Coral Adaptation and Acclimatization: A Most Ingenious Paradox

SYNOPSIS. Reef corals and the communities they form evidentlypossess effective mechanisms of adaptation and acclimation thathave ensured their survival and recurrence over geologic time.Current reef degradation suggests that these mechanisms arebeing taxed beyond their limits; understanding of the problemis hampered by serious inadequacies in our understanding ofphysiological stress responses, the range and implications ofreproductive strategies, and the mechanisms of calcificationand algal symbiosis. Reef community and population responsesto environmental change appear substantially different on differenttime scales, and a combination of short-term perspectives anddefinitional confusion complicates interpretation and predictionof reef responses. Calcium carbonate saturation state is nowrecognized as a potentially important control of reef calcification,which means that rising atmospheric CO₂ represents a directthreat to reef ecosystems on a global scale.     

Geographic analysis of nucleotide diversity and song sparrow (Aves: Emberizidae) population history

Mitochondrial DNA (mtDNA) control-region (CR) sequences were analysed to address three questions regarding the evolution of geographical variation in song sparrows. (i) Are mtDNA sequences more informative about phylogenetic relationships and population history than previously published restriction fragment (RFLP) data? (ii) Are song sparrow CR sequences evolving in a selectively neutral manner? (iii) What do the haplotype cladogram and geographical pattern of nucleotide diversity (π) suggest about the recent evolutionary history of song sparrow populations? Results from phylogenetic analyses of CR sequences corroborate RFLP results and reveal instances in which haplotypes do not group by locality. Neutrality tests ( 51 ) suggest that song sparrow mtDNA is evolving in a selectively neutral manner, although exceptions are noted. A novel geographical pattern of π suggests a model of song sparrow population history involving multiple Pleistocene refugia and colonization of some formerly glaciated regions from multiple sources. Moreover, application of coalescence theory to the haplotype cladogram suggests that two different haplotypes (48NF and 151HA) may have predominated in different parts of the song sparrow's range. This model provides insight into the current distribution of song sparrow mtDNA haplotypes and may explain the discordance between evolutionary history inferred from mtDNA and morphology in this species.     

Orientation of agents of wound myiasis to hosts and artificial stimuli in Hungary

Abstract. The orientation of adults of the myiasis species Wohlfahrtia magnified and Lucilia sericata to artificial visual stimuli (cloth targets) and olfactory stimuli ('swormlure-4', a potent screwworm attractant), was studied in sheep pastures near to Sarbogard in Hungary. Experiments with odour-baited cloth targets, enclosed in electrocuting grids, demonstrated that colour was an important factor influencing catches on targets: a black target caught most flies of both species, with other colours in the following order of effectiveness, blue > white > yellow. Wohlfahrtia magnified did not respond to swormlure-4 in the strong manner that L. sericata did. The sex ratios of W. magnifica caught on targets (67.2% males) and hand-netted from fence posts (68.8% males) were similar and biased towards males, whereas that of L. sericata on targets was strongly biased towards females (15.6% males), indicating a fundamental difference in the response of these two myiasis species towards the swormlure-baited targets. The orientation of these two species towards hosts was also recorded together with that of a third species, Phormia regina . Electric nets placed beside infested sheep caught significantly more flies of all three species than those placed beside uninfested sheep or in the absence of sheep. The sex ratio of W. magnified caught around infested sheep was the reverse of that on targets, with 68.5% females. Wohlfahrtia magnifica responded more strongly to healthy, uninfested sheep than did L. sericata and P. regina . The potential for use of targets both for population monitoring and control is discussed.     

The Effects of Salinity upon Galactosyl-Glycerol Content and Concentration of the Marine Red Alga Porphyra purpurea (Roth) C.Ag.

Changes in the major alcohol-soluble, low molecular weight carbohydratesof P. purpurea, O--D-galactopyranosyl-(1-2)-glycerol (‘floridoside’)and O--D-galactopyranosyl-(1-1)-glycerol (‘isofloridoside’),have been examined in response to salinity variation. ‘Floridoside’is shown to vary in absolute amount, increasing in hypersalineand decreasing in hyposaline media. ‘Isofloridoside’content per cell does not change in a similar manner. Responsesare almost identical under light or dark conditions, ‘floridoside’changes being complete within 24 h. Decreasing the externalwater potential using ionic and non-ionic solutes has the sameeffect upon galactosyl-glycerol content. The amount of ‘floridoside’synthesized, and degraded under hypersaline and hyposaline conditionsrespectively is shown to be insufficient to restore cell volumeto its original value. It is therefore suggested that the primaryfunction of ‘floridoside’ increases in concentratedsea-waters is that of a compatible solute, serving to protectthe cell during periods when the external salt content is increaseddramatically.     

