Venezuelan opossums and the origin of species


This video, in Spanish, from Venezuela about a mouse opossum is called Marmosa robinsoni.

From Wildlife Extra:

New study could change the traditional view of how species come about

A team of researchers from the City University of New York working on the Península de Paraguaná in Venezuela have made a discovery that could revolutionise our understanding of how the origin of a new species takes place.

Up to now it has been accepted that the primary drivers in a species becoming isolated, and consequently developing sufficiently separate characteristics to become genetically distinct, are physical in nature – the uplift of mountains, the formation of islands, the change in the course of a river, creating barriers.

The findings of the study of two species of mouse opossums, Marmosa xerophila and Marmosa robinsoni, have now added interactions among species as another way that populations can become geographically isolated, which could promote the formation of new species.

In their paper the authors, Eliécer E Gutiérrez, Robert A Boria and Robert P Anderson, say that these interactions might include, ‘the presence of particularly effective predators or strong competitors, or the absence of important prey or essential mutualistic species.’

This new theory has come about as a result of observations on the Paraguaná peninsula, which is separated from the mainland only by a spit of sand, in which the researchers found that M. robinsoni has become separated from populations of the same species found on the mainland, not because the habitat in between is unsuitable, but because it is mostly occupied by M. xerophila.

The inability of individuals of that population of M. robinsoni to mate with individuals of mainland populations could, in time, lead to their genetic differentiation and the origin of a new species.

To read more about the study go to www.ecography.org/content/august-2014.

Bird flight evolution, new research


This video from Canada says about itself:

The chukar partridge (Alectoris chukar)

Chukar partridge were introduced to the Kamloops area in the early 1950’s. They established themselves quickly and expanded in numbers due in a large part to the poor quality of our range land. With improved grazing practices and aggressive weed control the habitat has shrunk for these beautiful birds.

From Wildlife Extra:

Falling chicks could reveal the mysterious origins of flight

Two researchers from the University of California, Berkeley, may have just disproved a widely-accepted theory of how the origins of flight began.

Dennis Eva Evangelista, post-doctoral researcher at University of North Carolina, Chapel Hill, and Robert Dudley, UC Berkeley professor of integrative biology, undertook research to assess how baby birds (in this case the team used chukar partridges) react when they fall upside down.

Their results revealed that even birds that were just one-day old successfully flapped their wings in order to right themselves when they fell.

In the nest, the chicks used their wings to flip or roll themselves around. Nine days after hatching, 100 per cent of birds that were analysed in the study were found to have developed coordinated flapping and body pitch control, enabling them to right themselves.

“These abilities develop very quickly after hatching,” said Evangelista, who emphasised that no chicks were harmed during the research. “The results highlight the importance of manoeuvring and control in development and evolution of flight in birds.”

Dudley had argued for more than a decade against the popular theory of wing-assisted incline running (WAIR), which theorises that flight originated in theropod dinosaurs – the ancestors of birds – when they used symmetric wing flapping while running up an incline.

This theory argues that wings assisted running by providing lift, and that the ability to steer or manoeuvre is absent early on in the evolution of flight. To test this, the researchers tested the chicks to see if they flapped their wings while running up an incline. However, none of the birds did.

Dudley’s theory is that flight developed in tree-dwelling animals falling, and then evolving the ability to glide and fly. He believes that midair manoeuvrability preceded the development of flapping flight, allowing the ancestors of today’s birds to use their forelimbs as rudimentary wings.

The results of the study reveal that aerial righting using uncoordinated, asymmetric wing flapping, is very early development. “This experiment illustrates that there is a much broader range of aerodynamic capacity available for animals with these tiny, tiny wings than has been previously realised,” Dudley explains.

Okapi evolution, new research


This is an okapi video.

From Wildlife Extra:

New study sheds fresh light on okapi genetics

Very little is known about the mysterious and elusive okapi

A pioneering genetic study of the endangered Congolese okapi, using genetic techniques similar to those employed by crime scene forensics, has helped to unravel the mysteries of the species’ evolutionary origins and genetic structure.

