Lagomorphs are not as diverse as many other mammal groups, but they are widespread. They inhabit every continent except Antarctica and are absent from only a few places around the globe such as parts of South America, Greenland, Indonesia and Madagascar. Although not native to Australia, lagomorphs have been introduced there by humans and have since successfully colonized many parts of the continent.

Lagomorphs generally have a short tail, large ears, wide-set eyes and narrow, slit-like nostrils that they can scrunch tightly closed. The two subgroups of lagomorphs differ considerably in their general appearance. Hares and rabbits are larger and have long hind legs, a short bushy tail and long ears. Pikas, on the other hand, in contrast, are smaller than hares and rabbits and more rotund. They have round bodies, short legs and a tiny, barely-visible tail. Their ears are prominent but are rounded and not as conspicuous as those of hares and rabbits.

Lagomorphs often form the foundation of many predator-prey relationships in the ecosystems they inhabit. As important prey animals, lagomorphs are hunted by animals such as carnivores, owls and birds of prey. Many of their physical characteristics and specializations have evolved as a means of helping them escape predation. For example, their large ears enable them to hear approaching danger better; the position of their eyes enables them to have a near 360-degree range of vision; their long legs enable them to run quickly and out-maneuver predators.

Diet

Lagomorphs are herbivores. They feed on grass, fruits, seeds, bark, roots, herbs and other plant material. Since the plants they eat are difficult to digest, they expel a wet fecal matter and eat it to ensure that the material passes through their digestive system twice. This enables them to extract as much nutrition as possible from their food.

Habitat

Lagomorphs inhabit most terrestrial habitats including semi-deserts, grasslands, woodlands, tropical forests and arctic tundra. Their distribution is worldwide with the exception of Antarctica, southern South America, most islands, Australia, Madagascar, and the West Indies. Lagomorphs have been introduced by humans to many ranges in which they were not formerly found and often such introductions have lead to widespread colonization.

Classification

Lagomorphs are mammals. They are divided into two subgroups, the pikas and the hares and rabbits. The classification of lagomorphs is highly controversial. At one time, lagomorphs were considered to be rodents due to striking physical similarities between the two groups. But more recent molecular evidence has supported the notion that lagomorphs are no more related to rodents than they are to other mammal groups. For this reason they are now ranked as an entirely separate group of mammals.

Evolution

The earliest representative of the lagomorphs is thought to be Hsiuannania, a ground dwelling herbivore that lived during the Paleocene in China. Hsiuannania is know from just a few fragments of teeth and jaw bones. Despite the scant fossil record for early lagomorphs, what evidence there is indicates that the lagomorph clade originated somewhere in Asia.v

The earliest ancestor of rabbits and hares lived 55 million years ago in Mongolia. Pikas emerged about 50 million years ago during the Eocene. Pika evolution is difficult to resolve, as only seven species of pikas are represented in the fossil record.

The study was conducted by Beth Shapiro of Penn State University and Daniel Bradley of Trinity College Dublin. The results are published in the 7 July 2011 issue of the journal Current Biology.

Shapiro and Bradley report that the now-extinct Irish brown bears interbred with ancestral polar bears, leaving an unmistakable DNA fingerprint still carried by modern polar bears. That fingerprint, missing from the DNA of modern brown bears, confirms that interbreeding between polar bears and brown bears took place after the two lineages were already separate species.

The DNA fingerprint exists within the mitochondrial DNA of polar bears. Mitochondrial DNA is passed down the female lineage, from mother to offspring. This means that the ancient hybridization involved the mating of female Irish brown bears and prehistoric male polar bears.

Polar bears today differ markedly from their brown bear cousins. They two species differ in fur color, size, tooth structure, body shape, habitat and range. Yet the species can still interbreed. Polar-brown bear hybrids have been observed in the wild during recent years. Scientists think that many such crosses have occurred during the evolutionary history of the two species.

Study author Beth Shapiro suggests that climate fluctuations were, and are, an important factor in the interbreeding of polar bears and brown bears. As climate changes, so do the ranges of polar bears and brown bears. This cyclical expansion and contraction of the species' ranges brings them into contact periodically. During times when their ranges overlap, brown bears and polar bears can interbreed.

