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Selected AbstractsTrouble on the reef: the imperative for managing vulnerable and valuable fisheriesFISH AND FISHERIES, Issue 3 2005Yvonne Sadovy Abstract Reef fishes are significant socially, nutritionally and economically, yet biologically they are vulnerable to both over-exploitation and degradation of their habitat. Their importance in the tropics for living conditions, human health, food security and economic development is enormous, with millions of people and hundreds of thousands of communities directly dependent, and many more indirectly so. Reef fish fisheries are also critical safety valves in times of economic or social hardship or disturbance, and are more efficient, less wasteful and support far more livelihoods per tonne produced than industrial scale fisheries. Yet, relative to other fisheries globally, those associated with coral reefs are under-managed, under-funded, under-monitored, and as a consequence, poorly understood or little regarded by national governments. Even among non-governmental organizations, which are increasingly active in tropical marine issues, there is typically little focus on reef-associated resources, the interest being more on biodiversity per se or protection of coral reef habitat. This essay explores the background and history to this situation, examines fishery trends over the last 30 years, and charts a possible way forward given the current realities of funding, capacity, development patterns and scientific understanding of coral reef ecosystems. The luxury live reef food-fish trade is used throughout as a case study because it exemplifies many of the problems and challenges of attaining sustainable use of coral reef-associated resources. The thesis developed is that sustaining reef fish fisheries and conserving biodiversity can be complementary, rather than contradictory, in terms of yield from reef systems. I identify changes in perspectives needed to move forward, suggest that we must be cautious of ,fashionable' solutions or apparent ,quick fixes', and argue that fundamental decisions must be made concerning the short and long-term values of coral reef-associated resources, particularly fish, for food and cash and regarding alternative sources of protein. Not to address the problems will inevitably lead to growing poverty, hardship and social unrest in many areas. [source] Climate change and cereal aphids: the relative effects of increasing CO2 and temperature on aphid population dynamicsGLOBAL CHANGE BIOLOGY, Issue 1 2004Jonathan A. Newman Abstract Experimental evidence regarding the responses of cereal aphids to rising atmospheric CO2 has been ambiguous. Some studies suggest increased population sizes under future CO2 levels, others suggest decreased population sizes, and still others suggest little or no difference. Recently, Newman et al. (2003) constructed a general mathematical model of the aphid,grass interaction to investigate whether or not we should, in fact, expect a general aphid response to rising CO2. They concluded that aphid populations are likely to be larger under future CO2 concentrations if soil N levels are high, the aphid species' nitrogen requirement is low and the aphid species' density-dependent response in winged morph production is weak. In that model, and in field experiments, CO2 concentration influences aphid population dynamics through the effect it has on plant quality. However, future CO2 concentrations are also likely to be accompanied by higher ambient temperatures, a combination that has received little focus to date. In the present paper, the Newman et al. model is used to consider the combined effects of increased CO2 concentrations and temperature on aphid population sizes. It is concluded that, when both factors are elevated, aphid population dynamics will be more similar to current ambient conditions than expected from the results of experiments studying either factor alone. This result has important implications for future experimentation. [source] The transcriptomics of life-history trade-offs in whitefish species pairs (Coregonus sp.)MOLECULAR ECOLOGY, Issue 7 2008J. ST-CYR Abstract Despite the progress achieved in elucidating the ecological mechanisms of adaptive radiation, there has been little focus on documenting the extent of adaptive differentiation in physiological functions during this process. Moreover, a thorough understanding of the genomic basis underlying phenotypic adaptive divergence is still in its infancy. One important evolutionary process for which causal genetic mechanisms are largely unknown pertains to life-history trade-offs. We analysed patterns of gene transcription in liver tissue of sympatric dwarf and normal whitefish from two natural lakes, as well as from populations reared in controlled environments, using a 16 006-gene cDNA microarray in order to: (i) document the extent of physiological adaptive divergence between sympatric dwarf and normal species pairs, and (ii) explore the molecular mechanisms of differential life history trade-offs between growth and survival potentially involved in their adaptive divergence. In the two natural lakes, 6.45% of significantly transcribed genes showed regulation either in parallel fashion (2.39%) or in different directions (4.06%). Among genes showing parallelism in regulation patterns, we observed a higher proportion of over-expressed genes in dwarf relative to normal whitefish (70.6%). Patterns observed in controlled conditions were also generally congruent with those observed in natural populations. Dwarf whitefish consistently showed significant over-expression of genes potentially associated with survival through enhanced activity (energy metabolism, iron homeostasis, lipid metabolism, detoxification), whereas more genes associated with growth (protein synthesis, cell cycle, cell growth) were generally down-regulated in dwarf relative to normal whitefish. Overall, parallelism in patterns of gene transcription, as well as patterns of interindividual variation across controlled and natural environments, provide strong indirect evidence for the role of selection in the evolution of differential regulation of genes involving a vast array of potentially adaptive physiological processes between dwarf and normal whitefish. Our results also provide a first mechanistic, genomic basis for the observed trade-off in life-history traits distinguishing dwarf and normal whitefish species pairs, wherein enhanced survival via more active swimming, necessary for increased foraging and predator avoidance, engages energetic costs that translate into slower growth rate and reduced fecundity in dwarf relative to normal whitefish. [source] Chloroplast microsatellites reveal colonization and metapopulation dynamics in the Canary Island pineMOLECULAR ECOLOGY, Issue 10 2006MIGUEL NAVASCUÉS Abstract Chloroplast microsatellites are becoming increasingly popular markers for population genetic studies in plants, but there has been little focus on their potential for demographic inference. In this work the utility of chloroplast microsatellites for the study of population expansions was explored. First, we investigated the power of mismatch distribution analysis and the FS test with coalescent simulations of different demographic scenarios. We then applied these methods to empirical data obtained for the Canary Island pine (Pinus canariensis). The results of the simulations showed that chloroplast microsatellites are sensitive to sudden population growth. The power of the FS test and accuracy of demographic parameter estimates, such as the time of expansion, were reduced proportionally to the level of homoplasy within the data. The analysis of Canary Island pine chloroplast microsatellite data indicated population expansions for almost all sample localities. Demographic expansions at the island level can be explained by the colonization of the archipelago by the pine, while population expansions of different ages in different localities within an island could be the result of local extinctions and recolonization dynamics. Comparable mitochondrial DNA sequence data from a parasite of P. canariensis, the weevil Brachyderes rugatus, supports this scenario, suggesting a key role for volcanism in the evolution of pine forest communities in the Canary Islands. [source] | ||||||||||