Interacting forces of predation and fishing affect species’ maturation size

1. Fishing is a strong selective force and is supposed to select for earlier maturation at smaller body size. However, the extent to which fishing‐induced evolution is shaping ecosystems remains debated. This is in part because it is challenging to disentangle fishing from other selective forces (e.g., size‐structured predation and cannibalism) in complex ecosystems undergoing rapid change.
2. Changes in maturation size from fishing and predation have previously been explored with multi‐species physiologically structured models but assumed separation of ecological and evolutionary timescales. To assess the eco‐evolutionary impact of fishing and predation at the same timescale, we developed a stochastic physiologically size‐structured food‐web model, where new phenotypes are introduced randomly through time enabling dynamic simulation of species'' relative maturation sizes under different types of selection pressures.
3. Using the model, we carried out a fully factorial in silico experiment to assess how maturation size would change in the absence and presence of both fishing and predation (including cannibalism). We carried out ten replicate stochastic simulations exposed to all combinations of fishing and predation in a model community of nine interacting fish species ranging in their maximum sizes from 10 g to 100 kg. We visualized and statistically analyzed the results using linear models.
4. The effects of fishing on maturation size depended on whether or not predation was enabled and differed substantially across species. Fishing consistently reduced the maturation sizes of two largest species whether or not predation was enabled and this decrease was seen even at low fishing intensities (F = 0.2 per year). In contrast, the maturation sizes of the three smallest species evolved to become smaller through time but this happened regardless of the levels of predation or fishing. For the four medium‐size species, the effect of fishing was highly variable with more species showing significant and larger fishing effects in the presence of predation.
5. Ultimately our results suggest that the interactive effects of predation and fishing can have marked effects on species'' maturation sizes, but that, at least for the largest species, predation does not counterbalance the evolutionary effect of fishing. Our model also produced relative maturation sizes that are broadly consistent with empirical estimates for many fish species.

     

A catalog of bird specimens associated with Prince Maximilian of Wied-Neuwied and potential type material in the natural history collection in Wiesbaden

Bird specimens collected by 19^th century explorer and ornithologist Prince Maximilian of Wied-Neuwied form one of the foundation collections of the American Museum of Natural History in New York. However, parts of his collection remained in Germany and came to the Museum Wiesbaden. Since Wied described numerous new species without designating types, some of these specimens might be type material. Here we present a catalog of the 30 Wiesbaden specimens associated with him and discuss their potential type status. We conclude that 17 individuals in 11 species are potential type specimens that should be considered in future taxonomic work.     

An efficient chemical approach to bispecific antibodies and antibodies of high valency

Irreversible chemical programming of monoclonal aldolase antibody (mAb) 38C2 has been accomplished with β-lactam equipped mono- and bifunctional targeting modules, including a cyclic-RGD peptide linked to either the peptide (d-Lys⁶)-LHRH or another cyclic RGD unit and a small-molecule integrin inhibitor SCS-873 conjugated to (d-Lys⁶)LHRH. We also prepared monofunctional targeting modules containing either cyclic RGD or (d-Lys⁶)-LHRH peptides. Binding of the chemically programmed antibodies to integrin receptors α(v)β(3) and α(v)β(5) and to the luteinizing hormone releasing hormone receptor were evaluated. The bifunctional and bivalent c-RGD/LHRH and SCS-783/LHRH, the monofunctional and tetravalent c-RGD/c-RGD, and the monofunctional bivalent c-RGD chemically programmed antibodies bound specifically to the isolated integrin receptor proteins as well as to integrins expressed on human melanoma M-21 cells. c-RGD/LHRH, SCS-783/LHRH, and LHRH chemically programmed antibodies bound specifically to the LHRH receptors expressed on human ovarian cancer cells. This approach provides an efficient, versatile, and economically viable route to high-valency therapeutic antibodies that target defined combinations of specific receptors. Additionally, this approach should be applicable to chemically programmed vaccines.     

Early development of the kelp fly,Coelopa frigida (Diptera). II. Morphology of cleavage and blastoderm formation

Cleavage and blastoderm formation in Coelopa frigida are extremely rapid developmental processes. In short (6–7 minutes) successive cell cycles, nuclei multiply and spread out through the egg. The movement seems to be aided by endoplasmic vesicles and cisternae which are in direct contact with the nuclear membrane. The first cells to separate from the egg plasmodium in early superficial cleavage stages are the pole cells. Precursor material from multivesicular bodies forms the pole cell membranes. The primary nuclei from the posterior pole region are removed from the blastoderm by the pole cell segregation. Blastoderm nuclei from the regions adjacent to the posterior pole migrate into the residual periplasm after pole cell segregation has been completed and constitute the blastoderm nuclei in that region of the egg. Nucleoli are not revealed during internal cleavage. They appear in pole cells shortly after their segregation. The generation time of the blastoderm nuclei increases after the twelfth cleavage. Concurrently, nucleoli form in the blastoderm nuclei and permanent cell membranes separate individual blastoderm cells. After blastoderm cells have been separated from each other, they remain in contact with the interior yolk sac by means of cytoplasmic canals. This contact is maintained at least during the early phases of blastokinesis. Observations on nuclear migration and rapid membrane formation are discussed as examples of protein assembly from subunits as an alternative to de novo protein synthesis in early stages of development.     

Narratives of success among Irish and African Caribbean migrants

This paper compares the narratives of two men in midlife who migrated to the UK from Ireland and from the Caribbean as children, in the middle of the last century. We examine how success is narrated over the life course to show how migrants’ positioning of themselves differs from the ways in which they are positioned by outsiders, including in policy and public discourse. We conclude that while outsider narratives often polarise success and failure, insider understandings of success are dynamic and culturally and historically situated.     

Anatomisch-physiologische Untersuchungen an Blütennectarien

Ohne Zusammenfassung