Economic competition and evolution: Are there lessons from ecology?

After generally discussing models in ecology and economics that combine competition, optimization, and evolution, this article concentrates on models of intraspecific competition. It demonstrates the importance of diversity/inequalities within populations of species and other environments for the sustainability of their populations, given the occurrence of environmental change. This is demonstrated both for scramble (open-access) and contest competition. Implications are drawn for human populations and industrial organization. The possibility is raised that within-industry competition may not always exist between firms in all stages of the development of a new industry. Policy implications are considered. For example, it is argued that policies designed to encourage intense business competition and maximum economic efficiency have the drawback of eventually making industries highly vulnerable to exogenous economic changes.

A commentary on the impacts of metals and metalloids in the environment upon the metabolism of drugs and chemicals

The salient feature of metals is that unlike organic compounds they do not degrade in the environment and barely move from one environmental matrix to another. Human interventions take these compounds from their stable and non-bioavailable geological matrix into situations of biological accessibility. Studies in the 1970s and the 1980s of metal bioavailability and impacts of metals and metalloids were driven by the process of abatement of lead in the environment. Humans have clear and identifiable sources of exposure from fuels, food and leaded water pipes to lead. Interventions started at that time have dramatically lowered human lead exposure. Attention has now shifted to other metals, in particular, cadmium, which has seen increasing use. It is generally accepted that food crops grown on cadmium containing soils or soils naturally rich in this metal are the major source of exposure to humans other than exposure from smoking of cigarettes. This mini-review gives a summary and commentary on early studies on effects of lead on haem metabolism that provide us the clue to why investigations of the impacts of other toxic heavy metals and metalloids such as cadmium and arsenic on different human cytochrome P450 forms have become of great interest at the current time. (C) 2003 Elsevier Ireland Ltd. All rights reserved.

Ecology and evolution of primate colour vision

More than one hundred years ago, Grant Allen suggested that colour vision in primates, birds and insects evolved as an adaptation for foraging on colourful advertisements of plants-fruits and flowers. Recent studies have shown that well developed colour vision appeared long before fruits and flowers evolved. Thus, colour vision is generally beneficial for many animals, not only for those eating colourful food. Primates are the only placental mammals that have trichromatic colour vision. This may indicate either that trichromacy is particularly useful for primates or that primates are unique among placental mammals in their ability to utilise the signals of three spectrally distinct types of cones or both. Because fruits are an important component of the primate diet, primate trichromacy could have evolved as a specific adaptation for foraging on fruits. Alternatively, primate trichromacy could have evolved as an adaptation for many visual tasks. Comparative studies of mammalian eyes indicate that primates are the only placental mammals that have in their retina a pre-existing neural machinery capable of utilising the signals of an additional spectral type of cone. Thus, the failure of non-primate placental mammals to evolve trichromacy can be explained by constraints imposed on the wiring of retinal neurones.

Marine isocyanides and related natural products structure, biosynthesis and ecology

This review highlights structural and biosynthetic work on a group of nitrogen-functionalised terpenes that are almost exclusively found in marine invertebrates and the animals that feed on them. The chemical functionality reviewed includes isocyanides, isothiocyanates, formamides, thiocyanates, isocyanates, and dichloroimines. The literature through mid 2003 is reviewed and there are 143 citations.

Dietary ecology of the Australian freshwater turtle (Elseya sp.: Chelonia : Chelidae) in the Burnett River, Queensland

The Burnett River snapping turtle (Elseya sp.) from the Burnett, Mary and Fitzroy river systems is an undescribed Australian freshwater turtle, of which very little ecological information is known. This paper describes the dietary ecology of the species in the Burnett River catchment. Stomach and faecal samples were collected from turtles and an index of relative importance was used to rank food items found in stomach samples. This index indicated that algae and aquatic ribbon weed (Vallisneria) were the dominant food items consumed. No difference in diet was found between males and females. Although the sample size was small, diet appeared to vary slightly seasonally, with Elseya sp. selectively feeding on the flower buds of the Chinese elm tree (Celtis chinensis) and the seeds of the blackbean tree (Castanospermum australe) when these food items were seasonally available. Faecal samples suggest that the most ingested foods ( algae and aquatic ribbon weed) were also the most digestible. Although predominantly herbivorous, Elseya sp. was seen to eat carrion once in the wild.

