Diversity measures in macroinvertebrate and zooplankton communities related to the trophic status of subtropical reservoirs: Contradictory or complementary responses?

Macroinvertebrate communities have been widely used as a tool for assessing the environmental quality of freshwater ecosystems, whereas zooplankton communities have been to some extent neglected. However, the importance of using different indicators to achieve a more comprehensive framework of assessment regarding water quality has been recognized. This study compared estimates of species richness (number of species) and the Shannon–Wiener index for data on macroinvertebrate and zooplankton communities in tropical reservoirs and related them to their trophic state. The trop+hic classification was obtained by applying the Carlson index (1977) modified by Toledo et al. (1983), and the index of the Brazilian Society of the Environmental Technology Agency. The comparative response of the different indicators was analyzed using a series of bivariate correlations (Draftsman’s plot). The results illustrate that diversity measures, namely species richness, responded differently when related to the trophic classification of reservoirs, depending on the community considered. The species richness of zooplankton was positively related to hypereutrophic conditions, due to the higher number of rotifer species, including tolerant generalist species and at the same time, as a result of the exclusion of species from other groups, whereas for macroinvertebrates, species richness was negatively related to hypereutrophic conditions. Melanoides tuberculatus, which exhibits a high tolerance and competitive ability under such conditions, was the dominant species in macroinvertebrate communities, which excluded endemic species and reduced local richness and diversity. The same indicators applied to the zooplankton and macroinvertebrate communities might therefore provide contradictory responses regarding ecological quality assessment in tropical reservoirs, which suggest that zooplankton should be taken into account among the biological quality elements considered in the ecological quality assessment, management, and restoration of water bodies.     

Testing for Validity and Reliability in Cross-Cultural Research

A set of procedures is offered for assessing interraler reliability and certain aspects of validity of codes in cross-cultural studies. The method assumes that at least two independent raters have coded more than one trait. Each trait coded by one rater is correlated with each trait coded by a second, and all the codings by a single rater are intercorrelated with each other. The results are presented in a multitrait-multi-rater matrix. From this matrix it is possible to determine the interrater reliability and discriminant validity of trails in addition to a higher order concept based on pairs of traits.     

Can minimum convex polygon home ranges be used to draw biologically meaningful conclusions?

Many conclusions about mammalian ranging behaviour have been drawn based on minimum convex polygon (MCP) estimates of home range size, although several studies have revealed its unpredictable nature compared to that of the kernel density estimator. We investigated to what extent the choice of home range estimator affected the biological interpretation in comparative studies. We found no discrepancy when the question asked covered a wide range of taxa, as real and very large differences in range size were likely to have masked smaller differences due to the choice of home range estimator. However, when the question asked concerned within-species characteristics, the choice of home range estimator explained as much of the variation in range size as did the ecological variable in question. The implications for macro-ecological and intraspecific studies are discussed.     

The stable evolutionary fixation of a bifunctional tyrosine-pathway protein in enteric bacteria

Abstract The bifunctional T-protein (chorismate mutase-T: cyclohexadienyl dehydrogenase) of l -tyrosine biosynthesis was found to be present in all genera making up the enteric bacteria. The dehydrogenase component of the T-protein was active with both prephenate and l -arogenate, showing it to be a cyclohexadienyl dehydrogenase. The dehydrogenase component, but not the mutase component, of the T-protein was feedback-inhibited by l -tyrosine. Unlike some other bifunctional proteins, the T-protein has evolved recently and is not ubiquitous. However, once the biochemical specialization of bifunctionality becomes established, the results indicate that such character states are strongly conserved through evolutionary time. Thus, bifunctional proteins can provide particularly reliable markers for small (recent origin), intermediate, and large (ancient origin) phylogenetic clusters.     

Survival Expectations of the Obese: Is Excess Mortality Reflected in Perceptions?

Objective: This study compared self‐reported subjective life expectancy (i.e., probability of living to age 75) for normal‐weight, overweight, and obese weight groups to examine whether individuals are internalizing information about the health risks due to excessive weight. Research Methods and Procedures: Using data from the Health and Retirement Study, a total of 9035 individuals 51 to 61 years old were analyzed by BMI category. The primary outcome measure was individuals’ reports about their own expectations of survival to age 75. Absolute and relative risks of survival were compared with published estimates of survival to age 75. Results: Consistently, higher levels of BMI were associated with lower self‐estimated survival probabilities. Differences relative to normal weight ranged from 4.9% (p < 0.01) for male nonsmokers to 8.8% (p < 0.001) for female nonsmokers. However, these differences were substantially less than those obtained from published survival curve estimates, suggesting that obese individuals tended to underestimate mortality risks. Discussion: Individuals appeared to underestimate the mortality risks of excessive weight; thus, knowledge campaigns about the risks of obesity should remain a top priority.     

