INDIVIDUAL AND SPECIES-SPECIFIC SONG PATTERNS OF ROCK AND MEADOW PIPITS: PHYSICAL CHARACTERISTICS AND EXPERIMENTS

ABSTRACT

The songs of Anthus spinoletta littoralis and A. pratensis, in sympatric populations in SW Sweden were recorded, analysed in sound spectrographs and tested in the field. The purpose was to investigate: a) if the strophes are species specifically and individually distinct and, if so, whether pipits are able to make such distinctions; b) if the species-specific and individual-specific patterns are concentrated in different sections of the song and, if so, whether the species-specific section transmits individual-specific information and the individual-specific section transmits species-specific information as well.

The basic structure of the syllables in the terminating section of the strophe was found to be intraspecifically stereotyped, but varied between the two species. Replay experiments showed that territorial males could discriminate between con- and heterospecific strophes and this ability persisted when the terminating section of the strophe was replayed alone. The terminating part of the strophe did not seem to transmit individual-specific information to conspecific males. On the other hand, the basic structure of the syllables in the first section of the strophe was intraindividually stereotyped but varied between most conspecific males. Playback experiments showed that a territorial male could discriminate his neighbours' song patterns and this ability remained intact when the introductory phrase of the strophe was replayed alone. Both song pattern and position were necessary properties of the identifying signal in these pipits. But the introductory phrase of a total stranger did not seem to transmit unambiguous species-specific information to conspecific males.     

Left–right asymmetry: cilia stir up new surprises in the node

Cilia are microtubule-based hair-like organelles that project from the surface of most eukaryotic cells. They play critical roles in cellular motility, fluid transport and a variety of signal transduction pathways. While we have a good appreciation of the mechanisms of ciliary biogenesis and the details of their structure, many of their functions demand a more lucid understanding. One such function, which remains as intriguing as the time when it was first discovered, is how beating cilia in the node drive the establishment of left–right asymmetry in the vertebrate embryo. The bone of contention has been the two schools of thought that have been put forth to explain this phenomenon. While the ‘morphogen hypothesis’ believes that ciliary motility is responsible for the transport of a morphogen preferentially to the left side, the ‘two-cilia model’ posits that the motile cilia generate a leftward-directed fluid flow that is somehow sensed by the immotile sensory cilia on the periphery of the node. Recent studies with the mouse embryo argue in favour of the latter scenario. Yet this principle may not be generally conserved in other vertebrates that use nodal flow to specify their left–right axis. Work with the teleost fish medaka raises the tantalizing possibility that motility as well as sensory functions of the nodal cilia could be residing within the same organelle. In the end, how ciliary signalling is transmitted to institute asymmetric gene expression that ultimately induces asymmetric organogenesis remains unresolved.     

Has gene duplication impacted the evolution of Eutherian longevity?

One of the greatest unresolved questions in aging biology is determining the genetic basis of interspecies longevity variation. Gene duplication is often the key to understanding the origin and evolution of important Eutherian phenotypes. We systematically identified longevity‐associated genes in model organisms that duplicated throughout Eutherian evolution. Longevity‐associated gene families have a marginally significantly higher rate of duplication compared to non‐longevity‐associated gene families. Anti‐longevity‐associated gene families have significantly increased rate of duplication compared to pro‐longevity gene families and are enriched in neurodegenerative disease categories. Conversely, duplicated pro‐longevity‐associated gene families are enriched in cell cycle genes. There is a cluster of longevity‐associated gene families that expanded solely in long‐lived species that is significantly enriched in pathways relating to 3‐UTR‐mediated translational regulation, metabolism of proteins and gene expression, pathways that have the potential to affect longevity. The identification of a gene cluster that duplicated solely in long‐lived species involved in such fundamental processes provides a promising avenue for further exploration of Eutherian longevity evolution.     

Redrawing the map: mtDNA provides new insight into the distribution and diversity of short‐finned pilot whales in the Pacific Ocean

Correlations between morphological and genetic data provide evidence to delineate species or evolutionarily significant units, which then become the units to conserve in management plans. Here, we examine the distribution and genetic differentiation of two morphotypes of short‐finned pilot whale (Globicephala macrorhynchus) in the Pacific Ocean. Mitochondrial control region sequences from 333 samples were combined with 152 previously published sequences to describe genetic variability globally and population structure in the Pacific. Although genetic variability is low, we found strong differentiation at both broad and local levels across the Pacific. Based on genetics, two types are distributed throughout the Pacific, one predominantly in the eastern Pacific and the other in the western and central Pacific. In the eastern Pacific Ocean, no correlation was found between distribution and sea surface temperature. The two types have broad latitudinal ranges, suggesting their distributions are likely driven by more complex factors, such as prey distribution, rather than sea surface temperature.     

Movements of beluga whales (Delphinapterus leucas) in Bristol Bay,Alaska

We describe the annual distribution of beluga whales (Delphinapterus leucas) in Bristol Bay, Alaska, using data from 31 satellite‐linked transmitters during 2002–2011. Bristol Bay has one of the largest and best studied Pacific salmon (Oncorhynchus spp.) fisheries in the world, allowing us to link the seasonal distribution of belugas to that of salmon. During salmon migrations, beluga movements were restricted to river entrances. Belugas generally did not relocate to different river entrances or change bays during peak salmon periods. However, the location of belugas was not related to the number of salmon passing counting towers, suggesting that belugas were either selecting locations that were good for catching salmon or there were simply more salmon than belugas needed to supply their nutritional needs. The distribution of belugas expanded after salmon runs ended, and was greatest in winter when belugas ranged beyond the inner bays, traveling as far west as Cape Constantine. Belugas continued to frequent the inner bays in winter whenever sea ice conditions allowed, e.g., when winds moved sea ice offshore; however, they were never located south of the southern ice edge in open water or outside of Bristol Bay.     

The effect of close approaches for tagging activities by small research vessels on the behavior of humpback whales (Megaptera novaeangliae)

Small research vessels are often used as platforms for tagging activities to collect behavioral data on cetaceans and they have the potential to disturb that group or individual. If this disturbance is ignored, results and conclusions produced by that study could be inaccurate. Here land‐based behavioral data of migrating humpback whales (Megaptera novaeangliae) (n = 29) were used to determine the effect of close approaches for tagging by research vessels on their diving, movement and surface behaviors. Groups of whales were tagged, using digital recording tags, by small research vessels, as part of a behavioral response study. In groups that were approached for tagging, temporary changes in movement behaviors during close approaches were found, with subsequent recovery to “pre‐approach” levels. In female‐calf groups more long‐term changes in travel speed were found. Results suggest that, although close approaches for tagging by small vessels may cause behavioral changes in humpback whales, this change may be small and temporary. However, in female‐calf groups, the behavioral change may be greater and longer lasting. This study shows that when using small vessels for behavioral research, disturbance, and recovery should be measured to ensure integrity of data used for other analyses.     

Auditory anatomy of beaked whales and other odontocetes: Potential for cochlear stimulation via a “vibroacoustic duct mechanism”

Computed tomography (CT) and microcomputed tomography (microCT) were used to examine the structures involved in cochlear stimulation in odontocetes and terrestrial mammals. Cranial CT examined the osseous attachment of the skull to the tympanoperiotic complex (TPC) and the path of the endocranial foramen of the vestibulocochlear nerve (EFVN), which was assumed to contain the perilymphatic duct. Additional CTs of TPC were taken postextraction to examine the gross morphology of this structure. MicroCT was used to examine the acoustic windows of the cochlea, including the round and oval windows and the apertures of the cochlear and vestibular aqueducts. Cranial CT scans demonstrated an osseous connection between the skull and TPC in beaked whales and Physeter macrocephalus. EFVN traveled through a greater length of cranial bone and communicated more closely with the periotic bone in beaked whales than in other species. Ziphius cavirostris was observed to have a reduced medial sulcus of the mallear ridge (MSMR) and tympanic plate and an enlarged aperture of the cochlear aqueduct, respectively. The potential significance of these findings, including the role of the perilymphatic duct as a novel route of cochlear stimulation referred to as the “vibroacoustic duct mechanism,” are discussed.     

