Willis C.G.,Harvard University |
Willis C.G.,Duke University |
Ruhfel B.R.,Harvard University |
Primack R.B.,Boston University |
And 4 more authors.
PLoS ONE | Year: 2010
Invasive species have tremendous detrimental ecological and economic impacts. Climate change may exacerbate species invasions across communities if non-native species are better able to respond to climate changes than native species. Recent evidence indicates that species that respond to climate change by adjusting their phenology (i.e., the timing of seasonal activities, such as flowering) have historically increased in abundance. The extent to which non-native species success is similarly linked to a favorable climate change response, however, remains untested. We analyzed a dataset initiated by the conservationist Henry David Thoreau that documents the long-term phenological response of native and non-native plant species over the last 150 years from Concord, Massachusetts (USA). Our results demonstrate that nonnative species, and invasive species in particular, have been far better able to respond to recent climate change by adjusting their flowering time. This demonstrates that climate change has likely played, and may continue to play, an important role in facilitating non-native species naturalization and invasion at the community level. © 2010 Willis et al.
Kocher S.D.,Museum of Comparative Zoology |
Pellissier L.,University of Aarhus |
Pellissier L.,University of Fribourg |
Purcell J.,University of Lausanne |
And 4 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2014
Eusociality is taxonomically rare, yet associated with great ecological success. Surprisingly, studies of environmental conditions favouring eusociality are often contradictory. Harsh conditions associated with increasing altitude and latitude seem to favour increased sociality in bumblebees and ants, but the reverse pattern is found in halictid bees and polistine wasps. Here, we compare thelife histories and distributionsofpopulationsof176 speciesofHymenoptera from the Swiss Alps. We show that differences in altitudinal distributions and development times among social forms can explain these contrasting patterns: highly social taxa develop more quickly than intermediate social taxa, and are thus able to complete the reproductive cycle in shorter seasons at higher elevations. This dual impactofaltitude and development time onsociality illustrates that ecological constraints can elicit dynamic shifts in behaviour, and helps explain the complex distribution of sociality across ecological gradients. copy; 2014 The Author(s) Published by the Royal Society. All rights reserved.
News Article | January 21, 2016
For more than a century, two mysterious tree frog specimens collected by a British naturalist in 1870 and housed at the Natural History Museum in London were assumed to be part of a vanished species, never again found in the wild. Until now. A group of scientists, led by renowned Indian biologist Sathyabhama Das Biju, has rediscovered the frogs and also identified them as part of a new genus - one step higher than a species on the taxonomic ranking. Not only have they found the frogs in abundance in northeast Indian jungles, they believe they could also be living across a wide swathe of Asia from China to Thailand. "This is an exciting find, but it doesn't mean the frogs are safe," Biju said, adding that he hopes the discovery leads to more awareness of the dangers of unfettered development to the animals. The frogs were found at high altitudes in four northeast Indian states, underlining the rain-soaked region's role as a biodiversity hotspot. Some of the forest areas where Biju's team collected frogs in 2007 and 2008 were already slashed and burned by 2014 for agricultural development. The region's tropical forests are quickly disappearing because of programs to cut trees, plant rice, expand human settlements and build roads. Industrial growth amid a decade-long economic boom has also increased pollution, to which frogs are particularly vulnerable. That same sensitivity to climate and water quality makes them perfect environmental barometers, putting them at risk when ecological systems go awry. Of the more than 7,000 amphibian species known globally, about 32 percent are threatened with extinction, according to the International Union for Conservation of Nature. "This frog is facing extreme stress in these areas, and could be pushed to extinction simply from habitat loss," Biju said. "We're lucky in a way to have found it before that happens, but we're all worried." Finding the frogs was an accident. The team had been searching the forest