Variation in mating system among birds: ecological basis revealed by hierarchical comparative analysis of mate desertion

Since most bird species are socially monogamous, variation among species in social mating systems is determined largely by variation in the frequency of mate desertion. Mate desertion is expected to occur when the benefits, in terms of additional reproductive opportunities, outweigh the costs, in terms of reduced reproductive success from the present brood. However, despite much research, the relative importance of costs and benefits in explaining mating system variation is not well understood. Here, we investigate this problem using a comparative method. We analyse changes in the frequency of mate desertion at different phylogenetic levels. Differences between orders and families in the frequency of desertion are negatively associated with changes in the potential costs of desertion, but are not associated with changes in the potential benefits of desertion. Conversely, differences among genera and species in the frequency of desertion are positively associated with increases in the potential benefits of desertion, but not with changes in the potential costs of desertion. Hence, we suggest that mate desertion in birds originates through a combination of evolutionary predisposition and ecological facilitation. In particular, ancient changes in life-history strategy determine the costs of desertion and predispose certain lineages to polygamy, while contemporary changes in the distribution of resources determine the benefits of desertion and thereby the likelihood that polygamy will be viable within these lineages. Thus, monogamy can arise via two very different evolutionary pathways. Groups such as albatrosses (Procellariidae) are constrained to social monogamy by the high cost to desertion, irrespective of the potential benefits. However, in groups such as the accentors (Prunellidae), which are predisposed to desertion, monogamy occurs only when the benefits of desertion are very limited. These conclusions emphasise the additional power which a hierarchical approach contributes to the modern comparative method.     

Virtual water and water footprints do not provide helpful insight regarding international trade or water scarcity

Many authors have estimated the virtual water content of good and services traded internationally, and many have calculated national water footprints that account for the volumes of virtual water imported and exported. Some authors have suggested that international trade of virtual water has been harmful to selected exporting countries with limited water endowments. Some suggest also that current patterns of international trade should be rearranged to make better use of global water resources. Yet, countries do not actually trade in virtual water. They trade in goods and services for which water is one of many inputs. Wise choices regarding water resources and smart strategies regarding international trade cannot be determined by focusing on water alone. The notions of virtual water and water footprints are not helpful indicators of optimal strategies regarding water resources, particularly when considering issues such as water scarcity or international trade. I describe four perspectives regarding virtual water and water footprints, with the goal of demonstrating the inadequacies of these notions in policy discussions and in efforts to determine the optimal allocation and use of water resources. The four perspectives are: (1) international trade should not be modified or regulated to reflect the virtual water content of traded commodities or water footprints in the countries of trading partners, (2) countries do not save water by engaging in virtual water trade, (3) consumers in one country cannot alleviate water scarcity or improve water quality in other countries, and (4) water footprints are not analogous to carbon or ecological footprints.     

A critical rebuttal of the proposed division of the genus Arcobacter into six genera using comparative genomic,phylogenetic, and phenotypic criteria

The proposal to restructure the genus Arcobacter into six distinct genera was critically examined using: comparative analyses of up to 80 Epsilonproteobacterial genome sequences (including 26 arcobacters); phylogenetic analyses of three housekeeping genes and also 342 core genes; and phenotypic criteria. Genome sequences were analysed with tools to calculate Percentage of Conserved Proteins, Average Amino-acid Identity, BLAST-based Average Nucleotide Identity, in silico DNA–DNA hybridisation values, genome-wide Average Nucleotide Identity, Alignment Fractions and G + C percentages. Genome analyses revealed the genus Arcobacter sensu lato to be relatively homogenous, and phylogenetic analyses clearly distinguished the group from other Epsilonproteobacteria. Genomic distinction of the genera proposed by Pérez-Cataluña et al. [2018] was not supported by any of the measures used and a subsequent risk of strain misidentification clearly identified. Similarly, phenotypic analyses supported the delineation of Arcobacter sensu lato but did not justify the position of the proposed novel genera. The present polyphasic taxonomic study strongly supports the continuance of the classification of “aerotolerant campylobacters” as Arcobacter and refutes the proposed genus-level subdivision of Pérez-Cataluña et al. [2018].     

The role of the basal hypothalamus in the regulation of reproductive behavior in the lizard, Anolis carolinensis: lesion studies

Bilateral radiofrequency lesions in the anterior and posterior basal hypothalamus decreased courtship and agonistic behaviors in both intact, sexually active, and castrated, androgen treated male Anolis carolinensis. Intact males receiving lesions in the anterior basal hypothalamus had atrophied testes, aspermia, and decreased epithelial cell height of the renal sex segment. Lesions of the posterior basal hypothalamus had no effect on testicular activity or the development of accessory organs. All animals demonstrating behavioral changes had lesion destruction in the ventromedial nucleus and the accompanying periventricular system. It is concluded that the basal hypothalamus in male A. carolinensis is involved both in the regulation of reproductive behavior and pituitary function.