8 m) along and near the west coast of Tanna, which lies in the Median Sedimentary Basin of South Vanuatu, southwest Pacific. These reefs and raised lagoonal deposits represent several age groups: (i) 215 ka (marine oxygen-isotope stage 7) penultimate interglacial (highest elevation and oldest); (ii) one lagoonal deposit of ca 127 ka (marine oxygen-isotope stage 5e); (iii) three last interglacial reefs with ages 102, 89 and 81 ka (representing marine oxygen-isotope stages 5c, 5b and 5a, respectively, of the latter part of the last interglacial); (iv) a lagoonal deposit with a 92 ka age (5b); and (v) a Holocene reef (age >5.7-5.0 ka) (lowest elevation and youngest). A ca 4.9 ka regressive reef (at elevation of 1.5 m above sea-level) is consistent with an island-wide 6.5 m uplift (probably largely coseismic), and a probable further island-wide uplift occurred in the late Holocene. The U-series ages taken together with the heights of transgressive reefs show that uplift since 215 ka was, on average, at similar to0.52 mm/y; although since 5 ka the uplift rate was, on average, similar to1.6 mm/y (the assumption being that a 1.5 m above sea-level reef has a coseismic origin). Elevation of transgressive reefs 5a, 5b and 5c and their ages indicates an island-wide subsidence during the period ?124-89 ka (i.e. Late Quaternary uplift/subsidence was jerky). Late Quaternary uplift/subsidence on the northwest coast of Tanna is considered to be due to irregular thicknesses of crust being subducted beneath Tanna.

Mitochondrial control region diversity of the houbara bustard Chlamydotis undulata complex and genetic structure along the Atlantic seaboard of North Africa

The houbara bustard, Chlamydotis undulata, is a declining cryptic desert bird whose range extends from North Africa to Central Asia. Three subspecies are currently recognized by geographical distribution and morphology: C.u.fuertaventurae, C.u.undulata and C.u.macqueenii. We have sequenced 854 bp of mitochondrial control region from 73 birds to describe their population genetic structure with a particular sampling focus on the connectivity between C.u.fuertaventurae and C.u.undulata along the Atlantic seaboard of North Africa. Nucleotide and haplotypic diversity varied among the subspecies being highest in C.u.undulata, lowest in C.u.fuertaventurae and intermediate in C.u.macqueenii. C.u.fuertaventurae and C.u.undulata are paraphyletic and an average nucleotide divergence of 2.08% splits the later from C.u.macqueenii. We estimate that C.u.fuertaventurae and C.u.undulata split from C.u.macqueenii approximately 430 000 years ago. C.u.fuertaventurae and C.u.undulata are weakly differentiated (F-ST = 0.27, N-m = 1.3), indicative of a recent shared history. Archaeological evidence indicates that houbara bustards have been present on the Canary Islands for 130-170 000 years. However, our genetic data point to a more recent separation of C.u.fuertaventurae and C.u.undulata at around 20-25 000 years. Concordant archaeological, climatic opportunities for colonization and genetic data point to a scenario of: (i) initial colonization of the Canary Islands about 130 000 years ago; (ii) a period of secondary contact 19-30 000 years ago homogenizing any pre-existing genetic structure followed by; (iii) a period of relative isolation that persists today.

Regional climate change and harmful algal blooms in the northeast Atlantic

We investigated long-term spatial variability in a number of Harmful Algal Blooms (HABs) in the northeast Atlantic and North Sea using data from the Continuous Plankton Recorder. Over the last four decades. some dinoflagellate taxa showed pronounced variation in the south and east of the North Sea, with the most significant increases being restricted to the adjacent waters off Norway. There was also a general decrease along the eastern coast of the United Kingdom. The most prominent feature in the interannual bloom frequencies over the last four decades was the anomalously high values recorded in the late 1980s in the northern and central North Sea areas. The only mesoscale area in the northeast Atlantic to show a significant increase in bloom formation over the last decade was the Norwegian coastal region. The changing spatial patterns of HAB taxa and the frequency of bloom formation are discussed in relation to regional climate change, in particular, changes in temperature, salinity, and the North Atlantic Oscillation (NAO). Areas highly vulnerable to the effects of regional climate change on HABs are Norwegian coastal waters and the Skagerrak. Other vulnerable areas include Danish coastal waters, and to a lesser extent, the German and Dutch Bight and the northern Irish Sea. Quite apart from eutrophication, our results give a preview of what might happen to certain HAB genera under changing climatic conditions in temperate environments and their responses to variability of climate oscillations Such as the NAO.