Of Orcas and Species

By Rob and Maria

If you’ve been following the wildlife news circuit, you probably were quite intrigued by the story that broke earlier this week about the “type D” orcas, sometimes also referred to as the New Zealand killer whales, found in the Southern Ocean! These whales (well, dolphins, technically) are much smaller than other known killer whales; they have shorter, more rounded heads; their fins are pointier; and their classic killer whale eye patches are distinctively small. A handful of these unusual individuals were first observed in New Zealand in 1955, but they had not been definitively spotted since then. Of course, marine biology fans are abuzz—are they a whole separate species than the killer whales we all are familiar with? Time will tell. NOAA biologists (including a married couple team—we can appreciate a good nerd love story) are hard at work to unravel the mystery of these mysterious killer whales.

Of course, if these orcas are distinct enough to be considered a new species, that does lead to the question…what is a species? It’s not as easy as it sounds. Before you continue reading, take a moment, if you will, to brainstorm this question: how would you define a species?

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Keep brainstorming 😊

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What did you come up with? Perhaps something about looking similar, being able to mate, acting the same?

If you came up with any of those possibilities, you touched on a few different species concepts. Truth be told, what is a species is one of the trickiest questions in biology because it sounds so simple, but is in fact, quite difficult to answer. To help this matter, scientists have developed species concepts as working definitions, but no one species concept works in all situations.

For example, the biological species concept posits that “species are groups of interbreeding natural populations that are reproductively isolated from other such groups” (Mayr 1995 via Coyne and Orr 2004). This essentially means that a group of organisms that can interbreed – and don’t breed with other groups – can be defined as a species. “Reproductive isolation” may mean that they physically cannot breed with something else or they are prevented from breeding for some other reason.

The genotypic cluster species concept, on the other hand, defines a species as “a genetically distinguishable group of individuals that has few or no intermediates when in contact with other such clusters (Mallet 1995 via Coyne and Orr 2004). The gist of this concept suggests that a species can be defined if the group of organisms in question are genetically distinct from any other group of organisms.

If we continue, the morphological species concept suggests that a species is any group of organisms that are similar in physical form. The ecological species concept defines a species by their similarity in the roles they play in their ecosystem. And then there is the phylogenetic species concept, the evolutionary species concept, and many more. They all have their value, and they all have their drawbacks (e.g. How do you apply these to fossils? What about asexual species? etc.)

Will the exciting New Zealand killer whales be defined as their own species? We don’t know yet, but it rather reminds us of the work of Dr. Andrew Foote at Uppsala University in Sweden. For years, he has been following killer whales in the North Atlantic, and he has noticed something very interesting: the populations of these magnificent mammals seem to be diverging possibly into two species right before our eyes. His work has noticed that different groups of killer whales have learned to specialize on different prey items, but that specialization has led to both genetic differentiation and morphological changes in the populations (remember, in natural selection, individual animals do not change; but over time, the prevalence of traits in a population can change.) Foote and his team have noticed that the killer whales who specialize on smaller fish species have developed teeth that are better suited for this food source while killer whale populations that specialize on larger prey, like other mammals, have developed the larger teeth to more effectively do so. There is also genetic evidence that the two groups of killer whales are diverging. Exciting, huh?! (Links to a selection of Foote’s work at the bottom of the page.)

Time will tell for both Foote’s research and the New Zealand killer whales. We will just have to keep listening in. And heavens knows that we will! Maria has been a fan of killer whales since the quintessential 90’s movie Free Willy, and we were both lucky enough in 2017 to actually see killer whales in the wild off the coast of San Juan Island in the Pacific Northwest.

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Shortly after this, Maria hit emotional overload and cried into a bowl of broccoli cheese soup at a local cafe. True story.

As a shameless plug for the Whale Museum on San Juan Island in Washington state, we were gifted the adoption of Yoda and Spock, two Southern Resident killer whales from K pod in the Pacific Northwest. (Thanks Esha and Neil for the Christmas present!) The Whale Museum has a few other great resources on their website, if you’re interested in experiencing Orcas even from Pittsburgh. The Whale Museum and a local consulting firm operate an underwater microphone (hydrophone) at Lime Kiln Point State Park on San Juan Island, and you can listen in for the local Southern Residents if they happen to be in the area. You can also check out the marine mammal rescue and research work that the museum is involved in. Also, the Explore livecams link to an underwater camera in British Columbia that relatively often record orcas enjoying the rubbing rocks at the bottom of a cove.

Here are some more pictures of our day we saw whales, and until we chat again, keep exploring!

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The lighthouse at Lime Kiln State Park, where the hydrophone is positioned. Beautiful place.

 

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The orcas we saw that day were a transient group, rather than members of any of the three local pods. Comprised of a mother and her three sons, the group specialized on larger mammalian prey like sea lions and pilot whales, as opposed to salmon like the local pods. From what our guide told us, the small group size worked in their favor. It ensured that there would be enough food for each group member after a successful hunt.

 

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It was a little windy on the boat.

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Bonus: Sea lions!

 

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Friday Harbor on San Juan Island.

 

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Island mood.

 

Resources

Ecological, morphological and genetic divergence of sympatric North Atlantic killer whale populations, 2009

Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species, 2010

Genetic differentiation among North Atlantic killer whale populations, 2010

The influence of ecology on sociality in the killer whale (Orcinus orca), 2012

Geographic and temporal dynamics of a global radiation and diversification in the killer whale, 2015

Seasonal movements of killer whales between Iceland and Scotland, 2015

Sympatric speciation in killer whales? 2015

2 thoughts on “Of Orcas and Species

  1. What a phenomenal article. I’ve always been obsessed with Orca. I was so excited to hear about the transient pod. Thank you for putting so much information in one place, I loved the pictures and reading about them!

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