Migratory movements of individual humpback whales photographed off the eastern coast of Australia

Humpback whales (Megaptera novaeangliae) migrate long distances each year on a return journey from low‐latitude breeding grounds to high‐latitude feeding grounds. Migration is influenced by subtle and complex social behaviors and the assumption that whales transit directly through the migratory corridor off the east coast of Australia requires further investigation. From 2003 to 2005, we followed the movements of 99 individual whales within one migratory cycle from three locations, off Byron Bay during the whales' northern migration and in Hervey Bay and at Ballina during the southern migration. The median sighting interval of whales between Byron Bay and Hervey Bay (n = 26) was 52 d (IQR = 42.5–75.5); between Byron Bay and Ballina (n = 21) was 59 d (IQR = 47.0–70.0); and between Hervey Bay and Ballina (n = 33) was 9 d (8.0–14.0). The overall pattern observed from these resightings suggests that Group E1 humpback whales spend approximately two months in the northern quarter of their range during the austral winter months. Intraseason resightings of whales at Ballina (n = 13, median sighting interval = 7 d) also suggest that some individuals, particularly adult males, may circle back north during their general southward journey along this part of the coast, perhaps in an attempt to increase mating opportunities.     

Foraging ecology and niche overlap in pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales from waters of the U.S. mid‐Atlantic coast

A complementary approach of stomach content and stable isotope analyses was used to characterize the foraging ecology and evaluate niche overlap between pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales stranded on the U.S. mid‐Atlantic coast between 1998 and 2011. Food habits analysis demonstrated both species were primarily teuthophagous, with 35 species of cephalopods, and 2 species of mesopelagic fishes represented in their overall diets. Pianka's Index of niche overlap suggested high overlap between whale diets (O_n = 0.92), with squids from the families Histioteuthidae, Cranchidae, and Ommastrephidae serving as primary prey. Pygmy sperm whales consumed slightly larger prey sizes (mean mantle length [ML] = 10.8 cm) than dwarf sperm whales (mean ML = 7.8 cm). Mean prey sizes consumed by pygmy sperm whales increased with growth, but showed no trend in dwarf sperm whales. Significant differences were not detected in δ¹⁵N and δ¹³C values of muscle tissues from pygmy (10.8‰ ± 0.5‰, ?17.1‰ ± 0.6‰), and dwarf sperm whales (10.7‰ ± 0.5‰, ?17.0‰ ± 0.4‰), respectively. Isotopic niche widths also did not differ significantly and dietary overlap was high between the two species. Results suggest the feeding ecologies of the pygmy and dwarf sperm whales are similar and both species occupy equivalent trophic niches in the region.     

Diet of two commercially important shark species in the United Arab Emirates: milk shark,Rhizoprionodon acutus (Rüppell, 1837), and slit‐eye shark,Loxodon macrorhinus (Müller & Henle, 1839)

The diets of the milk shark, Rhizoprionodon acutus, and the slit‐eye shark, Loxodon macrorhinus, landed from the artisanal fishery in the Arabian Gulf waters of the United Arab Emirates were investigated to determine their dietary preferences. Stomach contents from 57 milk sharks and 53 slit eye sharks were collected from Abu Dhabi (R. acutus, n = 23), Dubai (R. acutus, n = 5; L. macrorhinus, n = 15) and Ras Al Khaimah (R. acutus, n = 29; L. macrorhinus, n = 38) during fishery surveys from January to May 2012. Prey items were identified to the lowest possible taxonomic level, grouped into five categories including ‘teleost fish’, ‘cephalopods’, ‘crustaceans’, ‘invertebrates’, and ‘other’. The diets of both species were described using the numeric, frequency and weight methods, and the index of relative importance (IRI). The majority of stomachs for both species had food, with 66.6% of milk shark stomachs and 90.5% of slit‐eye shark stomachs containing prey items, both dominated by small teleosts. Rhizoprionodon acutus fed on a wide variety of teleost species, primarily Engraulidae (anchovies) (28%), Gerreidae (mojarras) (5.6%) and Carangidae (jacks) (1.6%) with occasional crustacean and cephalopod prey (8%). On the other hand, L. macrorhinus seemed to have a preference for one species in terms of teleosts (anchovies) (35.1%) and fed on a wider variety of crustaceans and cephalopods (22.6%). There was little overlap in the diets of these two species, suggesting that they may either be using different habitats or that in these waters, the milk shark is a generalist species while the slit‐eye is a specialist feeder.     

Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway

Ecological diversity has been reported for killer whales (Orcinus orca) throughout the North Atlantic but patterns of prey specialization have remained poorly understood. We quantify interindividual dietary variations in killer whales (n = 38) sampled throughout the year in 2017–2018 in northern Norway using stable isotopic nitrogen (δ¹⁵N: ¹⁵N/¹⁴N) and carbon (δ¹³C: ¹³C/¹²C) ratios. A Gaussian mixture model assigned sampled individuals to three differentiated clusters, characterized by disparate nonoverlapping isotopic niches, that were consistent with predatory field observations: seal‐eaters, herring‐eaters, and lumpfish‐eaters. Seal‐eaters showed higher δ¹⁵N values (mean ± SD: 12.6 ± 0.3‰, range = 12.3–13.2‰, n = 10) compared to herring‐eaters (mean ± SD: 11.7 ± 0.2‰, range = 11.4–11.9‰, n = 19) and lumpfish‐eaters (mean ± SD: 11.6 ± 0.2‰, range = 11.3–11.9, n = 9). Elevated δ¹⁵N values for seal‐eaters, regardless of sampling season, confirmed feeding at high trophic levels throughout the year. However, a wide isotopic niche and low measured δ¹⁵N values in the seal‐eaters, compared to that of whales that would eat solely seals (δ_N‐measured = 12.6 vs. δ_N‐expected = 15.5), indicated a diverse diet that includes both fish and mammal prey. A narrow niche for killer whales sampled at herring and lumpfish seasonal grounds supported seasonal prey specialization reflective of local peaks in prey abundance for the two fish‐eating groups. Our results, thus, show differences in prey specialization within this killer whale population in Norway and that the episodic observations of killer whales feeding on prey other than fish are a consistent behavior, as reflected in different isotopic niches between seal and fish‐eating individuals.     

PYGMY SPERM WHALES KOGIA BREVICEPS IN THE NORTHEAST ATLANTIC: NEW INFORMATION ON STOMACH CONTENTS AND STRANDINGS

Little is known about the feeding ecology of pygmy sperm whales ( Kogia breviceps ) in the Northeast Atlantic. Results are presented on the stomach contents of five whales stranded on the Galician coast (NW Spain) between 1995 and 2002 and seven whales stranded on the French Atlantic coast between 1984 and 2001. These results are compared with those obtained from the stomach contents of two pygmy sperm whales (a pregnant female and her calf ) stranded on the Scottish (UK) coast in 1999, the first records of the species in Scotland. In 13 out of 14 cases, food remains consisted almost entirely of cephalopod beaks, although some crustacean and fish remains were also present. In all the Spanish specimens, the identified prey were oceanic species: the cephalopods Histioteuthis reversa , H. bonnellii , Todarodes sagittatus , the viperfish Chauliodus sloani , and the giant mysid Gnatophausia sp. The same cephalopod species were found in the stomachs of the whales stranded in Scotland, although both whales had also consumed neritic cephalopod species such as Rossia macrosoma and other sepiolids. In the French specimens, almost all prey identified were oceanic cephalopods ( H. reversa , Brachioteuthis riseii , T. sagittatus , Taonius pavo , etc. ), but remains of crustaceans and a neritic squid ( Loligo forbesi ) were also found. One whale from France had eaten mainly Henslow's swimming crab ( Polybius henslowi ). Results from the present study are consistent with those found by other authors in the Azores and the Canary Islands in that pygmy sperm whales appear to be mainly teuthophagous, with histioteuthid squids forming an important part of the diet. Strandings records suggest that occurrence of pygmy sperm whales in the NE Atlantic may be seasonal, with most strandings occurring in autumn and winter.     

