Why skunks stink, new research


This is a video about baby skunks from the USA.

From UC Davis in the USA today:

Social or stinky? New study reveals how animal defenses evolve

21 hours ago

When people see a skunk, the reaction usually is “Eww,” but when they see a group of meerkats peering around, they often think “Aww.”

Why some animals use noxious scents while others live in social groups to defend themselves against predators is the question that biologists Tim Caro of the University of California, Davis and Theodore Stankowich of California State University, Long Beach and sought to answer through a comprehensive analysis of predator-prey interactions among carnivorous mammals and birds of prey.

Their findings appear in the online edition of the journal Evolution.

“The idea is that we’re trying to explain why certain antipredator traits evolved in some species but not others,” said Stankowich, who noted that this study not only explains why skunks are stinky and why banded mongooses live in groups but also breaks new ground in the methodology of estimating predation risks.

Caro, Stankowich and Paul Haverkamp, a geographer who recently completed his Ph.D. at UC Davis, collected data on 181 species of carnivores, a group in which many species are small and under threat from other animals. They ran a comparison of every possible predator-prey combination, correcting for a variety of natural history factors, to create a potential risk value that estimates the strength of natural selection due to predation from birds and other mammals.

They found that noxious spraying was favored by animals that were nocturnal and mostly at risk from other animals, while sociality was favored by animals that were active during the day and potentially vulnerable to birds of prey.

“Spraying is a good close-range defense in case you get surprised by a predator, so at night when you can’t detect things far away, you might be more likely to stumble upon a predator,” Stankowich said.

Conversely, small carnivores like mongooses and meerkats usually are active during the day which puts them at risk from birds of prey. Living in a large social group means “more eyes on the sky” in daytime, when threats can be detected further away.

The social animals also use other defenses such as calling out a warning to other members of their group or even mobbing together to bite and scratch an intruder to drive it away.

The project was a major information technology undertaking involving plotting the geographic range overlap of hundreds of mammal and bird species, but will have long-term benefits for ongoing studies. The researchers plan to make their database, nicknamed the “Geography of Fear,” available to other researchers.

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New birds-of-paradise video


This video from the Cornell Lab of Ornithology in the USA says about itself:

Speciation: An Illustrated Introduction

9 Sep 2013

Explore more at http://www.birdsofparadiseproject.org.

There is a dizzying diversity of species on our planet. From genetic evidence we know that all of those species evolved from a single ancient ancestor. But how does one species split in to many? Through the evolutionary process of speciation — which begins when populations become isolated by changes in geography or by shifts in behavior so that they no longer interbreed. This video illustrates the speciation process in birds to help you understand the basis of earth’s biodiversity.

Including photographs and video by Tim Laman.

The Cornell Lab of Ornithology writes about this:

Our Birds-of-Paradise Videos Have Been Watched for 30+ Years. Here’s 8 More Minutes

Last year we launched our Birds-of-Paradise Project website, full of fascinating natural history videos and educational activities. Since then, our videos have been watched nearly 7 million times for a collective 31 years of viewing time. We’ve just uploaded 29 more videos, including this one that tackles the question of how one species can become many over thousands of generations.

Birds of Paradise: Revealing the World’s Most Extraordinary Birds: here.

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Galapagos conservation news


This video is called National Geographic HD – Galapagos Documental – Underwater Emotions IMAX.

From AboutMyPlanet:

Galapagos Islands Removed From Red List For Endangerment

October 16th, 2013, BY VeganVerve

The Galapagos Islands are famed for the part they played in developing Charles Darwin’s theory of evolution. The islands are home to many species not found elsewhere, much like other islands on the planet. It was the first ever World Heritage Site named by the United Nations Education, Scientific and Cultural Organization (Unesco) in 1978.

Then in 2007 the Galapagos Islands were placed on Unesco’s World Heritage Site red list for endangered sites. The reason for this listing was due to the increasing population, over fishing and increasing tourism. Non-native species introductions have also become a problem on the islands.

However, it was recently announced that Unesco’s World Heritage Committee has decided to remove the Galapagos Islands from their red list of endangered sites. Due to a recommendation from Brazil, the committee considered removing the islands from the list. After reviewing the information available, the committee decided that the Ecuadorian government was making strides towards improving the conditions on the islands.

The Galapagos Islands were recommended as a red list endangered site by the International Union for the Conservation of Nature (IUCN). This same organization is very concerned about the removal of the islands from the red list. According to the IUCN, the islands are not out of the clear yet and the islands should still remain protected.

The IUCN’s World Heritage Program leader, Tim Badman, stated: “IUCN’s recommendation for the Galapagos was that it should not be removed from the Danger List as there is work still to be done.” Badman stated: “Threats from tourism, invasive species and over fishing are still factors and the situation in the Galapagos remains critical.”

14 unique animals of the Galapagos Islands: here.

