[MARMAM] New publication: Narrow Acoustic Field of View Drives Frequency Scaling in Toothed Whale Biosonar

[Frants Jensen]

Dear MARMAM,

On behalf of my co-authors, I am pleased to announce our new paper
investigating scaling of toothed whale biosonar to evaluate the
evolutionary drivers of aquatic biosonar operation:

Jensen F. H., Johnson M., Ladegaard M., Wisniewska D., Madsen P. T.: Narrow
acoustic field of view drives frequency scaling in toothed whale biosonar.
Current Biology (2018), https://doi.org/10.1016/j.cub.2018.10.037

*Abstract: *Toothed whales are apex predators varying in size from 40-kg
porpoises to 50-ton sperm whales that all forage by emitting high-amplitude
ultrasonic clicks and listening for weak returning echoes. The sensory
field of view of these echolocating animals depends on the characteristics
of the biosonar signals and the morphology of the sound generator, yet it
is poorly understood how these biophysical relationships have shaped the
evolution of biosonar parameters as toothed whales adapted to different
foraging niches. Here we test how biosonar output, frequency, and
directivity vary with body size to understand the co-evolution of biosonar
signals and sound-generating structures. We show that the radiated power
increases twice as steeply with body mass (P ∝ M1.47 ± 0.25) than expected
from typical scaling laws of call intensity, indicating an evolutionary
hyperallometric investment into sound production structures that may be
driven by a strong selective pressure for long-range biosonar. We find that
biosonar frequency scales inversely with body size (F ∝ M−0.19 ± 0.03),
resulting in remarkably stable biosonar beamwidth that is independent of
body size. We discuss why the three main hypotheses for inverse frequency
scaling in animal communication signals do not explain frequency scaling in
toothed whale biosonar. We instead propose that a narrow acoustic field of
view, analogous to the fovea of many visual predators, is the primary
evolutionary driver of biosonar frequency in toothed whales, serving as a
spatial filter to reduce clutter levels and facilitate long-range prey
detection.

The paper is available via the following link:
https://www.cell.com/current-biology/fulltext/S0960-9822(18)31366-6

Please email me on frants.jen...@gmail.com for a pdf copy.

Best regards,
Frants Jensen
- - - - -
Frants Havmand Jensen
Associate Lecturer
Scottish Oceans Institute
St. Andrews University
Scotland, UK
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[MARMAM] Application open for thesis projects: ecology and behaviour of marine mammals and marine birds in Spain

[Bruno Diaz Lopez]

The Bottlenose Dolphin Research Institute (hereafter BDRI) offers a limited 
number of independent studies to advanced undergraduate and graduate students 
(bachelor and master students). 

The BDRI invites applications for thesis projects in a dynamic, international, 
and competitive research environment (i.e. we use the term “thesis” 
synonymously with “dissertation” and “report”). The main research topics of the 
BDRI include marine mammal ecology, ethology, ecological modelling and 
bioacoustics (on dolphins, porpoises, baleen whales and otters in Atlantic 
waters) in different parts of the world, as well as marine bird ecology. Highly 
motivated bachelor and master students in the fields of zoology, marine 
biology, veterinary and related disciplines are invited to apply for a thesis 
project at the BDRI. 

We do not confer degrees but rather provide a research environment including a 
fully equipped and staffed laboratory, accommodation, and training in the field 
under the mentorship of experienced marine scientists. The BDRI offers to the 
students the chance to work through the many steps of research, collecting the 
data on the field, and analysing the data at the lab.

To carry out a project with the BDRI means that our students will concentrate 
on and analyse specific data from our already-existing long-term research 
dataset. Students will participate in the data collection of our on-going 
marine mammal and marine bird research program in Galician waters (Spain) and 
will receive supervision from both Bruno Díaz López, PhD (Director and Chief 
Biologist) and Séverine Methion, MSc (Principal Investigator and Marine 
Ecologist). The BDRI office is located in a pleasant research centre located in 
O Grove, Galicia (Spain). The institute and research vessel are equipped with 
the state-of-the-art technology, and the study area has especially good 
conditions for marine mammals and marine birds research. The BDRI is a very 
international environment, and the everyday working language is English. 
 
Below you can see a list of the project topics that will be offered in 2019 at 
BDRI’s headquarters in Spain:

CETACEAN ECOLOGY. These projects include spatial analysis and creation of 
models from cetacean distribution data recorded in Atlantic waters (Galicia, 
Spain). Outcomes of these studies will provide more information on the 
distribution of cetacean species in Galicia, and about the impact of human 
activities on cetacean distribution. Applicants should have a strong interest 
in GIS or modelling.

CETACEAN BEHAVIOUR. These projects include analysis of behavioural data about 
cetaceans recorded in Atlantic waters (Galicia, Spain). Outcomes of these 
studies will provide important information on individual and group behaviour of 
these species, as well as information on the impact of human activities on 
their behaviour. Applicants should have a strong interest in ethology and 
conservation.

