scholarly journals Bird Predation On Spiders: Ecological Mechanisms And Evolutionary Consequences

2007 ◽  
Vol 35 (3) ◽  
pp. 509-529 ◽  
Author(s):  
Bengt Gunnarsson
Keyword(s):  
Bird Predation ◽  
Ecological Mechanisms ◽  
Evolutionary Consequences

scholarly journals Temperature-related birth sex ratio bias in historical Sami: warm years bring more sons

2007 ◽  
Vol 4 (1) ◽  
pp. 60-62 ◽  
Author(s):  
Samuli Helle ◽  
Samuli Helama ◽  
Jukka Jokela
Keyword(s):  
Sex Ratio ◽  
Environmental Temperature ◽  
Environmental Variability ◽  
Offspring Sex Ratio ◽  
Sex Ratio Bias ◽  
Parental Fitness ◽  
Biased Sex Ratio ◽  
Ecological Mechanisms ◽  
Evolutionary Consequences ◽  
Human Birth

The birth sex ratio of vertebrates with chromosomal sex determination has been shown to respond to environmental variability, such as temperature. However, in humans the few previous studies on environmental temperature and birth sex ratios have produced mixed results. We examined whether reconstructed annual mean temperatures were associated with annual offspring sex ratio at birth in the eighteenth to nineteenth century Sami from northern Finland. We found that warm years correlated with a male-biased sex ratio, whereas a warm previous year skewed sex ratio towards females. The net effect of one degree Celsius increase in mean temperature during these 2 years corresponded to approximately 1% more sons born annually. Although the physiological and ecological mechanisms mediating these effects and their evolutionary consequences on parental fitness remain unknown, our results show that environmental temperature may affect human birth sex ratio.

scholarly journals Sexual reproduction in the fungal foliar pathogen Zymoseptoria tritici is driven by antagonistic density-dependence mechanisms

2018 ◽  
Author(s):  
Frédéric Suffert ◽  
Ghislain Delestre ◽  
Sandrine Gélisse
Keyword(s):  
Density Dependence ◽  
Sexual Reproduction ◽  
Vertical Position ◽  
Ecological Knowledge ◽  
Zymoseptoria Tritici ◽  
Asexual Multiplication ◽  
Ecological Mechanisms ◽  
Evolutionary Consequences ◽  
Foliar Pathogens ◽  
Host Tissues

AbstractThis study provides empirical evidence for antagonistic density-dependence mechanisms driving sexual reproduction in the wheat fungal pathogen Zymoseptoria tritici. Biparental crosses with 12 increasing inoculum concentrations, in controlled conditions, showed that sexual reproduction in Z. tritici was impacted by an Allee effect due to mate limitation and a competition with asexual multiplication for resource allocation. We found that asexual multiplication was itself affected by competition for host resources between the two parental isolates, as illustrated by the decrease in asexual fruiting body density and sporulation intensity observed with increasing lesion density. Consistent with these results for controlled co-inoculation, we found that the intensity of sexual reproduction varied with both cropping period and the vertical position of the host tissues in the field. An optimal lesion density maximizing offspring (ascospores) number was established, and its eco-evolutionary consequences are considered here. Two ecological mechanisms may be involved: competition for resources between the two modes of reproduction (decrease in the host resources available for sexual reproduction due to their prior use in asexual multiplication), and competitive disequilibrium between the two parental isolates, due to differential interaction dynamics with the host, for example, leading to an imbalance between mating types. Conceptual models based on these results suggest that sexual reproduction plays a key role in the evolution of pathogenicity traits, including virulence and aggressiveness. Ecological knowledge about the determinants of sexual reproduction in Z. tritici may, therefore, open up new perspectives for the management of other fungal foliar pathogens with dual modes of reproduction.

Chemical Ecology and Off-Flavour Substances

1988 ◽  
Vol 20 (8-9) ◽  
pp. 167-178
Author(s):  
O. M. Skulberg
Keyword(s):  
Environmental Factors ◽  
Chemical Ecology ◽  
Aquatic Environment ◽  
Metabolic Pathways ◽  
Chemical Properties ◽  
Relevant Research ◽  
Fundamental Research ◽  
Biotic Effects ◽  
Ecological Mechanisms ◽  
Ecological Importance

Off-flavour substances may be regarded as a resource which can be used to study special ecological mechanisms. Relevant research on off-flavours is inextricably combined with the study of perception, ethology, genetic control etc. The chemicals concerned are commonly perceived by the senses of olfaction and gustation. Thus research on the chemical ecology of off-flavour substances in the aquatic environment involves the study of a variety of disciplines. For example the biochemistry of the relevant substances and appropriate metabolic pathways must be considered. Chemical properties are important for the behaviour of the substances. The production of off-flavours by organisms is related to phenological circumstances. The biotic effects of ecologically significant substances are dependent on several environmental factors. This paper draws attention to the possible application of fundamental research in this area to selected problems of ecological importance.

scholarly journals Boon and Bane of DNA Double-Strand Breaks

2021 ◽  
Vol 22 (10) ◽  
pp. 5171
Author(s):  
Ingo Schubert
Keyword(s):  
Negative Impact ◽  
Biological Effects ◽  
Double Strand Breaks ◽  
Immunoglobulin Gene ◽  
Dna Double Strand Breaks ◽  
Endogenous Factors ◽  
Strand Breaks ◽  
Chromatin Elimination ◽  
Evolutionary Consequences ◽  
Cell Lethality

DNA double-strand breaks (DSBs), interrupting the genetic information, are elicited by various environmental and endogenous factors. They bear the risk of cell lethality and, if mis-repaired, of deleterious mutation. This negative impact is contrasted by several evolutionary achievements for DSB processing that help maintaining stable inheritance (correct repair, meiotic cross-over) and even drive adaptation (immunoglobulin gene recombination), differentiation (chromatin elimination) and speciation by creating new genetic diversity via DSB mis-repair. Targeted DSBs play a role in genome editing for research, breeding and therapy purposes. Here, I survey possible causes, biological effects and evolutionary consequences of DSBs, mainly for students and outsiders.

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