Search results for "MAR"

Pigmentation polymorphism in the invasive amphipod Dikerogammarus villosus : some insights into its maintenance

2004

Dikerogammarus villosus, a freshwater invasive amphipod, exhibits conspicuous pigmentation polymorphism. This polymorphism is documented in two recently colonized areas, the Saand Moselle rivers (north-eastern France), and some of the mechanisms by which pigmentation polymorphism can arise and be maintained are addressed. Body size, reproductive status, fecundity and mate choice are compared among morphs of D. villosus in field samples collected in summer 2001. Body size and female gonad developmental stage were comparable among the different morphs, suggesting that polymorphism is not the result of changes in pigmentation with age or moult- cycle. Fecundity and reproductive status (paired …

Tropical Fruits as an Opportunity for Sustainable Development in Rural Areas: The Case of Mango in Small-Sized Sicilian Farms

2018

Over the last decades, in many rural areas in Southern Europe, farmers have abandoned agricultural activity, especially on small-sized farms, leading to an exodus from rural areas towards urbanized ones. In this context, in the early 1980s, some Sicilian farmers introduced mango on their small-sized farms, as certain areas of Sicily are well suited to tropical and subtropical crops, but also to meet increasing consumer interest for these fruits, as they are perceived as functional foods. This paper aimed to evaluate the economic sustainability of mango and to determine whether its introduction could be considered as an alternative to traditional crops. In particular, an economic-financial a…

Sandbar shark aggregation in the central Mediterranean Sea and potential effects of tourism

2021

An aggregation of sandbar sharks Carcharhinus plumbeus occurs every summer around the remote uninhabited islet of Lampione (Pelagie Islands Marine Protected Area, south-western Mediterranean Sea), attracting an increasing number of tourists for a shark watching experience. Despite the ecological and socio-economic importance of this rare occurrence in Mediterranean waters, there is a lack of scientific data and lack of information as to the potential impact of tourist activities on the presence and behaviour of this shark species. Using baited underwater videos, this study provides the first assessment of this shark aggregation, as well as a preliminary evaluation of the potential effects t…

Naturalization and spread of the alien species Ozognathus cornutus (LeConte, 1859) (Coleoptera: Ptinidae: Ernobiinae) in Italy

2021

AbstractOzognathus cornutus(LeConte, 1859) (Coleoptera: Ptinidae: Ernobiinae), species native to North America, is a saproxylophagous species and is known to feed on decaying tissues within conspicuous galls and on vegetal decaying organic material such as dried fruits or small wood shavings and insect excrements in galleries made by other woodboring species. A few years after the first record in 2011, its naturalization in Italy is here reported. The insect was found as successor in galls ofPsectrosema tamaricis(Diptera Cecidomyiidae),Plagiotrochus gallaeramulorum,Andricus multiplicatusandSynophrus politus(Hymenoptera Cynipidae).The galls seem to have played an important ecological role in…

Closely related crabs from opposite niches adopt different mechanisms to adjust oxygen transport

2008

The successful colonization of new environments is often achieved through adaptations or key innovations of existing physiological or biochemical mechanisms. The oxygen supply in marine invertebrates represent a complex and deeply integrated system which plays a fundamental role in animal adaptive plasticity. In particular, species which inhabit highly stochastic environments as shallow water or intertidal bands, have to cope with extremely different regimes of oxygen availability and effectively maintain a stable aerobic metabolism. Within this framework, we have focused on comparative physiology of Portunid Crabs hemocyanin, to evaluate the role molecular heterogeneity and functional plas…

Spatial structure and β-diversity of phytoplankton in Tibetan Plateau lakes: nestedness or replacement?

2017

Spatial patterns and β-diversity of phytoplankton assemblages depend on the relative importance of species dispersal capacity and species-sorting. Variability in species composition, composed by differences in species richness (nestedness) and/or species replacement, may be caused by niche availability and environmental selection. A field survey was carried out in Tibetan plateau on 38 lakes. Tibetan plateau lakes, located at high elevation, are harsh ecosystems characterized by low temperatures, low available nutrients, high UV amount, and strong salinity gradients. Only well-adapted species can survive in these environments. We therefore hypothesized that environmental filtering was the m…

Some like it deep : Intraspecific niche segregation in ruffe (Gymnocephalus cernua)

2017

Generalist fishes commonly show intraspecific niche segregation along the littoral–pelagic resource axis in lakes. Recent studies have shown that the deep, cold and seemingly unproductive profundal zone can also offer underutilised resources and facilitate specialised individuals, and can contribute to lake food webs via methane-derived carbon pathways. Despite numerous examples from salmonid fish species, such intraspecific niche segregation along a littoral–profundal resource axis has not been reported in percids or other predominantly littoral benthivorous fishes. Here, we describe a case of ruffe (Gymnocephalus cernua: Percidae) populations consisting of shallow- and deep-water dwelling…

2018

Marine life of the Southern Ocean has been facing environmental changes and the direct impact of human activities during the past decades. Benthic communities have particularly been affected by such changes although we only slowly understand the effect of environmental changes on species physiology, biogeography, and distribution. Species distribution models (SDM) can help explore species geographic responses to main environmental changes. In this work, we modeled the distribution of four echinoid species with contrasting ecological niches. Models developed for [2005-2012] were projected to different time periods, and the magnitude of distribution range shifts was assessed for recent-past c…

Evolutionary ecology of fast seed germination—A case study in Amaranthaceae/Chenopodiaceae

2017

Abstract Germination is a vulnerable and risky step in a plant’s life cycle. Particularly under harsh environmental conditions, where time windows favourable for seedling establishment and survival are short or unpredictable, germination speed might play a highly adaptive role. We investigated the germination speed of 107 Amaranthaceae s.l. at two different temperatures and related the results to various plant and habitat traits taking into account the molecular phylogenetic relatedness of the species sampled. Germination speed is a fast evolving trait in Amaranthaceae s.l. It evolves towards significantly faster optima in C4 and halophyte lineages, albeit for different reasons. While C4 ph…

The relation between circadian asynchrony, functional redundancy, and trophic performance in tropical ant communities

2016

The diversity-stability relationship has been under intense scrutiny for the past decades, and temporal asynchrony is recognized as an important aspect of ecosystem stability. In contrast to relatively well-studied interannual and seasonal asynchrony, few studies investigate the role of circadian cycles for ecosystem stability. Here, we studied multifunctional redundancy of diurnal and nocturnal ant communities in four tropical rain forest sites. We analyzed how it was influenced by species richness, functional performance, and circadian asynchrony. In two neotropical sites, species richness and functional redundancy were lower at night. In contrast, these parameters did not differ in the t…