Search results for "behavior"
showing 10 items of 13975 documents
Sex Allocation Theory for Facultatively Sexual Organisms Inhabiting Seasonal Environments: The Importance of Bet Hedging
2018
Adaptive explanations for dormancy often invoke bet hedging, where reduced mean fitness can be adaptive if it associates with reduced fitness variance. Sex allocation theory typically ignores variance effects and focuses on mean fitness. For many cyclical parthenogens, these themes become linked, as only sexually produced eggs undergo the dormancy needed to survive harsh conditions. We ask how sex allocation and the timing of sex evolve when this constraint exists in the form of a trade-off between asexual reproduction and sexual production of dormant eggs—the former being crucial for within-season success and the latter for survival across seasons. We show that male production can be tempo…
Kin selection in interactions between gametes: Gamete competition, gamete limitation, and sex allocation
2023
Kin selection on one hand, and gamete interactions in post-ejaculatory sexual selection on the other are two major research themes that have risen to prominence over the past half century and have simultaneously developed into central fields of research in evolutionary biology. There is a natural connection between the two: when gametes interact with each other, very commonly many of them originate from the same parent and are thus siblings. For example, sperm competition will almost always involve competition between sibling gametes even if the interacting parents are not related to each other. If parents are related to each other, the relatedness between gametes increases further. Here we…
The Impact of Adolescent Internet Addiction on Sexual Online Victimization: The Mediating Effects of Sexting and Body Self-Esteem
2021
Adolescents’ problematic use of the internet and the risk of sexual online victimization are an increasing concern among families, researchers, professionals and society. This study aimed to analyze the interplay between adolescents’ addiction to social networks and internet, body self-esteem and sexual–erotic risk behavior online: sexting, sextortion and grooming. While sexting refers to the voluntary engagement in texting sexual–erotic messages, sextortion and grooming are means of sexual–erotic victimization through the use of the internet. Participants were 1763 adolescents (51% girls), aged 12 to 16 years (M = 14.56
Development and validation of the Adolescent Sexting Scale (A-SextS) with a Spanish sample
2020
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Sexual behavior and sexual health of transgender women and men before treatment: Similarities and differences
2020
BACKGROUND: There is a lack of research on the sexual health of transgender individuals, as well as a paucity of data about overall sexual health indexes before treatment. AIMS: This study aims to analyze the main issues involved in transgender individuals’ sexual behavior (with and without a partner), overall sexual health indexes, and potential predictors of sexual health, comparing trans men and trans women on all the variables assessed. METHODS: 260 trans people were recruited at a transgender health clinic in Spain. Participants completed the Sexual Behavior Questionnaire for transgender people before receiving any treatment. RESULTS: Overall results show that trans women have a more e…
New Gynandromorph Records for Chirocephalus diaphanus (Branchiopoda, Anostraca, Chirocephalidae)
2021
We report and describe new Chirocephalus diaphanus Prévost, 1803 gynandromorphs from Tunisia and review the literature of anostracan gynandromorphy and other, possibly associated, somatic aberrations, with comments on their evolutionary significance. Our material has three specimens that are specifically deformed on the left side of the head.
Modelling the relationship between sexual reproduction and rhizome growth in Posidonia oceanica (L.) Delile
2006
The relationship between flowering and growth performance of Posidonia oceanica (L.) Delile in meadows distributed along the south-eastern coast of Sicily (Italy) was investigated by means of a statistical model (generalized linear mixed model) combined with the lepidochronological analysis. Over a 28-year period, 67 floral stalk remains were observed. The highest flowering index was recorded in lepidochronological year 1998 (10.1%) and the Inflorescence Frequency per age showed a clear decrease corresponding to 15-year-old shoots. The sexual reproductive event had positive effects on rhizome elongation (cm year−1) and leaf production (no. leaves year−1) in the same flowering year, whilst n…
Forest nurseries and the National Recovery and Resilience Plan: the case of Sicily and Apulia (Italy)
2023
In Italy, the National Recovery and Resilience Plan (NRRP) foresees the planting of ca. 6.6 million trees to establish urban and peri-urban forests in 14 metropolitan cities. This ambitious project requires a significant number of native trees and shrubs, currently unavailable in Italian public and private nurseries. This survey analyzes the state of forest nurseries in two administrative regions of southern Italy, i.e. the “Filici” forest nursery (province of Agrigento, Sicily) and the Gargano Mountain Reclamation Consortium (province of Foggia, Apulia), to evaluate the adequacy of Sicilian and Apulian forest nurseries as potential sources of plant material to meet the requirements of the …
Large-scale genotyping identifies 41 new loci associated with breast cancer risk
2013
Journal article Breast cancer is the most common cancer among women. Common variants at 27 loci have been identified as associated with susceptibility to breast cancer, and these account for ~9% of the familial risk of the disease. We report here a meta-analysis of 9 genome-wide association studies, including 10,052 breast cancer cases and 12,575 controls of European ancestry, from which we selected 29,807 SNPs for further genotyping. These SNPs were genotyped in 45,290 cases and 41,880 controls of European ancestry from 41 studies in the Breast Cancer Association Consortium (BCAC). The SNPs were genotyped as part of a collaborative genotyping experiment involving four consortia (Collaborat…
Niche position drives interspecific variation in occupancy and abundance in a highly-connected lake system
2019
Highlights • We studied interspecific variation in occupancy and abundance of freshwater species. • Occupancy and abundance correlated positively for both diatoms and macroinvertebrates. • Niche position had clearest effects on variation in occupancy and abundance. • The more marginal the niche position, the rarer a species is. We examined how niche position, niche breadth, biological traits and taxonomic relatedness affect interspecific variation in occupancy and abundance of two commonly-used biological indicator groups, i.e. diatoms and macroinvertebrates. We studied 291 diatom and 103 macroinvertebrate species that occupied the littoral zones of a large (305 km2) highly-connected freshw…