A comparative study of population genetic structure reveals patterns consistent with selection at functional microsatellites in common sunflower.

Microsatellites, also known as short tandem repeats (STRs), have long been considered non-functional, neutrally evolving regions of the genome. Recent findings suggest that they can function as drivers of rapid adaptive evolution. Previous work on the common sunflower identified 479 transcribed microsatellites where allele length significantly correlates with gene expression (eSTRs) in a stepwise manner. Here, a population genetic approach is used to test whether eSTR allele length variation is under selection. Genotypic variation among and within populations at 13 eSTRs was compared with that at 19 anonymous microsatellites in 672 individuals from 17 natural populations of sunflower from across a cline running from Saskatchewan to Oklahoma (distance of approximately 1600 km). Expected heterozygosity, allelic richness, and allelic diversity were significantly lower at eSTRs, a pattern consistent with higher relative rates of purifying selection. Further, an analysis of variation in microsatellite allele lengths (lnRV), and heterozygosities (lnRH), indicate recent selective sweeps at the eSTRs. Mean microsatellite allele lengths at four eSTRs within populations are significantly correlated with latitude consistent with the predictions of the tuning-knob model which predicts stepwise relationships between microsatellite allele length and phenotypes. This finding suggests that shorter or longer alleles at eSTRs may be favored in climatic extremes. Collectively, our results imply that eSTRs are likely under selection and that they may be playing a role in facilitating local adaptation across a well-defined cline in the common sunflower.

Phylogenomics and historical biogeography of West Indian Rock Iguanas (genus Cyclura).

The genus Cyclura includes nine extant species and six subspecies of West Indian Rock Iguanas and is one of the most imperiled genera of squamate reptiles globally. An understanding of species diversity, evolutionary relationships, diversification, and historical biogeography in this group is crucial for implementing sound long-term conservation strategies. We collected DNA samples from 1 to 10 individuals per taxon from all Cyclura taxa (n = 70 ingroup individuals), focusing where possible on incorporating individuals from different populations of each species. We also collected 1-2 individuals from each of seven outgroup species of iguanas (Iguana delicatissima; five Ctenosaura species) and Anolis sagrei (n = 12 total outgroup individuals). We used targeted genomic sequence capture to isolate and to sequence 1,872 loci comprising of 687,308 base pairs (bp) from each of the 82 individuals from across the nuclear genome. We extracted mitochondrial reads and assembled and annotated mitogenomes for all Cyclura taxa plus outgroup species. We present well-supported phylogenomic gene tree/species tree analyses for all extant species of Cyclura using ASTRAL-III, SVDQuartets, and StarBEAST2 methods, and discuss the taxonomic, biogeographic, and conservation implications of these data. We find a most recent common ancestor of the genus 9.91 million years ago. The earliest divergence within Cyclura separates C. pinguis from a clade comprising all other Cyclura. Within the latter group, a clade comprising C. carinata from the southern Lucayan Islands and C. ricordii from Hispaniola is the sister taxon to a clade comprising the other Cyclura. Among the other Cyclura, the species C. cornuta and C. stejnegeri (from Hispaniola and Isla Mona) form the sister taxon to a clade of species from Jamaica (C. collei), Cuba and Cayman Islands (C. nubila and C. lewisi), and the eastern (C. rileyi) and western (C. cychlura) Lucayan Islands. Cyclura cychlura and C. rileyi form a clade whose sister taxa are C. nubila and C. lewisi. Cyclura collei is the sister taxon to these four species combined.

Correlated Population Genetic Structure in a Three-Tiered Host-Parasite System: The Potential for Coevolution and Adaptive Divergence.