Coconut (Cocos nucifera) in vitro ecology: Modifications of headspace and medium additives can optimize somatic embryogenesis

Of those explants tested, immature zygotic embryo tissues proved to be the best for initiating callus with potential for somatic embryogenesis. Slicing of this tissue and use of the central sections (near to and including the meristematic tissue) gave the best embryogenic response. Slices that were placed under illumination necrosed more rapidly and to a greater degree than those incubated in the dark. Explant slice necrosis could be prevented or severely retarded by the addition of activated charcoal into the medium. Washing the explants for short periods of time prior to culture was also found to improve callus production. Prolonged washing resulted in low rates of callus production. In an attempt to prevent ethylene accumulation in the culture vessel headspace, AVG, an ethylene biosynthesis inhibitor and STS, a chemical which reduces the physiological action of ethylene, were successfully used to promote somatic embryogenesis. Spermidine, putrescine and spermine, polyamines that are known to delay plant senescence and promote somatic embryogenesis in some plant species, enhanced the rate of somatic embryogenesis when they were introduced into the callus induction medium. The use of polyethylene glycol in combination with abscisic acid helped promote somatic embryo formation and maturation as well as the subsequent formation of plantlets. The use of all of these improvements together has created a new and improved protocol for coconut somatic embryogenesis. This new protocol puts significant emphasis on improving the in vitro ecology of the explant, callus and somatic embryogenic tissues.

Ecology of Leptocoris Hahn (Hemiptera: Rhopalidae) Soapberry Bugs in Australia

Soapberry bugs are worldwide seed predators of plants in the family Sapindaceae. Australian sapinds are diverse and widespread, consisting of about 200 native trees and shrubs. This flora also includes two introduced environmental weeds, plus cultivated lychee (Litchi chinensis Sonn.), longan (Dimocarpus longan Lour.) and rambutan (Nephelium lappaceum L.). Accordingly, Australian soapberry bugs may be significant in ecology, conservation and agriculture. Here we provide the first account of their ecology. We find five species of Leptocoris Hahn in Australia, and list sapinds that do and do not serve as reproductive hosts. From museum and field records we map the continental distributions of the insects and primary hosts. Frequency of occupation varies among host species, and the number of hosts varies among the insects. In addition, differences in body size and beak length are related to host use. For example, the long-beaked Leptocoris tagalicus Burmeister is highly polyphagous in eastern rainforests, where it occurs on at least 10 native and non-native hosts. It aggregates on hosts with immature fruit and commences feeding before fruits dehisce. Most of its continental range, however, matches that of a single dryland tree, Atalaya hemiglauca F. Muell., which has comparatively unprotected seeds. The taxon includes a smaller and shorter-beaked form that is closely associated with Atalaya, and appears to be taxonomically distinct. The other widespread soapberry bug is the endemic Leptocoris mitellatus Bergroth. It too is short-beaked, and colonises hosts phenologically later than L. tagalicus, as seeds become more accessible in open capsules. Continentally its distribution is more southerly and corresponds mainly to that of Alectryon oleifolius Desf. Among all host species, the non-native environmental weeds Cardiospermum L. and Koelreuteria Laxm. are most consistently attacked, principally by L. tagalicus. These recent host shifts have biocontrol implications. In contrast, the sapinds planted as fruit crops appear to be less frequently used at present and mainly by the longer-beaked species.

Ecology - Corals fail a test of neutrality

Ecologists continue to wrestle with a central question in biodiversity studies — the prediction of species’ distributions in various environments. A merger of different theories is the long-term prospect.

Endocrine-disrupting compounds: A review of their challenge to sustainable and safe water supply and water reuse

The relevance of endocrine-disrupting compounds as potential contaminants of drinking water is reviewed, particularly in the reuse of wastewater. Growing populations and increasing intensification of land and water use for industry and agriculture have increased the need to reclaim wastewater for reuse, including to supplement the drinking water supply. The variety of anthropogenic chemicals that have been identified as potential endocrine disruptors in the environment and the problems arising from their use as human and livestock pharmaceuticals, as agricultural chemicals and in industry are discussed. The potentially adverse impact of these chemicals on human health and the ecology of the natural environment are reviewed. Data for the removal of estrogenic compounds from wastewater treatment are presented, together with the comparative potencies of estrogenic compounds. The relative exposure to estrogens of women on oral contraceptives, hormone replacement therapy, and through food consumption is estimated. A brief overview of some methods available or under development for the assessment of estrogenic activity in environmental samples is provided. The review concludes with a discussion of the directions for further investigation, which include human epidemiology, methodology development, and wastewater monitoring. (C) 2006 Wiley Periodicals, Inc.

Endoparasite communities of five fish species (Labridae : Cheilininae) from Lizard Island: how important is the ecology and phylogeny of the hosts?

The parasite community of animals is generally influenced by host physiology, ecology, and phylogeny. Therefore, sympatric and phylogenetically related hosts with similar ecologies should have similar parasite communities. To test this hypothesis we surveyed the endoparasites of 5 closely related cheilinine fishes (Labridae) from the Great Barrier Reef. They were Cheilinus chlorounts, C. trilobatus, C. fasciatils, Epibulus insidiator and OxYcheilinus diagrainnia. VVe examined the relationship between parasitological variables (richness, abundance and diversity) and host characteristics (bodv weight, diet and phuylogeny). The 5 fishes had 31 parasite species with 9-18 parasite species per fish species. Cestode larvae (mostly Tetraphyllidea) were the most abundant and prevalent parasites followed by nematodes and digeneans. Parasites, body size and diet of hosts differed between fish species. In general, body weight, diet and host phylogeny each explained some of the variation in richness and composition of parasites among the fishes. The 2 most closely related species, Cheilinus chlorourus and C. trilobatus, had broadly similar parasites but the Other fish species differed significantly in all variables. However, there was no all -encompassing pattern. This may, be because different lineages of parasites may react differently to ecological variables. We also argue that adult parasites may respond principally to host diet. In contrast, larval parasite composition may respond both to host diet and predator-prey interactions because this is the path by which many, parasites complete their life-cycles. Finally, variation in parasite phylogeny and parasite life-cycles among hosts likely increase the complexity of the system making it difficult to find all-encompassing patterns between host characteristics and parasites, particularly when all the species in rich parasite communities are considered.

Host recognition by a polyphagous lepidopteran (Helicoverpa armigera): primary host plants, host produced volatiles and neurosensory stimulation

An important question in the host-finding behaviour of a polyphagous insect is whether the insect recognizes a suite or template of chemicals that are common to many plants? To answer this question, headspace volatiles of a subset of commonly used host plants (pigeon pea, tobacco, cotton and bean) and nonhost plants (lantana and oleander) of Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) are screened by gas chromatography (GC) linked to a mated female H. armigera electroantennograph (EAG). In the present study, pigeon pea is postulated to be a primary host plant of the insect, for comparison of the EAG responses across the test plants. EAG responses for pigeon pea volatiles are also compared between females of different physiological status (virgin and mated females) and the sexes. Eight electrophysiologically active compounds in pigeon pea headspace are identified in relatively high concentrations using GC linked to mass spectrometry (GC-MS). These comprised three green leaf volatiles [(2E)-hexenal, (3Z)-hexenylacetate and (3Z)-hexenyl-2-methylbutyrate] and five monoterpenes (alpha-pinene,beta-myrcene, limonene, E-beta-ocimene and linalool). Other tested host plants have a smaller subset of these electrophysiologically active compounds and even the nonhost plants contain some of these compounds, all at relatively lower concentrations than pigeon pea. The physiological status or sex of the moths has no effect on the responses for these identified compounds. The present study demonstrates how some host plants can be primary targets for moths that are searching for hosts whereas the other host plants are incidental or secondary targets.

Levels of 12 perfluorinated chemicals in pooled Australian serum, collected 2002-2003, in relation to age, gender, and region

Pooled serum samples from 3802 Australian residents were analyzed for four perfluoroalkylsulfonates, seven perfluoroalkylcarboxylates, and perfluorooctanesulfonamide (PFOSA). Serum was collected from men and women of five different age groups and from rural and urban regions in Australia. The highest mean concentration was obtained for perfluorooctane sulfonate (PFOS, 20.8 ng/mL) followed by perfluorooctanoic acid (PFOA, 7.6 ng/mL), perfluorohexane sulfonate (PFHxS, 6.2 ng/mL), perfluorononanoic acid (PFNA, 1.1 ng/mL), and PFOSA (0.71 ng/mL). Additional four PFCs were detected in 5-18 % of the samples at concentrations near the detection limits (0.1-0.5 ng/mL). An increase in PFOS concentration with increasing age in both regions and genders was observed. The male pool levels of some of the age groups compared to females were higher for PFOS, PFOA, and PFHxS. In contrast, PFNA concentrations were higher in the female pools. No substantial difference was found in levels of PFCs between the urban and rural regions. The levels are equal or higher than previously reported serum levels in Europe and Asia but lower compared to the U. S. A. These results suggest that emissions from production in the Northern Hemisphere are of less importance for human exposure.