econintersect.com
       
  

FREE NEWSLETTER: Econintersect sends a nightly newsletter highlighting news events of the day, and providing a summary of new articles posted on the website. Econintersect will not sell or pass your email address to others per our privacy policy. You can cancel this subscription at any time by selecting the unsubscribing link in the footer of each email.



posted on 03 September 2016

How Songbirds Island-Hopped Their Way From Australia To Colonise The World

from The Conversation

-- this post authored by Chris Chris Cooney, University of Sheffield

The songbirds that are common in gardens all across the world have a surprisingly distant origin. They all evolved from a common ancestor that emerged from what is now Australia around 24m years ago. How they managed to leave this isolated part of the world and spread all over the planet has long been a mystery to scientists.

But a new study suggests they began spreading just as the islands in and around Indonesia were being formed, creating a pathway for them to cross what had previously been thousands of kilometres of open ocean.

Songbirds are a tremendously diverse group of small perching birds, made up of over 5,000 known species distributed across the world. Common examples include the European robin (Erithacus rubecula) and the North American song sparrow (Melospiza melodia). Together, songbirds account for almost half of all bird species alive today.

Although fossils of birds are rare, the ancestor of all songbirds is thought to have originated in Australia, at a time when the Australian landmass was separated from all other land by a vast ocean in all directions. So, despite the birds' extensive evolutionary spread, it remained unclear how this diverse and cosmopolitan family arose from a single ancestral species on an isolated continent.

However, a recent study published in the journal Nature Communications sheds new light on this question. Using genetic and fossil data, the authors reconstructed the evolutionary "family tree" for songbirds. They then linked this to information on different species' geographic locations to understand how early songbirds spread between different continents over the course of millions of years.

This confirmed that songbirds originated in Australia just over 30m years ago. But the most eye-catching finding is that songbirds started to spread out of Australia much more recently than previously thought. This process appears to have started approximately 24m years ago, at the same time as the formation of Wallacea, a group of islands bridging the ocean-filled gap between Australia and Asia. So this may explain how songbirds were able to leave Australia and radiate across the rest of the world, by island-hopping their way to Asia.

Secrets in the DNA

To gain these novel insights, the researchers first collected DNA from many songbird species across the world. DNA molecules are the building blocks of life and bear the imprint of our evolutionary past. Close relatives tend to have more similar DNA to each other than to distant relatives. So by comparing DNA between songbird species that are related by different amounts, it is possible to reconstruct their evolutionary past and generate a family tree for the entire songbird group.

By mapping the geographic location of living species onto this family tree, the authors were then able to reconstruct where and when new songbird species evolved. The first songbirds originated in the landmass that would eventually become Australia. More surprisingly, though, the first major burst of evolution within songbirds coincided with a period of tectonic collision when islands began forming in the waters north of Australia. This provided the first land link between Australasia and the south-eastern tip of Asia (Sundaland).

Deep ocean dotted with islands separates Australia and Asia Maximilian Dörrbecker/Wikimedia Commons, CC BY-SA

These novel insights have at least three interesting implications. The first is that it resolves the longstanding question of how and when songbirds arrived in Asia. Previous attempts to date the spread of the birds from Australia pointed to a much earlier time, when the landmass was isolated by thousands of kilometres of open ocean.

We now know that the islands of Wallacea provided the first plausible corridor out of Australia, resulting in waves of songbird expansion through Asia to the rest of the globe. This colonisation of previously uninhabited regions seems to have then triggered the evolution of many new songbird species, as the group began to adapt to these novel environments and habitats.

Game of chance

This leads to the second important conclusion: the role of chance in evolution. Paleontologist Stephen J. Gould argued that if the tape of life were rewound and allowed to run again from the start, chances are we would see a very different set of evolutionary outcomes. Features of songbird evolution appear to support this message. Without the chance collision of two tectonic plates millions of years ago, songbirds may have never left Australia and the world's garden bird feeders may now be playing host to a very different set of species than they do today.

