Can terrestrial ectotherms escape the heat of climate change by moving?

Whether movement will enable organisms to alleviate thermal stress is central to the biodiversity implications of climate change. We use the temperature-dependence of ectotherm performance to investigate the fitness consequences of movement. Movement to an optimal location within a 50 km radius will only offset the fitness impacts of climate change by 2100 in 5 per cent of locations globally. Random movement carries an 87 per cent risk of further fitness detriment. Mountainous regions with high temperature seasonality (i.e. temperate areas) not only offer the greatest benefit from optimal movement but also the most severe fitness consequences if an organism moves to the wrong location. Doubling dispersal capacity would provide modest benefit exclusively to directed dispersers in topographically diverse areas. The benefits of movement for escaping climate change are particularly limited in the tropics, where fitness impacts will be most severe. The potential of movement to lessen climate change impacts may have been overestimated.     

The surface topography and ultrastructure of the tegument and haptor of Pricea multae (Monogenea)

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and 1986. The surface topography and ultrastructure of the tegument and haptor of Pricea multae (Monogenea). International Journal for Parasitology 16: 581–589. Pricea multae is a gill parasite of Scomberomorus spp. In the present study, the surface specialization and ultrastructure of the tegument and haptor were examined in detail. The buccal cavity and the preoral pit bear uniciliated sensory endings. The genital atrium opens on the ventral surface whereas the vaginal pore opens on the dorsal surface of the anterior region. The general body surface is elevated by pits and folds together with papillae-like uniciliated sensory endings. Microvilli are uncommon.

The syncytium of the tegument is bounded by apical and basal plasma membranes. Some electron-dense granules and electron-lucent vesicles were observed exocytosing at the apical surface. The tegumental perikarya lie amongst the muscle blocks underneath the basal lamina. The body wall muscle fibres are non-striated consisting of thick and thin myofilaments. Each muscle fibre is limited by a sarcolemma and separated from neighbouring fibres by interstitial material.

The haptor possesses two rows of pincer-type clamps. The clamps may be withdrawn by muscles into cavity-like depressions. Electron-dense fibrils are embedded within the clamp sclerite matrix. The intrinsic muscles of the clamp include radial muscles enclosed within the basal lamina. The muscle fibres enclosed within the basal lamina of the clamp appear to differ from the body wall muscles by the absence of interstitial material, the possession of well defined gap junctions between the sarcolemma of adjacent muscle fibres, abundant sarcoplasmic reticulum and numerous mitochondria. The extrinsic muscles of the clamp presumably arise from the dorso-lateral surface of the haptor and are apparently connected to the tendon of the clamp. A cluster of gland cells occurs in the haptor beneath each clamp. The haptor is richly supplied with nerve fibres which are associated with groups of neurones. Each axon is non-myelinated and contains presumed neurosecretory granules. The peripheries of some of the large axons are subdivided by invaginations of the axon wall.     

INFLUENCE OF VEGETATION,TOPOGRAPHY, AND ROADS ON COUGAR MOVEMENT IN SOUTHERN CALIFORNIA

Abstract: Models of individual movement can help conserve wide-ranging carnivores on increasingly human-altered landscapes, and cannot be constructed solely by analyzing the daytime resting locations typically collected in carnivore studies. We examined the movements of 10 female and 7 male cougars (Puma concolor) at 15-min intervals during 44 nocturnal or diel periods of hunting or traveling in the Santa Ana Mountain Range of southern California, USA, between 1988 and 1992. Cougars tended to move in a meandering path (mean turning angle ∼54°), and distance moved (mean and mode ∼300 m) was not correlated with turning angle. Cougars used a broader range of habitats for nocturnal or diel movements than for previously described daybed locations for this same population. Riparian vegetation ranked highest in a compositional analysis of vegetation types selected during movement; grassland, woodland and urbanized sites were least selected. During periods of stasis (we presume many of these were stalking locations), patterns of selection were less marked. Cougars spent a disproportionate amount of time in highly ranked vegetation types, and traveled slowest through riparian habitats and fastest through human-dominated areas. Our results suggest that travel speed may provide an efficient index of habitat selection in concert with other types of analysis. Hunting or traveling individuals consistently used travel paths that were less rugged than their general surroundings. Traveling cougars avoided 2-lane paved roads, but dirt roads may have facilitated movement. Maintenance and restoration of corridors between large wildlands is essential to conserving cougars in southern California. Our results indicate that riparian vegetation, and other vegetation types that provide horizontal cover, are desirable features in such corridors, that dirt roads should not impede cougar use of corridors, and that corridors should lie along routes with relatively gentle topography. Our results suggest that cougars do not key in on highway-crossing structures in a way that creates a prey trap. Our empirical frequency distributions of distances and turning angles, along with cougar responses to vegetation, topography, and roads can help parameterize an individually-based movement model for cougars in human-altered landscapes.     