Galápagos finches that inspired Darwin under threat from parasitical flies: here.

Australian fairy-wren females prefer red


This video, recorded in Australia, is called IRES Red-backed Fairy-wren Research.

By Nidhi Subbaraman, NBC News, today:

Fooled by a Sharpie! Cheating birds steered to fidelity with red marker

Out in the Australian scrubland, scientists are using Sharpies to trick promiscuous female fairy-wrens from mating outside their subspecies, an “extra-marital” behavior that may be stalling evolution in its tracks.

Two groups of fairy-wrens live in Northwestern Australia: You can tells the males apart easily — one group has an orange band of feathers on their backs and the others are crimson red.

Females find partners within their subspecies — orange to orange and red to red — to nest and raise their brood with. But they also seek out other mates, aside from their “social” fathers-to-be, and that’s when they look for a bit of variety, Daniel Baldassarre and Michael Webster, ornithologists at Cornell University have found: They recorded how female birds from the orange group had a clear preference for red males outside their main relationships.

Not a natural red-back: A coat of non-toxic marker on an orange-backed fairy-wren (right) makes it as attractive to females as the naturally scarlet subspecies (left), photo by Daniel Baldassarre

Over two breeding seasons, the birders tracked 39 male fairy-wrens. They painted the feathers of one group of 13 red, coated another 13 in clear marker, tracked how the remaining 13 did with their natural orange back.

It turned out that just a coat of Sharpie-like coloring was enough to fool the females — orange-backed males with the PrismaColor Carmine Red dye job fathered twice more offspring than naturally orange males who lived in the same area, Baldassare and Webster found. Also, the redback males only attracted female birds that were cheating on their primary mate, they explain in the Wednesday issue of the Proceedings of the Royal Society B.

Was the red color irresistible to the females? Were they curious because it was new? “We don’t know that,” Webster told NBC News, that’s something they’re exploring in studies this year.

Webster says the orange and red subspecies of fairy-wren are in the process of diverging into two distinct species — something we know birds and mammals and reptiles do naturally over time, ever since Darwin observed his various species of finches on the Galapagos Islands.

When the orange-back females mate outside their species, they mix genetic material, stalling the usual course of divergent evolution.

For the Aussie fairy-wrens, this roadblock isn’t a big deal in itself. (And, the researchers won’t be trying to alter the birds’ behavior, chasing after orange birds with a red Sharpie any time soon.)

But this behavior does suggest that other related species of birds, mammals and reptiles that are being brought closer because of human factors could be “melding together into one species,” West said.

Daniel Baldassarre and Michael Webster are authors of “Experimental evidence that extra-pair mating drives asymmetrical introgression of a sexual trait.

See also here.

Extinct ape didn’t walk upright


This video says about itself:

The Ape That Took Over the World (Documentary)

14 Jan 2013

In 2001, scientists announced an amazing discovery: the oldest skull of a human ancestor ever found. The 3½ million year old fossil was remarkably complete, and unlike any previous fossil find. Its discovery – by a team led by Meave Leakey of the famous Leakey fossil-hunting family – has revolutionised our understanding of how humans evolved.

The great mystery of our evolution is how an ape could have evolved into the extraordinary creature that is a human being. There has never been another animal like us on the planet. And yet ten million years ago there was no sign that humans would take over the world. Instead the Earth was dominated by the apes. More than 50 different species of ape roamed the world – ten million years ago Earth really was the planet of the apes. Three million years later, most had vanished. In their place came something clearly related to the apes, but also completely different: human beings!

From the India Times:

Ancient Apes Didn’t Walk Upright

July 27, 2013, 3:46 pm IST

WASHINGTON: The ancient ape did not walk on two legs like humans do, as was previously believed, a new study has found, contradicting long-held assumptions.

The new study, led by University of Texas at Austin, found a 9- to 7-million-year-old ape from Italy did not, in fact, walk habitually on two legs. The findings refute a long body of evidence, suggesting that Oreopithecus had the capabilities for bipedal (moving on two legs) walking.

The study, published in the Journal of Human Evolution, confirms that anatomical features related to habitual upright, twolegged walking remain exclusively associated with humans and their fossil ancestors. “Our findings offer new insight into the Oreopithecus locomotor debate,” said anthropologists Gabrielle A Russo.

“While it’s certainly possible that Oreopithecus walked on two legs to some extent, as apes are known to employ short bouts of this activity, an increasing amount of anatomical evidence clearly demonstrates that it didn’t do so habitually,” said Russo.

The researchers analysed the fossil ape to see whether it possessed lower spine anatomy consistent with bipedal walking.

According to the findings, the anatomy of Oreopithecus lumbar vertebrae and sacrum is unlike that of humans, and more similar to apes, indicating that it is incompatible with the functional demands of walking upright as a human does.

