1,721,014 research outputs found
The adaptive significance of male subadult plumage in the black redstart: Dyeing experiments
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Monitoraggio della longevità dei semi di Brassica villosa subsp drepanensis conservati a lungo termine
No full textDifferent stress from parasites and mate choice in two female morphs of the blue‐tailed damselfly
Full text linkIn Odonates, female colour polymorphism is common and implies the presence of two or more female types with different colours and behaviours. To explain this phenomenon, sev- eral hypotheses have been proposed that consider morph frequency, population density, the presence of parasites, and mating behaviour. We studied the blue-tailed damselfly Ischnura elegans, a species with a blue androchrome morph and two gynochrome morphs (the com- mon green infuscans, and the rare orange rufescens-obsoleta). The size of adult males and females, the presence of parasites, and pairing behaviour between males and the three female morphs was assessed in field conditions throughout the reproductive season in NW Italy. Moreover, growth and emergence success of larvae produced by the different morphs was analyzed in standardized conditions. In the field, males showed a preference for the gynochrome infuscans females, despite a similar frequency of androchrome females. In test conditions, male preference for the infuscans females was also observed. Paired males and paired androchrome females were larger than unpaired individuals, while there were no differences in size between paired and unpaired infuscans females. Males and androchrome females were more parasitized than infuscans females. The survival and emergence success of larvae produced by androchrome females was higher than those of offspring produced by the infuscans females. Our results suggest that a higher survival of progeny at the larval stage could counterbalance the higher parasitism and the lower pairing success of andro- morph adult females and highlight the importance of considering the whole life-cycle in polymorphism studies
Age at first reproduction and longest-lived individuals in the Pallid Swift Apus pallidus.
Full text linkSwifts are long-living birds with delayed maturation; however, the age at first reproduction and their maximum life span is known for a few species. We discuss here some data about these parameters, using observations collected during our long-standing study on Pallid Swift Apus pallidus in Northern Italy. The longest-lived bird in our dataset was still recovered breeding 19 calendar years after maturity, and the youngest confirmed age at first breeding was 3 years (i.e., bird in 4th calendar year). No breeding attempts have been verified for individuals in their second and third calendar year
Testing the impact of agricultural practices on protist and metazoan communities in rice paddy soils through environmental DNA
Full text linkSoil is a fundamental environment hosting a high biodiversity and enclosing numerous microhabitats. Multiple studies have proved that the adoption of more sustainable practices in crop cultivation results in improved soil biodiversity conservation, whereas conventional agronomic practices can have detrimental impacts on soil attributes. Besides, rice is a major staple food and at the same time, the landscape heterogeneity within its agroecosystem is of fundamental need for several different organisms linked permanently or temporarily to water.
In this study, we used an environmental DNA metabarcoding approach targeting two different genes, the 18S rRNA and the cytochrome C oxidase subunit I (COI), aiming to assess the changes in the protist and metazoan soil communities and their functional diversity under three different rice cultivation managements (i.e. agroforestry, organic and conventional), and along four stages of the rice growth cycle (i.e. basal, vegetative, flowering and maturation phases).
Results showed that the most abundant phyla in the rice paddy soil were Cercozoa and Ciliophora for protists, and Annelida, Nematoda and Arthropoda for metazoan. In particular, Cercozoa were abundant in the agroforestry cropping system, while Ciliophora showed higher abundance in control cover crop field. Annelida were more abundant in the conventional cultivation regime, while both Nematoda and Arthropoda were less abundant, with a significant increase in the organic and agroforestry regimes. Considering the taxonomical and functional diversities, slight differences among treatments were identified both in protists and in metazoans because of the combined effect of agricultural management and the succession of drying-flooding phases during the growing season.
The community’s beta diversity described a positive effect of the organic and agroforestry cropping systems, highly dissimilar from the community found in the conventional rice field. Soil physical-chemical properties did not differ significantly from one treatment to another. This study broadens our understanding of the effects of agricultural practices on the biodiversity inhabiting the soil in rice agroecosystems, highlighting the positive impact of organic and agro-forestry management as suitable environments for the rice soil biocenosis. It also contributes to emphasizing the importance of soil biodiversity conservation and the benefits of redesigning agricultural practices
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