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Ecological Radiation (ecological + radiation)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Laboratory spawning, larval development, and metamorphosis of the limpets Lottia digitalis and Lottia asmi (Patellogastropoda, Lottiidae)

INVERTEBRATE BIOLOGY, Issue 1 2002
Matthew C. Kay
Abstract. This study describes and compares laboratory spawning, larval development, and metamorphosis in the patellogastropod limpets Lottia digitalis and Lottia asmi. Both species were dioecious and freely spawned their gametes, which were fertilized externally. Eggs from L. digitalis and L. asmi averaged 155 and 134 ,m in diameter, respectively. Early cleavage patterns were typical of other patellogastropods. Swimming trochophore larvae had developed , 15 hours after fertilization, and ultimately developed into lecithotrophic veliger larvae that reached metamorphic competence at 5.25,5.5 days after fertilization (13°C). Food particles were frequently visible in the gut of newly metamorphosed individuals one day after settlement, and adult shell growth was typically initiated within 2,4 days of settlement. Small egg size in L. asmi, relative to other eastern Pacific lottiids, may be directly related to the need for high fecundity in this small-bodied species; however, developmental information is available for relatively few lottiid species. Because broadcasting lottiids do not secure egg masses in safe microhabitats for development, this reproductive mode may have been conducive to their ecological radiation into novel habitats. [source]

Phylogeny and ecological radiation of New World thistles (Cirsium, Cardueae , Compositae) based on ITS and ETS rDNA sequence data

MOLECULAR ECOLOGY, Issue 1 2003
Dean G. Kelch
Abstract Sequence data from a portion of the external transcribed spacer (ETS) and internal transcribed spacers (ITS-1 and ITS-2) of 18S-26S nuclear ribosomal DNA were used to resolve historical biogeography and ecology of true thistles (Cirsium, Cardueae, Compositae) in the New World. The 650 base-pair, 3, portion of the ETS examined here showed a level of variation across taxa similar to that of the ITS sequences included. A maximum-likelihood tree based on combined ETS and ITS sequences leads us to suggest that the New World species of true thistles constitute a major lineage, which in turn comprises several smaller lineages. A western North American lineage shows weak quartet-puzzling support, but includes a well-supported lineage of species endemic to the California Floristic Province. Comparisons of this Californian lineage with other neoendemic angiosperm groups of the region show that the Californian Cirsium lineage exhibits unusually high ecological diversity for a group displaying such low levels of rDNA sequence divergence across taxa. Similarly low levels of sequence divergence were found throughout the New World Cirsium lineage. These results indicate either that Cirsium underwent a rapid ecological radiation in North America, or that rDNA evolution in North American Cirsium has been highly conservative. [source]

INTRAMARGINAL VEINED LAURACEAE LEAVES FROM THE ALBIAN,CENOMANIAN OF CHARENTE-MARITIME (WESTERN FRANCE)

PALAEONTOLOGY, Issue 2 2009
CLÉMENT COIFFARD
Abstract:,Eucalyptolaurus depreii gen. et sp. nov. is proposed for angiosperm leaves newly collected from uppermost Albian , lowermost Cenomanian of Charente-Maritime (western France). They consist of simple, narrow, elongate laminas with entire margins and intramarginal veins. The epidermal cells of adaxial cuticle shows small, rounded, blunt papillae outward that protrude inward and fuse together as rolls along and parallel to the margins, while the adaxial cuticle bears brachyparacytic stomatal apparatus that exhibit sunken guard cells and hair bases consisting of a thick-walled pore surrounded by radially arranged differentiated cells. Resin bodies occur inside the mesophyll. These characters closely resemble the lauroid taxa ,Myrtophyllum' and Pandemophyllum from the Cenomanian of the Czech Republic and Dakota (USA) respectively. The narrow angle of basilaminar secondaries and the whole suite of features in the guard cells (sunken guard cells embedded into subsidiary cells and stomatal ledges) strongly support close affinity with the Lauraceae. From the Cenomanian lauraceous reproductive organs and their related leaves already showed high disparity and diversity. In addition they displayed a broad ecological range from freshwater floodplains to brackish swamps. This combined to high diversity of reproductive organs suggest ecological radiation of Lauraceae by the Cenomanian. [source]