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High genetic diversity in a small population: the case of Chilean blue whales.
Ecol Evol. 2014 Apr;4(8):1398-412
Authors: Torres-Florez JP, Hucke-Gaete R, Rosenbaum H, Figueroa CC
Abstract It is generally assumed that species with low population sizes have lower genetic diversities than larger populations and vice versa. However, this would not be the case for long-lived species with long generation times, and which populations have declined due to anthropogenic effects, such as the blue whale (Balaenoptera musculus). This species was intensively decimated globally to near extinction during the 20th century. Along the Chilean coast, it is estimated that at least 4288 blue whales were hunted from an apparently pre-exploitation population size (k) of a maximum of 6200 individuals (Southeastern Pacific). Thus, here, we describe the mtDNA (control region) and nDNA (microsatellites) diversities of the Chilean blue whale aggregation site in order to verify the expectation of low genetic diversity in small populations. We then compare our findings with other blue whale aggregations in the Southern Hemisphere. Interestingly, although the estimated population size is small compared with the pre-whaling era, there is still considerable genetic diversity, even after the population crash, both in mitochondrial (N = 46) and nuclear (N = 52) markers (Hd = 0.890 and Ho = 0.692, respectively). Our results suggest that this diversity could be a consequence of the long generation times and the relatively short period of time elapsed since the end of whaling, which has been observed in other heavily-exploited whale populations. The genetic variability of blue whales on their southern Chile feeding grounds was similar to that found in other Southern Hemisphere blue whale feeding grounds. Our phylogenetic analysis of mtDNA haplotypes does not show extensive differentiation of populations among Southern Hemisphere blue whale feeding grounds. The present study suggests that although levels of genetic diversity are frequently used as estimators of population health, these parameters depend on the biology of the species and should be taken into account in a monitoring framework study to obtain a more complete picture of the conservation status of a population.
PMID: 24834336 [PubMed]
There are serious global conservation concerns for inshore dolphin species, but the status of species in north Australian waters is poorly understood. Over a 2.9-year period, we estimated population size of the Australian snubfin (Orcaella heinsohni), humpback (Sousa sp.) and bottlenose (Tursiops sp.) at a remote and largely unmodified site in the Northern Territory, Australia. This study contributes to a better understanding of the conservation status of these three species, provides one of the few benchmarks against which population size in impacted areas can be compared, and will help guide methodologies for environmental impact assessments for the projected rapid development of much of the north Australian coastline. Photograph by Carol Palmer.
For decades, submariners and scientists have been puzzled by a strange, low-frequency quacking sound emanating through ocean waters. Now, researchers have finally pinpointed the 'bio-duck' sound's origin.
Evidence for vocal learning in juvenile male killer whales, Orcinus orca, from an adventitious cross-socializing experiment.
J Exp Biol. 2014 Apr 15;217(Pt 8):1229-37
Authors: Crance JL, Bowles AE, Garver A
Abstract Killer whales (Orcinus orca) are thought to learn their vocal dialect. Dispersal in the species is rare, but effects of shifts in social association on the dialect can be studied under controlled conditions. Individual call repertoires and social association were measured in three adult female killer whales and three males (two juveniles and an adult) during two periods, 2001-2003 and 2005-2006. Three distinct dialect repertoires were represented among the subjects. An adventitious experiment in social change resulted from the birth of a calf and the transfer of two non-focal subjects in 2004. Across the two periods, 1691 calls were collected, categorized and attributed to individuals. Repertoire overlap for each subject dyad was compared with an index of association. During 2005-2006, the two juvenile males increased association with the unrelated adult male. By the end of the period, both had begun producing novel calls and call features characteristic of his repertoire. However, there was little or no reciprocal change and the adult females did not acquire his calls. Repertoire overlap and association were significantly correlated in the first period. In the second, median association time and repertoire similarity increased, but the relationship was only marginally significant. The results provided evidence that juvenile male killer whales are capable of learning new call types, possibly stimulated by a change in social association. The pattern of learning was consistent with a selective convergence of male repertoires.
PMID: 24744421 [PubMed - in process]
Wintering Habitat Model for the North Atlantic Right Whale (Eubalaena glacialis) in the Southeastern United States.
PLoS One. 2014;9(4):e95126
Authors: Gowan TA, Ortega-Ortiz JG
Abstract The coastal waters off the southeastern United States (SEUS) are a primary wintering ground for the endangered North Atlantic right whale (Eubalaena glacialis), used by calving females along with other adult and juvenile whales. Management actions implemented in this area for the recovery of the right whale population rely on accurate habitat characterization and the ability to predict whale distribution over time. We developed a temporally dynamic habitat model to predict wintering right whale distribution in the SEUS using a generalized additive model framework and aerial survey data from 2003/2004 through 2012/2013. We built upon previous habitat models for right whales in the SEUS and include data from new aerial surveys that extend the spatial coverage of the analysis, particularly in the northern portion of this wintering ground. We summarized whale sightings, survey effort corrected for probability of whale detection, and environmental data at a semimonthly resolution. Consistent with previous studies, sea surface temperature (SST), water depth, and survey year were significant predictors of right whale relative abundance. Additionally, distance to shore, distance to the 22°C SST isotherm, and an interaction between time of year and latitude (to account for the latitudinal migration of whales) were also selected in the analysis presented here. Predictions from the model revealed that the location of preferred habitat differs within and between years in correspondence with variation in environmental conditions. Although cow-calf pairs were rarely sighted in the company of other whales, there was minimal evidence that the preferred habitat of cow-calf pairs was different than that of whale groups without calves at the scale of this study. The results of this updated habitat model can be used to inform management decisions for a migratory species in a dynamic oceanic environment.
PMID: 24740091 [PubMed - in process]
Scientists used satellite tags to track Cuvier's beaked whales as they dove to depths of up to 9,816 feet and held their breath for more than two hours.
Pleistocene survival of an archaic dwarf baleen whale (Mysticeti: Cetotheriidae).
Naturwissenschaften. 2013 Apr;100(4):365-71
Authors: Boessenecker RW
Abstract Pliocene baleen whale assemblages are characterized by a mix of early records of extant mysticetes, extinct genera within modern families, and late surviving members of the extinct family Cetotheriidae. Although Pleistocene baleen whales are poorly known, thus far they include only fossils of extant genera, indicating Late Pliocene extinctions of numerous mysticetes alongside other marine mammals. Here a new fossil of the Late Neogene cetotheriid mysticete Herpetocetus is reported from the Lower to Middle Pleistocene Falor Formation of Northern California. This find demonstrates that at least one archaic mysticete survived well into the Quaternary Period, indicating a recent loss of a unique niche and a more complex pattern of Plio-Pleistocene faunal overturn for marine mammals than has been previously acknowledged. This discovery also lends indirect support to the hypothesis that the pygmy right whale (Caperea marginata) is an extant cetotheriid, as it documents another cetotheriid nearly surviving to modern times.
PMID: 23525578 [PubMed - indexed for MEDLINE]
Long-Range Movement of Humpback Whales and Their Overlap with Anthropogenic Activity in the South Atlantic Ocean.
Conserv Biol. 2014 Feb 4;
Authors: Rosenbaum HC, Maxwell SM, Kershaw F, Mate B
Abstract Humpback whales (Megaptera novaeangliae) are managed by the International Whaling Commission as 7 primary populations that breed in the tropics and migrate to 6 feeding areas around the Antarctic. There is little information on individual movements within breeding areas or migratory connections to feeding grounds. We sought to better understand humpback whale habitat use and movements at breeding areas off West Africa, and during the annual migration to Antarctic feeding areas. We also assessed potential overlap between whale habitat and anthropogenic activities. We used Argos satellite-monitored radio tags to collect data on 13 animals off Gabon, a primary humpback whale breeding area. We quantified habitat use for 3 cohorts of whales and used a state-space model to determine transitions in the movement behavior of individuals. We developed a spatial metric of overlap between whale habitat and models of cumulative human activities, including oil platforms, toxicants, and shipping. We detected strong heterogeneity in movement behavior over time that is consistent with previous genetic evidence of multiple populations in the region. Breeding areas for humpback whales in the eastern Atlantic were extensive and extended north of Gabon late in the breeding season. We also observed, for the first time, direct migration between West Africa and sub-Antarctic feeding areas. Potential overlap of whale habitat with human activities was the highest in exclusive economic zones close to shore, particularly in areas used by both individual whales and the hydrocarbon industry. Whales potentially overlapped with different activities during each stage of their migration, which makes it difficult to implement mitigation measures over their entire range. Our results and existing population-level data may inform delimitation of populations and actions to mitigate potential threats to whales as part of local, regional, and international management of highly migratory marine species. CuantificaciÃ³n de los Movimientos de Gran Amplitud y el Traslape Potencial con Actividad AntropogÃ©nica y las Ballenas Jorobadas en el OcÃ©ano AtlÃ¡ntico Sur.
PMID: 24495092 [PubMed - as supplied by publisher]
A speculative life rendering of the fossil whale Balaenoptera bertae unearthed in the San Francisco Bay Area.
The whale belongs within the same genus as minke and fin whales, indicating... The pre-Ice Age marine mammal community of the North Pacific formed a strangely eclectic scene, research by a Geology PhD student at New Zealand's University of Otago reveals.
Accounting for female reproductive cycles in a superpopulation capture-recapture framework.
