Search results for "Breeding"
showing 10 items of 475 documents
Restrictive mate choice criteria cause age-specific inbreeding in female black grouse, Tetrao tetrix
2012
Inbreeding is generally rare in large, natural populations yet mate choice often appears to be random with respect to kinship. This suggests that the risks of inbreeding may be small because passive mechanisms of inbreeding avoidance, for example dispersal, are effective at lowering inbreeding risk. Previous theoretical and empirical studies have assumed that the risks of inbreeding are constant over an individual’s life span, but in the lek-breeding black grouse, inbreeding increases with female age. To determine whether inbreeding avoidance mechanisms are also age dependent, we generated four null models of random mate choice ranging from complete randomness to more biologically realistic…
Effects of harvesting timber stands on goshawk nesting in two European areas
2001
We evaluated the effects of harvesting timber stands on goshawk (Accipiter gentilis) nesting in two European areas (central Italy and eastern France), by studying their occupancy and reproductive performance. We found no difference in the productivity of goshawk pairs reproducing in unlogged vs. logged stands. When considering the same nesting stand, before and after timber harvesting, we noted no differences in the number of young per breeding pair nora year effect. We observed that 87.5% of goshawk pairs nesting in logged stands moved away only when the original stand structure was altered by > 30%, and then only to the nearest neighbouring mature stand (maximum distance ca. 1.5 km). The …
Effects of Inbreeding, Outbreeding, and Supplemental Pollen on the Reproduction of a Hummingbird-pollinated Clonal Amazonian Herb
2010
Understory herbs are an essential part of tropical rain forests, but little is known about factors limiting their reproduction. Many of these herbs are clonal, patchily distributed, and produce large floral displays of nectar-rich 1-d flowers to attract hummingbird pollinators that may transport pollen over long distances. The aim of this study was to investigate the effects of clonality, cross-proximity, and patchy distribution on the reproduction of the hummingbird-pollinated Amazonian herb Heliconia metallica. We experimentally pollinated flowers within populations with self-pollen and with pollen of different diversity, crossed flowers between populations, and added supplemental pollen …
Pollination biology in an endangered rocky mountain toadflax (Linaria cavanillesii)
2013
Knowledge about the reproductive system of species inhabiting rocky habitats is scarce. The reproductive biology (floral biology, experimental pollination, insect visits, inbreeding depression, and seed predation) of the rupicolous Linaria cavanillesii was analyzed under field and experimental conditions. Self-compatibility was revealed by the high fruit set, seed set, and seed mass in the pollination experiment. Furthermore, results disclose that this species does not need insect visitors for seed production since fruit set after autonomous self-pollination was similar to that by hand cross-pollination. Self-offsprings were not affected by a strong degree of inbreeding depression in early …
SELFING ABILITY AND MALE STERILITY IN SENECIO VERNALIS WALDST. ET KIT. (ASTERACEAE) FROM ISRAEL
1994
Two major findings relating to the breeding system of Senecio vernalis from Israel are reported. First, isolation experiments failed to confirm the existence of a widespread, truly self-compatible and predominantly self-pollinating breeding system in Israeli populations of S. vernalis. However, a single S. vernalis plant derived from a natural stand at Jerusalem was found to be self- compatible and strongly self-pollinating. In its progeny, there were signs of inbreeding depression commonly associated with selfed offspring of outbreeding species. Selfing ability ratios in this progeny indicate a single dominant gene for selfing ability in S. vernalis. The implications of these observations …
Genética de la conservación: la aplicación de los conceptos de la evolución a la conservación de la diversidad biológica
2013
La comprensión de las fuerzas de cambio evolutivo que actúan sobre las poblaciones, en conjunción con las técnicas más modernas de análisis genético, lleva aplicándose en los últimos veinte años al servicio de la conservación de la biodiversidad. Esta nueva aplicación de la genética ha recibido el nombre de genética de la conservación.
Evidence suggests an opportunistic entomophagous diet of the White Stork Ciconia ciconia in Sicily during breeding and post-breeding periods
2022
Insects are known to represent a critical part of the White Stork Ciconia ciconia diet throughout its breeding range. Yet, the composition of the diet in the storks breeding in the Mediterranean regions remains poorly explored. Here, we investigated the diet of a population of white storks from Sicily through pellets collected in 2003, 2007, and 2020. A total of 1,928 prey items were identified and classified into six categories. Insects dominated the diet in all years and represented 99.06% of the whole prey number. Two orders of insects were mainly consumed, namely Orthoptera, which were the most frequent prey, followed by Coleoptera. Within these, carabid beetles were dominant, followed …
Advancements in DEMO WCLL breeding blanket design and integration
2018
The water-cooled lithium-lead breeding blanket is a candidate option for the European Demonstration Power Plant (DEMO) nuclear fusion reactor. This breeding blanket concept relies on the liquid lithium-lead as breeder-multiplier, pressurized water as coolant, and EUROFER as structural material. The current design is based on DEMO 2015 specifications and represents the follow-up of the design developed in 2015. The single-module-segment approach is employed. This is constituted by a basic geometry repeated along the poloidal direction. The power is removed by means of radial-toroidal (i.e., horizontal) water cooling tubes in the breeding zone. The lithium-lead flows in a radial-poloidal dire…
Development and application of multiscale procedures for the thermomechanical analysis of the DEMO Water-Cooled Lithium Lead Breeding Blanket
2022
The Breeding Blanket is an essential component of the DEMO fusion reactor and its design is one of the pivotal purposes of the DEMO project. Indeed, this component has to withstand severe operating conditions, as it is directly exposed to the plasma, making its design particularly challenging. In particular, the Water-Cooled Lithium-Lead (WCLL) BB concept is one of the candidates currently considered for the conceptual design of the European DEMO reactor. The development of a robust BB system is crucial for the design of the whole DEMO reactor and the thermo-mechanical assessment of the whole BB segments is mandatory to allow checking their structural performances in different loading scena…