Three subspecies of Northern Bahamian Rock Iguanas, Cyclura cychlura, are currently recognized: C. c. cychlura, restricted to Andros Island, and C. c. figginsi and C. c. inornata, native to the Exuma Island chain. Populations on Andros are genetically distinct from Exuma Island populations, yet genetic divergence among populations in the Exumas is inconsistent with the 2 currently recognized subspecies from those islands. The potential consequences of this discrepancy might include the recognition of a single subspecies throughout the Exumas rather than 2. That inference also ignores evidence that populations of C. cychlura are potentially adaptively divergent. We compared patterns of population relatedness in a three-tiered host-parasite system: C. cychlura iguanas, their ticks (genus Amblyomma, preferentially parasitizing these reptiles), and Rickettsia spp. endosymbionts (within tick ectoparasites). Our results indicate that while C. c. cychlura on Andros is consistently supported as a separate clade, patterns of relatedness among populations of C. c. figginsi and C. c. inornata within the Exuma Island chain are more complex. The distribution of the hosts, different tick species, and Rickettsia spp., supports the evolutionary independence of C. c. inornata. Further, these patterns are also consistent with two independent evolutionarily significant units within C. c. figginsi. Our findings suggest coevolutionary relationships between the reptile hosts, their ectoparasites, and rickettsial organisms, suggesting local adaptation. This work also speaks to the limitations of using neutral molecular markers from a single focal taxon as the sole currency for recognizing evolutionary novelty in populations of endangered species.

Transcribed microsatellite allele lengths are often correlated with gene expression in natural sunflower populations.

Microsatellites are common in genomes of most eukaryotic species. Due to their high mutability, an adaptive role for microsatellites has been considered. However, little is known concerning the contribution of microsatellites towards phenotypic variation. We used populations of the common sunflower (Helianthus annuus) at two latitudes to quantify the effect of microsatellite allele length on phenotype at the level of gene expression. We conducted a common garden experiment with seed collected from sunflower populations in Kansas and Oklahoma followed by an RNA-Seq experiment on 95 individuals. The effect of microsatellite allele length on gene expression was assessed across 3,325 microsatellites that could be consistently scored. Our study revealed 479 microsatellites at which allele length significantly correlates with gene expression (eSTRs). When irregular allele sizes not conforming to the motif length were removed, the number of eSTRs rose to 2,379. The percentage of variation in gene expression explained by eSTRs ranged from 1%-86% when controlling for population and allele-by-population interaction effects at the 479 eSTRs. Of these eSTRs, 70.4% are in untranslated regions (UTRs). A gene ontology (GO) analysis revealed that eSTRs are significantly enriched for GO terms associated with cis- and trans-regulatory processes. Our findings suggest that a substantial number of transcribed microsatellites can influence gene expression.

Heterozygosity-Fitness Correlations Reveal Inbreeding Depression in Neonatal Body Size in a Critically Endangered Rock Iguana.

Inbreeding depression, though challenging to identify in nature, may play an important role in regulating the dynamics of small and isolated populations. Conversely, greater expression of genetic load can enhance opportunities for natural selection. Conditional expression concentrates these opportunities for selection and may lead to failure of detection. This study investigates the possibility for age-dependent expression of inbreeding depression in a critically endangered population of rock iguanas, Cyclura nubila caymanensis. We employ heterozygote-fitness correlations to examine the contributions of individual genetic factors to body size, a fitness-related trait. Nonsignificant reductions in homozygosity (up to 7%) were detected between neonates and individuals surviving past their first year, which may reflect natural absorption of inbreeding effects by this small, fecund population. The majority of variation in neonate body size was attributed to maternal or environmental effects (i.e., clutch identity and incubation length); however, heterozygosity across 22 microsatellite loci also contributed significantly and positively to model predictions. Conversely, effects of heterozygosity on fitness were not detectable when adults were examined, suggesting that inbreeding depression in body size may be age dependent in this taxon. Overall, these findings emphasize the importance of taking holistic, cross-generational approaches to genetic monitoring of endangered populations.

A Novel Approach for Total Nasal Reconstruction.

A 61-year-old woman who lost her nose, upper lip, and most of her midface bony structures because of cancer 20 years previously underwent advanced surgical reconstruction. This patient previously underwent multiple reconstructive surgeries that failed to satisfactorily restore her nose. Therefore, a multistage reconstruction was performed to recreate a complete nose and increase her upper lip length. Because of a lack of sufficient facial bone and nasal supporting structures, the reconstruction was extremely challenging. Virtual surgical planning technology was used to create a customized titanium nasal plate. The patient's nose was successfully reconstructed using the nasal plate, costal cartilage, and a paramedian forehead flap. The patient is highly satisfied with the cosmetic and functional results and has had marked psychosocial improvement since the reconstruction.

Transcriptome profiles of sunflower reveal the potential role of microsatellites in gene expression divergence.

The mechanisms by which natural populations generate adaptive genetic variation are not well understood. Some studies propose that microsatellites can function as drivers of adaptive variation. Here, we tested a potentially adaptive role for transcribed microsatellites with natural populations of the common sunflower (Helianthus annuus L.) by assessing the enrichment of microsatellites in genes that show expression divergence across latitudes. Seeds collected from six populations at two distinct latitudes in Kansas and Oklahoma were planted and grown in a common garden. Morphological measurements from the common garden demonstrated that phenotypic variation among populations is largely explained by underlying genetic variation. An RNA-Seq experiment was conducted with 96 of the individuals grown in the common garden and differentially expressed (DE) transcripts between the two latitudes were identified. A total number of 825 DE transcripts were identified. DE transcripts and nondifferentially expressed (NDE) transcripts were then scanned for microsatellites. The abundance of different motif lengths and types in both groups were estimated. Our results indicate that DE transcripts are significantly enriched with mononucleotide repeats and significantly depauperate in trinucleotide repeats. Further, the standardized mononucleotide repeat motif A and dinucleotide repeat motif AG were significantly enriched within DE transcripts while motif types, C, AT, ACC and AAC in DE transcripts, are significantly differentiated in microsatellite tract length between the two latitudes. The tract length differentiation at specific microsatellite motif types across latitudes and their enrichment within DE transcripts indicate a potential functional role for transcribed microsatellites in gene expression divergence in sunflower.

The Lesser Antillean Iguana (Iguana delicatissima) on St. Eustatius: Genetically Depauperate and Threatened by Ongoing Hybridization.

The Lesser Antillean Iguana (Iguana delicatissima) is an endangered species threatened by habitat loss and hybridization with non-native Green Iguanas (Iguana iguana). Iguana delicatissima has been extirpated on several islands, and the Green Iguana has invaded most islands with extant populations. Information is essential to protect this species from extinction. We collected data on 293 iguanas including 17 juveniles from St. Eustasius, one of the few remaining I. delicatissima strongholds. Genetic data were leveraged to test for hybridization presence with the Green Iguana using both mitochondrial and nuclear genes, including 16 microsatellite loci. The microsatellites were also analyzed to estimate genetic diversity, population structure, and effective population size. Using molecular and morphological data, we identified 286 I. delicatissima individuals captured during our first fieldwork effort, and 7 non-native iguanas captured during a second effort, showing hybridization occurs within this population. Comparing homologous microsatellites used in studies on Dominica and Chancel, the I. delicatissima population on St. Eustatius has extremely low genetic diversity (HO = 0.051; HE = 0.057), suggesting this population is genetically depauperate. Furthermore, there is significant evidence for inbreeding (FIS = 0.12) and weak spatial genetic structure (FST = 0.021, P = 0.002) within this population. Besides immediate threats including hybridization, this population's low genetic diversity, presence of physiological abnormalities and low recruitment could indicate presence of inbreeding depression that threatens its long-term survival. We conclude there is a continued region-wide threat to I. delicatissima and highlight the need for immediate conservation action to stop the continuing spread of Green Iguanas and to eliminate hybridization from St. Eustatius.

Phylogeography of the endangered Lesser Antillean iguana, Iguana delicatissima: a recent diaspora in an archipelago known for ancient herpetological endemism.

Iguana delicatissima is an endangered endemic of the Lesser Antilles in the Caribbean. Phylogeographic analyses for many terrestrial vertebrate species in the Caribbean, particularly lizards, suggest ancient divergence times. Often, the closest relatives of species are found on the same island, indicating that colonization rates are so low that speciation on islands is often more likely to generate biodiversity than subsequent colonization events. Mitochondrial sequence analysis of the region spanning ND4 was performed on I. delicatissima individuals from islands across the species' range to estimate genetic divergence among geographically isolated populations. Five unique haplotypes were recovered from 46 individuals. The majority of animals carry a single common haplotype. Two of the haplotypes were only present in individuals classified as hybrids from Îles des Saintes. The final 2 haplotypes, single nucleotide substitutions, were present in animals from Îlet Chancel of Martinique and Saint Barthélemy, respectively. Despite the great distances between islands and habitat heterogeneity within islands, this species is characterized by low haplotype diversity. The low mtDNA variation of I. delicatissima suggests a single colonization coupled with rapid range expansion, potentially hastened by human-mediated dispersal.

Influence of weeds on Argentine ant (Hymenoptera: Formicidae) and obscure mealybug (Hemiptera: Pseudococcidae) in a central California vineyard.

Obscure mealybug is a pest of grapes in the cool climate regions of coastal California, is found on some vineyard weeds, and is tended by the Argentine ant. A study was conducted at a vineyard in Arroyo Grande, CA, to evaluate the impact of weeds on ant activity on grapevines, and the role that ants and weeds have on obscure mealybug infestation in grape clusters. The incidence of the fungus Botrytis cinerea was recorded as well. Treatments were weed exclusion versus the presence of weeds, and ant exclusion versus the presence of ants. Ant activity was evaluated weekly using sugar-based monitoring stations, and mealybug infestation and Botrytis incidence of clusters were evaluated at harvest. Ant exclusion reduced the overall number of ant visits by 82%, and ants increased mealybug infestation of clusters by 53%. Ant activity was 33% higher in the weeds treatment, but there was no impact of weeds on mealybug infestation. We suggest that the higher ant activity recorded in the weeds treatment may have been an artifact of the sugar-based sampling method. Botrytis incidence was three times higher with ants, but did not differ between weeds and weed exclusion treatments. The study supports other research showing a relationship between mealybug infestation and the presence of ants, as well as the lack of impact of floor vegetation on mealybug infestation of grape clusters. It is the first report of a relationship between ants and Botrytis, although it is more likely that the higher Botrytis incidence found here is a result of increased mealybug density than a direct effect by ants.

Double-blind, bilateral pain comparison with simultaneous injection of 2% lidocaine versus buffered 2% lidocaine for periocular anesthesia.

PURPOSE: Determine if raising the pH of 2% lidocaine with epinephrine 1:100 000 to a physiologic level decreases pain perception during periocular, subcutaneous anesthesia. DESIGN: Double-blind, prospective, randomized study. Simultaneous unilateral injections of buffered and unbuffered lidocaine solutions were given before surgery to patients having bilateral, periocular surgery. PARTICIPANTS: Fifty-four consecutive patients (27 male and 27 female; mean age, 68 years; standard deviation, 11 years). INTERVENTION: Patients were given simultaneous injections of buffered and unbuffered 2% lidocaine with epinephrine 1:100 000. The needles were inserted simultaneously and the anesthesia was injected for a 20-second count for a total volume of 1.0 ml per injected side. MAIN OUTCOME MEASURES: After the simultaneous injections, the patients were asked to rate the pain on each side on a Likert-type visual analog scale of 0 to 10. RESULTS: Sixty-five percent of patients preferred the buffered lidocaine with a scaled pain reduction of 0.9 (P = 0.0005). Additionally, for the patients who believed that the buffered solution was less painful, the mean decrease in scaled pain rating was 2, for a 51% reduction in pain level (P = 0.001). No gender differences were noted. CONCLUSIONS: Buffering 2% lidocaine with epinephrine 1:100 000 with sodium bicarbonate 8.4% offers a clinically and statistically significant reduction in pain experienced by two-thirds of patients receiving periocular subcutaneous anesthesia.

Engineering genes for predictable protein expression.

The DNA sequence used to encode a polypeptide can have dramatic effects on its expression. Lack of readily available tools has until recently inhibited meaningful experimental investigation of this phenomenon. Advances in synthetic biology and the application of modern engineering approaches now provide the tools for systematic analysis of the sequence variables affecting heterologous expression of recombinant proteins. We here discuss how these new tools are being applied and how they circumvent the constraints of previous approaches, highlighting some of the surprising and promising results emerging from the developing field of gene engineering.

Gene expression assays for actin, ubiquitin, and three microsatellite-encoding genes in Helianthus annuus (Asteraceae).