floor for other amphibians in 2007 when, one night, "we heard a full musical orchestra coming from the treetops. It was magical. Of course we had to investigate," Biju said. For the study of the new frog genus, Frankixalus, published Wednesday by the Public Library of Science journal PLOS ONE, Biju and his doctoral students teamed up with researchers from the central Indian state of Pune, Sri Lanka, Brussels and the American Museum of Natural History. They looked at the frogs' behavior, collected specimens and described their outer appearance and skeletal features. But it wasn't until they had sequenced the frogs' genetic code that they confirmed it as a new genus, and surprisingly found another DNA match from a single tadpole specimen reported recently under a mistaken identity in China. The frogs had long been considered lost to science, with the first - and only - previously known specimens collected in 1870 by British naturalist T.C. Jerdon in the forests of Darjeeling. Over decades, the frogs were reclassified at least four times in cases of incorrect identity as scientists drew conclusions from their enlarged snouts or the webbing between their toes. Biju believes the frogs remained hidden from science so long because of their secretive lifestyle living in tree holes at heights up to 6 meters (20 feet) above ground. Most tree frogs live in shrubs or tree holes closer to the ground. But other experts suggest that, while the uniquely high habitat does make them hard to find, the frogs probably remained in obscurity simply because there are so few scientists working in the remote region. "This part of Southeast Asia, in particular, is poorly inventoried," said James Hanken, a biology professor and director of the Museum of Comparative Zoology at Harvard University. Given the habitat threats and alarming rate of extinctions worldwide, he said the "remarkable" tree frog find "points out that we may be losing even more species than we know or can fully document." "It doesn't in any way offset the tragic losses represented by global amphibian extinction," said Hanken, who was not involved in the tree frog study. Biju's team named the new frog genus Frankixalus after herpetologist Franky Bossuyt, who was Biju's adviser when he was a student at the Vrije Universiteit in Brussels. Only two species within the genus have been identified, including the Frankixalus jeronii first described in the 19th century. The scientists are still trying to confirm whether a second collected species was mistakenly named within another genus of tree frogs. There are now 18 tree frog genera known worldwide. The study documents the tree frogs' unusual maternal behavior, with the females laying fertilized eggs in a tree hole filled with water, and then returning at regular intervals after the tadpoles hatch to feed them with unfertilized eggs. "This is incredible," Biju said, excitedly dumping a pile of pickled tadpoles onto a glass-covered table in his office at the University of Delhi, and selecting one to place under a microscope. The magnification reveals a clutch of undigested eggs still inside the tadpole's belly. "Do you see these eggs? Just imagine, the mother is coming back over and over and dropping these eggs for her babies to eat." Rather than nascent teeth, the tadpoles have smooth, suction-like mouths to pull in the eggs. Their eyes are positioned on the top of their heads, rather than on the sides. Biju suggested the feature may help the tadpoles see eggs being dropped by mother frogs into the hole during feeding time. Fully grown, the frogs are about as big as a golf ball. Uniquely, they feed mostly on vegetation, rather than insects and larvae. "Frogs have been around for 350 million years, and have evolved to face so many habitat challenges," said Biju, who is known in India by the nickname "The Frog Man" and has discovered 89 of the 350 or so frog species known to be in the country. Scientists said the work was crucial for both understanding the planet's biological diversity and raising awareness about the need for conservation. Already, Australia has seen the extinction of one frog species that brooded tadpoles in its stomach, while Central America recently lost its brightly colored golden toad. "Species discoveries and rediscoveries ... can bring excitement and focus to animals like amphibians that, despite being the most threatened vertebrate group, are underrepresented in the media and scientific literature," said herpetologist Robin Moore, co-founder of the Washington, D.C.-based Amphibian Survival Alliance. "Wonder and inspiration tend to be more powerful motivators than despair."
News Article | March 25, 2016
Prairie dogs are cute, furry and are vicious serial killers with a thirst for blood, according to a new study. These animals are highly social, intelligent creatures who only consume plants for their dietary intake. Ground squirrels are apparently killed by the creatures in an effort to reduce competition for food, researchers deduced. Both species of animals consume a similar diet, including prickly pears and specific grasses. Similar behavior, first noted in prairie dogs in Colorado during 2007, has never before been seen taking place among herbivores. Five additional years of study by researchers revealed the behavior was most common in May, as young squirrels first venture out of their nests on the search for food. Biologists examined survival rates of youngsters born to parents of squirrel-killing, and compared that data to prairie dogs born to parents who did not murder their neighboring rodents. The study found that reducing populations of ground squirrels led to greater survival rates for young prairie dogs. The behavior was also the driving factor driving fitness in the creatures, far outpacing any other characteristic driving health. "Although carnivores are known to kill competing species, who would have thought that herbivores do so as well? In the case of carnivores, one possibility is that the species are eliminating potential predators on their young, but that doesn't seem likely in this case," Jonathan Losos of the Museum of Comparative Zoology at Harvard University told Discovery News. One possibility for the unusual behavior may be that groundhogs living in areas of dense grasslands are more likely to encounter ground squirrels, driving the murderous behavior. As humans introduce foreign species to areas outside their natural habitats, such activities may become more common, researchers speculate. During the study, researchers recorded 47 prairie dogs that killed ground squirrels, with 36 of the animals being females. The deadliest specimen seen was "Killer Supreme," who was recorded killing nine squirrels over the course of four years. They may be cute, but prairie dogs can be cold-blooded killers. Research into how prairie dogs murder ground squirrels to reduce competition for food was profiled in the journal Proceedings of the Royal Society B.
Archibald S.B.,Simon Fraser University |
Archibald S.B.,Brandon University |
Greenwood D.R.,Museum of Comparative Zoology |
Mathewes R.W.,Simon Fraser University
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2013
We test Janzen's (1967) hypothesis that the low temperature seasonality in the modern tropics accounts for increased local species turnover (beta diversity) across montane landscapes relative to those of the more seasonal Temperate Zone. In the Eocene, low seasonality extended beyond the hot tropics to Polar Regions, therefore, its effects on montane dispersal ability should have been decoupled from low latitude. We sampled fossil insect communities across the Okanagan Highlands: a thousand kilometer transect of temperate, low temperature seasonality, higher mid-latitude Eocene uplands of far-western North America. We find high species turnover, supporting a prime role of temperature fluctuation in controlling montane beta diversity. This high upper mid-latitude montane endemism is consistent with greater Eocene global biodiversity. © 2012 Elsevier B.V.
News Article | March 16, 2016
Vladimir Nabokov's influence on Russian and English literature and language is assured. Many people also know of the novelist's lifelong passion for butterflies. But his notable contributions to the science of lepidopterology and to general biology are only beginning to be widely known. Nabokov was no amateur entomologist. He served for six years as curator of the butterfly collection at Harvard University's Museum of Comparative Zoology in Cambridge, Massachusetts, and published a dozen papers on taxonomy — the description and classification of organisms — that remain important. His observations on butterfly morphology have stimulated breakthrough research in evolutionary biology. Several of his original biogeographic hypotheses have been confirmed in the past few years. Fine Lines, a collection edited by Stephen Blackwell and Kurt Johnson, explains the importance of Nabokov's scientific work and traces its influence on his novels. The book begins with 154 of Nabokov's black-and-white and colour drawings of butterflies' fine anatomical structures. Most represent the European, Asian and American species of the 'blues' of the tribe Polyommatini, Nabokov's favourite group. Ten essays follow, by prominent researchers including evolutionary biologist James Mallet, current Harvard butterfly curator Naomi Pierce and lepidopterist Robert Pyle, explaining the interplay of science and art in Nabokov's writings. Fine Lines clearly demonstrates the significant impact that science had on Nabokov's evolution as a writer. The decision to open the book with the drawings is a masterstroke. They illustrate one of the most important aspects of Nabokov's creativity — his tremendous attention to details, described with scrupulous precision. In his novels, he seamlessly marshals minutiae — impressions, passing fancies, ideas — to create a universe strongly rooted in