Navigation Links
Oh mother, where art thou?
Date:3/14/2013

Biologists since Aristotle have puzzled over the reasons for mass strandings of whales and dolphins, in which groups of up to several hundred individuals drive themselves up onto a beach, apparently intentionally. Recent genetic research has shed some light on whether family relationships play a role in these enigmatic and often fatal beachings of otherwise healthy whales.

One hypothesis regarding the reason for strandings is that "care-giving behavior," mediated largely by family relationships, plays a critical role. In this scenario, the stranding of one or a few whales, because of sickness or disorientation, triggers a chain reaction in which healthy individuals are drawn into the shallows in an effort to support their family members.

A recent study published in the Journal of Heredity (DOI:10.1093/jhered/est007) questions this explanation, using genetic data to describe the kinship of individual long-finned pilot whales involved in mass strandings in New Zealand and Tasmania. The largest of these strandings included more than 150 whales, all of which died.

The study found that stranded groups are not necessarily members of one extended family, evidence that contradicts the hypothesis that stranding groups all descend from a single ancestral mother. Further, many stranded calves were found with no mother in evidence.

Long-finned pilot whales are the most common species to strand en masse and it has long been assumed this tendency was related to the species' social organization. Previous studies have shown that pilot whales have a matrilineal social organization, in which neither males nor females disperse from the group into which they were born. This group structure is also found in killer whales, but is otherwise thought to be rare in mammals.

"If kinship-based social dynamics were playing a critical role in these pilot whale strandings, first, we would expect to find that the individuals in a stranding event are, in fact, all related to each other. Second, we would expect that close relatives, especially mothers and calves, would be found in close proximity to each other when they end up on the beach during a stranding event," explained Marc Oremus of the University of Auckland and first author of the study.

Researchers analyzed both mitochondrial DNA, which is inherited exclusively from the mother, and microsatellite genotypes, which are inherited from both parents, from 490 whales involved in 12 stranding events. Contrary to the hypothesis that stranding groups consist of whales descended from a single ancestral mother (the "extended matriline" hypothesis), multiple matrilines were found in the groups stranded together.

In some strandings, the researchers assessed the spatial relationships of individual whales on the beach. The position of each stranded whale was mapped to determine if individuals found near each other were related. No correlation was found between location and kinship, even when considering only the location of nursing calves and their mothers, who were often widely separated when the group drove itself onto the shore.

Most surprising was the evidence of "missing mothers" that is, many of the stranded calves and juveniles had no identifiable mother among the other beached whales.

"Several scenarios could account for the lack of spatial cohesion, including the disruption of social bonds among kin before the actual strandings," commented Oremus. "In fact, the separation of related whales might actually be a contributing causal factor in the strandings, rather than simply a consequence."

The results of this study have important implications for rescue efforts aimed at "refloating" stranded whales. "Often, stranded calves are refloated with the nearest mature females, under the assumption that this is the mother," explained Scott Baker, co-author and Associate Director of the Marine Mammal Institute at Oregon State University. "Well-intentioned rescuers hope that refloating a mother and calf together will prevent re-stranding. Unfortunately, the nearest female might not be the mother of the calf. Our results caution against making rescue decisions based only on this assumption."

The researchers acknowledge an important remaining question: where are the "missing mothers?" Had these adult females successfully refloated or had they never stranded in the first place? To answer this question, the researchers conclude that genetic samples are needed from all whales involved in strandings, including from those individuals that do eventually make it back to sea.


'/>"/>
Contact: Nancy Steinberg
nsteinberg@charter.net
541-961-3459
American Genetic Association
Source:Eurekalert  

Related biology news :

1. Where the wild things go… when theres nowhere else
2. Satellite visualization tool for high-res observation accessible from anywhere with internet access
3. International study: Where theres smoke or smog, theres climate change
4. MBL scientists find bipolar marine bacteria, refuting everything is everywhere idea
5. Bumblebees do best where there is less pavement and more floral diversity
6. Bioengineered marine algae expands environments where biofuels can be produced
7. Water resources management and policy in a changing world: Where do we go from here?
8. Le Rouge et le Noir: Where the black dahlia gets its color
9. Risk of cardiac arrest depends on where you live
10. Coral scientists use new model to find where corals are most likely to survive climate change
11. Success of engineered tissue depends on where its grown
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Oh mother, where art thou?
(Date:5/20/2016)... -- VoiceIt is excited to announce its new marketing ... working together, VoiceIt and VoicePass will offer an ... slightly different approaches to voice biometrics, collaboration between ... Both companies ... "This marketing and technology partnership allows VoiceIt ...
(Date:5/3/2016)... VILNIUS, Lithuania , May 3, 2016 /PRNewswire/ ... today released the MegaMatcher Automated Biometric Identification ... deployment of large-scale multi-biometric projects. MegaMatcher ABIS can ... and accuracy using any combination of fingerprint, face ... of MegaMatcher SDK and MegaMatcher ...
(Date:4/26/2016)... April 27, 2016 Research ... Multi-modal Biometrics Market 2016-2020"  report to their offering.  ... The analysts forecast the global multimodal ... 15.49% during the period 2016-2020.  Multimodal ... sectors such as the healthcare, BFSI, transportation, automotive, ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... June 23, 2016 , ... ... and Mold) microbial test has received AOAC Research Institute approval 061601. , “This ... introduced last year,” stated Bob Salter, Vice President of Regulatory and Industrial Affairs. ...
(Date:6/23/2016)... ... June 23, 2016 , ... ... launch of the Supplyframe Design Lab . Located in Pasadena, Calif., the ... future of how hardware projects are designed, built and brought to market. , ...
(Date:6/23/2016)...  Blueprint Bio, a company dedicated to identifying, protecting ... has closed its Series A funding round, according to ... "We have received a commitment from Forentis Fund that ... meet our current goals," stated Matthew Nunez . ... complete validation on the current projects in our pipeline, ...
(Date:6/23/2016)... Prairie, WI (PRWEB) , ... June 23, 2016 ... ... consultancy focused on quality, regulatory and technical consulting, provides a free webinar ... is presented on July 13, 2016 at 12pm CT at no charge. , ...
Breaking Biology Technology: