Reproductive Capacity Evolves in Response to Ecology through Common Changes in Cell Number in Hawaiian Drosophila.

Lifetime reproductive capacity is a critical fitness component. In insects, female reproductive capacity is largely determined by the number of ovarioles, the egg-producing subunits of the ovary [e.g., 1]. Recent work has provided insights into ovariole number regulation in Drosophila melanogaster. However, whether mechanisms discovered under laboratory conditions explain evolutionary variation in natural populations is an outstanding question. We investigated potential effects of ecology on the developmental processes underlying ovariole number evolution among Hawaiian Drosophila, a large adaptive radiation wherein the highest and lowest ovariole numbers of the family have evolved within 25 million years. Previous studies proposed that ovariole number correlated with oviposition substrate [2-4] but sampled largely one clade of these flies and were limited by a provisional phylogeny and the available comparative methods. We test this hypothesis by applying phylogenetic modeling to an expanded sampling of ovariole numbers and substrate types and show support for these predictions across all major groups of Hawaiian Drosophila, wherein ovariole number variation is best explained by adaptation to specific substrates. Furthermore, we show that oviposition substrate evolution is linked to changes in the allometric relationship between body size and ovariole number. Finally, we provide evidence that the major changes in ovarian cell number that regulate D. melanogaster ovariole number also regulate ovariole number in Hawaiian drosophilids. Thus, we provide evidence that this remarkable adaptive radiation is linked to evolutionary changes in a key reproductive trait regulated at least partly by variation in the same developmental parameters that operate in the model species D. melanogaster.

Re-annotation of eight Drosophila genomes.

The sequenced genomes of the Drosophila phylogeny are a central resource for comparative work supporting the understanding of the Drosophila melanogaster non-mammalian model system. These have also facilitated evolutionary studies on the selected and random differences that distinguish the thousands of extant species of Drosophila. However, full utility has been hampered by uneven genome annotation. We have generated a large expression profile dataset for nine species of Drosophila and trained a transcriptome assembly approach on D. melanogaster that best matched the extensively curated annotation. We then applied this to the other species to add more than 10000 transcript models per species. We also developed new orthologs to facilitate cross-species comparisons. We validated the new annotation of the distantly related Drosophila grimshawi with an extensive collection of newly sequenced cDNAs. This re-annotation will facilitate understanding both the core commonalities and the species differences in this important group of model organisms, and suggests a strategy for annotating the many forthcoming genomes covering the tree of life.

Genome Sequence of Flavobacterium akiainvivens IK-1T, Isolated from Decaying Wikstroemia oahuensis, an Endemic Hawaiian Shrub.

Flavobacterium spp. have been cultivated from diverse aquatic and terrestrial habitats. F. akiainvivens IK-1(T) was cultivated from decaying wood of Wikstroemia oahuensis, an endemic Hawaiian shrub. The strain's genome sequence may provide insights into niche adaptation and evolution of the genus in a mid-ocean archipelago.

Flavobacterium akiainvivens sp. nov., from decaying wood of Wikstroemia oahuensis, Hawai'i, and emended description of the genus Flavobacterium.

Strain IK-1(T) was isolated from decaying tissues of the shrub Wikstroemia oahuensis collected on O'ahu, Hawai'i. Cells were rods that stained Gram-negative. Gliding motility was not observed. The strain was oxidase-negative and catalase-positive. Zeaxanthin was the major carotenoid. Flexirubin-type pigments were not detected. The most abundant fatty acids in whole cells of IK-1(T) grown on R2A were iso-C(15:0) and one or both of C(16:1)ω7c and C(16:1)ω6c. Based on comparisons of the nucleotide sequence of the 16S rRNA gene, the closest neighbouring type strains were Flavobacterium rivuli WB 3.3-2(T) and Flavobacterium subsaxonicum WB 4.1-42(T), with which IK-1(T) shares 93.84 and 93.67% identity, respectively. The G+C content of the genomic DNA was 44.2 mol%. On the basis of distance from its nearest phylogenetic neighbours and phenotypic differences, the species Flavobacterium akiainvivens sp. nov. is proposed to accommodate strain IK-1(T) ( =ATCC BAA-2412(T) =CIP 110358(T)) as the type strain. The description of the genus Flavobacterium is emended to reflect the DNA G+C contents of Flavobacterium akiainvivens IK-1(T) and other species of the genus Flavobacterium described since the original description of the genus.

