Evidence for asymmetric migration load in a pair of ecologically divergent stickleback populations

Gene flow between ecologically divergent populations can prevent local adaptation, resulting in lower mean fitness and directional selection within a population. Such maladaptation should tend to be stronger in populations receiving a relatively larger fraction of immigrants. We test this expectation by comparing the strength of selection in a pair of three-spine stickleback populations in adjoining but unequal-sized lake basins in British Columbia. A larger deeper basin is connected to a smaller shallower basin by a short channel that allows extensive migration between populations. The two basins contain distinct habitats and prey communities, and stickleback stomach contents and isotope ratios differ accordingly. Trophic morphology is correlated with diet, so we would expect these ecological differences to be accompanied by morphological divergence. However, high gene flow appears to constrain adaptive divergence: microsatellites indicate that the two basins represent a single panmictic gene pool, and phenotypic divergence is very subtle. As a result, fish in the smaller lake basin are subject to persistent directional selection towards a more benthic phenotype, whereas the larger population exhibits no significant selection. The results illustrate the potentially asymmetrical effect of migration-selection balance, and its effect on fitness within populations.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 273–287.     

Eight polymorphic microsatellite markers for kelp bass,Paralabax clathratus,amplified in three multiplex polymerase chain reaction sets

Kelp bass, Paralabrax clathratus, is an important sport fishery of California, USA and Baja, Mexico. Here we describe eight microsatellite loci developed for this species. Two loci were derived from known primers for other species in the family, Serranidae and six were developed anew using a clone enrichment protocol. Loci were arranged into three multiplex PCR (polymerase chain reaction) sets for fast throughput; 564 individuals from nine populations across the species’ range were genotyped. Polymorphism ranged from four to 47 alleles and all populations at all loci displayed Hardy–Weinberg and linkage equilibrium.     

Effects of illumination source, culture ventilation and sucrose on potato (Solanum tuberosum) microtuber production under short days

The culture yield of a simple method of microtuber production of potato was increased by assessing the interactions of illumination source (Thorn Lighting (Philips) “Colour 84” lamps (TL‐84) or Grolux lamps (Sylvania) in a conventional growth room or natural light in a glasshouse cabinet), type of vessel closure (unventilated or ventilated) and sucrose concentration (1%, 2%, 4% or 8%). Microtuber initiation and growth in unventilated cultures was 100% at 8% sucrose falling to 40–50% at 4% sucrose and was absent at 1% or 2%. With ventilation, rapid tuberisation (90–100%) occurred at initial sucrose concentrations of 2–8%, but only when the medium was allowed to dry before transfer of cultures to short days. Water supplementation of cultures at day 28 prevented tuberisation at 1–4% sucrose up to day 56. The fresh weight and dry weight of microtubers per plant increased significantly with sucrose concentration, with ventilation of cultures and under natural light. In ventilated cultures, the mean number of usable microtubers (± 0.1 g weight) increased from between 1.0–1.4 per plant at 8% sucrose to between 1.6–2.6 per plant at 4% sucrose, with the highest numbers (1.8–2.6 per plant) produced under natural light for the cvs Desirée and King Edward. The mean % dry matter content of microtubers was reduced to 11.3% at 4% sucrose compared with 17.3% at 8% sucrose, but the survival rate of microtubers after 6 months storage was unaffected. Microtuber production under short days was improved at a higher intensity of natural light with culture ventilation in a partially‐shaded glasshouse cabinet, whilst using reduced inputs (lower sucrose supply and no lamps).     

Biomass, reproductive output, and physiological responses of rapid-cycling Brassica (Brassica rapa) to ozone and modified root temperature

Brassica rapa L. (rapid-cycling Brassica), was grown in environmentally controlled chambers to determine the interactive effects of ozone (O₃) and increased root temperature (RT) on biomass, reproductive output, and photosynthesis. Plants were grown with or without an average treatment of 63 ppb O₃. RT treatments were 13°C (LRT) and 18°C (HRT). Air temperatures were 25°C/15°C day/night for all RT treatments.
Ozone affected plant biomass more than did root temperature. Plants in O₃ had significantly smaller total plant d. wt, shoot weight, leaf weight, leaf area and leaf number than plants grown without O₃. LRT plants tended to have slightly smaller total plant d. wt, shoot weight, root weight, leaf weight, leaf area, and leaf number than HRT plants. For all variables, LRT plants grown in O₃ had the smallest biomass, and plants grown in HRT without O₃ had the largest biomass.
Ozone reduced both fruit weight and fruit number; LRT also reduced fruit weight but had no effect on fruit number. Ozone reduced photosynthesis but RT had no effect. Conductance and internal CO₂ were unaffected by O₃ or RT.
These studies indicate that plant growth with LRT might be more reduced in the presence of O₃ than growth in plants with HRT, which might be able to compensate for O₃-caused reductions in photosynthesis to avoid decreased biomass and reproductive output.     

Development of Organized Structures in Callus Derived from Explants of Cocos nucifera L.