BOTTLENOSE DOLPHIN COMMUNICATION. These projects include analysis of 
bio-acoustical and behavioural data recorded from a study area characterized by 
different levels of anthropogenic impact (Atlantic waters or Mediterranean 
waters). Outcomes of these studies will provide more information on the 
function of specific social vocalisations and influence of the environment and, 
in some cases anthropogenic activities. Applicants should have a strong 
interest in bioacoustics. 
 
BOTTLENOSE DOLPHIN SOCIETY and MARK-RECAPTURE. These projects include analysis 
of mark-recapture data about bottlenose dolphins or common dolphins recorded in 
Atlantic waters (Galicia, Spain). Outcomes of these studies will provide more 
information about dolphin society and, in some cases the impact caused by human 
activities. Applicants should have a strong interest in photo- identification 
and social studies. 
 
DOLPHIN SKIN PIGMENTATION AND BODY MARKS. These projects include analysis of 
photographic data (bottlenose dolphins and common dolphins) recorded in 
Atlantic waters (Galicia, Spain). Outcomes of these studies will provide more 
information about cetacean external body conditions, taking into account intra- 
and inter-specific interactions, infections, diseases and in some cases the 
impact caused by human activities. Applicants should have a strong interest in 
photographic analysis, veterinary, and conservation.
 
MARINE BIRD ECOLOGY. These projects include spatial analysis and creation of 
models from data about marine birds recorded in Atlantic waters (Galicia, 
Spain). Outcomes of these studies will provide more information about marine 
bird distribution (seagulls, cormorant, shag, waders, auks and more) and the 
impact caused by human activities. Applicants should have a strong interest in 
GIS or modelling.
 
FEEDING ECOLOGY OF EURASIAN OTTER. This project include data recorded in 
Atlantic waters in 2018. Outcomes of these studies will provide more 
information about European otter (Lutra lutra) feeding 

[MARMAM] New Publication: "Demography and genetics suggest reversal of dolphin source-sink dynamics, with implications for conservation"

[Oliver Manlik]

Dear colleagues,

on behalf of my co-authors, I am pleased to announce the following publication 
on population structure, gene flow and dispersal of bottlenose dolphin 
(Tursiops aduncus) populations:


Manlik O, Chabanne D, Daniel C, Bejder L, Allen SJ, Sherwin WB. 2018. 
Demography and genetics suggest reversal of dolphin source-sink dynamics, with 
implications for conservation. Marine Mammal Science, doi:10./mms.12555.

https://onlinelibrary.wiley.com/doi/10./mms.12555


In short:

Our analysis of dolphin genes has revealed information about their past 
migrations, showing just how crucial migrants might be for other populations. 
The new study, published in the journal Marine Mammal Science, is an 
illustration of how modern genetics can use information from genes to gain a 
glimpse into the past, unravelling past migration patterns of animals, and 
therefore help inform the future.


Abstract:

The forecast for the viability of populations depends upon metapopulation 
dynamics: the combination of reproduction and mortality within populations, as 
well as dispersal between populations. This study focuses on an Indo‐Pacific 
bottlenose dolphin (Tursiops aduncus) population in coastal waters near 
Bunbury, Western Australia. Demographic modeling of this population suggested 
that recent reproductive output was not sufficient to offset mortality. 
Migrants from adjacent populations might make up this deficit, so that Bunbury 
would act as a “sink,” or net recipient population. We investigated historical 
dispersal in and out of Bunbury, using microsatellites and mitochondrial DNA of 
193 dolphins across five study locations along the southwestern Australian 
coastline. Our results indicated limited gene flow between Bunbury and adjacent 
populations. The data also revealed a net‐dispersal from Bunbury to neighboring 
populations, with microsatellites showing that more than twice as many 
individuals per generation dispersed out of Bunbury than into Bunbury. 
Therefore, in historic times, Bunbury appears to have acted as a source 
population, supporting nearby populations. In combination with the prior 
finding that Bunbury is currently not producing surplus offspring to support 
adjacent populations, this potential reversal of source‐sink dynamics may have 
serious conservation implications for Bunbury and other populations nearby.


For questions or details about publication feel free to contact me at: 
oliver.man...@uaue.ac.ae (or: o.man...@unsw.edu.au)


Cheers, Oliver Manlik


Dr. Oliver Manlik
Conjoint Associate Lecturer
Ecology and Evolution Research Centre
Biological, Earth and Environmental Sciences (BEES)
University of New South Wales
Sydney, NSW 2052
Australia

E-mail: o.man...@unsw.edu.au
www.bees.unsw.edu.au/oliver-manlik
--

Assistant Professor,
Biology Department, College of Science,
United Arab Emirate University, UAE

E-mail: oliver.man...@uaeu.ac.ae


---
Researchgate Profile 


Twitter: @OManlik

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