Spoon-billed sandpipers are small wading shorebirds with a distinct spatulate bill. During the breeding season, adult spoon-billed sandpipers are donned in red-brown feathers on their head, neck and breast. They have a black-brown upper body and a pale rufous fringe. Outside of the breeding season, the sandpipers' red-brown feathers fade to a pale brownish-grey and their belly feathers turn white. Spoon-billed sandpipers feed by pecking and probing mudflats exposed at low tide. During the breeding season, spoon-billed sandpipers occupy specialized habitat in northeastern Russia. They nest near lagoons and freshwater pools and forage at nearby estuaries or mudflats. In fall, the spoon-billed sandpiper populations migrate southward along the western rim of the Pacific Ocean to their wintering grounds in Bangladesh and Myanmar. There they occupy habiats such as tidal mudflats and saltpans.

Sadly, habitat destruction in all parts of their range (breeding grounds, wintering grounds and migratory stopovers) has devastated spoon-billed sandpiper numbers. The species is also threatened by hunting and climate change. Since the species experiences low breeding success, and few fledgelings survive to adulthood, their population is vulnerable and shrinking.

To combat the many threats facing spoon-billed sandpipers, BirdLife International has launched a project called "Saving Spoony's Chinese Wetlands". The program has been selected as part of Disney's Friends for Change initiative and will receive at least $25,000 in support from Disney's Friends for Change initiative. That support could increase to $50,000 or even $100,000 if enough people stop by the Disney website and vote for BirdLife's "Saving Spoony's Chinese Wetlands" project.

Shubin's early research, while an Assistant Professor at the University of Pennsylvania, focused on Devonian sites in Pennsylvania. From the rock exposures that lined newly cut roads, Shubin's team unearthed fossils of giant predatory fish, armored fish, and limb bones from early tetrapods. The fossils enabled Shubin's team to describe a river delta ecosystem that existed in the region 365 million years ago. But the bones Shubin's team recovered from the Pennsylvania sites were clearly too young to answer a question that was fast becoming Shubin's core interest: how did tetrapods evolve from fish? In Pennsylvania's Devonian rocks, the transition from fishes to the first tetrapods had already taken place. As Neil Shubin described it in a lecture he gave on his work, "the party was over by the time the rocks that we were working with [in Pennsylvania] were laid down."

So Shubin and his colleagues had to look elsewhere if they were going to find the fish-tetrapod transitional fossils they sought. They developed a fossil search image—a set of criteria that would guide their fossil hunting endeavors. The set out to find rocks of the right age, the right type and the right exposure. After some deliberation and a serendipitous glance at a map in an undergraduate geology textbook, they found a location that matched their search criteria: Ellesmere Island in Nunavut, Canadian Arctic.

In 1999, Shubin and his team, which included vertebrate palaeontolgist Ted Daeschler and zoologist Farish Jenkins, Jr., started organizing an expedition to explore Devonian age rocks in the Canadian Arctic. They spent several years excavating sites that appeared to have been located at the bottom of an ancient ocean. Not a likely place to find a transitional fish-tetrapod fossil. Then in 2002, they moved their activities to Bird Quary, the site that two years later offered up the fossil remains of Tiktaalik.

Neil Shubin currently serves as a Robert R. Bensley Professor at the University of Chicago where he is also the Associate Dean for Organismal and Evolutionary Biology and a Professor on the Committee on Evolutionary Biology. Shubin is also a Provost at The Field Museum in Chicago.

Talks and Publications by Neil Shubin

In a two-part video (part I and part II), Shubin discusses the planning and research that lead up to the discovery of Tiktaalik.

His book, Your Inner Fish, explores the connection between paleontology—in particular, the anatomy of fossil life forms—and present day human anatomy. It delves into the subject of how humans are shaped by their ancestors and what it means for who we are today.

Important scientific publications by Neil Shubin include:

• Daeschler, E., Shubin, N., & Jenkins, F. (2006) A Devonian tetrapod-like fish and the evolution of the tetrapod body plan. Nature, 440(7085), 757-763. DOI: 10.1038/nature04639
• Shubin, N., Daeschler, E., & Jenkins, F. (2006) The pectoral fin of Tiktaalik roseae and the origin of the tetrapod limb. Nature, 440(7085), 764-771. DOI: 10.1038/nature04637
• Shubin, N., Tabin, C., & Carroll, S. (2009) Deep homology and the origins of evolutionary novelty. Nature, 457(7231), 818-823. DOI: 10.1038/nature07891

Only male lions grow manes—females lack the long fur around their face and neck. This difference in appearance between the sexes mean that lions are sexually dimorphic.