Canadian fossil horse DNA discovery


This video is called Evolution Of The Horse.

From the BBC:

26 June 2013 Last updated at 17:46 GMT

Ancient horse bone yields oldest DNA sequence

By Jonathan Ball, BBC News

A fragment of a fossilised bone thought to be more than 700,000 years old has yielded the genome of an ancient relative of modern-day horses.

This predates all previous ancient DNA sequences by more than 500,000 years.

The study in the journal Nature

I have replaced the not working link to that Nature article on the BBC site with a link which does work.

was made possible because the bone was found preserved in Canadian permafrost following the animal’s demise.

The study also suggested that the ancestor of all equines existed around four million years ago.

A remnant of the long bone of an ancient horse was recovered from the Thistle Creek site, located in the west-central Yukon Territory of Canada.

Palaeontologists estimated that the horse had last roamed the region sometime between a half to three-quarters of a million years ago.

An initial analysis of the bone showed that despite previous periods of thawing during inter-glacial warm periods, it still harboured biological materials – connective tissue and blood-clotting proteins – that are normally absent from this type of ancient material.

DNA puzzle

And this finding was significant as study co-author of the paper, Dr Ludovic Orlando from the University of Copenhagen, explained to the BBC World Service programme Science in Action.

“We were really excited because it meant that the preservation was really good,” he told the BBC. …

From the resulting equine DNA fragments, they reconstructed a draft of its genome. Although the derived sequence data only covered around 70% of the entire genome, this was sufficient foundation for some revealing analyses.

The tell-tale presence of Y chromosome markers showed that the Thistle Creek bone had belonged to a male.

But the DNA also enabled them to reconstruct the evolutionary history of the larger Equus genus, which includes modern-day horses and zebras.

To do this, the scientists also determined the DNA sequence of a donkey, an ancient pre-domestication horse dating back around 43,000 years, five modern horses and a Przewalski’s horse, which possibly represents the last surviving truly wild horse population.

Family trees, based on similarity of the DNA sequences, revealed the relationships between these equine stable-mates and their longer evolutionary history.

Heirs and grazes

The Thistle Creek genome was reassuringly ancestral to the modern horses – positioned as it was at the base of the tree.

Geological dating evidence meant that the researchers could calibrate the rate of evolution in the different branches, and from this look back into the depths of the tree to approximate the age of the Equus genus ancestor – the forerunner to the donkey, zebra and horse.

Horse bone fragments DNA was extracted from pieces of the ancient bone

The results suggested it grazed the grasslands between 4 and 4.5 million years ago – twice as long ago as most previous estimates. …

Over the last two million years horses had experienced significant population expansions and collapses associated with climatic changes, and one collapse coincided with the date when the Thistle Creek and modern horses diverged. …

But would we recognise the Equus ancestor as a horse?

“Even if you look at the Przewalski horse, which has a divergence time of only about 50,000 years ago… and compare it to the domestic horse, you can already see differences,” observed Prof Willerslev.

“I would definitely say it would not look like a horse as we know it… but we would expect it to be a one-toed horse.”

See also here. And here. And here.

Galápagos Darwin’s finches evolution, new study


This video says about itself:

May 14, 2012

Darwin’s Finches in the Galapagos: Small Ground-finch, Large Ground-finch, Sharp-beaked Ground-finch (Vampire Finch), Common Cactus-finch, Small Tree-finch, Warbler finch.

From the Biological Journal of the Linnean Society in Britain:

Adaptive divergence in Darwin’s small ground finch (Geospiza fuliginosa): divergent selection along a cline

Article first published online: 14 JUNE 2013

Abstract

We examine here, in a single year (2005), phenotypic divergence along a 560-m elevation gradient in Darwin‘s small ground finch (Geospiza fuliginosa) in the Galápagos Islands. In this sample, four composite measures of phenotypic traits showed significant differences along the 18-km geographical cline extending from lowlands to highlands.

Compared with lowland birds, highland birds had larger and more pointed beaks, and thicker tarsi, but smaller feet and claws. Finches in an intervening agricultural zone had predominantly intermediate trait values. In a second, mark–recapture study we analyse selection on morphological traits among birds recaptured across years (2000–2005) in lowland and highland habitats.

Birds were more likely to survive in the highlands and during the wet season, as well as if they had large beaks and bodies. In addition, highland birds exhibited higher survival rates if they had small feet and pointed beaks – attributes common to highland birds as a whole. Lowland birds were more likely to survive if they possessed the opposite traits. Selection therefore reinforced existing morphological divergence, which appears to reflect local adaptation to differing resources during the predominantly drought-ridden conditions that characterized the 5-year study. Alternative explanations – including genetic drift, matching habitat choice, deformation by parasites, and the effects of wear – received little or no support.

Why Philornis downsi, the fly that “loves birds”, poses a risk to Finches on Galapagos Islands: here.