Dactylorhiza incarnata (L.) Soó (Orchidaceae, Liliopsida) on the northern border of its distribution area: Population structure and seed productivity

The results of the study of the population biology of the rare orchid Dactylorhiza incarnata (L.) Soó on the territory of the Komi Republic (north-east of European Russia), where the species is located on the northern border of its range, are presented. Data on the population structure, morphometric features of plants, and reproductive characteristics of the species are given. It was found that the size of plants and the number of flowers in the inflorescence of this species in the region is lower than in the more southern parts of its range. The populations size ranges from 30 to 350 individuals with their average density of 0.7–3.7 per 1 m2 , and it is common for this species in other parts of its distribution area. Reproductive success is associated with the weather of the second decade of June because the flowering time of the species in the region happens in this time. It was found that the seed size of D. incarnata (0.55×0.20 mm) on its northern border is smaller than in other parts of the range. The seed productivity is rather high: one fruit contains an average of 6.2 thousands of seeds and one individual could produce about 49.4 thousands of seeds. Temperature during flowering time and precipitation during seed ripening may affect seed quality. The presence of juvenile individuals (%) in all the studied populations shows seed recruitment in populations of this species at the northern limit of the range, despite a lower seed set in comparison with southern populations.

Epigenetic Measurement of Key Vertebrate Population Biology Parameters

The age, sex, and sexual maturity of individual animals are key parameters in assessing wild populations and informing conservation management strategies. These parameters represent the reproductive potential of a population and can indicate recovery rates or vulnerabilities. Natural populations of wild animals are difficult to study; logistically, economically, and due to the impacts of invasive biomonitoring. Genetic and epigenetic analyses offer a low impact, low cost, and information-rich alternative. As epigenetic mechanisms are intrinsically linked with both biological aging and reproductive processes, DNA methylation can be used as a suitable biomarker for population biology study. This review assesses published research utilizing DNA methylation analysis in relation to three key population parameters: age, sex, and sexual maturity. We review studies on wild vertebrates that investigate epigenetic age relationships, with successful age estimation assays designed for mammals, birds, and fish. For both determination of sex and identification of sexual maturity, very little has been explored regarding DNA methylation-based assays. Related research, however, confirms the links between DNA methylation and these processes. Future development of age estimation assays for underrepresented and key conservation taxa is suggested, as is the experimental development and design of DNA methylation-based assays for both sex and sexual maturity identification, further expanding the genomics toolkit for population biology studies.

Population biology of accessory gland-expressed de novo genes in Drosophila melanogaster

Early work on de novo gene discovery in Drosophila was consistent with the idea that many such genes have male-biased patterns of expression, including a large number expressed in the testis. However, there has been little formal analysis of variation in the abundance and properties of de novo genes expressed in different tissues. Here we investigate the population biology of recently evolved de novo genes expressed in the D. melanogaster accessory gland, a somatic male tissue that plays an important role in male and female fertility and the post mating response of females, using the same collection of inbred lines used previously to identify testis-expressed de novo genes, thus allowing for direct cross tissue comparisons of these genes in two tissues of male reproduction. Using RNA-seq data we identify candidate de novo genes located in annotated intergenic and intronic sequence and determine the properties of these genes including chromosomal location, expression, abundance, and coding capacity. Generally, we find major differences between the tissues in terms of gene abundance and expression, though other properties such as transcript length and chromosomal distribution are more similar. We also explore differences between regulatory mechanisms of de novo genes in the two tissues and how such differences may interact with selection to produce differences in D. melanogaster de novo genes expressed in the two tissues.

The Sea Cucumber Holothuria (Halodeima) atra (Jager, 1833), in South Tarawa Lagoon (Republic of Kiribati): Environmental Variability, Population Biology and Fishing Pressure

<p>Holothuria atra or lollyfish is the most common sea cucumber in the Pacific and Indian Oceans. The current status of Holothria atra at 13 sites of South Tarawa lagoon (Republic of Kiribati) was established by using biological surveys and fishers' questionnaires. A preliminary investigation was conducted in order to assess how and why environmental variability and fishing pressure have affected the spatial and temporal distribution, mean abundant and mean size of this species at the sites. The 13 sites were selected randomly, and marked with a GPS on the map of South Tarawa. Sedimentary characteristics were determined for each site, and a qualitative assessment of sites health was made. Lollyfish length, biomass and abundance and transect density were calculated for each site. The weight of organic matter content and size of sediment sample were determined. Data were analysed using Kruskal-Walis (KW) and Repeated measures (RM) ANOVA tests. This thesis shows that the environmental variability could not offer reasons as to why the biological data of lollyfish varied from one site to another. However, other factors that were tested may explain the variation in biological data. Fishing pressure is one of those parameters that can regulate the lollyfish distribution and density and responses from local fishers indicate that fishing pressure is high and that the lollyfish resource is under considerable harvest pressure. Dissolved oxygen concentration in the water column and in the sediment may be also involved in the variation in lollyfish distribution and density but this was not tested. The findings of this research lead to a number of recommendations for the sustainable harvest of lollyfish in Tarawa lagoon. These include consideration of gear restrictions, lollyfish size and number limits, and the establishment of marine protected areas under co-management arrangements.</p>

The Sea Cucumber Holothuria (Halodeima) atra (Jager, 1833), in South Tarawa Lagoon (Republic of Kiribati): Environmental Variability, Population Biology and Fishing Pressure

<p>Holothuria atra or lollyfish is the most common sea cucumber in the Pacific and Indian Oceans. The current status of Holothria atra at 13 sites of South Tarawa lagoon (Republic of Kiribati) was established by using biological surveys and fishers' questionnaires. A preliminary investigation was conducted in order to assess how and why environmental variability and fishing pressure have affected the spatial and temporal distribution, mean abundant and mean size of this species at the sites. The 13 sites were selected randomly, and marked with a GPS on the map of South Tarawa. Sedimentary characteristics were determined for each site, and a qualitative assessment of sites health was made. Lollyfish length, biomass and abundance and transect density were calculated for each site. The weight of organic matter content and size of sediment sample were determined. Data were analysed using Kruskal-Walis (KW) and Repeated measures (RM) ANOVA tests. This thesis shows that the environmental variability could not offer reasons as to why the biological data of lollyfish varied from one site to another. However, other factors that were tested may explain the variation in biological data. Fishing pressure is one of those parameters that can regulate the lollyfish distribution and density and responses from local fishers indicate that fishing pressure is high and that the lollyfish resource is under considerable harvest pressure. Dissolved oxygen concentration in the water column and in the sediment may be also involved in the variation in lollyfish distribution and density but this was not tested. The findings of this research lead to a number of recommendations for the sustainable harvest of lollyfish in Tarawa lagoon. These include consideration of gear restrictions, lollyfish size and number limits, and the establishment of marine protected areas under co-management arrangements.</p>