The third and perhaps most striking conclusion is that the common ancestor of all modern songbird species is likely to have lived just over 30m years ago. In evolutionary terms, this is surprisingly recent, especially compared to the probable age of the ancestor of all birds (about 95m years). When you consider that songbirds account for over half of all bird species on Earth (over 5,000 species), the relatively recent origins of songbirds mean they evolved into new species at an even faster rate than previously thought.

By resolving these issues, the study has also set the stage for new and important questions about evolution. Perhaps the most intriguing question now is why a once-small group of Australian songbirds went on to become such a diverse and widespread component of life on Earth.

The ConversationChris Cooney, Postdoctoral research associate, University of Sheffield

This article was originally published on The Conversation. Read the original article.

>>>>> Scroll down to view and make comments <<<<<<

Click here for Historical News Post Listing










Make a Comment

Econintersect wants your comments, data and opinion on the articles posted.  As the internet is a "war zone" of trolls, hackers and spammers - Econintersect must balance its defences against ease of commenting.  We have joined with Livefyre to manage our comment streams.

To comment, using Livefyre just click the "Sign In" button at the top-left corner of the comment box below. You can create a commenting account using your favorite social network such as Twitter, Facebook, Google+, LinkedIn or Open ID - or open a Livefyre account using your email address.



You can also comment using Facebook directly using he comment block below.





Econintersect Contributors


search_box

Print this page or create a PDF file of this page
Print Friendly and PDF


The growing use of ad blocking software is creating a shortfall in covering our fixed expenses. Please consider a donation to Econintersect to allow continuing output of quality and balanced financial and economic news and analysis.


Take a look at what is going on inside of Econintersect.com
Main Home
Analysis Blog
The Expected Effects of Petitions to Improve the Monetary System
Energy and Falling Productivity
News Blog
Big Sam In Bad Company
Other Ways To Spend Your AirPod Budget
Crashing Space Station Shows Why China Must Start To Collaborate In Orbit
NFL Edges Towards A Full House In London
What We Read Today 28 September 2016
October 2016 Economic Forecast: Outlook Insignificantly Declines But Little Economic Strength Entering 4Q2016
1 Minute. 34 Seconds. In The U.S., That's All It Takes To Register To Vote. A Single Registration Lasts A Lifetime Of Elections. We've Made It Easy For You Here: Http://g.co/elections/134
Durable Goods New Orders Unchanged in August 2016
90% Rally In Sugar Prices Since Late 2015
U.S. Real Wage Growth: Slowing Down With Age - Part 2 Of 2
Infographic Of The Day: Four Tips To Grow Wealth
Early Headlines: Asia Stocks Down, Yen Rises, Oil Soft, Wells CEO Gives Up Bonuses, Trump Didn't Want To Embarass Clinton, US Asset Bubbles, US Crime Rates Falling And More
What is Democracy, Anyway?
Investing Blog
Banks Of Absurdity
Investing.com Technical Summary 27 September 2016
Opinion Blog
The Federal Reserve Note
Trump, Trade And Taxes
Precious Metals Blog
War On Cash Turns To $20, $50, And $100 Bills
Live Markets
28Sep2016 Market Close: Wall Street Closes Higher After A Sluggish Start In The Morning, Crude Prices Close Higher In Face Of GS Saying Crude Will Fall, Indicators Neutral
Amazon Books & More






.... and keep up with economic news using our dynamic economic newspapers with the largest international coverage on the internet
Asia / Pacific
Europe
Middle East / Africa
Americas
USA Government



Crowdfunding ....






























 navigate econintersect.com

Blogs

Analysis Blog
News Blog
Investing Blog
Opinion Blog
Precious Metals Blog
Markets Blog
Video of the Day
Weather

Newspapers

Asia / Pacific
Europe
Middle East / Africa
Americas
USA Government
     

RSS Feeds / Social Media

Combined Econintersect Feed
Google+
Facebook
Twitter
Digg

Free Newsletter

Marketplace - Books & More

Economic Forecast

Content Contribution

Contact

About

  Top Economics Site

Investing.com Contributor TalkMarkets Contributor Finance Blogs Free PageRank Checker Active Search Results Google+

This Web Page by Steven Hansen ---- Copyright 2010 - 2016 Econintersect LLC - all rights reserved