Relationships Among Reproductive Morphology, Behavior, and Testosterone in a Natural Population of Green Anole Lizards

Laboratory studies of reproductive systems have long supported the idea that neural and/or muscular structures used frequently are often enhanced in size. However, field studies integrating behavioral, morphological, and hormonal data are needed to better understand relationships in natural environments. We examined a natural population of green anole lizards (Anolis carolinensis) to determine whether variation in reproductive morphology both within and between the sexes paralleled differences in courtship and copulatory behaviors and circulating testosterone levels. Display rate in males was positively correlated with the sizes of the cartilage supporting the dewlap (a throat fan used in courtship and aggression) and renal sex segments (portions of the kidney that function similarly to the mammalian prostate), but correlated negatively with seminiferous tubule size. Plasma testosterone in males was negatively correlated with display behavior and was not correlated with any measures of morphology. Females, which display rarely, exhibited no relationships between morphology and frequency of behavior. Comparisons between the sexes show that males have consistently larger courtship and copulation morphologies than females, even when accounting for sex differences in body size. The results not only support the idea of relationships between increased function and enhanced structures, but also show the complexity of mechanistic interactions associated with reproductive behavior in wild animals

The Burden of Motherhood: The Effect of Reproductive Load on Female Lizard Locomotor, Foraging, and Social Behavior

The costs of reproduction, involving demands associated with both current and future reproductive efforts, may place a substantial burden on females. However, animals may minimize these costs by modifying their behavior across the reproductive cycle. We examined the effects of reproductive load on three types of behavior (locomotion, foraging, and social displays) in green anole lizards (Anolis carolinensis) by comparing egg, follicle, and oviduct mass and volume with field observational data. We found that female locomotor and social display behaviors decreased as reproductive load increased, suggesting behavioral modification in these traits, but we detected no relationship between foraging and reproductive load. We also examined these relationships across eight Anolis species using a phylogenetically informed analysis and found no associations between the evolution of reproductive load and any of the three behaviors. These results suggest that the evolution of increased reproductive load is not associated with the interspecific variation in behavior across the anoles and may result from varying life history traits or selective ecological pressures across species

Short-time homomorphic wavelet estimation

Successful wavelet estimation is an essential step for seismic methods like impedance inversion, analysis of amplitude variations with offset and full waveform inversion. Homomorphic deconvolution has long intrigued as a potentially elegant solution to the wavelet estimation problem. Yet a successful implementation has proven difficult. Associated disadvantages like phase unwrapping and restrictions of sparsity in the reflectivity function limit its application. We explore short-time homomorphic wavelet estimation as a combination of the classical homomorphic analysis and log-spectral averaging. The introduced method of log-spectral averaging using a short-term Fourier transform increases the number of sample points, thus reducing estimation variances. We apply the developed method on synthetic and real data examples and demonstrate good performance.Comment: 13 pages, 5 figures. 2012 J. Geophys. Eng. 9 67

Multiple mantle upwellings in the transition zone beneath the northern East-African Rift system from relative P-wave travel-time tomography

Mantle plumes and consequent plate extension have been invoked as the likely cause of East African Rift volcanism. However, the nature of mantle upwelling is debated, with proposed configurations ranging from a single broad plume connected to the large low-shear-velocity province beneath Southern Africa, the so-called African Superplume, to multiple lower-mantle sources along the rift. We present a new P-wave travel-time tomography model below the northern East-African, Red Sea, and Gulf of Aden rifts and surrounding areas. Data are from stations that span an area from Madagascar to Saudi Arabia. The aperture of the integrated data set allows us to image structures of 100 km length-scale down to depths of 700– 800 km beneath the study region. Our images provide evidence of two clusters of low-velocity structures consisting of features with diameter of 100–200 km that extend through the transition zone, the first beneath Afar and a second just west of the Main Ethiopian Rift, a region with off-rift volcanism. Considering seismic sensitivity to temperature, we interpret these features as upwellings with excess temperatures of 100 6 50 K. The scale of the upwellings is smaller than expected for lower mantle plume sources. This, together with the change in pattern of the low-velocity anomalies across the base of the transition zone, suggests that ponding or flow of deep-plume material below the transition zone may be spawning these upper mantle upwellings

Lower edge of locked Main Himalayan Thrust unzipped by the 2015 Gorkha earthquake

