Search results for "EED"

Demographic characterization and genetic variability of the Girgentana goat breed by the analysis of genealogical data

2004

The aim of this paper is to present an overview of the actual Sicilian Girgentana population structure by the analysis ofgenealogical data. Statistics show that in 1983 the population consisted of 30,000 Girgentana goats; ten years lateralmost 98% of the entire Girgentana population disappeared. The remaining population consists of 461 individuals (134males and 327 females), with 368 living animals. The effective population size is 380 individuals. The inbreeding rate pergeneration was equal to 0.13%. The average estimated inbreeding level within the living male population was equal to0.8% (0-15%); and the average inbreeding level within the living female population was equal to 0.7% (0-31%…

Seed dormancy and germination of an endangered coastal plantEryngium maritimum(Apiaceae)

2013

INTRODUCTION Eryngium maritimum L. is a littoral species growing on sand dunes and shingle beaches. Although it is listed among the species widespread in western and southern Europe, overall its population is declining (Van der Maarel & Van der Maarel-Versluys, 1996). The species is included in the Red Data Book of Latvia (Fatare, 2003) and is protected in several other European countries. In northern Europe and in the Baltic Region it grows near the limits of its current area of distribution and therefore is at a greater risk of extinction because in small and isolated populations there is a risk of inbreeding depression. For example, in Eryngium alpinum partial self-incompatibility causes…

Survival Rates of Young MagpiesPica picain a Mountain Population of Eastern Spain

2007

Abstract. The aim of this study was to estimate the survival of young Magpies between fledging and the next breeding season and to identify some of the factors affecting it. A total of 50 nestlings were colour-ringed in two breeding seasons in the valley of the Pitarque River (Teruel, E Spain), and were monitored weekly until May of the following year. 59 nestlings were also colour-ringed in two nearby localities (4–5 km) to detect possible dispersal to and from our study area. Mark-recapture analyses were used to estimate weekly survival, which was assumed to be constant for periods of four weeks in order to reduce the number of parameters. Models with the effect of time, age class, season…

Inbreeding depression in perennial Lychnis viscaria (Caryophyllaceae): effects of population mating history and nutrient availability.

2005

We studied inbreeding depression in a perennial plant, Lychnis viscaria, in three populations differing in their inbreeding history and population size by measuring several traits at two nutrient levels over the plant's life cycle. The observed levels of inbreeding depression (cumulative inbreeding depression, from -0.057 to 0.629) were high for a plant with a mixed mating system. As expected, the population with a low level of isozyme variation expressed the least inbreeding depression for seed germination. Highest inbreeding depression for germination was found in the largest and genetically most variable population. No clear differences between populations in expression of inbreeding dep…

2014

Captive breeding for conservation purposes presents a serious practical challenge because several conflicting genetic processes (i.e., inbreeding depression, random genetic drift and genetic adaptation to captivity) need to be managed in concert to maximize captive population persistence and reintroduction success probability. Because current genetic management is often only partly successful in achieving these goals, it has been suggested that management insights may be found in sexual selection theory (in particular, female mate choice). We review the theoretical and empirical literature and consider how female mate choice might influence captive breeding in the context of current genetic…

Highly asymmetric fine-scale genetic structure between sexes of African striped mice and indication for condition dependent alternative male dispersa…

2011

Sex-biased dispersal is observed in many taxa, but few studies have compared sex-biased dispersal among and within populations. We addressed the magnitude and habitat dependency of sex-biased dispersal in social African striped mice by separating group-related from population-related genetic variance to understand the contribution of each sex to deme structure. As dispersal over unoccupied habitat is likely to be more costly than dispersal within a population, we predicted that individuals leaving the natal population have a lower body condition, being inferior to heavier territorial individuals. Fine-scale genetic structure was detected in both sexes. Female relatedness decreased continuou…

Seed dispersal, braeding system, tree density and the spatial pattern of trees – a simulation approach

2002

Summary Tropical tree populations with low densities and with clumped spatial distributions are at risk in the face of fragmentation. It is therefore important to understand factors driving spatial patterns of tree populations. An important set of factors which may influence the spatial pattern of plants, could be the spatial distribution of possible seed sources such as the breeding system (monoecious, dioecious), tree density and the spatial pattern of the parent population. Another set of important factors might be dispersal of seeds away from the parent plants characterised by the mean dispersal distance and by the distribution of dispersal distances (either negative exponential or logn…

Changes of effective gene dispersal distances by pollen and seeds across successive life stages in a tropical tree

2013

Pollen and seed dispersal are the two key processes in which plant genes move in space, mostly mediated by animal dispersal vectors in tropical forests. Due to the movement patterns of pollinators and seed dispersers and subsequent complex spatial patterns in the mortality of offspring, we have little knowledge of how pollinators and seed dispersers affect effective gene dispersal distances across successive recruitment stages. Using six highly polymorphic microsatellite loci and parentage analyses, we quantified pollen dispersal, seed dispersal, and effective paternal and maternal gene dispersal distances from pollen- and seed-donors to offspring across four recruitment stages within a pop…

Competition for breeding sites and site-dependent population regulation in a highly colonial seabird, the common guillemot Uria aalge

2004

Summary 1. The hypothesis of site-dependent population regulation predicts that birds utilize available nesting sites in a pre-emptive (ideal despotic) manner, leading to density dependence in heterogeneous habitats as poorer sites are used at higher population densities. At small population sizes adaptive site choice protects populations against fluctuations (the buffer effect). 2. Common guillemots Uria aalge (Pontoppidan) breed at high density on sea-cliffs. The population breeding on the Isle of May, Scotland increased by 60% between 1981 and 2000. A good nest-site is a prerequisite for successful breeding and there is much competition for the best sites. Throughout this period, site us…

WHO BEARS THE COSTS OF INTERSPECIFIC COMPETITION IN AN AGE-STRUCTURED POPULATION?

2003

Social and density-dependent life history processes may differ according to age and the reproductive history of individuals. Arvicoline rodents have a typical, season-dependent, bimodal, age distribution of breeding individuals within a population. This distribution may influence population fluctuations. In this study, we measured effects of interspecific competition from field voles (Microtus agrestis) on various fitness components of female bank voles (Clethrionomys glareolus) in an age-structured breeding population in large (0.25 ha) outdoor enclosures. We monitored survival, reproduction, and space use of experimental bank vole populations with females from two different age groups. Wi…