The study, conducted by scientists from Cardiff University and the Zoological Society of London (ZSL), analysed okapi faeces collected from the rainforest, skin samples from museums, clippings of dried skin and artefacts found in villages across its range in DRC.

“Our research showed that okapi are both genetically distinct and diverse – not what you might expect from an endangered animal at low numbers,” said chief investigator of the study, Dr David Stanton from ZSL’s Institute of Zoology and Cardiff University’s School of Biosciences.

He added: “Higher genetic diversity means that the okapi are equipped with the necessary genes capable of withstanding changes to their environment. Beyond that they are also more likely to survive to produce offspring bearing their own resilient genetic traits. Consequently, the population will continue for more generations because of the success of these individuals.

“This rich and distinct genetic variation is likely to be a result of periods of forest fragmentation and expansion in the Congo Basin in the ancient past. The data show that okapi have survived through historic changes in climate, and therefore indicate that the species may be more resilient to future changes.

“There is a concern however, that much of this genetic diversity will be lost in the near future, due to rapidly declining populations in the wild making efforts to conserve the species, facilitated by the IUCN Species Survival Commission’s Giraffe and Okapi Specialist Group, critical.”

It is hoped that the new information collected during the study will prove indispensable for future conservation management of the species and, ultimately, its survival.

In the past 20 years the wild okapi’s numbers have halved. Prior to the study, little was known about the enigmatic animal, endemic to the rainforests of central and north-eastern Democratic Republic of Congo (DRC) in Central Africa. Ongoing threat from armed conflict, habitat fragmentation, human encroachment and poaching has rendered the species endangered, according to a 2013 assessment led by ZSL and IUCN for the IUCN Red List of Threatened Species.

Only known to the Western world since 1901, when the species was discovered by a ZSL Fellow and described at a meeting of the Society, the elusive okapi is nearly impossible to observe in the wild because of its shy nature and the remoteness of the rainforests it inhabits; a trait that has helped it avoid getting caught in the cross-fire of Congo’s long-running civil conflict.

Dr Noëlle Kümpel, co-chair of the IUCN SSC Giraffe and Okapi Specialist Group and ZSL collaborator on the research, said “The IUCN Red List assessment we carried out last year highlighted that the okapi is faring worse than previously thought, with okapi populations shrinking and becoming more fragmented. It’s therefore critical that we support ICCN to step up conservation efforts across the okapi’s range, and in particular ensure the integrity and security of the protected areas where okapi are found – which includes flagship World Heritage Sites like Virunga National Park and the Okapi Wildlife Reserve.”

Download the full study here.

Galapagos islands, evolution and sea levels


This video says about itself:

How Have Sea-Levels Influenced Evolution on the Galapagos Islands?

This movie is a simple 0 m to -210 m geographical loop sequence at 5 m increments. Important features are the substantial gaps between Galapagos’ “core” islands even at -100 m. However, below c. -130 m the various islands begin coalescing.

Research: “Exploring the combined role of eustasy and oceanic island thermal subsidence in shaping biodiversity on the Galápagos” by Jason R. Ali and Jonathan C. Aitchison from the Journal of Biogeography.

From Wiley Research News:

The Galapagos Islands have an iconic status in the history of evolutionary study, now new research shows that the islands’ own geological past may have influenced the evolution of the chain’s native species.

Writing in the Journal of Biogeography, Jason Ali and Jonathan Aitchison explore how fluctuating sea level changes over thousands of years impacted the island chain’s ecology. They estimate that when the sea retreated, most recently 20,000 years ago, the water would have been 144m below its current level.

As a result, Santa Cruz, the island in the center of the archipelago, would have expanded, enveloping many of the smaller islands, while creating a series of shallow ‘land bridges’ between the volcanic outcroppings. Such bridges explain the range and diversity of the islands’ species, such as snakes, geckos and iguanas, which appear landlocked to modern eyes.