Large earthquakes are thought to release strain on previously locked faults. However, the details of how earthquakes are initiated, grow and terminate in relation to pre-seismically locked and creeping patches is unclear ^1-4. The 2015 Mw 7.8 Gorkha, Nepal earthquake occurred close to Kathmandu in a region where the prior pattern of fault locking is well documented ^5. Here we analyze this event using seismological records measured at teleseismic distances and Synthetic Aperture Radar imagery. We show that the earthquake originated northwest of Kathmandu within a cluster of background seismicity that fringes the bottom of the locked portion of the Main Himalayan Thrust fault (MHT). The rupture propagated eastwards for about 140 km, unzipping the lower edge of the locked portion of the fault. High-frequency seismic waves radiated continuously as the slip pulse propagated at about 2.8 km s-1 along this zone of presumably high and heterogeneous pre-¬seismic stress at the seismic-aseismic transition. Eastward unzipping of the fault resumed during the Mw 7.3 aftershock on May 12. The transfer of stress to neighbouring regions during the Gorkha earthquake should facilitate future rupture of the areas of the MHT adjacent and up-dip of the Gorkha earthquake rupture.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/ngeo251

The 2009 Samoa–Tonga great earthquake triggered doublet

Great earthquakes (having seismic magnitudes of at least 8) usually involve abrupt sliding of rock masses at a boundary between tectonic plates. Such interplate ruptures produce dynamic and static stress changes that can activate nearby intraplate aftershocks, as is commonly observed in the trench-slope region seaward of a great subduction zone thrust event1. The earthquake sequence addressed here involves a rare instance in which a great trench-slope intraplate earthquake triggered extensive interplate faulting, reversing the typical pattern and broadly expanding the seismic and tsunami hazard. On 29 September 2009, within two minutes of the initiation of a normal faulting event with moment magnitude 8.1 in the outer trench-slope at the northern end of the Tonga subduction zone, two major interplate underthrusting subevents (both with moment magnitude 7.8), with total moment equal to a second great earthquake of moment magnitude 8.0, ruptured the nearby subduction zone megathrust. The collective faulting produced tsunami waves with localized regions of about 12 metres run-up that claimed 192 lives in Samoa, American Samoa and Tonga. Overlap of the seismic signals obscured the fact that distinct faults separated by more than 50 km had ruptured with different geometries, with the triggered thrust faulting only being revealed by detailed seismic wave analyses. Extensive interplate and intraplate aftershock activity was activated over a large region of the northern Tonga subduction zone

Hydrous upwelling across the mantle transition zone beneath the Afar Triple Junction

The mechanisms that drive the upwelling of chemical heterogeneity from the lower to upper mantle (e.g., thermal versus compositional buoyancy) are key to our understanding of whole mantle con- vective processes. We address these issues through a receiver function study on new seismic data from recent deployments located on the Afar Triple Junction, a location associated with deep mantle upwelling. The detailed images of upper mantle and mantle transition zone structure illuminate features that give insights into the nature of upwelling from the deep Earth. A seismic low-velocity layer directly above the mantle transition zone, interpreted as a stable melt layer, along with a prominent 520 km discontinuity sug- gest the presence of a hydrous upwelling. A relatively uniform transition zone thickness across the region suggests a weak thermal anomaly (<100 K) may be present and that upwelling must be at least partly driven by compositional buoyancy. The results suggest that the lower mantle is a source of volatile rich, chemically distinct upwellings that influence the structure of the upper mantle, and potentially the chemis- try of surface lavas

Large-scale wind disturbances promote tree diversity in a Central Amazon forest

Canopy gaps created by wind-throw events, or blowdowns, create a complex mosaic of forest patches varying in disturbance intensity and recovery in the Central Amazon. Using field and remote sensing data, we investigated the short-term (four-year) effects of large (&gt;2000 m2) blowdown gaps created during a single storm event in January 2005 near Manaus, Brazil, to study (i) how forest structure and composition vary with disturbance gradients and (ii) whether tree diversity is promoted by niche differentiation related to wind-throw events at the landscape scale. In the forest area affected by the blowdown, tree mortality ranged from 0 to 70%, and was highest on plateaus and slopes. Less impacted areas in the region affected by the blowdown had overlapping characteristics with a nearby unaffected forest in tree density (583±46 trees ha-1) (mean±99% Confidence Interval) and basal area (26.7±2.4 m2 ha-1). Highly impacted areas had tree density and basal area as low as 120 trees ha-1 and 14.9 m2 ha-1, respectively. In general, these structural measures correlated negatively with an index of tree mortality intensity derived from satellite imagery. Four years after the blowdown event, differences in size-distribution, fraction of resprouters, floristic composition and species diversity still correlated with disturbance measures such as tree mortality and gap size. Our results suggest that the gradients of wind disturbance intensity encompassed in large blowdown gaps (&gt;2000 m2) promote tree diversity. Specialists for particular disturbance intensities existed along the entire gradient. The existence of species or genera taking an intermediate position between undisturbed and gap specialists led to a peak of rarefied richness and diversity at intermediate disturbance levels. A diverse set of species differing widely in requirements and recruitment strategies forms the initial post-disturbance cohort, thus lending a high resilience towards wind disturbances at the community level. © 2014 Marra et al