Size matters: the (negative) allometry of copulatory duration in mammals

The amount of time taken to copulate varies enormously among mammals. Because copulation likely exposes animals to an increased risk of predation, and uses time and energy that could be spent on foraging, smaller mammals (which are vulnerable to more predators and have a shorter time-to-starvation than larger mammals) should spend less time copulating than do larger mammals. Furthermore, if extended copulation reflects competition among males, then the duration of mating (after correction for body size) should be greater in mammals in which females mate with more than one male. We tested these predictions using comparative data from 113 mammalian species in 85 genera, 40 families, and 14 orders, while controlling for the effect of phylogeny. We found: (1) the relationship between duration of copulation and body size to be negative, not positive; (2) no relationship with inferred multiple mating by females (based upon relative testes mass). We suggest that small mammals may find the sustained maneuvering and body positioning of copulation easier than do large mammals. This hypothesis is supported by an apparently isometric relationship between duration of copulation and ratio of power to mass.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 185–193.     

Habitat Use of Fox Squirrels in an Urban Environment

Abstract: Tree squirrels are one of the most familiar mammals found in urban areas and are considered both desirable around homes and, conversely, a pest. We examined fox squirrel (Sciurus niger) habitat use in inner city and suburban areas using radiotelemetry. We estimated habitat selection ratios at differing scales by season and fox squirrel activity. Telemetry data suggests that during periods of inactivity radiocollared fox squirrels (n = 82) selected 1) areas with greater tree canopy, 2) live oaks (Quercus fusiromis and Q. virginiana), and 3) trees with larger diameters and canopies. When inactive during the winter and spring, fox squirrels also preferred, within their core areas, to use the inside of buildings, and during periods of activity in the autumn and spring, fox squirrels preferred grassy areas. During periods of activity, fox squirrels avoided using pavement but did not exclude it from their core-area movements. Fox squirrels' ability to use buildings and to tolerate pavement in core-area movements make vast areas of the urban environment available to fox squirrels. In evaluating habitat variables that increased fox squirrel activity in urban areas, we found the number of large and medium trees, amount of pavement and grassy areas, canopy cover, number of oaks, and the area covered by buildings were all important factors in predicting fox squirrel activity in an urban environment. Our data suggests urban planners, animal damage control officials, wildlife managers, and landscapers who want to control urban fox squirrel populations through habitat manipulation should consider the reduction of oaks trees, a reduction of the canopy cover, and restricting the access of fox squirrels to buildings. Alternatively, home owners and squirrel enthusiasts hoping to bolster fox squirrel populations in urban areas should consider increasing the number of large mast—bearing trees and canopy cover and providing nest boxes.     

The Role of Extracellular Ca2+ in the Activation of Pectinaria Oocytes

Several events are associated with fertilization in oocytes. Two such events are an increase in cytoplasmic Ca²⁺ concentration and the resumption of meiosis. Oocytes of the marine annelid, Pectinaria gouldii , are in metaphase I arrest when they are spawned. In this report we investigate the relationship between Ca²⁺ and resumption of meiosis in this species. Meiosis in unfertilized oocytes could be re-initiated with the divalent cation ionophore, A23187. Oocytes in Ca²⁺ free sea water, however, did not resume meiosis in the presence of the ionophore. Furthermore, it was observed that Ca²⁺ must be present for at least 15 min following ionophore treatment for meiosis to resume. These results suggest that extracellular Ca²⁺ is required for the re-initiation of meiosis in this species.     

Isolation of polymorphic microsatellite loci in the Hawaii amakihi (Hemignathus virens) and their use in other honeycreeper species

We report the isolation and characterization of five polymorphic microsatellite loci in the Hawaii amakihi, Hemignathus virens, one of the most common native Hawaiian forest birds. These loci exhibit high levels of allelic diversity and heterozygosity in the three honeycreeper species we screened, and promise to be useful in our investigation of differences between honeycreeper populations at different elevations.