Clonal propagation of the coconut palm was attempted using tissueculture. Callus initiated from slices of seedling stem and fromthe rachillae of young inflorescences was maintained on agarmedium containing 2,4-D at 10^–4 M. Reduction of the 2,4-Dconcentration over several sub-cultures resulted in the developmentof nodular structures that resemble some of the stages in thedevelopment of the zygotic embryo. Cocos nucifera L., coconut palm, callus, organogenesis, embryogenesis, clonal propagation     

Eradication of Feral Pigs From Pinnacles National Monument

Abstract: Feral pigs (Sus scrofa) have caused considerable damage where they have been introduced around the world. At Pinnacles National Monument, California, USA, managers were concerned that feral pigs were damaging wetland habitats, reducing oak regeneration, competing with native wildlife, and dispersing nonnative plant species through soil disturbance. To address these threats the National Park Service constructed an exclosure around 57 km² of monument land and through cooperation with the Institute for Wildlife Studies eradicated all feral pigs within the area. Trapping, ground-hunting, hunting dogs, and Judas techniques were used to remove feral pigs. Trapping techniques removed most pigs, but a combination of techniques was required to cause eradication. A series of bait sites and transects across the monument helped focus removal efforts and facilitated detection of the last remaining feral pigs in the exclosure. Consistent funding and cooperation from the National Park Service allowed for a seamless and comprehensive program that provided intensive removal of feral pigs. The successful eradication of feral pigs at Pinnacles National Monument should encourage managers in other areas to implement future control or eradication programs.     

Systematics and Ecology of Shell-Boring Polychaetes from New England

In a survey of shell-boring polychaeles of New England, representativesof five families were found: Spionidae, Cirratulidae, Capitellidae,Terebellidae, and Sabellidae. The five spionid species were studied extensively. These includePolydora commensalis Andrews, found only in shells occupiedby hermit crabs, P. concharum Verrill, P. socialis (Schmarda), P. websleri Hartman, and Boccardia hamata (Webster) , foundin various types of shell. Breeding periods were defined andthe larval development described for each species. Polydoraconcharum deposits egg capsules inwinter months, while the oilierpolydorids spawn in spring or summer. Morphology of planktoniclarvae is distinct in each species, although P. websteri larvaemay be confused with non-boring species such as P. ligni Webster.Polydora socialis adults are found in both shells and sedimentand have a unique grinding apparatus, a gizzard, between theesophagus and intestine. The cirratulid, Dodecaceria sp., follows an asexual mode ofreproduction. The syslematics of Dodecaceria is complex owingto multiple modes of reproduction. No sexually mature individualswere observed during the course of this study. Asexual budswerefound in the Fall. A sabellid, Pseudopolamilla reniformis (Miiller), is commonlyfound in theshells of Placopeclen magellanicits (Gmelin) inMaine waters. Its reproductionis unknown.     

Pale biological implications of some Upper Ordovician juvenile asteroids (Echinodermata)

Blake, D. B. 1990 10 15: Pale biological implications of some Upper Ordovician juvenile asteroids (Echinodermata). Lethaia , Vol. 23, pp. 347–357. Oslo. ISSN 0024–1164.
Two patterns have been recognized in the early dorsal skeletal development of modern asteroids. The skeleton of well-preserved juveniles of the Late Ordovician species Promopalaeaster finei is similar in fundamental ossiclar arrangement to one of these patterns, suggesting continuity of developmental sequence. Similarities include presence of large terminal ossicles and double rows of marginal ossicles. Ancient and modern juveniles differ in that in P. finei , podial pores leading to the interior of the arms are lacking, thus providing an ontogenetic argument that such pores are phylogenetically derived within the class. An unpaired interbrachial marginal, or axillary, is present distal to the oral frame; positioning supports earlier suggestions that the axillary is the homologue of the odontophore ossicle of modern asteroids. Comparisons between P. finei and another Ordovician species, Macroporaster matutinus , suggest the need for greater mouth frame flexibility contributed to the evolution of the modern odontophore. Axillary development is linked to the common absence of actinal ossicles from Paleozoic species. ▭ Asteroidea, Echinodermata, functional morphology, ontogeny, phylogeny, Ordovician, Paleozoic .     

Predation by the Ordovician asteroid Promopalaeaster on a pelecypod

Blake, D.B. & Guensburg, T.E. 1994 10 15: Predation by the Ordovician asteroid Promopalaeaster on a pelecypod. An Ordovician Prornopalaeaster (Echinodermata: Asteroidea) wrapped about a Cuneamya? (Mol-lusca: Pelecypoda) in the extraoral feeding posture characteristic of Jurassic to modern members of the Asteriidae documents an early origin for this behavioral complex. Modern asteriids are convergent on Promopalaeastet; there is no direct phylogenetic linkage between the two. This fossil occurrence, combined with the success of modem Asteriidae, demonstrates that biological evolution and geological change need not outmode complex life habits. The fossil supports the notion of asteroids as Paleozoic-type predators, and its existence suggests that asteroids were not significant contributors to changing faunal structures in shelf seas during the Phanerozoic. Asteroidea, Pelecypoda, functional morphology, evolutionary ecology.