Biomedical subjects

Alistair G B Poore

Publications and source records attributed to Alistair G B Poore.

4 recordsLinked to original sources

PubMed2006

Ecological consequences of copper contamination in macroalgae: effects on epifauna and associated herbivores.

Many contaminants of the marine environment are able to chelate to sediments, bind within organic matrices, or be accumulated by organisms such as invertebrates and macroalgae. Marine macroalgae are recognized as effective and efficient bioaccumulators of heavy metals and are sometimes used as bioindicators. Macroalgae support abundant and diverse communities of mobile invertebrates that play key roles in temperate marine environments. However, the potential ecological consequences of the contamination of algae on associated epifauna are yet to be considered. In this study, the brown alga Sargassum linearifolium was experimentally spiked with copper to assess the effects of contamination on epifaunal invertebrates in both field and laboratory assays. Copper contamination greatly reduced the colonization of a variety of epifaunal taxa in the field. Laboratory assays further examined the effects of contaminated macroalgae on habitat preferences, feeding rates, survivorship, and growth in the herbivorous amphipod Peramphithoe parmerong. Adult P. parmerong were less likely to select spiked macroalgae in short-term habitat preference assays and consumed spiked algae at lower rates in feeding assays. In a longer-term (30-d) experiment, survivorship of juvenile amphipods was reduced by up to 75% by contaminated macroalgae, but no effects on the growth of survivors was observed. Heavy metal contamination of macroalgae is a widespread phenomenon that has the potential for substantial negative consequences for associated invertebrate fauna. This issue warrants further investigation by marine ecotoxicologists.

Animals↗

PubMed2004

Spatial associations among algae affect host use in a herbivorous marine amphipod.

Host plant choice by herbivores may be constrained by the spatial arrangement of plants with selection of poor quality hosts being more likely if preferred hosts are locally rare. I tested whether the presence of a herbivorous marine amphipod, Peramphithoe parmerong, on a poor quality host could be explained by the relative abundance and spatial arrangement of alternative brown algal hosts. Amphipods strongly preferred the high quality Sargassum linearifolium over the poor quality Padina crassa in laboratory assays with a higher tendency to select Padina crassa when it was relatively more abundant. In the field, however, adults colonised both hosts to equal densities. Rates of colonisation were independent of host quality but strongly affected by the identity of neighbouring hosts with those algae in close proximity to S. linearifolium receiving far greater densities of amphipods than those surrounded by Padina crassa. There was no evidence that the presence of adult Peramphithoe parmerong on Padina crassa was due to local scarcity of S. linearifolium. In contrast, the distribution and behaviour of juveniles were predictable from differences in food quality, with most inhabiting the high quality S. linearifolium and few emigrating from this host. The success of a simple adaptive model based on food quality to predict juvenile, but not adult, behaviour indicates that the relative importance of food quality varies with age, and that other factors are important determinants of adult movements among hosts.

Adaptation, Physiological↗

PubMed2004

Selection in modular organisms: is intraclonal variation in macroalgae evolutionarily important?

Theoretical and practical difficulties occur when defining the units of selection in modular organisms that grow by iteration of repeated parts (modules). Modules may become physically autonomous through fragmentation and may vary because of genetic variation arising in somatic cell lineages. Since cells destined for gamete production are not sequestered in early development, heritable variation and selection among asexual progeny are possible. We used the branching red macroalgae Delisea pulchra and Asparagopsis armata to test whether modules fulfill three fundamental criteria for units of selection: that they replicate, that they display heritable variation, and that selective agents distinguish among the variants. We detected significant phenotypic variation among modules for fitness-related traits (growth, secondary metabolite concentrations, and rates of tissue loss to herbivory) in each species and significant heritability estimates for secondary metabolite production and tissue loss to herbivory in D. pulchra. Variation in growth rate among A. armata modules was largely phenotypic with small but important estimates of genetic variation. Our results indicate that selection may indeed act on phenotypic variation among modules within individuals and that this process may effect evolutionary change within asexual lineages given sufficient genetic variation in the traits examined.

Animals↗

PubMed2004

Spatial interactions within modular organisms: genetic heterogeneity and organism fitness.

Modular organisms are composed of iterated units of construction that vary in their spatial arrangement. This variation is expected to affect the fitness of modular organisms due to interactions among neighboring modules and the potential for such organisms to be genetically heterogeneous. We devise a spatially explicit model to investigate how spatial interactions among neighboring modules affect organism fitness. We show that fitness is strongly dependent on the spatial arrangement of modules in both genetically homogeneous and heterogeneous organisms, and that the magnitude of the variation is dependent on the strength of interactions among modules. Organism fitness is more variable with interactions among modules that are symmetrical (each affects each other in the same directions) than with asymmetrical interactions (neighbors affect each other in different directions). We conclude by discussing potential extension of the present framework to a general dynamic model of spatially structured organism development.

Adaptation, Physiological↗