Ecol Appl. 2013 Oct;23(7):1677-90
Authors: Carroll EL, Childerhouse SJ, Fewster RM, Patenaude NJ, Steel D, Dunshea G, Boren L, Baker CS
Abstract Superpopulation capture-recapture models are useful for estimating the abundance of long-lived, migratory species because they are able to account for the fluid nature of annual residency at migratory destinations. Here we extend the superpopulation POPAN model to explicitly account for heterogeneity in capture probability linked to reproductive cycles (POPAN-tau). This extension has potential application to a range of species that have temporally variable life stages (e.g., non-annual breeders such as albatrosses and baleen whales) and results in a significant reduction in bias over the standard POPAN model. We demonstrate the utility of this model in simultaneously estimating abundance and annual population growth rate (lamda) in the New Zealand (NZ) southern right whale (Eubalaena australis) from 1995 to 2009. DNA profiles were constructed for the individual identification of more than 700 whales, sampled during two sets of winter expeditions in 1995-1998 and 2006-2009. Due to differences in recapture rates between sexes, only sex-specific models were considered. The POPAN-tau models, which explicitly account for a decrease in capture probability in non-calving years, fit the female data set significantly better than do standard superpopulation models (deltaAIC > 25). The best POPAN-tau model (AIC) gave a super-population estimate of 1162 females for 1995-2009 (95% CL 921, 1467) and an estimated annual increase of 5% (95% CL--2%, 13%). The best model (AIC) gave a superpopulation estimate of 1007 males (95% CL 794, 1276) and an estimated annual increase of 7% (95% CL 5%, 9%) for 1995-2009. Combined, the total superpopulation estimate for 1995-2009 was 2169 whales (95% CL 1836, 2563). Simulations suggest that failure to account for the effect of reproductive status on the capture probability would result in a substantial positive bias (+19%) in female abundance estimates.
PMID: 24261048 [PubMed - in process]
For those titillated by Strangelovian fantasies of nuclear apocalypse, the early 1980s were a golden age. That was the height of the Cold War, when nuclear arms and rhetoric escalated, and President Ronald Reagan envisioned a space-based anti-missile “shield”–promptly dubbed “Star Wars” by skeptics–that could thwart attacks by the “Evil Empire,” also known as the Soviet Union.
Late last week Texas public health officials confirmed a new wave of dengue fever has cropped up in the southernmost tip of Texas, marking the first outbreak the state has seen since 2005. The news came on the heels of reporting in Scientific American about how scientists are trying to uncover why the mosquito-borne infection is cropping up in Florida but not in other regions of the nation that host the same Aedes aegypti species of dengue-carrying mosquitoes.
GENETIC AND MORPHOLOGICAL APPROACHES DISTINGUISH THE THREE SIBLING SPECIES OF THE ANISAKIS SIMPLEX SPECIES COMPLEX, WITH A SPECIES DESIGNATION AS ANISAKIS BERLANDI N. SP. FOR A. SIMPLEX SP. C (NEMATODA: ANISAKIDAE).
J Parasitol. 2013 Nov 13;
Authors: Mattiucci S, Cipriani P, Webb SC, Paoletti M, Marcer F, Bellisario B, Gibson DI, Nascetti G
Abstract Abstract Numerous specimens of the three sibling species of the Anisakis simplex species complex (A. pegreffii, A. simplex (sensu stricto) and A. simplex sp. C), recovered from cetacean species stranded within the known geographical ranges of these nematodes, were studied morphologically and genetically. The genetic characterization was performed on diagnostic allozymes and sequences analysis of nuclear (ITS of rDNA) and mitochondrial (mtDNA cox2 and rrnS) genes. These markers showed: (i) the occurrence of sympatry of the two sibling species A. pegreffii and A. simplex sp. C in the same individual host, the pilot whale Globicephala melas, from New Zealand waters; (ii) the identification of specimens of A. pegreffii in the striped dolphin Stenella coeruleoalba from the Mediterranean Sea; (iii) the presence of A. simplex (s. s.) in the pilot whale G. melas and the minke whale Balaenoptera acutorostrata from the NE Atlantic waters. No F1 hybrids were detected among the three species using the nuclear markers. The phylogenetic inference, obtained by Maximum Parsimony (MP) analysis of separate nuclear (ITS rDNA region), combined mitochondrial (mtDNA cox2 and rrnS) sequences datasets, and by concatenated analysis obtained at both Maximum Parsimony (MP) and Bayesian (BI) phylogenetic inference of the sequences datasets at the three studied genes, resulted in a similar topology. They were congruent in depicting the existence of the three species as distinct phylogenetic lineages, and the tree topologies support the finding that A. simplex (s. s.), A. pegreffii and A. berlandi n. sp. (= A. simplex sp. C) represent a monophyletic group. The morphological and morphometric analyses revealed the presence of morphological features that differed between the three biological species. Morphological analysis using Principle Component Analysis, and Procrustes Analysis, combining morphological and genetic datasets, showed the specimens clustering into three well-defined groups. Nomenclatural designation and formal description are given for A. simplex species C: the name Anisakis berlandi n. sp. is proposed. Key morphological diagnostic traits are: between A. berlandi n. sp. and A. simplex (s. s.): ventriculus length, tail shape, tail length/total body length ratio and left spicule length/total body length ratio; between A. berlandi n. sp. and A. pegreffii: ventriculus length and plectane 1 width/plectane 3 width ratio; and between A. simplex (s. s.) and A. pegreffii: ventriculus length, left and right spicule length/total body length ratios and tail lengthy/total body length ratio. Ecological data pertaining to the geographical ranges and host distribution of the three species are updated.
PMID: 24224764 [PubMed - as supplied by publisher]