Do female grey seals select genetically diverse mates?

Like most mammals, grey seals, Halichoerus grypus, are thought to be polygynous. However, genetic analysis reveals that as few as 1% of males gain reproductive success that is significantly above average. At the same time there appear to be more full siblings than can be accounted for by chance, implying some level of partner fidelity. We used an enlarged data set to show that, on average, maternal half-siblings who have different fathers are significantly more diverse than expected from random mating. This unexpected pattern is too strong to be accounted for by influxes of males from other breeding colonies and hence implies female choice for partner diversity. We argue that behavioural mate choice is an unlikely explanation and speculate that naturally occurring antisperm antibodies could modulate sperm competition through weak immunointolerance of sperm from previous partners. Whatever the mechanism, choice for diverse partners will tend to increase the local effective population size. We used a simple model to show that such a strategy could be favoured at the level of the individual in small closed or semiclosed populations of long-lived species where polygyny would lead to a rapid increase in the level of inbreeding

Diversity and Systematics of Limbless Skinks (Anomalopus) from Eastern Australia and the Skeletal Changes that Accompany the Substrate Swimming Body Form

Published: 27 September 2021Limb-reduced and limbless scincid lizards pose problems in untangling their relationships because of a strong tendency toward convergent evolution in which functional characters mask phylogenetic history. Their often small size makes cranial characters difficult to study, and collections of such species are often small and patchy because of their cryptic behavior. One such genus, Anomalopus (Sphenomorphinae), currently includes seven species of reduce-limbed and limbless skinks that occur in tropical and subtropical habitats in eastern Australia. The discovery of previously unreported populations of limbless skinks assignable to Anomalopus has prompted our revision of the morphology and systematics of this genus. We report new DNA sequence data and new morphological data by using X-ray micro-computed tomography scanning that corroborate published molecular data on sphenomorphine phylogeny, leading us to propose a new generic arrangement that recognizes the species of Anomalopus as belonging to three genera. The newly discovered populations represent two new species currently known from only three small and disjunct areas. We review the osteology of the three genera of the former Anomalopus, finding new characters and variable patterns of interspecific and interclade variation. The same morphological characters are modified in every limb-reduced sphenomorphine clade, but to differing degrees and in different combinations in each.Mark N. Hutchinson, Patrick Couper, Andrew Amey, Jessica Worthington Wilme

Study on the cytochrome P-450- and glutathione-dependent biotransformation of trichloroethylene in humans

Objectives: To investigate in humans the contribution of the cytochrome P-450- and glutathione-dependent biotransformation of trichloroethylene (TRI) under controlled repeated exposure in volunteers, and under occupational conditions. Methods: Volunteers were exposed to TRI, using repeated 15 min exposures at 50 and 100 ppm. This exposure schedule resulted in internal doses of 1.30 and 2.40 mmol of TRI respectively. Urine samples were collected for a minimum of 45 h. Urine samples were also collected from occupationally exposed workers. The samples were analysed for the known human metabolites of TRI, trichloroethanol (TCE), trichloroacetic acid (TCA) and both regio-isomeric forms of the mercapturic acid N-acetyl-S-(dichlorovinyl)-L-cysteine (DCV-NAC), and for (dichlorovinyl)-L-cysteine (DCVC). In order to further elucidate the metabolism of TRI in humans, we analysed samples for dichloroacetic acid and for the proposed break-down products of 1,2 and 2,2-dichlorovinyl-L-cysteine after deamination: the S-conjugates of 3-mercaptolactic acid, 3-mercaptopyruvic acid and 2-mercaptoacetic acid. Results: None of the glutathione metabolites was found in urine of volunteers. In workers occupationally exposed to TRI at levels between 0.4 and 21 ppm [8-h time-weighted average (TWA)], levels of DCV-NAC in urine samples collected at the end of the 4th working day and also next morning were below detection limit (0.04 μmol/l). This confirms the findings of Bernauer et al. (1996) that these metabolites are excreted at very low levels in humans. Urinary levels of DCVC and six postulated metabolites of dichlorovinyl-S-cysteine conjugates via deamination were also below 0.04 μmol/l, indicating that at most 0.05% of the dose in excreted in the form of these metabolites. These data further strengthen the argument for a very low activity of glutathione-mediated metabolism for chronically exposed workers. Conclusions: This study gives additional data which indicate that glutathione-medicated metabolism is of minor importance in humans exposed to TRI. In spite of indications to the contrary, significant metabolism of the cysteine conjugate via β-lyase, which could result in a toxic metabolite, cannot be ruled out completely

Crecimiento inicial de Palo de Rosa (Aniba rosaeodora Ducke) en distintos ambientes de fertilidad Growth of initial Rosewood (Aniba rosaeodora Ducke) in different environnement of fertility

Los estudios de requerimientos nutricionales son de gran importancia para identificar aquellos más importantes en el desarrollo fisiológico y crecimiento de plántulas. Con el objetivo de evaluar las exigencias nutricionales y los efectos de la omisión de macronutrientes en el crecimiento de plántulas de Aniba rosaeodora; se realizó un experimento en el vivero del INPA-Amazonas-Brasil teniendo como substrato un suelo Podozolico Rojo de baja disponibilidad de nutrientes. Se utilizaron 8 tratamientos bajo la técnica del nutriente faltante: Control (Suelo con macronutrientes), Suelo natural, y la omisión de un macronutriente por vez (-N, -P, -K, -Ca, -Mg, -S). Se evaluaron las siguientes características: tasa de crecimiento relativo (TCR), Tasa de asimilación neta (TAN), peso de la materia seca de la parte aérea (MSPA) y de las raíces (MSR), contenido de nutrientes en las hojas, concluyendo que el N, Mg y Ca, demostraron ser limitantes al crecimiento en suelo con pequeña disponibilidad; Las plántulas de A. rosaeodora presentaron un bajo requerimiento nutricional para el P, K y S. La omisión de Ca y N perjudica TCR de la especie. Los elementos más importantes para la MSPA fueron el Ca y el Mg; actuando el Mg más en el área foliar; por otro lado la omisión de azufre favorece la absorción de macronutrientes (N, P, K, Ca, Mg).<br>Studies of nutritional requirements are of great importance for identifying the most important nutrients in physiologic development and seedling growth. A greenhouse pot experiment was conducted at INPA to evaluate the mineral nutritional demands and the effects of macronutrient omission in the plant growth of Aniba rosaeodora Ducke. The following treatments were used: Complete (fertilization with N, P, K, Ca, Mg, S, B and Zn), Standard (nature soil), Complete without N, Complete without P, Complete without K, Complete without Ca, Complete without Mg, and Complete without S. An Ultisoil with low nutrient availability was used as a substratum. The following characteristics were evaluated, relative growth rate (RGR), net assimilation rate (NAR), plant height, diameter, dry matter production of the aerial part (DMPAP) and amount of nutrient in the dry matter of leaves. We concluded from the results that: low availability of N, Ca and Mg constraints the growth of the Aniba rosaeodora plants. Seedlings of A. rosaeodora required little P, K and S. The omission of Ca and N harmed the RGR of the species. The most important elements for DMPAP were Ca and Mg; the Mg acting more in the leaf area; on the other hand, the omission of sulfur favored the macronutrient absorption (N, P, K, Ca, Mg)