Distribution and abundance of sei whales off the west coast of the Falkland Islands

Little information exists on the current status of Southern Hemisphere sei whales (Balaenoptera borealis). We assessed their distribution and abundance along the west coast of the Falkland Islands (southwest Atlantic) during February and March 2018, using line transect and nonsystematic surveys. Abundance estimates were generated for a single survey stratum using design- and model-based approaches. Sightings of sei whales and unidentified baleen whales (most, if not all, likely to be sei whales) occurred from the coast to the 100 m depth isobath that marked the offshore boundary of the stratum. The modeled distribution predicted highest whale densities in King George Bay and in the waters between Weddell Island and the Passage Islands. Sei whale abundance was estimated as 716 animals (CV = 0.22; 95% CI [448, 1,144]; density = 0.20 whales/km²) using the design-based approach, and 707 animals (CV = 0.11; 95% CI [566, 877]; density = 0.20 whales/km²) using the model-based approach. For sei whales and unidentified baleen whales combined, the equivalent estimates were 916 animals (CV = 0.19; 95% CI [606, 1,384]; density = 0.26 whales/km²) and 895 animals (CV = 0.074; 95% CI [777, 1,032]; density = 0.25 whales/km²). The data indicate that the Falkland Islands inner shelf region may support globally important seasonal feeding aggregations of sei whales, and potentially qualify as a Key Biodiversity Area.     

Cephalopod remains from stomachs of sperm whales (Physeter macrocephalus) that mass‐stranded along the Oregon coast

On 16 June 1979, a herd of 41 sperm whales stranded near the mouth of the Siuslaw River in Florence, Oregon. The stomach contents from 32 whales were collected, identified to the lowest taxonomic level possible, enumerated, and measured. A total of 20,247 cephalopod lower beaks that represented 24 species from 14 different families were recovered. The most numerous species were Histioteuthis hoylei (25.9%), Taonius borealis (12.9%), Galiteuthis phyllura (11.2%), Gonatopsis/Berryteuthis type (10.9%), and Moroteuthis robusta (10.7%). Reconstructed estimates of mass indicated that M. robusta contributed almost 50% of the total mass of cephalopods consumed, followed by H. hoylei (19.3%), and T. borealis (7.0%). The most important species in the diet of stranded whales were M. robusta, H. hoylei, T. borealis, G. phyllura, Octopoteuthis deletron, and Gonatopsis/Berryteuthis type. There were significant differences in the diet of males and females, but no differences between sperm whales of different age groups. Overall, sperm whales primarily consumed small cephalopods that were likely eaten south of 45ºN in or near the California Current System. This study provides new estimates of the food habits of sperm whales in the northeast Pacific from one of the largest strandings of this species.     

Laboratory study of the susceptibility of hatchery reared Atlantic sturgeon (Acipenser oxyrinchus Mitchill, 1815) larvae to predation

The aim of the study was to determine the susceptibility to predation of Atlantic sturgeon larvae (Acipenser oxyrinchus) reared under traditional hatchery conditions. Experiments were conducted to determine whether predators would prey on Atlantic sturgeon if alternative prey was available and if the presence of substrate on the tank bottom impacted the number of Atlantic sturgeon consumed. European perch (Perca fluviatilis) was used as the predator, and the alternative prey were three‐spined stickleback (Gasterosteus aculeatus) or gudgeon (Gobio gobio). The predators and alternative prey were obtained from the wild. The mortality of sturgeon (n = 10) and alternative prey (n = 10) caused by four predators was recorded during 15 min trials. Trials with three‐spined stickleback and gudgeon as alternative prey were performed separately. Each experimental trial was repeated five times. The predators consumed significantly more Atlantic sturgeon than alternative prey in both the experimental setups when the bottom of the tank was covered with gravel and stone substrate and when there was no substrate. In trials with three‐spined stickleback the mortality of Atlantic sturgeon in both experimental setups was 94 ± 8.94%, while that of three‐spined stickleback in the setup with substrate was 20 ± 19.23%, and without substrate it was 22 ± 10.00%. European perch also consumed more Atlantic sturgeon than they did gudgeon, and the mean Atlantic sturgeon mortality in the experimental setup with substrate was 94 ± 5.48%, while for gudgeon it was 48 ± 8.37%. In the experimental setup without substrate the predators also consumed substantially more Atlantic sturgeon than gudgeon, with a mean Atlantic sturgeon mortality of 94 ± 8.94%, while for gudgeon it was 76 ± 5.48%. The study indicated that hatchery reared Atlantic sturgeon larvae are susceptible to predation by European perch. Predation could impact the survival of juvenile Atlantic sturgeon in the natural environment, and it could be one of the factors that is impeding the restoration of this species in the Baltic Sea basin.     

