After 15 years of research in the waters of the South Atlantic and Indian Oceans, scientists from the Wildlife Conservation Society, the American Museum of Natural History, and an international coalition of organizations have unveiled the largest genetic study of humpback whale populations ever conducted in the Southern Hemisphere.
By analyzing DNA samples from more than 1,500 whales, researchers can now peer into the population dynamics and relatedness of Southern Hemisphere humpback whales as never before, and help inform management decisions in the sometimes politically charged realm of whale conservation.The results of the massive analysis appear in PLoS One, an interactive open-access journal for scientific and medical research. Other contributors to the study include: Columbia University; University of Pretoria; Environment Study of Oman; Instituto Baleia Jubarta and PURCS (Brazil); University of Cape Town; Marine and Coastal Management (South Africa); Faculdade de Biociências; Agence Nationale des Parcs Nationaux (Gabon); Association Megaptera (France); Université de La Rochelle (France).
So little is known about southern ocean basin humpbacks that researchers initially used old whaling records for insights into whale population boundaries.
Researchers collected skin samples from 1,527 whales from fourteen sampling sites from the Southwestern and Southeastern Atlantic Ocean, and the Southwestern and Northern Indian Oceans. The populations are known as Breeding Stocks A (Southwest Atlantic Ocean), B (Southeast Atlantic Ocean), C (Southwest Indian Ocean), and X (Northern Indian Ocean), based on information amassed and designated by the International Whaling Commission, including data from 19th and 20th Centuries commercial whaling.
The scientists collected samples from living whales with biopsy darts fired from crossbows. The darts harmlessly bounce off the marine mammals as they surface to breathe. Samples came also from skin which is continually sloughed off by the animals and collected by the research teams.
Once collected, the samples were brought to the lab at the AMNH Sackler Institute for Comparative Genomics and examined through a technique called polymerase chain reaction (PCR), which "amplifies" specific regions of DNA which then can be used to statistically inform researchers about gene flow between populations. The research team specifically focused on mitochondrial DNA, which is passed through maternal lines of a population, in order to measure interchange between groups.
The findings so far have revealed:
The highest rate of gene flow between populations is between whales that breed on either side of the African continent (Breeding Stocks B and C), with an estimated one or two reproductively active whales every year swimming from one ocean to join whales in another breeding ground. Authors of the current study previously identified the same individual whale in both Atlantic and Indian Ocean breeding grounds at different times, the first recorded instance of a humpback whale traveling between these two oceans.
A lower rate of gene flow between humpbacks breeding on opposite sides of the Atlantic (one population along coastal Brazil and the other along the coast of Southern Africa). While no individual whales have been detected traveling across the Southern Atlantic to both breeding grounds, genetic similarities reveal a slight degree of populations interacting. Interestingly, an examination of humpback whale songs between the two populations are similar, another hint at interchange between the two groups, most likely in the whales' feeding grounds in Antarctic waters.
Breeding Stock X, which inhabits the northern Indian Ocean off the Arabian Peninsula, numbers fewer than 200 whales and is the most distinct in terms of genetics and migratory behavior. Unlike the other humpback populations, it is non-migratory and only distantly related to the nearest group of humpbacks (which breed off Madagascar and the eastern coast of Southern Africa). As a small, insular group, the "X" population is unique and therefore a conservation priority.
In addition to examining the population boundaries of humpbacks in the Southern Hemisphere, the study also gives scientists some insight into the mysterious and mercurial nature of marine ecosystems, with currents, water depth, and other unseen factors serving as shifting conduits and barriers between marine populations and ecosystems.
On an interesting historical note, Rosenbaum and his co-authors used old whaling records to guide their research on whale populations. One set of charts—titled "The Distribution of Certain Whales as Shown by Logbook Records from American Whale Ships"—was compiled by Charles Townsend of the New York Zoological Society (now WCS) and recorded the locations of more than 50,000 whale captures (including humpback whales) between 1761-1920. According to the charts, many humpback whales were captured in the Gulf of Guinea, Southeastern African and northeastern Madagascar, the same locations where humpbacks congregate today. "Townsend was attempting to identify distribution and possible boundaries between whale populations or 'breeding stocks,'" noted Rosenbaum. "We're still trying to answer the same question with molecular technology in concert with whaling logbook records."
"Understanding the needs of humpbacks and other whale species can be challenging in terms of direct observations of these animals in the wild. Molecular technology gives us a window into the lives of whales that can help us understand the ecological forces shaping their movements and distribution," added Rosenbaum. "We can also use our findings to inform management decisions for a species that is only now beginning to recover from centuries of commercial whaling."
The humpback whale is a baleen whale that grows up to approximately 50 feet in length. The species has distinctively long pectoral fins and a head with knobs on the top and lower jaw. The humpback is also known for its acrobatics (such as full body breaching) and haunting songs, typically sung by males and possibly a mating behavior. The slow-swimming species was hunted commercially until the International Whaling Commission protected the species globally in 1966. Current estimates for humpback whale numbers are widely debated. While they are recovering, total population sizes may only perhaps be a small percent of the original global population.
This study was generously supported by The Eppley Foundation For Research, Flora Family Foundation, and Lenfest Ocean Program.
John Delaney | EurekAlert!
Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences