Search Results - (Author, Cooperation:J. S. Johnston)

2014-05-17

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; *Ceanothus ; Gene Frequency ; *Genetic Speciation ; Genetic Variation ; *Genome, Insect ; Herbivory ; Insects/classification/*genetics ; Phylogeny ; *Selection, Genetic

2015-05-16

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Amino-Acid N-Acetyltransferase ; Animals ; Bees/classification/*genetics ; DNA Transposable Elements ; *Evolution, Molecular ; Gene Expression Regulation ; Gene Regulatory Networks ; *Genetic Drift ; Genome, Insect/genetics ; Phylogeny ; Selection, Genetic ; *Social Behavior ; Transcription Factors/chemistry/genetics ; *Transcriptome

1432-1939

Springer Online Journal Archives 1860-2000

Biology

Summary In the Hawaiian species, Drosophila mimica, it was necessary to determine the dispersal pattern in order to interpret genetic heterogeneity observed in the population. In addition, the pattern of colonization and speciation in the Drosophila community may have been affected by the dispersal behavior and response to infrequent conditions of environmental factors which would encourage sporadic movement. It was not possible in this experiment to measure such behavior directly, but predictions are possible. Dispersal patterns are formulated in terms of component behavioral responses to particular environmental cues. Under appropriate field measurements, the relationship of behavior patterns of D. mimica to air movement, light, humidity, and food substrate were sufficient to interpret a complex dispersal pattern in the field. Predictions were made for other movement patterns over longer distances and with infrequent occurrence. Present results are explainable by the response of D. mimica to low velocity air currents. Flies move into the current at velocities less than about 3.3 km/hr, and this response is consistent with field observations of insect and air movements. Visible light intensities from more than 10 to about 100 lux were most acceptable to this species, and movement was restricted to light periods. Based upon responses of D. mimica to wind, light, humidity, and attractive areas, long range dispersal would likely occur between two habitats when each had suitable food substrates, the weather was very humid, overcast, and when there was a slight air current between the habitats. Movement would be unidirectional only if air current patterns were stable. The most precise navigation would be at air current velocities below 3.3 km/hr, where olfactory orientation on the substrate in the new habitat would be possible and short flights would be upwind. However, longer range movements would be possible downwind at slightly higher velocities. Genetic data on D. mimica has been interpreted to reflect differences in selection between at least moderately isolated habitats. Our results indicate that, instead of isolated populations, these habitats contain populations that are part of a single deme with sporadic mixing. Genetic heterogeneity may temporarily result from intense localized selection pressure between periods of mixing. Furthermore, the presence of several sibling species (some undescribed) in Kipuka Puaulu and in several neighboring areas clearly illustrates the fragmentation of gene pools and the genetic differentiation which is possible. Since D. mimica might move from one kipuka to another, spatial isolation is unlikely to play a major role in speciation, whereas habitat selection and ethological isolation may be the principal mechanisms of speciation.

Electronic Resource

1432-1939

Springer Online Journal Archives 1860-2000

Biology

Summary TheDrosophila community of Kipuka Puaulu, Hawaii Volcanoes National Park, was studied by field measurements and laboratory experiments. Phototactic responses were related to oviposition substrates forD. mimica andD. imparisetae, and were shown to reinforce substrate attractiveness. Both species were associated with rottingSapindus fruit, butD. imparisetae, less light tolerant thanD. mimica, was found in deeper shade. Individuals of a third species,D. kambysellisi, were strongly attracted to substratePisonia leaves. The attraction was strong enough to override strong positive phototaxis. The significance of this behavior was related to the adaptive strategy of the species. The sibling species,D. mimica andD. kambysellisi, utilized different substrates and were strongly separated spatially. Differences in substrates and mobility were related to the “grain size” of their environment. Males ofD. kambysellisi andD. imparisetae are located in leking sites above their respective females during the day. This behavior parallels the relatively greater light tolerance of males than of females. The same light response dimorphism inD. mimica is not accompanied by leking behavior, since they mate at night or in greatly subdued light.

Electronic Resource

1432-1939

Springer Online Journal Archives 1860-2000

Biology

Summary TheDrosophila community of Kipuka Puaulu, Hawaii Volcanoes National Park, was studied by field measurements and laboratory experiments. Phototactic responses were related to oviposition substrates forD. mimica andD. imparisetae, and were shown to reinforce substrate attractiveness. Both species were associated with rottingSapindus fruit, butD. imparisetae, less light tolerant thanD. mimica, was found in deeper shade. Individuals of a third species,D. kambysellisi, were strongly attracted to substratePisonia leaves. The attraction was strong enough to override strong positive phototaxis. The significance of this behavior was related to the adaptive strategy of the species. The sibling species,D. mimica andD. kambysellisi, utilized different substrates and were strongly separated spatially. Differences in substrates and mobility were related to the “grain size” of their environment. Males ofD. kambysellisi andD. imparisetae are located in leking sites above their respective females during the day. This behavior parallels the relatively greater light tolerance of males than of females. The same light response dimorphism inD. mimica is not accompanied by leking behavior, since they mate at night or in greatly subdued light.

Electronic Resource

1573-6849

aneuploidy ; DNA content ; inversion ; translocation

Springer Online Journal Archives 1860-2000

Biology

Abstract Haplopappus gracilis (n=2),Haplopappus revenil (n=4), andHaplopappus wigginsii (n=4) are isolated by F1 hybrid sterility due mainly to translocation heterozygosity. There is no evidence that this can be overcome at the diploid level so that introgression can occur among them. They are also separated geographically, but occasional populations ofH. gracilis andH. ravenil may be brought together along roadways to form sterile hybrids. There were no statistically significant differences in nuclear DNA content among the same or structurally different aneuploidn=2 andn=3 chromosome races or ecotypes ofH. gracilis. Some of theH. gracilis races were not significantly different from one race of the ancestralH. ravenii, and these samples of both species were from plants growing on poor soils in contrast to accessions from normal habitats. How much and which classes of DNA in these species are subject to changes induced by environmental effects is not known. There were no correlations between DNA amounts and altitude, latitude, and longitude.H. wigginsii had a greater amount of DNA per nucleus than eitherH. ravenii orH. gracilis, and its increased DNA content may reflect a more rapid accumulation of noncoding sequences due to facultative self-compatibility not found in the other two species.

Electronic Resource

1741-2765

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract To record forces of up to 1500 Ib in the experimental cutting of branches from trees in the forest, a completely portable device was built using a ring as sensing element and mechanical amplification to obtain a full-scale chart deflection of over one inch.

Electronic Resource