It was long thought that manes were shaped largely on the anvil of sexual selection. Males with more impressive manes won more mates and left more offspring. Of course, there were other tentative explanations as well. One was that a lion's mane creates an illusion of bulk, making a male lion appear bigger and fiercer than it would if it lacked a mane. The mane thus is shaped merely by its ability to entice mates but also for its effectiveness in discouraging male rivals. Another explanation was that the mane provides a lion with protection during a fight, making it difficult for attackers to grasp at the lion's vulnerable neck area. Although there may be truth in all of these explanations, there's yet more to the story of the lion's mane.

In 2002, Peyton West and Craig Packer from the University of Minnesota published a paper in the journal Science exploring the many factors that influence lions' manes. The details they gathered revealed that a lion's mane communicates a wealth of information—the condition of the mane reflects the lion's nutrition, testosterone levels, fighting ability, health, age and the climate in which it lives.

Peyton West and Craig Packer found that there are two characteristics of manes that convey different types of information. The first of these characteristics is mane darkness. A lion with a darker mane tends to have better nutrition, higher testosterone levels, a longer reproductive life-span, and a higher offspring survival rate than a lion with a lighter colored mane. The second of these characteristics is mane length. A lion with a longer mane tends to have higher fighting success and better health than a lion with a shorter mane.

Mane length and darkness are also influenced by climate. Lions that live in warmer habitats have shorter, lighter manes than those that inhabit cooler regions. Throughout the year, an individual lion's mane can vary based on the temperatures that prevail—a lion's mane is darker during cooler months than it is during hotter months.

If a lion's mane can be altered by the temperature of the habitat in lives in, then it is susceptible to the effects of climate change. As temperatures around the globe edge upwards, lions' manes are likely to change in response. The lions of the future may well have lighter colored, shorter manes.

There are two basic groups that shape the social lives of lions: prides and coalitions. A pride is a group of 1 to 18 female lions and their young. A coalition is a group of 1 to 9 male lions. A coalition of males competes with other male coalitions for exclusive access to a pride of females. A coalition that wins a pride remains associated with the pride for a period of about 3 to 4 years. After that time, challenges from other coalitions of nomadic males often prevail and the resident coalition is displaced.

When one coalition ousts another from its place within a pride, the consequences are fatal for any unweaned cubs sired by the previous coalition's males. The incoming coalition males kill the cubs and evict any subadult males from the pride. Adult females are thus hastened to return to estrous and mate with the new males.

Within the pride-coalition group, males compete with one another to form pairs with females. Once all males have paired off with females, they prevents other males from mating with their mate. But often there are more females than there are males and the unpaired females choose among the males as mates. In this case, unpaired females often prefer darker-maned males, as they are more likely to have greater vitality, fighting prowess and social status than their lighter-maned counterparts.

This unique structure is formed by the animal's ribs which are flattened and fused to its backbone. The skeletal oddities of the turtle do not stop with its ribs. Another skeletal arrangement unique to turtles is in evident in the placement of their shoulder blades. Instead of being located on the turtle's back (as they are in all other vertebrates), the turtle's shoulder blades lie within its ribcage. To accommodate this odd skeletal arrangement, the muscles that connect the turtle's shoulder blades to the trunk have been twisted and folded.

How did this bizarre arrangement of the turtle's shoulder blades and supporting musculature evolve? Until recently, no one really knew. The fossil record offered few insights, since no transitional forms had been unearthed that show the shoulder blade migrating over generations towards the inside of the ribcage. But now a team of scientists led by Hiroshi Nagashima from the RIKEN Center for Developmental Biology in Japan have found some clues as to how the turtle's unique bone structure could have evolved. These clues have surfaced not from examining the fossil record but from studying the embryos of turtles and other vertebrates. By comparing the embryos of Chinese soft-shelled turtles (Pelodiscus sinensi) at various stages of development to those of mice and chickens, Nagashima's team was able to visualize just how the turtle's shell develops and how the shoulder blade ends up on the underside of its shell.

During the early stages of development, the embryos of all three species have shoulder blades that sit on their back, outside of the ribcage. As the mouse and chicken embryos develop, the shoulder blades remain on the animal's back. The ribs become embedded in a layer of muscle know as the muscle plate. In contrast, as the turtle embryo develops, the second pair of ribs swings forward and grows over the shoulder blades. Meanwhile, the muscle plate tucks inward and forms the edge of the turtle's shell.

Ngashima's work not only describes a possible mechanism for the turtle's odd anatomy, but it also provides context for a recently discovered fossil turtle, Odontochelys. Onontochelys was a turtle that lacked an upper shell but posessed a lower shell (also called a plastron). It had short ribs that did not fan out as the modern turtle's do. Consequently, Onontochelys' second pair of ribs did not swing over its shoulder blades during development.