Prefeeding larval development time is not correlated with egg size in regular echinoids (Strongylocentrotus species)

Summary

We compared prefeeding development times, from fertilized egg to prism larva, for Strongylocentrotus embryos from four clutches of eggs (each from a different species) differing in size. Development times did not vary consistently with egg diameter, and trends among eggs of different sizes varied with stage of development. In some cases, development times for eggs of intermediate diameter (S. franciscanus) were longer than those for larger or smaller eggs. Although mean egg diameters in clutches ranged from 84 μm (S. purpuratus) to 162 μm (S. pallidus), differences in development time to the last embryonic stage (prism) were very small. We conclude that the inverse relationship between parental investment in offspring and premetamorphic development time in echinoids depends only on the functional consequences of reduced size of feeding larval stages: effects of egg size on prefeeding development time are not evident.     

Selective predation by larval Agabus (Coleoptera: Dytiscidae) on mosquitoes: support for conservation-based mosquito suppression in constructed wetlands

1. Wetland insect predators can structure aquatic prey communities via selective predation, but receive considerably less attention than vertebrate predators. We conducted laboratory experiments to test selective predation by two species of larval dytiscid beetles ( Agabus ; Coleoptera: Dytiscidae) and the potential contribution of these beetles to suppression of mosquito populations in constructed wetlands.
2.  Agabus consumed copepods, ostracods and mosquito larvae in no-choice tests. When offered a choice, 76% of all prey consumed were mosquito larvae, indicating selective predation. Subsequent experiments revealed this preference was due to ease of capture of mosquito larvae over alternative prey.
3. Cannibalism and intraguild predation were common within and between species of Agabus , which may reduce the overall impact of the observed selective predation.
4.  Agabus larvae selectively preyed on mosquito larvae over alternative prey, which is not characteristic of some fish used as biological control agents for mosquitoes. Predator exclusion or similar experiments in the field could document how these results translate into a natural setting.
5. The findings of this study suggest developing mosquito suppression strategies focused on conservation of native wetland predators. These strategies are preferable to introducing non-native generalist predators, or applying pesticides.     

Five hundred million years of extinction and recovery: a phanerozoic survey of large‐scale diversity patterns in fishes

Abstract: Fishes include more than half of all living animals with backbones, but large‐scale palaeobiological patterns in this assemblage have not received the same attention as those for terrestrial vertebrates. Previous surveys of the fish record have generally been anecdotal, or limited either in their stratigraphic or in their taxonomic scope. Here, we provide a broad overview of the Phanerozoic history of fish diversity, placing a special emphasis on intervals of turnover, evolutionary radiation, and extinction. In particular, we provide in‐depth reviews of changes during, and ecological and evolutionary recovery after, the end‐Devonian (Hangenberg) and Cretaceous–Palaeogene (K–Pg) extinctions.     

Wood density predicts plant damage and vegetative recovery rates caused by cyclone disturbance in tropical rainforest tree species of North Queensland,Australia

Abstract The ability to withstand disturbance (resistance) and the ability to recover biomass following disturbance (resilience) were investigated in Australian wet tropical rainforest tree species. These two attributes are expected to be negatively correlated, because investment of biomass in structural support (conferring resistance) results in trees exhibiting high wood densities and slow growth rates, and vice versa. We examined species’ responses to disturbance caused by a severe tropical cyclone to test this hypothesized trade‐off. We assessed cyclone damage in six species in three Mabi rainforest fragments on the Atherton Tablelands. Species differed in the proportion of individuals within four damage categories (minor damage, severe branch damage, snapped, uprooted). Resistance was positively related to wood density. We found a positive correlation between the proportion of trees experiencing minor damage only and wood density, supporting the hypothesized association between resistance and mechanical strength. Among the subset of trees in which stems snapped, rates of resprouting differed between species and were highest in low wood density species and lowest in species with highest wood density. Resilience, characterized as the ability to recover biomass following disturbance and estimated as growth rate standardized for stem diameter at breast height (g day^?1 · mm^?1), was negatively related to wood density. Thus, species with low wood densities were more likely to suffer stem and branch damage owing to cyclonic winds, but also demonstrated highest resprouting and fastest responses in terms of redeveloping biomass in the 8 months following disturbance. This suggests that a species’ position along the resistance–resilience spectrum can be predicted by mean wood density, which may allow managers to predict species’ responses to future cyclones. Our findings also provide mechanistic evidence for the ‘direct regeneration’ model of post‐cyclone succession, where response is characterized by resprouting and species composition is unchanged.     

A preliminary investigation of temporal patterns in semiarid ant communities: Variation with habitat type

Abstract This study reports on preliminary findings of habitat‐contingent temporal variability in ant assemblages in Purnululu National Park in northern Australia's semiarid tropics, by sampling at the end of the dry season (October 2004) and the end of the wet season (April 2005). Six grids of 15 pitfall traps were established in each of the spinifex, sandplain and gorge habitats. Community composition was dominated by behaviourally dominant ants (Iridomyrmex spp.) and climate specialists (Melophorus and Meranoplus spp.). Ant activity was higher in the wet season sampling period, with greater species richness and abundance. Interestingly, temporal variation in ant assemblage richness, abundance and composition varied markedly with habitat type. While there were large differences between sampling periods for the spinifex and sandplain habitat, this was not the case in the gorges. These temporal changes in ant assemblages are postulated to be linked with major environmental differences between the two sampling periods, driven by seasonal climatic conditions. It is likely that these changes influenced the ant assemblages through species differences in physiological tolerance levels, ecological requirements and competitive ability. This study demonstrates the need, in highly seasonal environments, to consider the temporal context of studies in relation to habitat type, particularly when undertaking biodiversity surveys and monitoring.     

Isolation and characterization of tetranucleotide microsatellite markers in a mouth‐brooding haplochromine cichlid fish (Pseudocrenilabrus multicolor victoriae) from Uganda

Eight tetranucleotide microsatellite loci were isolated from the haplochromine cichlid fish, Pseudocrenilabrus multicolor victoriae, an important model species for studies in respiratory ecology, conservation, and evolution. We surveyed variation at these loci in 23 individuals from western Uganda, finding four to 19 alleles per locus and an average expected heterozygosity of 0.8575. These microsatellite loci will be used to examine gene flow and population structure in Ugandan P. m. victoriae.     

Variable microsatellite markers for a snapping shrimp (Alpheus armillatus) species complex

Snapping shrimp (Alpheus) are an important ecological component of tropical marine systems and are excellent models for studies of phylogeography and behavioural ecology. Here, I describe 10 variable microsatellite loci for the Alpheus armillatus species complex of snapping shrimp. The primers were tested on 60 individuals representing three evolutionary lineages within the complex, and yielded three to 21 alleles. These loci will be effective tools in future studies on population genetics and mating behaviour in this complex.     

Induction of the Feline Oncornavirus Associated Cell Membrane Antigen in Human Cells

BY N-terminal amino-acid sequence analysis, Glenner et al.¹ have shown that amyloid fibrils are very similar to the variable part of an immunoglobulin kappa light chain (Bence-Jones protein Ker) and they suggested that amyloid is constituted by immunoglobulin light chains.