Search results for "Reproduction"

Influence of male mating history on female reproductive success among monandrous Naryciinae (Lepidoptera: Psychidae)

2011

1. Multiple male copulations can have detrimental effects on female fitness due to sperm limitation. 2. Monandrous Naryciinae females are immobile while the males are short-lived and do not feed. Multiple male mating is therefore expected to lead to sperm limitation in females. Sperm limitation and male limitation are hypothesised as causes of the repeated evolution of parthenogenetic reproduction in the Psychidae. 3. In this study, the effects of multiple male mating on female reproduction are investigated in several species of Naryciinae by allowing males multiple copulations. The results for two species, Siederia listerella and Dahlica lichenella, are compared. The sex ratios of 53 natur…

Copepod limnocalanus macrurus mating in relation to vertical migrations and aspects of feeding rates in the Bothnian Sea (Baltic Sea)

2006

The studies of calanoid copepod Limnocalanus macrurus feeding rates and mating related to vertical migration were conducted in October 2005 in the Bothnian Sea. The monocyclic copepod Limnocalanus macrurus develops mostly to adult and larger copepodites stages in autumn and these stages were investigated. Bothnian Sea is a brackish-water basin in Baltic Sea with comparatively big depth therefore Limnocalanus macrurus which prefer to live in deep and cold water is more abundant in this Baltic Sea part. Recent observations in the Bothnian Sea showed that Limnocalanus macrurus performs diel vertical migrations and adults approve stricter tendency to stay under thermocline layer at night than c…

Sexual signalling and viability in a wolf spider ( Hygrolycosa rubrofasciata ): measurements under laboratory and field conditions

1999

This study examined the crucial prediction of the conditional-handicap theory, the relationship between male sexual trait size and male viability, in the wolf spider Hygrolycosa rubrofasciata. In this species, males court females by drumming dry leaves with their abdomen, and males with the highest drumming rate enjoy highest mating success. We determined male drumming rate, body mass, and mobility, which reflects mate-searching activity, in relation to male survival. Because it is often difficult to know how results obtained from laboratory studies reflect the natural world, particularly when the measured variable is survival, we repeated our study in both laboratory and field conditions. …

Increased susceptibility to oxidative stress as a proximate cost of reproduction

2004

Chronic Background Radiation Correlates With Sperm Swimming Endurance in Bank Voles From Chernobyl

2022

Sperm quantity and quality are key features explaining intra- and interspecific variation in male reproductive success. Spermatogenesis is sensitive to ionizing radiation and laboratory studies investigating acute effects of ionizing radiation have indeed found negative effects of radiation on sperm quantity and quality. In nature, levels of natural background radiation vary dramatically, and chronic effects of low-level background radiation exposure on spermatogenesis are poorly understood. The Chernobyl region offers a unique research opportunity for investigating effects of chronic low-level ionizing radiation on reproductive properties of wild organisms. We captured male bank voles (Myo…

Lifting the Vendace, Coregonus albula, on the Life Table : Survival, Growth and Reproduction in Different Life-Stages during Very High and Low Abunda…

2021

We analyzed the variability in vendace population parameters in the context of a life table. Parameters related to growth, fecundity and survival were estimated for post-recruitment (age > 1 growing season) life stages of Lake Southern Konnevesi vendace in both very high and low population abundance regimes. Pre-recruitment survival producing population stability was then determined. We found a very strong compensatory density dependence in growth, fecundity and survival: during low abundance, a lifetime reproductive output of a female was almost 20 times that of the abundant regime. To maintain the low abundance regime, pre-recruitment survival must counterbalance it by decreasing to a ver…

Despidos laborales. Fracturas sociales e identitarias

2008

The thousands of collective dismissals which have opened the beginning of the century in Spain do not just mean nearly two hundred thousand jobs (lots of them with a very long validity) and the same amount of broken life projects, but also ways of social reproduction, broken identities, institutions and social guarantees that crumble. Amazingly, these social upheavals often become eclipsed by discourses that appeal to economic considerations, the requirements of modernization or the requests of the logic of globalization. At this article, the consequences of the break of the social link intertwined along the second half of the twentieth century are investigated. For that, we have been rebui…

European funding for reproduction research—A multinational perspective

2008

Funds from the European Union are not the only source available to the continent's reproductive research community. Each country independently sponsors the work of these scientists, but, as illustrated by snapshots in the following pages, there are huge differences in the commitment of the various European nations to tackle the challenges of reproductive biomedicine.

Sex, social reproduction, and mobile telephony as responses to precarity in urban Tanzania

2019

The gendered effects of neoliberal economic restructuring around the world are usually studied in their most dramatic forms: cross-border migration, exploitation, resistance, and violence. This chapter examines significant transformations arising from economic restructuring in the nexus between gender, labour, and urban space — transformations in which mobile technologies are deeply implicated. It explores how mobile phones are used by the poor for day-to-day survival in Tanzania’s largest city. The chapter shows how gendered economic bargains are negotiated at the very bottom of a survival economy located within the dynamics of a globalized economic system. An important characteristic of m…

Does social capital matter for European regional growth?

2015

Abstract This paper analyzes the role of different elements of social capital in economic growth for a sample of 85 European regions during the period 1995–2008. Despite the remarkable progress that social capital and European regional economic growth literatures have experienced over the last two decades, initiatives combining the two are few, and entirely yet to come for the post-1990s period. Recent improvements in data availability allow this gap in the literature to be closed, since they enable the researcher to consider the traditionally disregarded Eastern and Central European (ECE) regions. This is particularly interesting, as they are all transition economies that recently joined t…