Stomach contents of mass-stranded short-finned pilot whales (Globicephala macrorhynchus) from North Carolina

We examined the stomach contents of 27 short‐finned pilot whales (Globicephala macrorhynchus) that mass stranded on the North Carolina coast on 15 January 2005. Eleven whales had prey parts in their forestomachs. We used frequency of occurrence and numerical abundance to assess the relative importance of prey. Brachioteuthis riisei (numerical abundance 28%), an oceanic species, was the most important cephalopod prey, but Taonius pavo (12%) and Histioteuthis reversa (9%) also represented a substantial part of the diet. A large number of otoliths belonging to the fish Scopelogadus beanii were present (25%). These results differ from reports of the stomach contents of short‐finned pilot whales from the Pacific coast in which neritic species dominate the diet. Our findings also suggest that there is a considerable difference between the diet of short‐ and long‐finned pilot whales (Globicephala melas) in the western North Atlantic. The latter feed predominantly on the long‐finned squid (Loligo pealei) whereas the former feed on deep‐water species. Our results indicate the whales fed primarily off the continental shelf prior to stranding.     

Fatty acid‐based diet estimates suggest ringed seal remain the main prey of southern Beaufort Sea polar bears despite recent use of onshore food resources

Polar bears (Ursus maritimus) from the southern Beaufort Sea (SB) subpopulation have traditionally fed predominantly upon ice‐seals; however, as the proportion of the subpopulation using onshore habitat has recently increased, foraging on land‐based resources, including remains of subsistence‐harvested bowhead whales (Balaena mysticetus) and colonial nesting seabirds has been observed. Adipose tissue samples were collected from this subpopulation during the springs of 2013–2016 and analyzed for fatty acid signatures. Diet estimates were generated for the proportional consumption of ringed seal (Pusa hispida), bearded seal (Erignathus barbatus), and beluga whale (Delphinapterus leucas), relative to onshore foods, including bowhead whale remains and seabird, as represented by black guillemot (Cepphus grylle mandtii) nestlings and eggs. Quantitative fatty acid signature analysis (QFASA) estimated that the ice‐obligate prey, ringed seal, remained the predominant prey species of SB polar bears (46.4 ± 1.8%), with much lower consumption of bearded seal (19.6 ± 2.0%), seabird (17.0 ± 1.2%), bowhead whale (15.0 ± 1.4%), and hardly any beluga whale (2.0 ± 0.5%). Adult and subadult females appeared to depend more on the traditional ringed seal prey than adult and subadult males. Diet estimates of SB polar bears showed significant interannual variability for all prey (F_{12, 456} = 3.17, p < .001). Longer‐term estimates suggested that both types of onshore prey, bowhead whale remains and seabird, have represented a moderate proportion of the food resources used by SB polar bears since at least the start of the 21st Century.     

