PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

'Severe reduction' in killer whale numbers during last Ice Age

2014-02-05
(Press-News.org) Contact information: Leighton Kitson
leighton.kitson@durham.ac.uk
44-019-133-46074
Durham University
'Severe reduction' in killer whale numbers during last Ice Age

Whole genome sequencing has revealed a global fall in the numbers of killer whales during the last Ice Age, at a time when ocean productivity may have been widely reduced, according to researchers at Durham University.

The scientists studied the DNA sequences of killer whale communities across the world.

They found a severe decline in whale numbers leading to a bottleneck and consequent loss of genetic diversity approximately 40,000 years ago when large parts of the Earth were covered in ice.

The only exception to this was found in a killer whale population off the coast of South Africa that retained high variations in genetic diversity.

As greater genetic diversity indicates larger population size, the researchers believe the South African community of killer whales escaped the bottleneck faced by other communities.

They said an important factor could have been the Bengeula upwelling system – which delivers nutrient rich cold water to the oceans off South Africa – remaining stable despite the last glacial period.

This nutrient rich water would have been able to sustain the supplies of fish and dolphins that killer whales in this part of the world feed on.

The researchers added that other major upwelling systems around the world – the California current off North America; Humboldt off South America; and the Canary current off the coast of North Africa – were either disrupted or collapsed altogether during the last glacial or Pleistocene periods (40,000 to 2.5 million years ago).

This could potentially have reduced the food supply to killer whales in these areas, leading to the fall in their numbers.

Further research looking at the genetic diversity of the ocean's other top predators, such as sharks, might potentially suggest a negative impact on their numbers too, the researchers suggested.

Such a finding could support concerns about the potential impact changes in climate could have on ocean ecosystems in future, the researchers added.

The reseach, funded by the Natural Environment Research Council in the UK, is published in the journal Molecular Biology and Evolution.

During earlier glacial periods, killer whale populations were likely to have been stable in size, the researchers said.

While it was likely that other factors affecting killer whale populations were "overlapping and complex", the researchers ruled out hunting as an effect on the bottleneck in populations, as hunting by early man could not have happened on a sufficient enough scale to promote the global decline in killer whale numbers during that period.

Corresponding author Professor Rus Hoelzel, in the School of Biological and Biomedical Sciences, said: "Killer whales have a broad world-wide distribution, rivalling that of humans. At the same time, they have very low levels of genetic diversity.

"Our data suggest that a severe reduction in population size during the coldest period of the last ice age could help explain this low diversity, and that it could have been an event affecting populations around the world.

"However, a global event is hard to explain, because regional modern-day killer whale populations seem quite isolated from each other. What could have affected multiple populations from around the world all at the same time?

"The uniquely high levels of diversity we found for the population off South Africa suggest a possible explanation. These whales live in an environment that has been highly productive and stable for at least the last million years, while some data suggest that ocean productivity may have been reduced during the last glacial period elsewhere in the world.

"If this is the case, then further research may suggest an impact on other ocean top predators during this time. It would also support concerns about the potential for climate disruptions to impact ocean ecosystems in future."

INFORMATION:

Genetic materials for this study were derived from either archive material from earlier studies, or from museum specimens.



ELSE PRESS RELEASES FROM THIS DATE:

How states can encourage web-based health care in hospitals

2014-02-05
ANN ARBOR—In the first national look at how broadly web-based technologies are being used to provide health care, a University of Michigan researcher has found that 42 percent of U.S. hospitals use some ...

Study finds dramatic rise in skin cancer among middle-aged adults

2014-02-05
ROCHESTER, Minn — Feb. 3, 2014 — A new Mayo Clinic study found that among middle-aged men and women, 40 to 60 years old, the overall incidence of skin cancer increased nearly eightfold between 1970 and 2009, ...

Off-the-shelf materials lead to self-healing polymers

2014-02-05
CHAMPAIGN, Ill. — Look out, super glue and paint thinner. Thanks to new dynamic materials developed at the University of Illinois, removable paint and self-healing plastics soon could be household ...