“As soon as I saw that that half the islands in the archipelago were sat on a single, shallow, submarine platform, I realized that the implications for biology could be significant,” said Dr. Ali. “My geological knowledge told me that sea-level falls must have regularly re-connected the islands, and that this must have profoundly shaped the landlocked biota’s distribution, and very likely its composition.”

Ecuador has declared an emergency in the Galapagos Islands, saying that a cargo ship which ran aground last week still poses a threat to the archipelago’s fragile ecosystem: here. See also here.

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Sponges made human evolution possible, new research


This video is called Sponge Feeding.

From daily Haaretz in Israel:

The precursor to life on earth? The humble sponge, new research says

New paper says sea sponges may have led to more oxygenated water in the deep ocean, leading to evolution of more complex forms of life on earth – including humans.

Mar. 10, 2014 | 12:15 PM

Sea sponges may have been the precursor to all life on earth, including human life, according to new research.

A new paper published in the Nature Geoscience journal says that sea sponges may have added oxygen to the deep ocean, helping forge an environment where more complex life forms could evolve, Discovery News reported Monday.

Earlier this year, research found that the earliest sponges could have survived in waters with very little oxygen. The research presented in this latest paper builds on this.

“There had been enough oxygen in ocean surface waters for over 1.5 billion years before the first animals evolved, but the dark depths of the ocean remained devoid of oxygen,” said a press release from Tim Lenton of the University of Exeter, according to Discovery News. “We argue that the evolution of the first animals could have played a key role in the widespread oxygenation of the deep oceans. This in turn may have facilitated the evolution of more complex, mobile animals,” the press release said.

According to DNA analysis, sea sponges first emerged at least 700 million years ago – a time when the oceans contained little oxygen. Oxygen levels in the oceans rose between 700 and 600 million years ago, and animal fossils have been found dating to 650 million years ago.

The above is some of the evidence that supports the theory. The way that sponges feed is further evidence, Discovery News said. As they feed, water circulates through sponges, carrying nutrients, and also particles of organic matter. All those years ago, these particles would have included dead microbial matter that eats up oxygen as it rots. Removing these rotting particles from the ocean would have led to increased oxygen in the water, according to researchers.

With more oxygen, more complex life forms would have been able to emerge, including animals that prey on each other, and eat each other, according to Discovery News. This would have paved the way for today’s food webs and the marine ecosystem.

The theory that earth creatures, including humans, first evolved from underwater ones is widely accepted, Discovery News noted, adding that scientists believe sponges may have been an “Animal Eve” that led to the evolution of all animals today.

The research also solves the riddle of whether oxygenated waters predated the humble sponge, or the other way around. “The effects we predict suggest that the first animals, far from being a passive response to rising atmospheric oxygen, were the active agents that oxygenated the ocean around 600 million years ago,” the researchers said. “They created a world in which more complex animals could evolve, including our very distant ancestors.”

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Female songbirds’ songs, new research


This video from North America says about itself:

9 Feb 2009

This female Blue Jay was perched on a branch overlooking my patio, and amusing me with beautiful vocal skills.

From Nature:

Female song is widespread and ancestral in songbirds

Karan J. Odom,Michelle L. Hall, Katharina Riebel, Kevin E. Omland & Naomi E. Langmore

04 March 2014

Abstract

Bird song has historically been considered an almost exclusively male trait, an observation fundamental to the formulation of Darwin’s theory of sexual selection. Like other male ornaments, song is used by male songbirds to attract females and compete with rivals. Thus, bird song has become a textbook example of the power of sexual selection to lead to extreme neurological and behavioural sex differences.

Here we present an extensive survey and ancestral state reconstruction of female song across songbirds showing that female song is present in 71% of surveyed species including 32 families, and that females sang in the common ancestor of modern songbirds. Our results reverse classical assumptions about the evolution of song and sex differences in birds. The challenge now is to identify whether sexual selection alone or broader processes, such as social or natural selection, best explain the evolution of elaborate traits in both sexes.

‘Teenage’ songbirds experience high mortality due to many causes, study finds: here.

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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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