Color Polymorphism in Spiny Spiders (Gasteracantha fornicata): Testing the Adaptive Significance of a Geographically Clinal Lure

Many sit‐and‐wait predators use conspicuous displays of color to attract prey. These displays sometimes express discrete polymorphisms; however, the adaptive drivers of such variation are not well understood. Here, we explore a previously unknown color polymorphism in the orb‐web spider Gasteracantha fornicata. We discovered that in North Queensland, Australia, female spiders exhibit dorsal bands appearing (to the human observer) either white or yellow and characterized by sigmoidal spectral curves centered on approx. 447 and 496 nm, respectively. Based on sensory drive theory, we hypothesized that morphs may be alternatively favored by the switch in ambient viewing conditions engendered by sunny vs. cloudy skies. We addressed this hypothesis indirectly by studying morph frequencies across a approx. 200 km geographic gradient of solar exposure (a surrogate for cloudiness), and by investigating the phenotypic signature of catch success via a resource stress experiment and in wild spiders. Our data indicate substantial geographic variation in morph frequency, with white morphs dominating at more cloudy northern locations. Rather than a gradual cline, morph frequency inverted mid‐way along this range and was closely fit by a logistic relationship with latitude. Experimentally restricted access to larger prey caused spiders to lose more mass than size and to exhibit less bright dorsal markings. Wild‐sampled spiders from two localities of divergent morph frequency indicated no differences in residual mass, but intriguingly, the white morph was larger and heavier (than the yellow morph) where it was relatively rare. Our data hint at negative frequency dependence, but remain broadly consistent with a sensory drive explanation based on cloudiness, and we suggest these as worthy avenues for closer investigation.     

Disordered Sleep and Myopia Risk among Chinese Children

Purpose

Disordered sleep and myopia are increasingly prevalent among Chinese children. Similar pathways may be involved in regulation of both sleep cycles and eye growth. We therefore sought to examine the association between disordered sleep and myopia in this group.

Methods

Urban primary school children participating in a clinical trial on myopia and outdoor activity underwent automated cycloplegic refraction with subjective refinement. Parents answered questions about children''s sleep duration, sleep disorders (Children''s Sleep Habits Questionnaire [CSHQ]), near work and time spent outdoors.

Results

Among 1970 children, 1902 (96.5%, mean [standard deviation SD] age 9.80 [0.44] years, 53.1% boys) completed refraction and questionnaires. Myopia < = -0.50 Diopters was present in both eyes of 588 (30.9%) children (1329/3804 = 34.9% of eyes) and 1129 children (59.4%) had abnormal CSHQ scores (> 41). In logistic regression models by eye, odds of myopia < = -0.50D increased with worse CSHQ score (Odds Ratio [OR] 1.01 per point, 95% Confidence Interval [CI] [1.001, 1.02], P = 0.014) and more night-time sleep (OR 1.02, 95% CI [1.01, 1.04, P = 0.002], while male sex (OR 0.82, 95% CI [0.70, 0.95], P = 0.008) and time outdoors (OR = 0.97, 95% CI [0.95, 0.99], P = 0.011) were associated with less myopia. The association between sleep duration and myopia was not significant (p = 0.199) for total (night + midday) sleep.

Conclusions

Myopia and disordered sleep were both common in this cohort, but we did not find consistent evidence for an association between the two.

Trial Registration

clinicaltrials.gov NCT00848900     

Lipid and reproductive cycles of bluegills (Lepomis macrochirus) exposed to 35 years of elevated environmental temperatures

1. We studied bluegills to compare how thermal perturbation affected lipid dynamics and reproductive cycles of fish from heated (Pond C) and normothermic (Par Pond) sites.

2. Bodies of bluegills contained over 90%, and gonads and livers 10% of the non-polar lipids.

3.Overall, the percent body lipids of bluegills from the heated pond was twice as high (12.4%) as that of Par Pond bluegills (6.6%).

4. During a prolonged reactor down period, when both ponds were normothermic, body lipids of bluegills from Pond C and Par Pond increased at a rate of approximately 3 and 1% of body mass per week, respectively.

5. Juveniles from Pond C had higher percent stored lipids than did adult males or females.

6. Lipid cycling in Par Pond bluegills was seasonal, whereas Pond C bluegill lipid cycles corresponded to long reactor down periods.     

Intron variation in marbled murrelets detected using analyses of single-stranded conformational polymorphisms

Combination of the targeted amplification of nuclear introns and the analysis of single-stranded conformational polymorphisms has the potential to provide an inexpensive, rapid, versatile and sensitive genetic assay for evolutionary studies and conservation. We are developing primers and protocols to analyse nuclear introns in vertebrates, and are testing them in a population genetic study of marbled murrelets Brachyramphus marmoratus . Here we present protocols and results for introns for aldolase B, α-enolase, glyceraldehyde-3-phosphate dehydrogenase and lamin A. Results suggest that this approach presents a potentially powerful method for detecting genetic variation within and among local populations and species of animals: (i) a variety of genes can be surveyed, including genes of special interest such as those involved in disease resistance; (ii) assays are rapid and relatively inexpensive; (iii) large numbers of genes can be assayed, enabling accurate estimation of variation in the total genome; (iv) almost any mutation can be detected in the genes amplified; (v) the exact nature of variation can be investigated by sequence analysis if desired; (vi) statistical methods previously developed for proteins and/or sequence data can be used; (vii) protocols can be easily transferred to other species and other laboratories; and (viii) assays can be performed on old or degraded samples, blood or museum skins, so that animals need not be killed. Results of analyses for murrelets support earlier evidence that North American and Asiatic subspecies represent reproductively isolated species, and that genetic differences exist among murrelets from different sites within North America.     

Mineral content of the forearms of babies born to Asian and white mothers.

Vitamin D deficiency is common in pregnant Asian women. The effect of maternal vitamin D deficiency on fetal skeletal mineralisation was assessed by measuring the bone mineral content of babies born to 45 Asian women, 19 Asian women who had received 1000 units of vitamin D during the last trimester, and 12 white women. The mean cord blood concentrations of 25-hydroxy vitamin D in the three groups were 5.9 +/- SE 0.9 nmol/l (2.4 +/- SE 0.4 ng/ml), 15.2 +/- 3.2 nmol/l (6.1 +/- 1.3 ng/ml), and 33.4 +/- 3.6 nmol/l (13.4 ng/ml), respectively. Despite this wide variation in values there was no significant difference in the bone mineral content (as assessed by photon absorptiometry) of the forearms of babies born to these women. This suggests that mineralization of the fetal skeleton is not impaired in maternal vitamin D deficiency. Craniotabes (skull softening) was present in seven of the 64 Asian babies. The bone mineral content in these babies was not significantly different from that of babies without this sign, and craniotabes should not therefore be taken as an indication of a generalized impairment in skeletal mineralization.     

Alteration of colonial morphology of Acholeplasma laidlawii and Acholeplasma modicum by infection with Mycoplasmatales viruses.

Morphologically aberrant colonies resulted from the infection of Acholeplasma laidlawii with two of its three known viruses and from Acholeplasma modicum cells naturally carrying virus. The patterns of colonial alteration differed between cells infected with the two A. laidlawii viruses. Colonies derived from single cells infected with the bullet-shaped virus MV-L1 (Mycoplasmatales virus-laidlawii-1) had a radial sectoring pattern of intracolonial swellings ("blebs"), whereas cells infected with the tailed icosahedral virus MV-L3 contained bubble-like blebs. Colonies from cellsinfected with the enveloped virus MV-L2 appeared identical to those obrained from uninfected cells. Aberrant colonies contained 10(6) colony-forming units of organisms and 10(6) plaque-forming units of virus serologically identical to the infecting type, indicating that both the virus and host organism were capable of simultaneous replication. Enumeration of virus by means of counting aberrant colonies was 30-fold more sensitive than infectious center assay for MV-L1 and 1.2- to 2-fold higher for MV-L3. Furthermore, blebbed colonies plaquing with a new virus specific to A. modicum. Thus, blebbing in colonies provides a valuable marker for detection of the Mycoplasmatales viruses.