Archive for June, 2007

Jun

27

2007
 
 

Hotspots feel the heat



They might have lots of species, but not necessarily evolutionary potential

some like it hotSeventy-seven percent of terrestrial vertebrate species are found in areas declared as biodiversity hotspots, which occupy just 2.3% of the Earth’s surface. Unfortunately, as a recently published study shows, the sheer number of species isn’t the end of the story. Phylogenetic diversity — the measure of how different species assemblages are — is arguably more important, because greater differences offer more evolutionary potential. Earlier claims that biodiversity hotspots are also centers of high phylogenetic diversity were welcome, but according to Ohio State University biologists Miles Spathelf and Tom Waite they were overstated. Reanalysis of the same data shows that Madagascar, with its unique lemurs and weird mongooses, skewed the results beyond belief. Taking the fabled island out of the equation left hotspots no more likely (in fact even less likely) to harbor primate and carnivore phylogenetic diversity than anywhere else. Source: Spathelf M & Waite TA (2007) Will hotspots conserve extra primate and carnivore evolutionary history? Diversity and Distributions DOI: 10.1111/j.1472-4642.2007.00386.x

Related story in Conservation magazine: Hotspot Mismatch for Most-Imperiled Species | Pollination Crisis in Biodiversity Hotspots

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Jun

25

2007
 
 

Hare today, gone tomorrow



Agri-environment schemes benefit common species but not rare ones

running to stand stillAgri-environment schemes are commonly supposed to promote biodiversity, but a recently published study claims they don’t deliver. Writing in the Journal of Applied Ecology, Queen’s University Belfast biologist Neil Reid and colleagues present evidence that the Environmentally Sensitive Area scheme in Northern Ireland has resulted in greater numbers of commonplace rabbits Oryctolagus cuniculus and foxes Vulpes vulpes, but has done little for the much rarer Irish hares Lepus timidus. That’s exactly what shouldn’t happen: rabbits graze endangered plants and foxes have a taste for threatened ground-nesting birds. In the period between 1999 and 2003, some 24 billion Euros have been plowed into Europe’s agri-environment schemes. Maybe it’s time to think again… Source: Reid N, McDonald RA & Montgomery I (2007) Mammals and agri-environment schemes: hare haven or pest paradise? Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2007.01336.x

Related story in Conservation magazine: Agriculture versus Biodiversity

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Jun

22

2007
 
 

Australia’s top dog



Dingoes control lesser predators and herbivores, protect native wildlife

poor little chapDingoes Canis lupus dingo are a conservationist’s best friend in Australia, mounting evidence shows. In the current pages of Austral Ecology, a contemplative group of scientists, fronted by Al Glen at the Dwellingup Research Centre, Australia, argue for the effectiveness of the introduced canine in protecting the native fauna and even flora against the ravages of other introduced mammals. Smaller predators such as red fox Vulpes vulpes and feral cat Felis catus, together with pesky herbivores such as rabbits Oryctolagus cuniculus, fall under the dingo’s influence. Yet despite numerous anecdotal benefits to Australia’s natural wellbeing, dingoes are still persecuted in parts of the country and have been almost completely wiped out in some areas. Glen and colleagues now call for systematic research into what the dingo can and can’t do for Oz’s embattled endemics. About time too. Source: Glen AC, Dickman CR, Soulé ME & MacKey BG (2007) Evaluating the role of the dingo as a trophic regulator in Australian ecosystems. Austral Ecology DOI: 10.1111/j.1442-9993.2007.01721.x

Related story in Conservation magazine: The Conundrum of Biological Control: Weighing Urgency Against Uncertainty

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Jun

21

2007
 
 

Survival rations



Selective removal of prey can help predators recover, Norwegian study finds

where's the trout?Scientists report this week on an experiment in which an entire lake was successfully switched between stable ecological states. Writing in Science, Umeå University’s Lennart Persson and colleagues describe how overharvesting of brown trout Salmo trutta to the point of near extinction left Lake Takvatn in northern Norway with an abundance of large Arctic charr Salvelinus alpinus. Removal of hundreds of thousands of charr during the 1980s, which reduced their density by 80%, caused a shift in their size distribution – towards there being lots of small, fast-growing fish. And that’s just what brown trout like to eat. The result was a steady increase in trout numbers to something approaching historical levels. Who’d have thought that to bring a predator back from the brink, you need to take its food away? Source: Persson L, Amundsen P-A, De Roos AM, Klemetsen A, Knudsen R & Primicerio R (2007) Culling prey promotes predator recovery – alternative states in a whole-lake experiment. Science DOI: 10.1126/science.1141412

Related story in Conservation magazine: Point of No Return

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Jun

19

2007
 
 

Arctic Spring leaps forward



Climate-driven high latitude phonological shifts outpace change elsewhere

frosty branchPhenological shifts – changes in the timing of nature’s main events – are happening all over the planet as a consequence of rapid climate change, but for sheer pace you can’t beat the High Arctic, according to new findings published in Current Biology. In just ten years, between 1996 and 2005, University of Aarhus in Roskilde, Denmark biologist Toke Høye and colleagues recorded an average advancement of 14.5 days in plant flowering, arthropod emergence and bird clutch laying dates. Changes in phenology, which on a current global basis are typically less than five days per decade, tend to be temperature driven, but at high latitudes such as Høye’s study site at Zackenberg, Greenland, snowmelt is the all-important factor. The alarmingly rapid rates mean that Arctic species are going to hit the evolutionary buffers soon – trophic networks are no doubt feeling the heat too. Source: Høye T, Post E, Meltofte H, Schmidt NM & Forchhammer MC (2007) Rapid advancement of Spring in the High Arctic. Current Biology DOI: tba, but click here