Structural differences between the resting eggs of Brachionus plicatilis and Brachionus rotundiformis (Rotifers, Brachionidae): an electron microscopic study

Surface topography and layering of resting eggs of Brachionus plicatilis and B. rotundiformis are described, based on scanning and transmission electron microscope studies. In B. plicatilis, the resting eggs are spherical with smooth wavy ridges on the surface, whereas these ridges are small and condensed in B. rotundiformis. The distribution of pores on the egg surface clearly distinguishes the two species.Ultrastructure of the egg membranes of both species varies greatly with regard to size, shape and sculpturing of each membrane. The alveolar and dense sublayers, which constitute the outer egg membrane (S1) are very thick (10–12 µm) in B. rotundiformis compared to B. plicatilis (4–5 µm). Thus, each species has a characteristic surface and membrane architecture. The functional roles of these membranes, during the resting phase of rotifers, are discussed.     

Diversity, abundance and depth distribution of demersal deep-water fishes off Lanzarote and Fuerteventura, Canary Islands

A total of 168 bottom longline operations were carried out at depths between 72 and 1102 m during four cruises off Lanzarote and Fuerteventura, Canary Islands. One hundred and twenty-eight operations were successful, resulting in the capture of 1167 fishes belonging to 55 species. Clear variations in fish total weight and number, species richness and diversity, and the relative abundance of single species occurred among five different depth zones between 100 and 1100 m. The particular platform topography of the Canary Islands may affect the density and diversity of slope-dwelling fishes. Whereas fish body length and weight showed an overall increase with depth, no such trends were found at the level of individual species. One species, Lepidopus caudalus , even revealed a bigger-shallower trend. Among three species of trichiurids, depth distribution patterns were detected that may reflect vertical space partitioning. In October 1995, an unusually high number of Mora moro with advanced gonadal maturity were collected off eastern Fuerteventura at 997 m depth. At lesser depths and during other seasons, only a few individuals of this species were caught in the same area. This indicated a seasonal variability in local abundance that is most probably related to reproduction. Mora moro has an excellent flesh and may represent a valuable fisheries resource. Open problems requiring further research in the study area such as selectivity effects of the fishing gear and possible influences of ecological factors on geographical distribution of the deep-water ichthyofauna, as well as important aspects of the future demersal fisheries management in the Canarian archipelago are briefly outlined.     

The surface topography of a monogenean Heterapta chorinemi from the gills of Scomberoides commersonianus

and 1986. The surface topography of a monogenean Heterapta chorinemi from the gills of Scomberoides commersonianus. International Journal for Parasitology 16: 595–600. The dorsal and ventral surfaces of H. chorinemi bear microvilli and boss-like structures. These may increase the surface area for respiratory gaseous exchange and absorption of nutrients from the surrounding medium. Uniciliated sensory endings, presumably rheoreceptors, are present over the entire surface whereas non-ciliated structures, possibly mechanoreceptors, are present only on the ventral surface of the haptor. The haptor possesses 6–10 pairs of pincer-type clamps and 30–40 pairs of open sucker-type clamps with scleritized jaws. The common genital atrium is situated on the ventral surface, the vaginal pore opens on the dorsal surface and the mouth is subterminal as described in previous light microscope studies.