Personal experience, work seniority improve mental health professionals' outlook

2014-02-05
One might think that after years of seeing people at their worst, mental health workers would harbor negative attitudes about mental illness, perhaps associating people with mental health ...

Telemedicine can reduce hospitalizations for nursing home residents

2014-02-05
LEBANON, NH (Feb. 4, 2014) – Telemedicine used at nursing homes during hours when doctors are not typically present is a viable way to reduce avoidable ...

New study shows core factors and strategies to turn primary care practices into PCMHs

2014-02-05
BOSTON – (February 4, 2014) – A new study conducted by Robert A. Gabbay, M.D., Ph.D., FACP, Senior Vice-President and Chief Medical Officer at Joslin Diabetes Center and Harvard ...

NASA satellite catches Australia's newborn Tropical Storm Edna and stubborn Fletcher

2014-02-05
Northeastern Australia has been watching two tropical low pressure areas over the last several days, and NASA's Aqua satellite captured both in one infrared image. Tropical Storm Edna ...

Fruit flies -- fermented-fruit connoisseurs -- are relentless party crashers

2014-02-05
That fruit fly joining you just moments after you poured that first glass of cabernet, has just used its poppy-seed-sized brain to conduct a finely-choreographed search, one that's been described ...

Taking statins to lower cholesterol? New guidelines

2014-02-05
ROCHESTER, Minn. — Feb. 4, 2014 — Clinicians and patients should use shared decision-making to select individualized treatments based on the new guidelines to prevent cardiovascular disease, according to a commentary ...

3D mapping biopsy finds 3x prostate cancer of ultrasound-guided biopsy

2014-02-05
Ultrasound-guided biopsies miss prostate cancers that are detected by the slightly more expensive and slightly more invasive 3D mapping biopsies. For example, in a 2006 study of 180 men diagnosed ...

LAST 30 PRESS RELEASES:

Exercise as an anti-ageing intervention to avoid detrimental impact of mental fatigue

UMass Amherst Nursing Professor Emerita honored as ‘Living Legend’

New guidelines aim to improve cystic fibrosis screening

Picky eaters by day, buffet by night: Butterfly, moth diets sync to plant aromas

Pennington Biomedical’s Dr. Leanne Redman honored with the E. V. McCollum Award from the American Society for Nutrition

CCNY physicists uncover electronic interactions mediated via spin waves

Researchers’ 3D-printing formula may transform future of foam

Nurture more important than nature for robotic hand

Drug-delivering aptamers target leukemia stem cells for one-two knockout punch

New study finds that over 95% of sponsored influencer posts on Twitter were not disclosed

New sea grant report helps great lakes fish farmers navigate aquaculture regulations

Strain “trick” improves perovskite solar cells’ efficiency

How GPS helps older drivers stay on the roads

Estrogen and progesterone stimulate the body to make opioids

Dancing with the cells – how acoustically levitating a diamond led to a breakthrough in biotech automation

Machine learning helps construct an evolutionary timeline of bacteria

Cellular regulator of mRNA vaccine revealed... offering new therapeutic options

Animal behavioral diversity at risk in the face of declining biodiversity

Finding their way: GPS ignites independence in older adult drivers

Antibiotic resistance among key bacterial species plateaus over time

‘Some insects are declining but what’s happening to the other 99%?’

Powerful new software platform could reshape biomedical research by making data analysis more accessible

Revealing capillaries and cells in living organs with ultrasound

American College of Physicians awards $260,000 in grants to address equity challenges in obesity care

Researchers from MARE ULisboa discover that the European catfish, an invasive species in Portugal, has a prolonged breeding season, enhancing its invasive potential

Rakesh K. Jain, PhD, FAACR, honored with the 2025 AACR Award for Lifetime Achievement in Cancer Research

Solar cells made of moon dust could power future space exploration

Deporting immigrants may further shrink the health care workforce

Border region emergency medical services in migrant emergency care

Resident physician intentions regarding unionization

[Press-News.org] 'Severe reduction' in killer whale numbers during last Ice Age