Population structure and possible migratory links of common minke whales, Balaenoptera acutorostrata, in the Southern Hemisphere

Mitochondrial DNA control region sequences were analyzed to investigate population structure and possible migratory links of common minke whales (Balaenoptera acutorostrata) in two ocean basins: western South Atlantic (WSA) and western South Pacific (WSP). The results of several different phylogenetic estimations consistently grouped all haplotypes but one (n = 1) from these two ocean basins into two separate clades. South and North Atlantic haplotypes were more closely related to each other than either was to haplotypes from the WSP. The interpopulation genetic distance between WSA and WSP whales was similar to that reported between North Pacific and North Atlantic common minke whales (0.0234). The migration rate between the two ocean basins was estimated at near-zero using MDIV. The genetic evidence presented here was consistent with the hypothesis of migratory links among Brazil, Chilean Patagonia and the Antarctic Peninsula, and between low-latitude and Antarctic waters of the WSP. The results suggest multiple populations of common minke whales in the Southern Hemisphere, which may have conservation as well as taxonomic implications. Our single locus results should be corroborated by additional analyses in a larger number of samples and at more genetic markers.     

Some like it cold: Temperature‐dependent habitat selection by narwhals

The narwhal (Monodon monoceros) is a high‐Arctic species inhabiting areas that are experiencing increases in sea temperatures, which together with reduction in sea ice are expected to modify the niches of several Arctic marine apex predators. The Scoresby Sound fjord complex in East Greenland is the summer residence for an isolated population of narwhals. The movements of 12 whales instrumented with Fastloc‐GPS transmitters were studied during summer in Scoresby Sound and at their offshore winter ground in 2017–2019. An additional four narwhals provided detailed hydrographic profiles on both summer and winter grounds. Data on diving of the whales were obtained from 20 satellite‐linked time‐depth recorders and 16 Acousonde? recorders that also provided information on the temperature and depth of buzzes. In summer, the foraging whales targeted depths between 300 and 850 m where the preferred areas visited by the whales had temperatures ranging between 0.6 and 1.5°C (mean = 1.1°C, SD = 0.22). The highest probability of buzzing activity during summer was at a temperature of 0.7°C and at depths > 300 m. The whales targeted similar depths at their offshore winter ground where the temperature was slightly higher (range: 0.7–1.7°C, mean = 1.3°C, SD = 0.29). Both the probability of buzzing events and the spatial distribution of the whales in both seasons demonstrated a preferential selection of cold water. This was particularly pronounced in winter where cold coastal water was selected and warm Atlantic water farther offshore was avoided. It is unknown if the small temperature niche of whales while feeding is because prey is concentrated at these temperature gradients and is easier to capture at low temperatures, or because there are limitations in the thermoregulation of the whales. In any case, the small niche requirements together with their strong site fidelity emphasize the sensitivity of narwhals to changes in the thermal characteristics of their habitats.     

Blue whale population structure along the eastern South Pacific Ocean: evidence of more than one population

Blue whales (Balaenoptera musculus) were among the most intensively exploited species of whales in the world. As a consequence of this intense exploitation, blue whale sightings off the coast of Chile were uncommon by the end of the 20th century. In 2004, a feeding and nursing ground was reported in southern Chile (SCh). With the aim to investigate the genetic identity and relationship of these Chilean blue whales to those in other Southern Hemisphere areas, 60 biopsy samples were collected from blue whales in SCh between 2003 and 2009. These samples were genotyped at seven microsatellite loci and the mitochondrial control region was sequenced, allowing us to identify 52 individuals. To investigate the genetic identity of this suspected remnant population, we compared these 52 individuals to blue whales from Antarctica (ANT, n = 96), Northern Chile (NCh, n = 19) and the eastern tropical Pacific (ETP, n = 31). No significant differentiation in haplotype frequencies (mtDNA) or among genotypes (nDNA) was found between SCh, NCh and ETP, while significant differences were found between those three areas and Antarctica for both the mitochondrial and microsatellite analyses. Our results suggest at least two breeding population units or subspecies exist, which is also supported by other lines of evidence such as morphometrics and acoustics. The lack of differences detected between SCh/NCh/ETP areas supports the hypothesis that eastern South Pacific blue whales are using the ETP area as a possible breeding area. Considering the small population sizes previously reported for the SCh area, additional conservation measures and monitoring of this population should be developed and prioritized.     