PREMISE OF THE STUDY: The "tuning knob" model of King et al. (Endeavor 21: 36-40, 1997) postulates that microsatellite mutations can alter phenotypes in a stepwise fashion. Some proposed mechanisms involve regulation of gene expression. To study the effect of microsatellites harbored in untranslated regions on gene expression in Helianthus annuus, we have developed TaqMan assays for three microsatellite-encoding genes, and two constitutively expressed genes, actin and ubiquitin, to serve as standards. METHODS AND RESULTS: All five TaqMan assays yielded strong log-linear relationships between cycle threshold (C(T)) values and cDNA concentrations (R(2) = 0.98-0.99). Standard curves were based on five concentrations for each of five individuals. Efficiencies ranged from 0.83 to 1.03. CONCLUSIONS: The developed tools will allow for relative quantification of gene expression across individuals. Genotyping these loci will allow for testing the "tuning knob" hypothesis. Further, the actin and ubiquitin assays should be generally applicable to gene expression studies in H. annuus.

Forensic Genetic Analyses of Melanistic Iguanas Highlight the Need to Monitor the Iguanid Trade.

Lizards within the Iguana iguana species complex are among the most common reptilian pets, with the widest natural geographic range among iguanids. Deep phylogenetic divergence distinguishes multiple mitochondrial clades, and several taxonomic changes have recently been proposed. These small populations, typically island endemics, are threatened by numerous factors, including the international pet trade. Recent investigations reveal the absence of required CITES permits for lawful export of animals, providing evidence of ongoing illegal trade. Additional monitoring of trade in iguanas can be achieved through the application of forensic molecular techniques. In this study, two captive melanistic iguanas were genotyped for molecular markers for which geographic distributions of alleles have been established. Mitochondrial sequencing indicates that both animals carry a haplotype known to originate from the islands of Saba and Montserrat, populations taxonomically proposed to be Iguana melanoderma. Genotypes at 15 microsatellite loci are equally consistent with this origin, given the results of a principal component analysis. This first forensic genetic assessment within the extensive I. iguana pet trade highlights the presence of illegal activity. The need for additional forensic assessments of pet-trade iguanas is evident, especially given that their value is driven by variety and rarity, which is further intensified by recent taxonomic changes.

Anxiety level in severe asthmatics undergoing bronchial thermoplasty procedure: An observational study.

Bronchial thermoplasty (BT) is one of the novel approved modalities in treating severe asthmatics to overcome their exacerbating symptoms such as increased anxiety. The purpose of this study was to evaluate anxiety level among severe asthmatics while undergoing BT procedure. This was an observational study where subjects self-evaluated their overall anxiety level using the burns anxiety inventory (BAI) questionnaire at baseline and prior to each of three BT treatments (broncho thermoplasty procedure 1, broncho thermoplasty procedure 2, and broncho thermoplasty procedure 3). The BAI questionnaire consisted of three different categories with each category having specific symptoms. Categories were grouped as: Anxious feelings, Anxious thoughts, and Physical symptoms. Subjects' Asthma Control Tests were also collected for analysis before and after the BT procedure. A total of 17 subjects with a mean age of 55.9 ±â€…14.5 years participated in the study. Fifty three percent were females (n = 9) and 41.2% (n = 7) were on prescribed anxiety medications. There was a significant drop in the patients' overall BAI anxiety level over time, P < .0001, in Anxious feelings (P = .0001), anxious thoughts (P = .001), and physical symptoms (P = .025). When analyzing the change in anxiety level among those who were not on prescribed anxiety medications, significant drop in overall anxiety level and in the subcategories were also noted. (P < .05). In addition, ACT scores showed a significant improvement (post vs pre) (18.5 ±â€…4.0 vs 13.3 ±â€…6.3, P = .03; Cohen's d = 0.73). This study shows the effectiveness of BT in decreasing severe asthmatic anxiety levels from baseline to last BT treatment and this benefit was mostly noted in those who were not on any anxiety medications. A limitation of this study is that all subjects were recruited from a single center. Therefore, to further validate the study findings, a multi-center study needs to be conducted with a larger sample size.