Odontocete occurrence in relation to changes in oceanography at a remote equatorial Pacific seamount

Seamounts are considered hot spots of biodiversity and can aggregate pelagic predators and their prey. Passive acoustic monitoring was conducted over 3 mo in 2012 to document the occurrence of odontocetes near a seamount chain in the central equatorial Pacific in relation to oceanographic changes over time. Beaked whale echolocation signals were most frequently encountered. The main beaked whale signal was an unknown type, BW38, which resembled signals produced by Blainville's beaked whales. It had high occurrence during high sea surface temperature and low sea surface salinity. Cuvier's beaked whales were the second most detected. They had an opposite pattern and were encountered more often when sea surface temperature was low and net primary productivity was high. Risso's dolphins and short‐finned pilot whales had high acoustic densities, and echolocated predominantly at night. Risso's dolphins occurred more often during low sea surface height deviation. False killer whales were less frequently detected and mostly occurred during the day. Sperm whale detections were fewer than expected and associated with high chlorophyll a. Short duration Kogiidae encounters occurred on average every third day. These types of long‐term site studies are an informative tool to comparatively assess species composition, relative abundance, and relationship to oceanographic changes.     

Seasonality of Antarctic minke whale (Balaenoptera bonaerensis) calls off the western Antarctic Peninsula

The Antarctic minke whale (Balaenoptera bonaerensis) is a difficult species to study because of its low visual detectability and preference for living within the sea ice habitat, accessible only by ice‐strengthened vessels. Recent identification of the Antarctic minke whale as the source of the seasonally ubiquitous bio‐duck call has allowed the use of this sound, as well as downsweeps, to investigate seasonality trends and diel patterns in Antarctic minke whale call production, and their relationship to sea ice cover. Passive acoustic data were collected using an autonomous Acoustic Recording Package (ARP) off the western Antarctic Peninsula. Bio‐duck calls were classified into four distinct call variants, with one variant having two subtypes. Bio‐duck calls were detected between April and November, with increasing call duration during the austral winter, indicating a strong seasonality in call production. Downsweeps, which were also attributed to Antarctic minke whales, were present throughout most months during the recording period, with a peak in July, and an absence in March and April. Both bio‐duck and downsweeps were significantly correlated with sea ice cover. No diel patterns were observed in bio‐duck calls or in downsweep call production at this site.     

Retrospective assessment of a single fiducial marker tracking regimen with robotic stereotactic body radiation therapy for liver tumours

AimTo investigate tumour motion tracking uncertainties in the CyberKnife Synchrony system with single fiducial marker in liver tumours.BackgroundIn the fiducial-based CyberKnife real-time tumour motion tracking system, multiple fiducial markers are generally used to enable translation and rotation corrections during tracking. However, sometimes a single fiducial marker is employed when rotation corrections are not estimated during treatment.Materials and methodsData were analysed for 32 patients with liver tumours where one fiducial marker was implanted. Four-dimensional computed tomography (CT) scans were performed to determine the internal target volume (ITV). Before the first treatment fraction, the CT scans were repeated and the marker migration was determined. Log files generated by the Synchrony system were obtained after each treatment and the correlation model errors were calculated. Intra-fractional spine rotations were examined on the spine alignment images before and after each treatment.ResultsThe mean (standard deviation) ITV margin was 4.1 (2.3) mm, which correlated weakly with the distance between the fiducial marker and the tumour. The mean migration distance of the marker was 1.5 (0.7) mm. The overall mean correlation model error was 1.03 (0.37) mm in the radial direction. The overall mean spine rotations were 0.27° (0.31), 0.25° (0.22), and 0.23° (0.26) for roll, pitch, and yaw, respectively. The treatment time was moderately associated with the correlation model errors and weakly related to spine rotation in the roll and yaw planes.ConclusionsMore caution and an additional safety margins are required when tracking a single fiducial marker.