Short-finned pilot whales in the South China Sea: Insights into regional distribution,movement pattern,and habitat characteristics

Little scientific knowledge is available for short-finned pilot whales in the South China Sea (SCS). Here, we integrated historical records, ship-based observation, and satellite-tagging data to investigate ecological and behavioral characteristics of pilot whales in the SCS. Historical records since the 1990s showed the widespread spatial occurrence of pilot whales along the coastal SCS, suggesting that the species may inhabit this region. During our dedicated ship-based surveys (2019–2022) in the SCS, 19 groups of pilot whales were encountered in Xisha-Zhongsha waters, which supported the hypothesis inferred from historical data. We believe that Xisha-Zhongsha waters are important habitats for pilot whales, demonstrated by the large group size (M = 44.7 ± 42.4 SD individuals), the high proportion of recorded maternal groups (17/19), mixed-species associations, and deep-water habitat characteristics. During field surveys, we conducted satellite-tagging experiments on two adult pilot whales, with tracking periods of 35 and 13 days, respectively. Satellite-tracking data provided evidence of possible residency of the tagged whales, as both displayed overlapping ranges and nondirectional movement. This research provides preliminary baseline data on occurrence, distribution, movement, habitat use, and likely residency of pilot whales in the SCS, which can facilitate future research and conservation effort.     

Ocean nomads: Distribution and movements of sperm whales in the North Pacific shown by whaling data and Discovery marks

We investigated the distribution and movements of sperm whales (Physeter macrocephalus) in the North Pacific by analyzing whaling data and movement data of whales marked with Discovery marks. Prior studies suggested that there were discrete “stocks” of sperm whales, assuming that the intervals between historical areas of concentration indicated subpopulation boundaries. Our analyses clearly refute this assumption: whaling and marking data suggest no obvious divisions between separate demes or stocks within the North Pacific. Sperm whales appear to be nomadic and show widespread movements between areas of concentration, with documented movements of over 5,000 km, time spans between marking and recovery over 20 yr, and ranges that cover many thousand km². Males appear to range more widely than females. Sperm whales likely travel in response to geographical and temporal variations in the abundance of medium‐ and large‐sized pelagic squids, their primary prey. Our analyses demonstrate that males and females concentrated seasonally in the Subtropical Frontal Zone (ca. 28ºN–34ºN) and the Subarctic Frontal Zone (ca. 40ºN–43ºN), and males also concentrated seasonally near the Aleutian Islands and along the Bering Sea shelf edge. It appears that the sperm whales targeted by the pelagic whalers range widely across this ocean basin.     

Sequence analysis of three canine adipokine genes revealed an association between TNF polymorphisms and obesity in Labrador dogs

Obesity is an emerging health problem in purebred dogs. Due to their crucial role in energy homeostasis control, genes encoding adipokines are considered candidate genes, and their variants may be associated with predisposition to obesity. Searching for polymorphism was carried out in three adipokine genes (TNF, RETN and IL6). The study was performed on 260 dogs, including lean (n = 109), overweight (n = 88) and obese (n = 63) dogs. The largest cohort was represented by Labrador Retrievers (n = 136). Altogether, 24 novel polymorphisms were identified: 12 in TNF (including one missense SNP), eight in RETN (including one missense SNP) and four in IL6. Distributions of five common SNPs (two in TNF, two in RETN and one in IL6) were further analyzed with regard to body condition score. Two SNPs in the non‐coding parts of TNF (c.‐40A>C and c.233+14G>A) were associated with obesity in Labrador dogs. The obtained results showed that the studied adipokine genes are highly polymorphic and two polymorphisms in the TNF gene may be considered as markers predisposing Labrador dogs to obesity.     