Characterization of long transcribed microsatellites in Helianthus annuus (Asteraceae).

PREMISE OF THE STUDY: Research on the evolutionary role of exonic microsatellites currently lacks an understanding of the evolutionary pressures that promote or limit their expansion. Contrasting levels of variability and genetic structures at anonymous and transcribed microsatellite loci of varying lengths are likely to provide useful insights regarding the relative strength of selection acting on different classes of microsatellites. We have developed primers for long transcribed microsatellites in Helianthus annuus to make these comparisons. METHODS AND RESULTS: Eight relatively long microsatellites from sequences in the expressed sequence tag database of H. annuus were characterized. A total of 63 individuals from three populations in Kansas were genotyped. The number of alleles per locus ranged from four to 11 with an average observed heterozygosity of 0.723. CONCLUSIONS: Our study has generated suitable tools for studying the population genetics of long transcribed microsatellites that are potentially influenced by selection.

Macroscale Superlubricity and Polymorphism of Long-Chain n-Alcohols.

Simple n-alcohols, such as 1-dodecanol, show anomalous film-forming and friction behaviors under elastohydrodynamic lubrication (EHL) conditions, as found inside bearings and gears. Using tribometer, diamond anvil cell (DAC), and differential scanning calorimetry (DSC) experiments, we show that liquid 1-dodecanol undergoes a pressure-induced solidification when entrained into EHL contacts. Different solid polymorphs are formed inside the contact depending on the temperature and pressure conditions. Surprisingly, at a moderate temperature and pressure, 1-dodecanol forms a polymorph that exhibits robust macroscale superlubricity. The DAC and DSC experiments show that superlubricity is facilitated by the formation of lamellar, hydrogen-bonded structures of hexagonally close-packed molecules, which promote interlayer sliding. This novel superlubricity mechanism is similar to that proposed for the two-dimensional materials commonly employed as solid lubricants, but it also enables the practical advantages of liquid lubricants to be maintained. When the pressure is increased, 1-dodecanol undergoes a polymorphic transformation into a phase that gives a higher friction. The DAC and DSC experiments indicate that the high-friction polymorph is an orthorhombic crystal. The polymorphic transformation pressure coincides with the onset of a dimple formation in the EHL films, revealing that the anomalous film shapes are caused by the formation of rigid orthorhombic crystals inside the contact. This is the first demonstration of a macroscale superlubricity in an EHL contact lubricated by a nonaqueous liquid that arises from bulk effects rather than tribochemical transformations at the surfaces. Since the superlubricity observed here results from phase transformations, it is continuously self-replenishing and is insensitive to surface chemistry and topology. This discovery creates the possibility of implementing superlubricity in a wide range of machine components, which would result in enormous improvements in efficiency and durability.

Mitochondrial heteroplasmy and paternal leakage in natural populations of Silene vulgaris, a gynodioecious plant.

It is currently thought that most angiosperms transmit their mitochondrial genomes maternally. Maternal transmission limits opportunities for genetic heterogeneity (heteroplasmy) of the mitochondrial genome within individuals. Recent studies of the gynodioecious species Silene vulgaris and Silene acaulis, however, document both direct and indirect evidence of mitochondrial heteroplasmy, suggesting that the mitochondrial genome is at times transmitted via paternal leakage. This heteroplasmy allows the generation of multi-locus recombinants, as documented in recent studies of both species. A prior study that employed quantitative PCR (q-PCR) on a limited sample provided direct evidence of heteroplasmy in the mitochondrial gene atp1 in S. vulgaris. Here, we apply the q-PCR methods to a much larger sample and extend them to incorporate the study of an additional atp1 haplotype along with two other haplotypes of the mitochondrial gene cox1 to evaluate the origin, extent, and transmission of mitochondrial genome heteroplasmy in S. vulgaris. We first calibrate our q-PCR methods experimentally and then use them to quantify heteroplasmy in 408 S. vulgaris individuals sampled from 22 natural populations located in Virginia, New York, and Tennessee. Sixty-one individuals exhibit heteroplasmy, including five that exhibited the joint heteroplasmy at both loci that is a prerequisite for effective recombination. The heteroplasmic individuals were distributed among 18 of the populations studied, demonstrating that heteroplasmy is a widespread phenomenon in this species. Further, we compare mother and offspring from 71 families to determine the rate of heteroplasmy gained and lost via paternal leakage and vegetative sorting across generations. Of 17 sibships exhibiting cox1 heteroplasmy and 14 sibships exhibiting atp1 heteroplasmy, more than half of the observations of heteroplasmy are generated via paternal leakage at the time of fertilization, with the rest being inherited from a heteroplasmic mother. Moreover, we show that the average paternal contribution during paternal leakage is about 12%. These findings are surprising, given that the current understanding of gynodioecy assumes that mitochondrial cytoplasmic male sterility elements are strictly maternally inherited. Knowledge of the dynamics of mitochondrial populations within individuals plays an important role in understanding the evolution of gynodioecy, and we discuss our findings within this context.

