Population variation in brain size of nine-spined sticklebacks (Pungitius pungitius) - local adaptation or environmentally induced variation?

Abstract Background Most evolutionary studies on the size of brains and different parts of the brain have relied on interspecific comparisons, and have uncovered correlations between brain architecture and various ecological, behavioural and life-history traits. Yet, similar intraspecific studies are rare, despite the fact that they could better determine how selection and phenotypic plasticity influence brain architecture. We investigated the variation in brain size and structure in wild-caught nine-spined sticklebacks (Pungitius pungitius) from eight populations, representing marine, lake, and pond habitats, and compared them to data from a previous common garden study from a smaller number of populations. Results Brain size scaled hypo-allometrically with body size, irrespective of population origin, with a common slope of 0.5. Both absolute and relative brain size, as well as relative telencephalon, optic tectum and cerebellum size, differed significantly among the populations. Further, absolute and relative brain sizes were larger in pond than in marine populations, while the telencephalon tended to be larger in marine than in pond populations. These findings are partly incongruent with previous common garden results. A direct comparison between wild and common garden fish from the same populations revealed a habitat-specific effect: pond fish had relatively smaller brains in a controlled environment than in the wild, while marine fish were similar. All brain parts were smaller in the laboratory than in the wild, irrespective of population origin. Conclusion Our results indicate that variation among populations is large, both in terms of brain size and in the size of separate brain parts in wild nine-spined sticklebacks. However, the incongruence between the wild and common garden patterns suggests that much of the population variation found in the wild may be attributable to environmentally induced phenotypic plasticity. Given that the brain is among the most plastic organs in general, the results emphasize the view that common garden data are required to draw firm evolutionary conclusions from patterns of brain size variability in the wild.</p

Securing accumulation by restoration – exploring spectacular corporate conservation, coal mining and biodiversity compensation in the German Rhineland

German energy giant and coal mine operator RWE makes two products: cheap electricity and ‘pretty new landscapes’. These ‘pretty new landscapes’ are biodiversity offsets to compensate for the destruction of the ancient Hambacher Forest for the world’s largest opencast lignite coal mine in the German Rhineland. Drawing on in-depth fieldwork including participant observation and interviews in and around the mine and its offset sites, this paper explores the relationship between coal mining, spectacularisation of conservation, the ecotourism–extraction nexus and accumulation by restoration. I illustrate the historic and contemporary importance of restoration activities to the accumulation process and explore the recent engagement of mine operator RWE in the provision of restored nature (in the form of ‘eco-points’), which constitute new business opportunities. The significance of RWE’s biodiversity work for accumulation by restoration lies not only in its profit opportunities but its productive power: the legitimation of coal mining and the making of new, ordered ‘ecologies of repair’. This productive power operates through the mobilising function of RWE’s offsetting work, which forms the foundation for corporate partnerships and alliances with conservation groups and volunteers. These lend legitimacy to RWE’s ‘repair work’ and form the basis for the ecotourism–extraction nexus by turning the mine and its offsets into ‘extractive attractions’ for visitors and ‘nature lovers’. Its power further manifests in the way it captures imaginations through novel imaginaries and narratives of sustainable coal mining, supposedly creating not only a ‘better nature’ but a ‘better future’. Positioning offsetting as social technology of governance, I explore RWE’s spectacular performance of sustainability and the ontological flattening to facilitate claims of commensurability and ‘offsettability’ of nature. These are integral to the ecotourism–extraction nexus and grounded in the belief in the human/corporate ability to recreate nature, a fascination with huge earth-shifting machinery and a commitment to high-modernist ideologies of control

Differences in Lateral Line Morphology between Hatchery- and Wild-Origin Steelhead

Despite identification of multiple factors mediating salmon survival, significant disparities in survival-to-adulthood among hatchery- versus wild-origin juveniles persist. In the present report, we explore the hypothesis that hatchery-reared juveniles might exhibit morphological defects in vulnerable mechanosensory systems prior to release from the hatchery, potentiating reduced survival after release. Juvenile steelhead (Oncorhynchus mykiss) from two different hatcheries were compared to wild-origin juveniles on several morphological traits including lateral line structure, otolith composition (a proxy for auditory function), and brain weight. Wild juveniles were found to possess significantly more superficial lateral line neuromasts than hatchery-reared juveniles, although the number of hair cells within individual neuromasts was not significantly different across groups. Wild juveniles were also found to possess primarily normal, aragonite-containing otoliths, while hatchery-reared juveniles possessed a high proportion of crystallized (vaterite) otoliths. Finally, wild juveniles were found to have significantly larger brains than hatchery-reared juveniles. These differences together predict reduced sensitivity to biologically important hydrodynamic and acoustic signals from natural biotic (predator, prey, conspecific) and abiotic (turbulent flow, current) sources among hatchery-reared steelhead, in turn predicting reduced survival fitness after release. Physiological and behavioral studies are required to establish the functional significance of these morphological differences

Functional morphology and feeding behavior of Streblospio benedicti and S. shrubsolii (Polychaeta: Spionidae)

Este artículo contiene 7 páginas, 3 figuras.The functional morphology of the feeding palps and prostomium of the spionid polychaetes Streblospio benedicti and S. shrubsolii was studied. Three functional groups of cilia of the feeding palps were found on both species – frontal cilia, latero-frontal cirri and lateral cilia. Frontal cilia line the food groove and transport food particles to the pharynx, and have been reported for all spionid polychaetes except species of the genus Scolelepis. Latero-frontal cirri deflect particles onto the frontal surface and have been observed in several spionid genera including Paraprionospio, Streblospio, Polydora and Dipolydora. Lateral cilia beat in continuous metachronal waves creating lateral vortices that potentially entrain suspended particles, and are known in Paraprionospio and Streblospio. The two species of Streblospio did differ in the distribution of prostomial papillae. These papillae are eversible and thought to function in particle selection as particles on the pharynx come in contact with the papillae. Prostomial papillae were restricted to the peripheral surface of S. benedicti and were widely scattered on all surfaces of the prostomium of S. shrubsolii. A conical tentaculate structure occurs between the branchiae of the first setiger of S. benedicti, but only a low raised elevation is present on S. shrubsolii.Peer reviewe