Spondias mombin L. attenuates ventricular remodelling after myocardial infarction associated with oxidative stress and inflammatory modulation

The objective of this study was to evaluate Spondias mombin L. (SM) pulp and its influence on cardiac remodelling after myocardial infarction (MI). Male Wistar rats were assigned to four groups: a sham group (animals underwent simulated surgery) that received standard chow (S; n = 20), an infarcted group that received standard chow (MI; n = 24), an infarcted group supplemented with 100 mg of SM/kg bodyweight/d, (MIS100; n = 23) and an infarcted group supplemented with 250 mg of SM/kg bodyweight/d (MIS250; n = 22). After 3 months of treatment, morphological, functional and biochemical analyses were performed. MI induced structural and functional changes in the left ventricle with worsening systolic and diastolic function, and SM supplementation at different doses did not influence these variables as analysed by echocardiography and an isolated heart study (P > .05). However, SM supplementation attenuated cardiac remodelling after MI, reducing fibrosis (P = .047) and hypertrophy (P = .006). Biomarkers of oxidative stress, inflammatory processes and energy metabolism were further investigated in the myocardial tissue. SM supplementation improved the efficiency of energy metabolism and decreased lipid hydroperoxide in the myocardium [group S (n = 8): 267.26 ± 20.7; group MI (n = 8): 330.14 ± 47.3; group MIS100 (n = 8): 313.8 ± 46.2; group MIS250: 294.3 ± 38.0 nmol/mg tissue; P = .032], as well as decreased the activation of the inflammatory pathway after MI. In conclusion, SM supplementation attenuated cardiac remodelling processes after MI. We also found that energy metabolism, oxidative stress and inflammation are associated with this effect. In addition, SM supplementation at the highest dose is more effective.     

Stomach content analysis of juvenile, scalloped hammerhead shark Sphyrna lewini captured off the coast of Mazatlán, Mexico

We quantified the diet of juvenile, scalloped hammerhead shark Sphyrna lewini in the area off Mazatlan, Sinaloa, Mexico, to understand their feeding ecology this shark. The prey species of Sphyrna lewini were identified and quantified from stomach content analysis. In addition, we determined the variations between genders. During two fishing seasons (2000–2001 and 2001–2002), we analyzed 232 stomachs, of which 85% contained food. The trophic spectrum was composed of three species of cephalopods, six of crustaceans and 19 species of fish from mainly pelagic and benthic habitats. According to the Index of Relative Importance (%IRI), the cephalopod Loliolopsis diomedeae with IRI = 18%, fish of the family Carangidae IRI = 25% and family Synodontidae IRI = 19% constituted the main prey in general. The trophic niche width was <0.4, which indicated that S. lewini juveniles in this area feed on a wide range of prey items, though they showed a preference for a few prey items.     

Cryptic speciation in the field vole: a multilocus approach confirms three highly divergent lineages in Eurasia

Species are generally described from morphological features, but there is growing recognition of sister forms that show substantial genetic differentiation without obvious morphological variation and may therefore be considered ‘cryptic species’. Here, we investigate the field vole (Microtus agrestis), a Eurasian mammal with little apparent morphological differentiation but which, on the basis of previous sex‐linked nuclear and mitochondrial DNA (mtDNA) analyses, is subdivided into a Northern and a Southern lineage, sufficiently divergent that they may represent two cryptic species. These earlier studies also provided limited evidence for two major mtDNA lineages within Iberia. In our present study, we extend these findings through a multilocus approach. We sampled 163 individuals from 46 localities, mainly in Iberia, and sequenced seven loci, maternally, paternally and biparentally inherited. Our results show that the mtDNA lineage identified in Portugal is indeed a distinct third lineage on the basis of other markers as well. In fact, multilocus coalescent‐based methods clearly support three separate evolutionary units that may represent cryptic species: Northern, Southern and Portuguese. Divergence among these units was inferred to have occurred during the last glacial period; the Portuguese lineage split occurred first (estimated at c. 70 000 bp ), and the Northern and Southern lineages separated at around the last glacial maximum (estimated at c. 18 500 bp ). Such recent formation of evolutionary units that might be considered species has repercussions in terms of understanding evolutionary processes and the diversity of small mammals in a European context.