Sperm attractant in the micropyle region of fish and insect eggs.

In some animals, such as fish, insects, and cephalopods, the thick egg coat has a narrow canal-a micropyle-through which spermatozoa enter the eggs. In fish, there is no indication that spermatozoa are attracted by eggs from a distance, but once spermatozoa come near the outer opening of the micropyle, they exhibit directed movement toward it, suggesting that a substance exists in this defined region to attract spermatozoa. Since Coomassie Blue (CB) binds preferentially to the micropyle region in flounder, herring, steelhead, and other fish, it probably stains this sperm guidance substance. This substance-a glycoprotein based on lectin staining-is bound tightly to the surface of the chorion, but can be removed readily by protease treatment. Although fertilization in fish (flounder) is possible after removal of this substance, its absence makes fertilization inefficient, as reflected by a drastic reduction in fertilization rate. The sperm "attraction" to the micropyle opening is species specific and is dependent on extracellular Ca(2+). Eggs of some insects, including Drosophila, have distinct micropyle caps with CB affinity, which also may prove to assist sperm entry. Our attempts to fertilize fly eggs in vitro were not successful.

Integration of wireless sensor networks into cyberinfrastructure for monitoring Hawaiian "mountain-to-sea" environments.

Monitoring the complex environmental relationships and feedbacks of ecosystems on catchment (or mountain)-to-sea scales is essential for social systems to effectively deal with the escalating impacts of expanding human populations globally on watersheds. However, synthesis of emerging technologies into a robust observing platform for the monitoring of coupled human-natural environments on extended spatial scales has been slow to develop. For this purpose, the authors produced a new cyberinfrastructure for environmental monitoring which successfully merged the use of wireless sensor technologies, grid computing with three-dimensional (3D) geospatial data visualization/exploration, and a secured internet portal user interface, into a working prototype for monitoring mountain-to-sea environments in the high Hawaiian Islands. A use-case example is described in which native Hawaiian residents of Waipa Valley (Kauai) utilized the technology to monitor the effects of regional weather variation on surface water quality/quantity response, to better understand their local hydrologic cycle, monitor agricultural water use, and mitigate the effects of lowland flooding.

A database of wing diversity in the Hawaiian Drosophila.

BACKGROUND: Within genus Drosophila, the endemic Hawaiian species offer some of the most dramatic examples of morphological and behavioral evolution. The advent of the Drosophila grimshawi genome sequence permits genes of interest to be readily cloned from any of the hundreds of species of Hawaiian Drosophila, offering a powerful comparative approach to defining molecular mechanisms of species evolution. A key step in this process is to survey the Hawaiian flies for characters whose variation can be associated with specific candidate genes. The wings provide an attractive target for such studies: Wings are essentially two dimensional, and genes controlling wing shape, vein specification, pigment production, and pigment pattern evolution have all been identified in Drosophila. METHODOLOGY/PRINCIPAL FINDINGS: We present a photographic database of over 180 mounted, adult wings from 73 species of Hawaiian Drosophila. The image collection, available at FlyBase.org, includes 53 of the 112 known species of "picture wing" Drosophila, and several species from each of the other major Hawaiian groups, including the modified mouthparts, modified tarsus, antopocerus, and haleakalae (fungus feeder) groups. Direct image comparisons show that major wing shape changes can occur even between closely related species, and that pigment pattern elements can vary independently of each other. Among the 30 species closest to grimshawi, diverse visual effects are achieved by altering a basic pattern of seven wing spots. Finally, we document major pattern variations within species, which appear to result from reduced diffusion of pigment precursors through the wing blade. CONCLUSIONS/SIGNIFICANCE: The database highlights the striking variation in size, shape, venation, and pigmentation in Hawaiian Drosophila, despite their generally low levels of DNA sequence divergence. In several independent lineages, highly complex patterns are derived from simple ones. These lineages offer a promising model system to study the evolution of complexity.

