New islands, happy feet: Study reveals island formation a key driver of penguin speciation

February 05, 2019

Ever since Darwin first set foot on the Galapagos, evolutionary biologists have long known that the geographic isolation of archipelogos has helped spur the formation of new species.

Now, an international research team led by Theresa Cole at the University of Otago, New Zealand, has found the same holds true for penguins. They have found the first compelling evidence that modern penguin diversity is driven by islands, despite spending the majority of their lives at sea.

"We propose that this diversification pulse was tied to the emergence of islands, which created new opportunities for isolation and speciation," said Cole.

Over the last 5 million years, during the Miocene period, (particularly within the last 2 million years), island emergence in the Southern Hemisphere has driven several branches on the penguin evolutionary tree, and also drove the more recent influence of human-caused extinctions of two recently extinct penguin species from New Zealand's Chatham Islands.

"Our findings suggest that these taxa were extirpated shortly after human settlement on the Chatham Islands," said Cole. "These findings thus potentially represent important new examples of human-driven, Holocene extinction in the Pacific."

"While our results reinforce the importance of islands in generating biodiversity, they also underscore the role of humans as agents of biodiversity loss, especially via the extinction of island-endemic taxa," said Cole. As many of the bones were from middens, our results provide direct evidence that our newly discovered extinct taxa was hunted by humans."

The publication appears in the advanced online edition of the journal Molecular Biology and Evolution.

About 20 modern penguin species exist, from the Antarctic emperor penguin, the forest dwelling Fiordland penguin and the tropical Galapagos penguin. A fossil record of more than 50 species can trace back penguin history to more than 60 million years ago - indicating that penguin diversity may have once been much higher than today.

Using historical skin samples and subfossils from natural history museums, along with blood samples, the researchers performed the largest survey to date, across all penguin taxa.

The team tested their island hypotheses using 41 near-complete mitochondrial genomes, representing all extant and recently extinct penguin taxa. They calibrated their mitogenomic evolution to make an evolutionary clock based on the fossil record.

"By using well-justified fossil calibrations, we resolve the timing and mechanisms of modern penguin diversification," said Cole.

They found that the two largest-bodied and most polar-adapted penguins are sister to all other living penguins. The DNA evidence also showed that genetically similar penguin species may be at the earlies stages of diversification.

The study provides important new data and perspectives to the debate on the origins of penguin diversity. It will also help better understand the role of islands as drivers of speciation to other animals and marine life.

The new taxa have been named Eudyptes warhami and Megadyptes antipodes richdalei after John Warham and Lance Richdale, pioneers in penguin biology.
-end-


Molecular Biology and Evolution (Oxford University Press)

Related Penguins Articles from Brightsurf:

Gentoo penguins are four species, not one, say scientists
First analysis combining genetic and physical differences of populations of gentoo penguins indicates they should be treated as four separate species.

Penguins are Aussies. Or are they Kiwis?
UC Berkeley and Pontifical Catholic University of Chile researchers sequenced the genomes of all 18 recognized species of penguin to assemble a family tree, showing that the largest of the penguins - king and emperor - split off from all other penguins not long after penguins arose 22 million years ago in Australia and New Zealand.

New Zealand's ancient monster penguins had northern hemisphere doppelgangers
New Zealand's monster penguins that lived 62 million years ago had doppelgangers in Japan, the USA and Canada, a study published today in the Journal of Zoological Systematics and Evolutionary Research has found.

Antarctic penguins happier with less sea ice
Researchers have been surprised to find that Adélie penguins in Antarctica prefer reduced sea-ice conditions, not just a little bit, but a lot.

Researchers go cuckoo: Antarctic penguins release an extreme amount of laughing gas
In a new study, researchers from the University of Copenhagen have demonstrated that penguins in Antarctica emit copious amounts of nitrous oxide via their feces.

Climate change and human activities threatens picky penguins
Eating a krill-only diet has made one variety of Antarctic penguin especially susceptible to the impacts of climate change, according to new research involving the University of Saskatchewan (USask) which sheds new light on why some penguins are winners and others losers in their rapidly changing ecosystem.

Whaling and climate change led to 100 years of feast or famine for Antarctic penguins
New research reveals how penguins have dealt with more than a century of human impacts in Antarctica and why some species are winners or losers in this rapidly changing ecosystem.

Researchers study chickens, ostriches, penguins to learn how flight feathers evolved
If you took a careful look at the feathers on a chicken, you'd find many different forms within the same bird -- even within a single feather.

What future do emperor penguins face?
Emperor penguins establish their colonies on sea ice under extremely specific conditions.

New sphenisciform fossil further resolves bauplan of extinct giant penguins
New Zealand is a key area for understanding the diversity of the extinct penguins and has even revealed the existence of 'giant' penguin species (larger than living penguins).

Read More: Penguins News and Penguins Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.