Conditional female strategies influence hatching success in a communally nesting iguana.

The decision of females to nest communally has important consequences for reproductive success. While often associated with reduced energetic expenditure, conspecific aggregations also expose females and offspring to conspecific aggression, exploitation, and infanticide. Intrasexual competition pressures are expected to favor the evolution of conditional strategies, which could be based on simple decision rules (i.e., availability of nesting sites and synchronicity with conspecifics) or on a focal individual's condition or status (i.e., body size). Oviparous reptiles that reproduce seasonally and provide limited to no postnatal care provide ideal systems for disentangling social factors that influence different female reproductive tactics from those present in offspring-rearing environments. In this study, we investigated whether nesting strategies in a West Indian rock iguana, Cyclura nubila caymanensis, vary conditionally with reproductive timing or body size, and evaluated consequences for nesting success. Nesting surveys were conducted on Little Cayman, Cayman Islands, British West Indies for four consecutive years. Use of high-density nesting sites was increasingly favored up to seasonal nesting activity peaks, after which nesting was generally restricted to low-density nesting areas. Although larger females were not more likely than smaller females to nest in high-density areas, larger females nested earlier and gained access to priority oviposition sites. Smaller females constructed nests later in the season, apparently foregoing investment in extended nest defense. Late-season nests were also constructed at shallower depths and exhibited shorter incubation periods. While nest depth and incubation length had significant effects on reproductive outcomes, so did local nest densities. Higher densities were associated with significant declines in hatching success, with up to 20% of egg-filled nests experiencing later intrusion by a conspecific. Despite these risks, nests in high-density areas were significantly more successful than elsewhere due to the benefits of greater chamber depths and longer incubation times. These results imply that communal nest sites convey honest signals of habitat quality, but that gaining and defending priority oviposition sites requires competitive ability.

Etiologies of apnea of infancy.

BACKGROUND: To date there are limited data in the literature to guide the initial evaluation for etiologies of apnea in full-term infants born at greater than or equal to 37 weeks conceptional age (apnea of infancy [AOI]). Pediatricians and pediatric pulmonologists are left to pursue a broad, rather than targeted and a stepwise approach to begin diagnostic evaluation. METHODS: We performed a retrospective chart review of 101 symptomatic full-term infants (age under 12 months) diagnosed with apnea with an inpatient multichannel pneumogram (six channels) or a fully attended overnight pediatric polysomnogram in our outpatient sleep center accredited by American Academy of Sleep Medicine (AASM), scored using the standards set forth by the AASM. The infant was diagnosed as having AOI if the apnea hypopnea index (AHI) was greater than 1 (AHI is defined as the number of apnea and hypopnea events per hour of sleep). The final diagnosis/etiology was determined based on physician clinical assessment and work up. We then determined the frequency for each diagnosis. RESULTS: We found that the three most common etiologies were gastroesophageal reflux disease (GERD) (48/101), upper airway abnormalities/obstruction (37/101), and neurological diseases (19/101). There were significant numbers of infants with multiple etiologies for AOI. CONCLUSION: Based on the frequencies obtained, pediatric practitioners caring for full-term infants with apnea of unknown etiology are advised to begin with evaluation of more likely causes such as GERD and upper airway abnormalities/obstruction before evaluating for less common causes.