Search results for "General Agricultural and Biological Sciences"

Otolith chemical composition suggests local populations of Antarctic silverfish Pleuragramma antarctica (Boulenger, 1902) around Antarctica are expos…

2021

The Antarctic silverfish Pleuragramma antarctica is a key species in the Southern Ocean ecosystem, and it is potentially threatened by the climate change affecting Antarctic ecosystems. Assessing the possible exposure to similar or different environmental conditions at early life stages and gathering information about connectivity or segregation between local populations of P. antarctica can be key for planning sound management strategies for this species. By using Laser Ablation Inductively Coupled Plasma Mass Spectrometry, we characterized the otolith chemical composition of 163 adult Antarctic silverfish collected from three areas located thousands of kilometers apart from each other: Ca…

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…

Why are defensive toxins so variable? An evolutionary perspective

2012

Defensive toxins are widely used by animals, plants and micro-organisms to deter natural enemies. An important characteristic of such defences is diversity both in the quantity of toxins and the profile of specific defensive chemicals present. Here we evaluate evolutionary and ecological explanations for the persistence of toxin diversity within prey populations, drawing together a range of explanations from the literature, and adding new hypotheses. We consider toxin diversity in three ways: (1) the absence of toxicity in a proportion of individuals in an otherwise toxic prey population (automimicry); (2) broad variation in quantities of toxin within individuals in the same population; (3)…

Elemental contamination of an open-pit mining area in the Peruvian Andes

2014

New technologies and higher prices of raw materials have promoted the expansion of mining activity throughout the world; if not properly regulated, this activity can lead to contamination of the local and regional environ- ment. The city of Cerro de Pasco is located close to a large open-pit mine and in recent years, several reports have pro- vided evidence of environmental contamination and related health problems. The aim of this paper is to evaluate the contamination in fluvial water, sediments and biological fluids from this area. The collective results show elevated metal and metalloid concentrations in rivers and sediments, especially in the areas downstream of the mine. For instance,…

Noise in ecosystems: a short review

2004

Noise, through its interaction with the nonlinearity of the living systems, can give rise to counter-intuitive phenomena such as stochastic resonance, noise-delayed extinction, temporal oscillations, and spatial patterns. In this paper we briefly review the noise-induced effects in three different ecosystems: (i) two competing species; (ii) three interacting species, one predator and two preys, and (iii) N-interacting species. The transient dynamics of these ecosystems are analyzed through generalized Lotka-Volterra equations in the presence of multiplicative noise, which models the interaction between the species and the environment. The interaction parameter between the species is random …

Function and Fiber-Type Specific Distribution of Hsp60 and αB-Crystallin in Skeletal Muscles: Role of Physical Exercise

2021

Simple Summary Skeletal muscle represents about 40% of the body mass in humans and it is a copious and plastic tissue, rich in proteins that are subject to continuous rearrangements. Physical exercise is considered a physiological stressor for different organs, in particular for skeletal muscle, and it is a factor able to stimulate the cellular remodeling processes related to the phenomenon of adaptation. All cells respond to various stress conditions by up-regulating the expression and/or activation of a group of proteins called heat shock proteins (HSPs). Although their expression is induced by several stimuli, they are commonly recognized as HSPs due to the first experiments showing thei…

Continental-scale patterns of pathogen prevalence: a case study on the corncrake

2014

Pathogen infections can represent a substantial threat to wild populations, especially those already limited in size. To determine how much variation in the pathogens observed among fragmented populations is caused by ecological factors, one needs to examine systems where host genetic diversity is consistent among the populations, thus controlling for any potentially confounding genetic effects. Here, we report geographic variation in haemosporidian infection among European populations of corncrake. This species now occurs in fragmented populations, but there is little genetic structure and equally high levels of genetic diversity among these populations. We observed a longitudinal gradient…

About the Influences of Some Major Biotic Drivers on the Population Dynamics in Host-parasite Systems: Interpretative Lessons from an Extended Nichol…

2020

Population dynamics within host-parasite systems in insects is governed by a series of factors, both endogenous and exogenous. Among them, five factors may be considered as major drivers: the respective inherent rates of increase of the host and of the parasite, the level of resource available to the host, the respective immigration rates of the host and of the parasite. While only the first two (the inherent rates of increase of host and parasite) are considered in the original Nicholson and Bailey model, an extended version of the model includes also the other three parameters, thus providing a broader (although still schematic) approach to the host-parasite population dynamics. A brief a…

REPLICATED ORIGIN OF FEMALE-BIASED ADULT SEX RATIO IN INTRODUCED POPULATIONS OF THE TRINIDADIAN GUPPY (POECILIA RETICULATA)

2014

There are many theoretical and empirical studies explaining variation in offspring sex ratio but relatively few that explain variation in adult sex ratio. Adult sex ratios are important because biased sex ratios can be a driver of sexual selection and will reduce effective population size, affecting population persistence and shapes how populations respond to natural selection. Previous work on guppies (Poecilia reticulata) gives mixed results, usually showing a female-biased adult sex ratio. However, a detailed analysis showed that this bias varied dramatically throughout a year and with no consistent sex bias. We used a mark-recapture approach to examine the origin and consistency of fema…

2022

The quality of wintering habitats, such as depth of snow cover, plays a key role in sustaining population dynamics of Arctic lemmings. However, few studies so far investigated habitat use during the Arctic winter. Here, we used a unique long-term time series to test whether lemmings are associated with topographical and vegetational habitat features for their wintering sites. We examined yearly numbers and distribution of 22 769 winter nests of the collared lemming Dicrostonyx groenlandicus (Traill, 1823) from an ongoing long-term research on Traill Island, Northeast Greenland, collected between 1989 and 2019, and correlated this information with data on dominant vegetation types, elevatio…