Water inputs across a tropical montane landscape in Veracruz,Mexico: synergistic effects of land cover,rain and fog seasonality,and interannual precipitation variability

Land‐cover change can alter the spatiotemporal distribution of water inputs to mountain ecosystems, an important control on land‐surface and land‐atmosphere hydrologic fluxes. In eastern Mexico, we examined the influence of three widespread land‐cover types, montane cloud forest, coffee agroforestry, and cleared areas, on total and net water inputs to soil. Stand structural characteristics, as well as rain, fog, stemflow, and throughfall (water that falls through the canopy) water fluxes were measured across 11 sites during wet and dry seasons from 2005 to 2008. Land‐cover type had a significant effect on annual and seasonal net throughfall (NTF <0=canopy water retention plus canopy evaporation; NTF >0=fog water deposition). Forest canopies retained and/or lost to evaporation (i.e. NTF<0) five‐ to 11‐fold more water than coffee agroforests. Moreover, stemflow was fourfold higher under coffee shade than forest trees. Precipitation seasonality and phenological patterns determined the magnitude of these land‐cover differences, as well as their implications for the hydrologic cycle. Significant negative relationships were found between NTF and tree leaf area index (R²=0.38, P<0.002), NTF and stand basal area (R²=0.664, P<0.002), and stemflow and epiphyte loading (R²=0.414, P<0.001). These findings indicate that leaf and epiphyte surface area reductions associated with forest conversion decrease canopy water retention/evaporation, thereby increasing throughfall and stemflow inputs to soil. Interannual precipitation variability also altered patterns of water redistribution across this landscape. Storms and hurricanes resulted in little difference in forest‐coffee wet season NTF, while El Niño Southern Oscillation was associated with a twofold increase in dry season rain and fog throughfall water deposition. In montane headwater regions, changes in water delivery to canopies and soils may affect infiltration, runoff, and evapotranspiration, with implications for provisioning (e.g. water supply) and regulating (e.g. flood mitigation) ecosystem services.     

COMPARISON OF THE OSMOTIC VOLUME CHANGES IN CHLOROPLASTS ISOLATED FROM DIFFERENT PLANTS

Chloroplasts were isolated from leaves of four plant species(spinach, New. Zealand spinach, Swiss Chard and tomato) andtheir osmotic behaviour was compared. Maximal contraction ofchloroplasts from all plant sources occurred at 0.3–0.4M sucrose. The volume of the particles at this sucrose concentrationwas also similar in all cases; 300 mm³ per 10¹⁰ chloroplasts.At higher and lower sucrose concentrations, the chloroplastsswell. The degree of swelling, especially in higher sucroseconcentrations, differed in chloroplasts from different sources.Tomato chloroplasts are most sensitive, and the spinach chloroplastsare the most resistant to all types of treatment. Tomato chloroplastsrequire rather high phosphate concentrations for good preservation. Changes in optical density at 520 mµ can be used to geta rough idea about the condition of the particles. (Received February 7, 1966; )     

The effect of salinity in the growth medium on carbohydrate metabolism in pea root tips

The effect of chloride and sulphate types of salinity on respiratorymechanism of pea roots was studied. Both types of salinity depressedthe absorption of external glucose and the rate of respirationand changed the relative part of the metabolic pathways. Thepercentage of the pentosephosphate pathway was increased byincreasing levels of NaCl salinity while NaaSOi salinity practicallydid not affect it. Chloride salinity depressed CO₂ evolutionfrom C-6 but did not affect the CO₂ evolution from C-1. Sulphatesalinity depressed both. Most of the glycolytic enzymes studiedwere depressed in roots grown in saline medium except glucosephosphateisomerase which was not affected by sulphate salinity but wasincreased more than ten fold by chloride salinity. Phosphogluconatedehydrogenase was not affected by salinity. Glucose-6-phosphatedehydrogenase was found in the mitochondria as well as in thesupernatant and both the mitochondrial and the supernatant enzymeswere active with NADP and NAD. Salinity of both types increasedthe NADP linked activity in the soluble fraction. The informationgained however is still not sufficient to explain adequatelythe effect of salinity on plant metabolism. (Received July 31, 1967; )     

ADENOSINE TRIPHOSPHATASE ACTIVITY IN GERMINATING LETTUCE SEEDS

Mitochondria isolated from lettuce seeds and seedlings are capableof hydrolyzing ATP. On basis of pH optima, there are at leasttwo and probably three enzymes possessing ATPase activity. Oneof them is inhibited by EDTA and all of them are inhibited byNaF. The ATP ase activity of the mitochondria is very slight in imbibedseeds but increases considerably with seedling growth. Othercomponents of the cell also contain ATP hydrolyzing enzymes;however, most of these phosphatases in the seedling seem tobe soluble enzymes. (Received December 12, 1961; )     

Five polymorphic microsatellite markers for the study of Cardiocondyla elegans (Hymenoptera: Myrmicinae)

We describe primer sequences for five microsatellite markers in Cardiocondyla elegans, an ant species with ergatoid males. Polymorphism of these loci was investigated using 236 individuals from 22 colonies from four locations. The microsatellites are dinucleotide repeats with four to 16 alleles, and the observed heterozygosity ranges from 0.244 to 0.720. We characterized these markers for the study of the population as well as the social structure of colonies.     

