Skip to content

Nature

The whales don't mix between ocean basins

by Dave Armstrong 21 May 2014
The whales don't mix between ocean basins

A happy humpback, if only those pesky gulls wouldn't interfere with the fishing! Humpback image; Credit: ©Shutterstock

Earth Times loves the humpback, from its hit songs to those great fins. Of any mammal, the many humpback migrations from the tropics to the Arctic are the longest known. Through time, this unique whale has become semi-speciated into 3 populations, according to DNA analysis that is also able to probe the humpback's ancient populations, back to the Pleistocene..

2700 individual whales' mitochondrial DNA sequences were investigated as well as the nuclear intronic sequences of 70 living whales from the 3 representative populations of ocean basins. With no actual geographical barrier, the Southern Ocean and the North Atlantic and North Pacific populations seem to be separated by the thermal barrier of the Equator. Past history indicates that the northern populations may have separated before the last glaciation. Female humpbacks naturally return to both feeding and breeding grounds, so the population would have followed this "maternal preference" in each of the groups.

There has been ancient gene flow between all of the oceans. The 3 populations have had connections and the Southern Hemisphere breeding grounds stretch as far as Costa Rica and Gabon, north of the equator. However there is no current evidence. Because there are no physical differences in measurements such as length, it has recently been assumed that there was no evidence of true subspecies in modern times.

Now we have evidence that the theorists are wrong! There were estimated to be up to 219 haplotypes (parts of genetic formulae) worldwide, containing sites where multiple substitutions had taken place. Only one haplotype was shared between North Atlantic and Southern Hemisphere whales, with 2 shared between North Pacific and Southern animals. Naturally, the greatest differences were found between the well-separated Atlantic and Pacific whales. Common alleles such as the actin allele were frequent in all populations. Only a few "private" characteristics, controlled by alleles presented themselves in the Southern Ocean populations.

How to interpret the results? Genetic diversity of mtDNA in the humpback may imply large ancestral populations or simply a restricted gene flow. Nuclear DNA is much less diverse. This makes an alternative argument for smaller ancestral populations or, more likely, loss of diversity from whaling, which would have caused population bottlenecks. Fin whales may well have similar population divergence. The cause really seems to be the equatorial temperature barrier.

The measurements suggest only mean 1.6 humpback migrants between any of the populations for each generation. This applies when either the mtDNA or the nuclear DNA are studied. Pulses of migrants could have escaped their home range under unusual climate conditions or there could be some regular slow migration. No matter, the subspecies are quite distinct and are ready to be named Megaptera novaeangliae kuzira in the North Pacific; Mn. novaeangliae in the North Atlantic and Mn. Australis in the Southern Hemisphere.

During the past million years, modern lineages have colonised the Atlantic and Pacific, probably about 200,000 years ago. The Pacific was colonised first, followed by a slow population expansion within an Atlantic population, maybe even as late as 55,000 years ago. Whether whaling caused reduced diversity or it was already present is debateable. If glaciations affected the humpback, then the data suggest it must have been long before recent Ice Ages, 12,000 years ago.

Jennifer Jackson of Oregon State University and her 8 colleagues from the British Antarctic Survey, Florida State University, James Cook University (Australia), Aukland University (NZ), Fundacion CEQUA (Chile), the Wildlife Conservation Society (US), and the American Museum of Natural History (US) all present their historic and enlightening paper today. "Global diversity and oceanic divergence of humpback whales (Megaptera novaeangliae)" can be found in - Proceedings of the Royal Society B.

We present our own connected story to fill you in on any information on how humpback songs might vary in Humpback whales singing different songs.


Trending Eco-Friendly Clothing

Love My Planet Women's Relaxed Fit Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Love My Planet Women's Relaxed Fit Hoodie
Love My Planet women's eco-friendly relaxed fit hoodieSize Guide Centimeters 8 10 12 14 16 18 Bust 84 88 92 97 103 108 Waist 66 70 75 80 85 91 Hips 91 95 99 104 109 116 Bust: Measure around the fullest part of...
£38.00
£38.00
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Penguins Hate Push-Ups men's eco-friendly pullover HoodieSize Guide Centimeters XS S M L XL XXL Height 171 175 179 183 189 195 Chest 86 93 99 104 116 129 Waist 71 76 81 89 99 112 Chest: Measure all round your chest just below...
£38.00
£38.00
Close
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Earth
Quick Add
Close
Notify me
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Lightning Bolt kids eco-friendly long sleeve t-shirtSize Guide Centimeters 3-4yrs 5-6yrs 7-8yrs 9-10yrs 11-12yrs Height 98 112 125 136 147 Chest 60 66 70 75 84 Chest: Measure all around your chest just below your armpits. Height: Your natural height If you fall between...
£18.00
£18.00
Close
Notify me
Notify me
Notify me
Union Jack Tote Bag
Earth
Quick Add
Close
Notify me
Notify me
Union Jack Tote Bag
Union Jack eco-friendly colour tote bagProduct Specification Organic Cotton Tote Bag. Twill Weave (170gsm). 37 x 42 cm (7cm gusset.) Made in India / Designed on the Isle of Wight. Wash Cool, Hang Dry.
£16.00
£16.00
Close
Notify me
Notify me
Prev Post
Next Post

Eco-Friendly Shop

Women's Clothing

Eco-Friendly Clothing for Women Our online shop offers a wide range of sustainable women’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Men's Clothing

Eco-Friendly Clothing for Men Our online shop offers a wide range of sustainable men’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Kids Clothing

Eco-Friendly Clothes for Kids Our online shop offers a wide range of sustainable kids clothing products, including t-shirts, hoodies and jumpers. Our garments...
Shop Now
Someone recently bought a
[time] ago, from [location]

Thanks for subscribing!

This email has been registered!

Shop the look

Choose Options

Earth Times
Sign up for exclusive updates, new arrivals & insider only discounts

Recently Viewed

Edit Option
Back In Stock Notification
this is just a warning
Login
Shopping Cart
0 items

Before you leave...

Take 20% off your first order

20% off

Enter the code below at checkout to get 20% off your first order

CODESALE20

Continue Shopping