The ecological, behavioral, and genetic factors influencing the diversification of Lake Malawi\u27s rock -dwelling cichlids

Rapid evolutionary radiations provide insight into the fundamental processes involved in species formation. Here I examine the diversification of one such group, the rock-dwelling cichlid fishes of Lake Malawi (mbuna), which have radiated from a single ancestor into more than 200 species over the past 700,000 years. Through the examination of several molecular phylogenies, a phylogenetic history of the mbuna is proposed. The diversification of this group has proceeded in three major bursts of cladogenesis each of which has been dominated by a single selective force (selection on habitat preferences, trophic morphology, and male nuptial coloration, respectively). A divergence with gene flow model is advocated with reference to this phylogenetic pattern. A population genetic survey of allele frequency distributions at four microsatellite loci is used to quantify levels of gene flow within the mbuna genus Metriaclima. Results from this study indicate that migration rates between adjacent populations are low such that slight variation in the selective environment may drive the divergence of populations. Speciation models involving genetic drift, population bottlenecks, founder events, microallopatric divergence, and divergence with gene flow are discussed with respect to these findings. Some of the factors contributing to the existence of highly diverse, densely packed mbuna communities are identified by examining male territorial behavior and habitat utilization within Metriaclima. By observing the recolonization of artificially vacated territories, I show that (1) territories are species-specific and (2) this species-specificity is associated with the width of the breeding caves. These results are discussed with respect to character displacement and sexual selection. The speciation of the mbuna has been closely tied to the diversification of male color patterns, yet little is known concerning the genetic basis of such a fundamental character. By (1) examining female mating preferences, (2) describing the cellular basis of color pattern variation, and (3) identifying the genetic basis of this variation, I show that differential male melanistic patterning, which plays a role in the reproductive isolation of two Metriaclima species, is controlled by a limited number of genes. The rapid diversification of the mbuna is discussed with reference to this finding

EMERGING BUSINESSES: THE SOUTH AFRICAN WINE INDUSTRY CASE

Emerging economies such as South Africa, only a few years out of apartheid, have been feeling the strains of socio-political change. While South Africa has experienced political reform, economic reform and access are slow to come. Currently, South Africa is the 7th largest producer of wine in the world. Although this industry is impressive, the apartheid era production practices have caused primarily the European consumers and media to be vocal about this issue. However, this concern has spread to other regions. The South African government and wine industry must respond to the external and internal market pressures and minimize transaction costs. Both entities want to increase wine exports and expand market share, however, given the socio-economic and political climate in the country neither knows how to manage this difficult process which emanates from deeply rooted distrust of groups within the country. Socio-political constraints facing previously disadvantaged groups (PDG) as emerging business owners need to be understood; and, measures which could be undertaken by government and industry need to be identified. The objectives of this research were to identify: institutional constraints and transaction costs faced by PDGs aspiring toward production and leadership roles in the wine industry; ways the government can collaborate with the KWV to build social capital and promote PDG ownership in the wine industry, thus minimizing social conflict; and, identify industry strategies to increase exports and international market share under the "New South Africa" banner. This analysis was based on primary and secondary data and information gathered on site. Several potential solutions were suggested for ways to include PDGs in the South African wine market while minimizing the impact on the market shares of existing producers. It is anticipated that the window of opportunity to increase exports and involve PDG is quite small.Agribusiness,

Some considerations for various positioning systems and their science capabilities

Containerless processing of materials at elevated temperatures is discussed with emphasis on high temperature chemistry, thermophysical properties, materials science, and materials processing. Acoustic and electromagnetic positioning of high temperature melts are discussed. Results from recent ground based experiments, including KC-135 testing of an acoustic levitator, are presented. Some current positioning technologies and the potential for enhancing them are considered. Further, a summary of these technologies and their science capabilities for the development of future experiments is given

The reproductive cycle of the thorny skate (Amblyraid radiata) in the western Gulf of Maine

The thorny skate (Amblyraja radiata) is a large species of skate that is endemic to the waters of the western north Atlantic in the Gulf of Maine. Because the biomass of thorny skates has recently declined below threshold levels mandated by the Sustainable Fisheries Act, commercial harvests from this region are prohibited. We have undertaken a comprehensive study to gain insight into the life history of this skate. The present study describes and characterizes the reproductive cycle of female and male thorny skates, based on monthly samples taken off the coast of New Hampshire, from May 2001 to May 2003. Gonadosomatic index (GSI), shell gland weight, follicle size, and egg case formation, were assessed for 48 female skates. In general, these reproductive parameters remained relatively constant throughout most of the year. However, transient but significant increases in shell gland weight and GSI were observed during certain months. Within the cohort of specimens sampled monthly throughout the year, a subset of females always had large preovulatory follicles present in their ovaries. With the exception of June and September specimens, egg cases undergoing various stages of development were observed in the uteri of specimens captured during all other months of the year. For males (n=48), histological stages Ill through VI (SIII-SVI) of spermatogenesis, GSI, and hepatosomatic index (HSI) were examined. Although there appeared to be monthly fluctuations in spermatogenesis, GSI, and HSI, no significant differences were found. The production and maintenance of mature spermatocysts (SVI) within the testes was observed throughout the year. These findings collectively indicate that the thorny skate is reproductively active year round

The reproductive cycle of the thorny skate (Amblyraja radiata) in the western Gulf of Maine

The thorny skate (Amblyraja radiata) is a large species of skate that is endemic to the waters of the western north Atlantic in the Gulf of Maine. Because the biomass of thorny skates has recently declined below threshold levels mandated by the Sustainable Fisheries Act, commercial harvests from this region are prohibited. We have undertaken a comprehensive study to gain insight into the life history of this skate. The present study describes and characterizes the reproductive cycle of female and male thorny skates, based on monthly samples taken off the coast of New Hampshire, from May 2001 to May 2003. Gonadosomatic index (GSI), shell gland weight, follicle size, and egg case formation, were assessed for 48 female skates. In general, these reproductive parameters remained relatively constant throughout most of the year. However, transient but significant increases in shell gland weight and GSI were obser ved during certain months. Within the cohort of specimens sampled monthly throughout the year, a subset of females always had large preovulatory follicles present in their ovaries. With the exception of June and September specimens, egg cases undergoing various stages of development were observed in the uteri of specimens captured during all other months of the year. For males (n=48), histological stages III through VI (SIII−SVI) of spermatogenesis, GSI, and hepatosomatic index (HSI) were examined. Although there appeared to be monthly fluctuations in spermatogenesis, GSI, and HSI, no significant differences were found. The production and maintenance of mature spermatocysts (SVI) within the testes was observed throughout the year. These findings collectively indicate that the thorny skate is reproductively active year round

Automated, Miniaturized Instrument for Measuring Gene Expression in Space

To facilitate astrobiological studies on the survival and adaptation of microorganisms and mixed microbial cultures to space environment, we have been developing a fully automated, miniaturized system for measuring their gene expression on small spacecraft. This low-cost, multi-purpose instrument represents a major scientific and technological advancement in our ability to study the impact of the space environment on biological systems by providing data on cellular metabolism and regulation orders of magnitude richer than what is currently available. The system supports growth of the organism, lyse it to release the expressed RNA, label the RNA, read the expression levels of a large number of genes by microarray analysis of labeled RNA and transmit the measurements to Earth. To measure gene expression we use microarray technology developed by CombiMatrix, which is based on electrochemical reactions on arrays of electrodes on a semiconductor substrate. Since the electrical integrity of the microarray remains intact after probe synthesis, the circuitry can be employed to sense nucleic acid binding at each electrode. CombiMatrix arrays can be sectored to allow multiple samples per chip. In addition, a single array can be used for several assays. The array has been integrated into an automated microfluidic cartridge that uses flexible reagent blisters and pinch pumping to move liquid reagents between chambers. The proposed instrument will help to understand adaptation of terrestrial life to conditions beyond the planet of origin, identify deleterious effects of the space environment, develop effective countermeasures against these effects, and test our ability to sustain and grow in space organisms that can be used for life support and in situ resource utilization during long-duration space exploration. The instrument is suitable for small satellite platforms, which provide frequent, low cost access to space. It can be also used on any other platform in space, including the ISS. It can be replicated and used with only small modifications in multiple biological experiments with a broad range of goals in mind

A cricket Gene Index: a genomic resource for studying neurobiology, speciation, and molecular evolution

<p>Abstract</p> <p>Background</p> <p>As the developmental costs of genomic tools decline, genomic approaches to non-model systems are becoming more feasible. Many of these systems may lack advanced genetic tools but are extremely valuable models in other biological fields. Here we report the development of expressed sequence tags (EST's) in an orthopteroid insect, a model for the study of neurobiology, speciation, and evolution.</p> <p>Results</p> <p>We report the sequencing of 14,502 EST's from clones derived from a nerve cord cDNA library, and the subsequent construction of a Gene Index from these sequences, from the Hawaiian trigonidiine cricket <it>Laupala kohalensis</it>. The Gene Index contains 8607 unique sequences comprised of 2575 tentative consensus (TC) sequences and 6032 singletons. For each of the unique sequences, an attempt was made to assign a provisional annotation and to categorize its function using a Gene Ontology-based classification through a sequence-based comparison to known proteins. In addition, a set of unique 70 base pair oligomers that can be used for DNA microarrays was developed. All Gene Index information is posted at the DFCI Gene Indices web page</p> <p>Conclusion</p> <p>Orthopterans are models used to understand the neurophysiological basis of complex motor patterns such as flight and stridulation. The sequences presented in the cricket Gene Index will provide neurophysiologists with many genetic tools that have been largely absent in this field. The cricket Gene Index is one of only two gene indices to be developed in an evolutionary model system. Species within the genus <it>Laupala </it>have speciated recently, rapidly, and extensively. Therefore, the genes identified in the cricket Gene Index can be used to study the genomics of speciation. Furthermore, this gene index represents a significant EST resources for basal insects. As such, this resource is a valuable comparative tool for the understanding of invertebrate molecular evolution. The sequences presented here will provide much needed genomic resources for three distinct but overlapping fields of inquiry: neurobiology, speciation, and molecular evolution.</p

Saurogobio punctatus sp nov., a new cyprinid gudgeon (Teleostei: Cypriniformes) from the Yangtze River, based on both morphological and molecular data

A new cyprinid gudgeon, Saurogobio punctatus sp. nov., is described based on specimens collected from the Yangtze River, China. The new species can be distinguished from its congeners by differences in both morphology and the cytochrome b (cytb) gene sequence. Numerous minute blackish spots are scattered on dorsal and caudal fins in S. punctatus sp. nov. v. absent in the other seven valid Saurogobio species. The new species can be further distinguished from its congeners by the following unique combination of characters: a dorsal fin with eight branched rays; absence of scales in chest area before pectoral origin; upper and lower lips thick, covered with papillae; and a papillose mental pad approximately triangular. Morphologically, the new species most resembles the Chinese lizard gudgeon Saurogobio dabryi, but the new species lays yellowish adhesive eggs v. white pelagic eggs in S. dabryi. A phylogenetic analysis of all Saurogobio species based on cytb gene sequences indicated that S. punctatus sp. nov was distinctly separated from its congeners, with mean sequence divergence ranging from 126 to 210%. Therefore, molecular data further supported the distinctiveness of the new species.</p

Age and growth estimates of the thorny skate (Amblyraja radiata) in the western Gulf of Maine

The northwest Atlantic population of thorny skates (Amblyraja radiata) inhabits an area that ranges from Greenland and Hudson Bay, Canada, to South Carolina. Despite such a wide range, very little is known about most aspects of the biology of this species. Recent stock assessment studies in the northeast United States indicate that the biomass of the thorny skate is below the threshold levels mandated by the Sustainable Fisheries Act. In order to gain insight into the life history of this skate, we estimated age and growth for thorny skates, using vertebral band counts from 224 individuals ranging in size from 29 to 105 cm total length (TL). Age bias plots and the coefficient of variation indicated that our aging method represents a nonbiased and precise approach for the age assessment of A. radiata. Marginal increments were significantly different between months (Kruskal-Wallis P<0.001); a distinct trend of increasing monthly increment growth began in August. Age-at-length data were used to determine the von Bertalanffy growth parameters for this population: L∞ = 127 cm (TL) and k= 0.11 for males; L∞ = 120 cm (TL) and k= 0.13 for females. The oldest age estimates obtained for the thorny skate were 16 years for both males and females, which corresponded to total lengths of 103 cm and 105 cm, respectively

Variation in smolt quality of juevnile spring Chinook Salmon

As juvenile salmon migrate from freshwater into saltwater, physiological changes must occur to allow fish to osmoregulate in the marine environment. Juvenile spring Chinook salmon migrate to the ocean at different time periods, most notably in the fall (August – November; i.e. fall smolts) and spring (February – May; i.e. spring smolts) after their first summer of rearing. We tested the ability of laboratory reared fall and spring smolts to osmoregulate when placed in salt water from freshwater by comparing differences in plasma sodium concentration after a 24-hr salt water challenge. The fish were reared under two different regimes in which we manipulated temperature and feed in order to produce different growth rates such that fall smolts exhibited a faster growth rate. We conducted four salt water challenges from 28 August – 11 December (approximately once per month). Interestingly, spring fish when tested in the fall still were able to be saltwater tolerant. All fish survived the salt water challenges. Fall smolts had significantly lower plasma sodium concentrations in the first two challenges, indicating a higher smolt quality. However, plasma sodium concentrations in fall smolts increased each month, suggesting they were reverting in smolt quality. Spring smolts had mean plasma sodium concentrations below the 170 mM/L threshold which has been suggestive smoltification. However, spring smolts had greater variation in plasma sodium concentrations with approximately 65% of the fish having levels below the smoltification threshold, compared to > 85% in fall smolts. The ability of fall and spring smolts to regulate plasma sodium during salt water challenges indicated both groups could survive in the ocean, suggesting that fall and spring smolts would migrate if there was a match between physiological and environmental factors