The effect of suspended sediments on Lake Texoma Daphnia: field distributions and in situ incubations

1. We measured the abundance and eggs per female of four Daphnia species in turbid and relatively clear regions of Lake Texoma (Oklahoma‐Texas, U.S.A.) on 12 dates over the course of 5 years. 2. Two species, Daphnia lumholtzi and Daphnia parvula, occurred and reproduced in turbid locations, but two other species, Daphnia mendotae and Daphnia pulicaria, occurred almost exclusively in relatively clear conditions. 3. To test the hypothesis that interference with foraging excludes clear‐water Daphnia species from turbid locations, we incubated adult D. mendotae at both a clear and a turbid site. In three successive experiments D. mendotae individuals incubated at the turbid site carried as many or more eggs than individuals incubated at the clear site.     

New highlights about the enigmatic marine snake Palaeophis maghrebianus (Palaeophiidae; Palaeophiinae) from the Ypresian (Lower Eocene) phosphates of Morocco

Abstract: Palaeophis maghrebianus belongs to the Palaeophiinae (Palaeophiidae). This snake subfamily is relatively poorly known, and it is mainly represented by disarticulated vertebrae and ribs and by a few vertebral segments. Its intracolumnar variability remains also poorly understood. The discovery of new isolated vertebrae and vertebral segments of Palaeophis maghrebianus in the Ypresian (Lower Eocene) Phosphates of Morocco enables us to provide a more detailed diagnosis of this species and to describe its intracolumnar variability. Moreover, the new material reveals that this species could reach gigantic size being, with Palaeophis colossaeus, one of the two longer palaeophiids. The microanatomical and histological analysis of some vertebrae illustrating diverse positions along the vertebral column reveals the presence of osteosclerosis, especially in the anterior and mid‐precloacal regions. The occurrence of this osseous specialization implies a role in buoyancy and body trim control in this taxon, which is considered a shallow marine dweller based on its anatomical features and geological data. Palaeophis maghrebianus also displays a dense vascular network suggesting a growth speed, and thus a metabolic rate, much higher than in the biggest extant snakes.     

Microsatellites loci isolated in the freshwater fish Brycon hilarii

We describe seven microsatellite loci, including tetra‐, tri‐ and dinucleotides, isolated from Brycon hilarii, which is a migratory fish inhabiting the Paraguay River basin (Brazil) and is highly valued for its meat quality. Three to eight alleles per locus were detected and the expected heterozygosity ranged from 0.31 to 0.81. Positive results were obtained with cross‐amplification in five other species of Brycon. These microsatellites provide a potential tool for wild population and aquaculture studies of B. hilarii and other species of the genus.     

Predators marked with chemical cues from one prey have increased attack success on another prey species

1. To reduce the risk of being eaten by predators, prey alter their morphology or behaviour. This response can be tuned to the current danger if chemical or other cues associated with predators inform the prey about the risks involved. 2. It is well known that various prey species discriminate between chemical cues from predators that fed on conspecific prey and those that fed on heterospecific prey, and react stronger to the first. It is therefore expected that generalist predators are more successful in capturing a given prey species when they are contaminated with chemical cues from another prey species instead of cues from the same prey species. 3. Here, a generalist predatory mite was studied that feeds on thrips larvae as well as on whitefly eggs and crawlers. Mites were marked with cues (i.e. body fluids) of one of these two prey species and were subsequently offered thrips larva. 4. Predators marked with thrips cues killed significantly fewer thrips than predators marked with whitefly cues, even though the predator's tendency to attack was the same. In addition, more thrips larvae sought refuge in the presence of a predatory mite marked with thrips cues instead of whitefly cues. 5. This suggests that generalist predators may experience improved attack success when switching prey species.     

Host preferences in a phonotactic parasitoid of field crickets: the relative importance of host song characters

Abstract.  1. Predators, including insect parasitoids, often eavesdrop on prey signals, and as a result, predation can have important effects on the evolution of prey signalling behaviour.
2. The phonotactic parasitoid fly, Ormia ochracea , uses the calling songs of male field crickets to locate their field crickets hosts. In the western USA, this fly parasitises the variable field cricket, Gryllus lineaticeps . Previous work with one fly population suggested that female flies, like female field crickets, preferentially orient to male songs with higher chirp rates and longer chirp durations, although a limited range of male song types was used in this previous study. The current study, with a different fly population, used field-based, two-speaker choice tests to examine: (1) the effect of male chirp rate and chirp duration on fly attraction, using a natural range of song types; and (2) the relative importance of these song types in host selection by the flies.
3. Three lines of evidence suggested that chirp rate is more important than chirp duration in host selection. (a) The flies consistently preferred higher chirp rates but only sometimes preferred longer chirp durations. (b) The flies consistently preferred higher chirp rate/shorter chirp duration songs to lower chirp rate/longer chirp duration songs. (c) Preferences for longer chirp durations could be eliminated by increasing the amplitude of the less attractive song type, while preferences for higher chirp rates could only sometimes be eliminated by increasing the amplitude of the less attractive song type.
4. Fly predation may favour lower chirp rates and shorter chirp durations in G. lineaticeps , and may have resulted in stronger selection on chirp rate than on chirp duration.