Evolution of sexual dimorphism in the olfactory brain of Hawaiian Drosophila.

In the fruitfly, Drosophila melanogaster, mate choice during courtship depends on detecting olfactory cues, sex pheromones, which are initially processed in the antennal lobe (AL), a primary olfactory centre of the brain. However, no sexual differences in the structure of the AL have been found in Drosophila. We compared the central brain anatomy of 37 species of Drosophilidae from the islands of the Hawaiian archipelago, uncovering an extreme sexual dimorphism within the AL in which two out of the 51 identifiable glomeruli were markedly enlarged in males. A phylogeny indicated that the sexual dimorphism of the homologous glomeruli arose 0.4-1.9 Myr ago independently in two species groups of Hawaiian endemic Drosophilidae. The corresponding glomeruli in D. melanogaster were also found to be sexually dimorphic. The formation of glomeruli of male size is prevented by the ectopic expression of female-type transformer (tra) cDNA in males, indicating that the glomerular sexual dimorphism is under the control of the sex-determination cascade of genes. It is suggested that a defined set of glomeruli in Drosophila can enlarge in response to sex-determination genetic signals, the mutations of which may result in species differences in sexual dimorphism of the brain.

INTERSEXUAL SELECTION IN THE MEDITERRANEAN FRUIT FLY: DOES FEMALE CHOICE ENHANCE FITNESS?

Adaptive hypotheses of female choice predict that females use male courtship displays as an indicator of male quality. A test of whether female choice is adaptive measuring direct and indirect effects of mate choice on females was made using a laboratory population of a lek-mating species, the Mediterranean fruit fly. The nonrandom mating observed in this species is thought to be strongly influenced by female choice. Whether female choice acts to increase fecundity or offspring quality was assessed using two different statistical tests. Multiple regression showed that females generally do not receive direct benefits as a result of mating with males which are successful in copulating with many females. However, in one trial the relationship between male quality and female benefit was nonlinear. Females which mate with males that obtain few matings (<2), and females which mate with males that obtain many matings (>6) enjoy increased fecundity. Mate choice does not, however, appear to enhance offspring quality as father/son correlation and sibling analysis showed no heritable component to male copulatory success.

CHEMICAL COMMUNICATION IN HAWAIIAN DROSOPHILA.

We are interested in elucidating the extent to which lekking Hawaiian Drosophila species have diverged from their continental counterparts, which engage in sexual behavior at communal food sources, with regard to the chemical communication systems that the flies employ. Accordingly, we have analyzed flies from three closely related Hawaiian Drosophila species in the adiastola subgroup. These species are of interest because the males engage in a unique behavior: while courting, they raise their abdomens over their heads and emit anal droplets. Analysis of the flies' behavior, the hydrocarbons in males' anal droplets, and males' cuticular hydrocarbons suggest that females' responses to males may be mediated by cuticular pheromones and/or pheromones in males' extruded droplets that enable the females to distinguish conspecific from heterospeciflc males. Conversely, perception of cuticular hydrocarbons from conspecific females enables D. adiastola males to distinguish females from a closely related species from conspecific females. On the basis of these observations, we suggest that the adiastola subgroup species are unique among drosophilids in that they utilize an anal droplet-mediated pheromone communication system, some or all components of which are species specific. However, the lekking Hawaiian Drosophila species are similar to D. melanogaster and related continental species in that the Hawaiian flies employ a cuticular pheromone communication system, some components of which are sex and species-specific.