Differential Item Functioning on Antisocial Behavior Scale Items for Adolescents and Young Adults from Single-Parent and Two-Parent Families

We investigated measurement equivalence in two antisocial behavior scales (i.e., one scale for adolescents and a second scale for young adults) by examining differential item functioning (DIF) for respondents from single-parent (n = 109) and two-parent families (n = 447). Even though one item in the scale for adolescents and two items in the scale for young adults showed significant DIF, the two scales exhibited non-significant differential test functioning (DTF). Both uniform and nonuniform DIF were investigated and examples of each type were identified. Specifically, uniform DIF was exhibited in the adolescent scale whereas nonuniform DIF was shown in the young adult scale. Implications of DIF results for assessment of antisocial behavior, along with strengths and limitations of the study, are discussed

Ecology and Biogeography of Free-Living Nematodes Associated with Chemosynthetic Environments in the Deep Sea: A Review

Background: Here, insight is provided into the present knowledge on free-living nematodes associated with chemosynthetic environments in the deep sea. It was investigated if the same trends of high standing stock, low diversity, and the dominance of a specialized fauna, as observed for macro-invertebrates, are also present in the nematodes in both vents and seeps. Methodology: This review is based on existing literature, in combination with integrated analysis of datasets, obtained through the Census of Marine Life program on Biogeography of Deep-Water Chemosynthetic Ecosystems (ChEss). Findings: Nematodes are often thriving in the sulphidic sediments of deep cold seeps, with standing stock values ocassionaly exceeding largely the numbers at background sites. Vents seem not characterized by elevated densities. Both chemosynthetic driven ecosystems are showing low nematode diversity, and high dominance of single species. Genera richness seems inversely correlated to vent and seep fluid emissions, associated with distinct habitat types. Deep-sea cold seeps and hydrothermal vents are, however, highly dissimilar in terms of community composition and dominant taxa. There is no unique affinity of particular nematode taxa with seeps or vents. Conclusions: It seems that shallow water relatives, rather than typical deep-sea taxa, have successfully colonized the reduced sediments of seeps at large water depth. For vents, the taxonomic similarity with adjacent regular sediments is much higher, supporting rather the importance of local adaptation, than that of long distance distribution. Likely the ephemeral nature of vents, its long distance offshore and the absence of pelagic transport mechanisms, have prevented so far the establishment of a successful and typical vent nematode fauna. Some future perspectives in meiofauna research are provided in order to get a more integrated picture of vent and seep biological processes, including all components of the marine ecosystem

Wadden Sea mussel beds invaded by oysters and slipper limpets: competition or climate control?

Introduced species are often considered to bea threat to residents, but not all reciprocal trends mayreflect species interaction. In the northern GermanWadden Sea, native mussel Mytilus edulis beds aredeclining and overgrown by introduced Pacific oystersCrassostrea gigas and slipper limpets Crepidula fornicata.We review the population development of thethree species and analyse whether the invading speciesmay be responsible for the decline of native mussels.The Pacific oyster predominately settles on musselbeds in the intertidal and the slipper limpet dominatesaround low water line. We compare the developmentof mussels and invaders in two subregions: musselbeds near the islands of Sylt and Amrum decreasedboth in the presence (Sylt) and absence (Amrum) ofthe two invading species and more detailed investigationscould not confirm a causal relationship betweenthe increasing invaders and decreasing mussel beds.There is evidence that the decline of mussel beds ismainly caused by failing spatfall possibly due to mildwinters, whereas the increase in slipper limpets andoysters is facilitated by mild winters and warm summers,respectively. We conclude that changing speciescomposition is a result of the climatic conditions inthe last decade and that there is no evidence yet thatthe exotic species caused the decline of the natives. Itremains an open question whether the species shift willcontinue and what the consequences for the nativeecosystem will be