Supporting dataset and methods for egg sizes, eggshell thicknesses and metal concentrations measured in the shells and contents of eggs of Capercaillies Tetrao urogallus.

The dataset presented in this data paper supports "Eggshell resorption, and embryonic mobilization and accumulation of calcium and metals in eggs of wild and captive Capercaillies Tetrao urogallus" (Orlowski et al., 2019) [1]. Here we present the supplementary data on the following: (1) egg sizes, regional eggshell thicknesses (at the equator, sharp pole and blunt pole) as well as the concentrations of two major micronutrients (Ca and Mg) and eight trace elements (Cr, Cu, Mn, Fe, Co, Cd, Pb and Zn), measured in the shells and contents of eggs of captive-bred and wild Capercaillies. (2) How the proportions of elements sequestered into eggshells become depleted during embryogenesis expressed as the %change of concentrations of various elements measured in the shells and contents of eggs at different stages of embryonic advancement (early dead embryos, late dead embryos and hatched eggs). (3) The relationships between the age of dead embryos and three regional eggshell thicknesses and concentrations of different elements measured in the shells and contents of these eggs.

Eggshell resorption, and embryonic mobilization and accumulation of calcium and metals in eggs of wild and captive Capercaillies Tetrao urogallus.

Although it is fairly well known that eggshells are the major source of Ca and other micronutrients for developing avian embryos, potential anatomical and/or ecological correlates explaining the variation in embryo-induced depletion of micronutrients from eggshells remain to be addressed. Using unhatched eggs at various developmental stages and post-hatched eggshells of wild and captive-bred birds of a large precocial species, the Capercaillie Tetrao urogallus, we explored two major questions. (i) Do egg size, regional eggshell thickness as well as levels of two major micronutrients (Ca and Mg) and eight trace elements (Cr, Cu, Mn, Fe, Co, Cd, Pb and Zn) measured in egg shells and contents vary with embryonic age within and between wild and captive-bred bird eggs? (ii) How the proportions of eggshell elements become depleted during the entire process of embryogenesis? The eggshells of wild Capercaillies were thinner at the equator and the sharp pole, and contained more Mg and Ca, while in their contents there was more Cu, Cd and Pb compared with captive birds. All ten metal concentrations measured in the egg contents increased (from 15% to 285% more) with the age of embryos. The concentrations of six elements measured in eggshells (Cu, Mn, Fe, Co, Cd and Zn) decreased consistently (from 15 to 70% less) during embryogenesis. This suggests the presence of these elements in the innermost decalcified shell layer and their further mobilization into the embryos/egg contents. Our results strongly imply that most trace elements present in the egg contents/developing embryos are mobilized from the eggshells. We highlight the fact that knowledge of the magnitude of embryogenesis-related functional changes in the physical (such as shell thickness) and chemical traits of the eggs and eggshells of oviparous vertebrates is fundamental for drawing correct inferences regarding the response of an individual to variable environmental conditions.

Bucking the trend in wolf-dog hybridization: first evidence from europe of hybridization between female dogs and male wolves.

Studies on hybridization have proved critical for understanding key evolutionary processes such as speciation and adaptation. However, from the perspective of conservation, hybridization poses a concern, as it can threaten the integrity and fitness of many wild species, including canids. As a result of habitat fragmentation and extensive hunting pressure, gray wolf (Canis lupus) populations have declined dramatically in Europe and elsewhere during recent centuries. Small and fragmented populations have persisted, but often only in the presence of large numbers of dogs, which increase the potential for hybridization and introgression to deleteriously affect wolf populations. Here, we demonstrate hybridization between wolf and dog populations in Estonia and Latvia, and the role of both genders in the hybridization process, using combined analysis of maternal, paternal and biparental genetic markers. Eight animals exhibiting unusual external characteristics for wolves - six from Estonia and two from Latvia - proved to be wolf-dog hybrids. However, one of the hybridization events was extraordinary. Previous field observations and genetic studies have indicated that mating between wolves and dogs is sexually asymmetrical, occurring predominantly between female wolves and male dogs. While this was also the case among the Estonian hybrids, our data revealed the existence of dog mitochondrial genomes in the Latvian hybrids and, together with Y chromosome and autosomal microsatellite data, thus provided the first evidence from Europe of mating between male wolves and female dogs. We discuss patterns of sexual asymmetry in wolf-dog hybridization.

Cytogenetic variation in farmed stock of Dybowski's sika deer.

The chromosome constitution of Dybowski's sika deer was studied on the basis of 15 samples obtained from farmed stock maintained in an enclosure. The diploid chromosome number was 2n=68, 2n=67 and 2n=66. The constitutive heterochromatin (C-bands) was located in the centromeric regions of all acrocentric chromosomes. Metacentric chromosomes were C-negative. Chromosomes of three pairs proved to be NORs carriers. The size polymorphism of silver deposits was identified in two animals. A cytogenetic analysis indicated that the farmed stock of Dybowski's sika deer demonstrates considerable variation. The chromosome polymorphism observed may be a valuable marker for the management and preservation of this species.