observation. The particular or apparently trivial was, for him, always worth probing. In his entomological studies, he analysed fine, nearly invisible, dots on the wings of New and Old World butterflies to hint at what may have happened on Earth millions of years ago. With no palaeontological data, Nabokov speculated that North and then South America were populated by five waves of butterflies migrating from Asia ( Psyche 52, 1–61; 1945) — a picture confirmed by DNA analysis almost 70 years on ( et al. Proc. R. Soc. B 278, 2737–2744; 2011). This pointillism is harder than it seems. Piling up millions of elements can easily end in chaos; to create a picture, one needs to understand the nature of these elements and to be able to choose between them. The core of scientific drawing differs greatly from photography in focusing on the heart of the matter and avoiding unnecessary details. This is important for science, and no less for art. Both have the same central goal — to reveal an unknown or invisible essence of things. That is one of the main points of Fine Lines. Yet science and art diverge in their communication. In science, the ability to convey the idea properly and simply is a matter of special talent, but almost everyone can learn to do it. Not so in art. Nabokov's drawings are scientifically perfect, but also staggeringly fine aesthetically. They show how the merging of content and form in art conveys ideas wonderfully. However, even the most wonderful idea becomes banal if artistry is lacking. The personal, artistic and scientific aspects of Nabokov's life were tightly intertwined. As one of the book's essayists, science writer Dorion Sagan, concludes, nature and art were a continuum for him: “the distinct but equally necessary paths of art and science seem to scale opposite sides of the same majestic mountainscape”. Nabokov's fiction is permeated by science, as Fine Lines amply reveals. He was a master in the use of motif and symbols. In his novel Lolita (Olympia, 1955), for instance, the town Lepingville is named after 'lepping', butterfly hunters' slang for chasing butterflies, and Elphinstone after Elphinstonia, a subgenus in the white butterfly genus Euchloe. The fictional play-within-the-novel, The Enchanted Hunters, is built almost entirely on symbols associated with butterflies. Diana, its protagonist, is both the virgin goddess of hunting and a butterfly species (Speyeria diana). In his essay, Nabokov scholar Brian Boyd reveals that Edusa Gold, who directs the play, is an echo of Colias edusa, an old but preocccupied name for the clouded yellow (now Colias croceus). I can add that her sister Electra Gold was named after Colias electra, an unavailable name for the African clouded yellow, now Colias electo. That these names are effectively hidden — no longer in use, but buried in lists of unavailable scientific epithets — chimes with the secrecy in this controversial novel. I prepared this review at the Nabokov House Museum in St Petersburg, Russia. While there, I discovered in the Nabokov family's copy of An Illustrated Natural History of British Butterflies and Moths by Edward Newman (William Glaisher, 1870) that Nabokov had, as a child, coloured in the black-and-white image of the clouded yellow with remarkable accuracy. As zoologist Victor Fet describes in Fine Lines, Nabokov's childhood concentration on butterfly collecting and drawing effectively provided very specific training in memory and paying attention, as well as that focus on minute detail. Few have so beautifully and meaningfully meshed serious scientific endeavour with artistic brilliance, visual and verbal. Fine Lines helps us to understand the phenomenon of creativity, without which neither good science nor true art can exist.
PubMed | Museum of Comparative Zoology
Type: Journal Article | Journal: Nature | Year: 2010
Among the extraordinary adaptations driven by sperm competition is the cooperative behaviour of spermatozoa. By forming cooperative groups, sperm can increase their swimming velocity and thereby gain an advantage in intermale sperm competition. Accordingly, selection should favour cooperation of the most closely related sperm to maximize fitness. Here we show that sperm of deer mice (genus Peromyscus) form motile aggregations, then we use this system to test predictions of sperm cooperation. We find that sperm aggregate more often with conspecific than heterospecific sperm, suggesting that individual sperm can discriminate on the basis of genetic relatedness. Next, we provide evidence that the cooperative behaviour of closely related sperm is driven by sperm competition. In a monogamous species lacking sperm competition, Peromyscus polionotus, sperm indiscriminately group with unrelated conspecific sperm. In contrast, in the highly promiscuous deer mouse, Peromyscus maniculatus, sperm are significantly more likely to aggregate with those obtained from the same male than with sperm from an unrelated conspecific donor. Even when we test sperm from sibling males, we continue to see preferential aggregations of related sperm in P. maniculatus. These results suggest that sperm from promiscuous deer mice discriminate among relatives and thereby cooperate with the most closely related sperm, an adaptation likely to have been driven by sperm competition.