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Jun

18

2007
 
 

Ecosystem (bodily) functions past



Evolutionary ties echo down the centuries as one extinct species endangers another

Going through the motionsThe extinction of the dodo Raphus cucullatus and other large herbivores might still be influencing the wildlife of Mauritius, according to preliminary data published in the African Journal of Ecology. Seeds of the endemic, critically endangered ebony Diospyros egrettarum don’t germinate well, it seems, unless they’ve passed through the digestive tract of an animal such as the long-gone giant tortoises Geochelone inepta and G. triserrata. Manchester University PhD student Adam Moolna found that when he fed ebony seeds to another giant tortoise G. gigantea, which acted as an analog for the extinct species, the seed’s germination rate shot up. The plant coevolved to survive herbivory – in fact, to use it as a means of dispersal – to the point where without undergoing the 18-day passage through the tortoise’s gut, a seed is much less likely to break through its own shell. Source: Moolna A (2007) Preliminary observations indicate that giant tortoise ingestion improves seed germination for an endemic ebony species in Mauritius. African Journal of Ecology DOI: 10.1111/j.1365-2028.2007.00807.x

Related story in Conservation magazine: Dig Deeper

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Jun

15

2007
 
 

Decomposing problems



Sperm whale strandings are linked to sea temperature, long term data show

a whale's taleThe North Sea is no place for sperm whales Physeter macrocephalus – they have trouble navigating shallow waters and their favorite squid prey don’t live there. So it’s no surprise that scientists have long been interested in understanding why every now and then one — or even a group — of the giant cetaceans washes up dead. Strandings have been recorded since the mid-Sixteenth century, and analysis of these data by Aberdeen University marine biologist Graham Pierce and colleagues has dispelled a few choice hypotheses on why the whales get into trouble. Writing in Fisheries Research, Pierce’s team present evidence that sea temperature anomalies are the most significant factor associated with strandings. They speculate that climatic shifts change the distribution of squid Gonatus fabricii. Female squid congregate in Arctic waters off Norway to spawn, dangerously close to the edge of the North Sea “trap” from which the whales seem to have difficulty escaping. The findings at least let us off the hook (slightly): clumps in the pattern of strandings have been going on far longer than the most destructive period of whaling. Source: Pierce GJ, Santos MB, Smeenk C, Saviliev A & Zuur AF (2007) Historical trends in the incidence of strandings of sperm whales (Physeter macrocephalus) on North Sea coasts: an association with positive temperature anomalies. Fisheries Research DOI: 10.1016/j.fishres.2007.06.001

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Jun

14

2007
 
 

What are we putting in our tigers?



Contraceptive implants have long-term impact on zoo tiger reproduction

love catsYou might think that stopping tigers from breeding is the last thing we’d want, but for zoos the world over, making sure that only the right animals get to do the business — genetically speaking — is the top priority. Consequently, female tigers Panthera tigris are often given a contraceptive implant to allow them a full social life without, er, getting into trouble. However, a study published recently in Zoo Biology raises concerns that having an implant might do long term damage to a tiger’s prospects of getting pregnant. A group led by St. Louis Zoo biologist Cheri Asa found that females often struggled to conceive even after the implant had been surgically removed. For critically endangered species, such as Amur or Sumatran tigers, messing about with female’s reproductive abilities is potentially disastrous, but given the drastic alternatives (such as surgical removal of ovaries) a contraceptive implant is undoubtedly the lesser evil. Source: Chuei JY, Asa CS, Hall-Woods M, Ballou J & Traylor-Holzer K (2007) Restoration of reproductive potential after expiration or removal of melengestrol acetate contraceptive implants in tigers (Panthera tigris). Zoo Biology DOI: 10.1002/zoo.20137

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Jun

13

2007
 
 

Soaking up the C



Anthropogenic nitrogen can help forests absorb anthropogenic carbon

hope that we're growing out of trouble?The amount of carbon locked up by temperate and boreal forests is strongly influenced by how much nitrogen is available, according to a study published this week in Nature. Federico Magnani, a forestry scientist at the University of Bologna, Italy, and a large group of international collaborators, conducted a carefully controlled analysis of fine-scale data on nitrogen flux and forest growth time-series across Western Europe and North America. After accounting for factors such as wildfire, disease outbreaks, harvesting and other types of disturbance, nitrogen availability emerged as the major influence on forest growth. As anthropogenic nitrogen sources sky rocket, their fertilizing effect on high latitude forests is taking the edge off the worst excesses of our carbon addiction. We should be grateful for small mercies. Source: Magnani F, Mencuccini M, Borghetti M, Berbigier P, Berninger F, Delzon S, Grelle A, Hari P, Jarvis PG, Kolari P, Kowalski AS, Lankreijer H, Law BE, Lindroth A, Loustau D, Manca G, Moncrieff JB, Rayment M, Tedeschi V, Valentini R & Grace J (2007) The human footprint in the carbon cycle of temperate and boreal forests. Nature DOI: 10.1038/nature05847

Related story in Conservation magazine: That Sinking Feeling

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Jun

12

2007
 
 

Six degrees of separation



Anchovy and sardine populations take turns to collapse: it’s a temperature thing

where's the fish?Anchovy and sardine fisheries are famous for their dramatic collapses, but a new study suggests the cause isn’t overexploitation. Writing in the Canadian Journal of Fisheries and Aquatic Sciences, three Japanese biologists led by Akinori Takasuka at the National Research Institute of Fisheries Science, Yokohama, show that the optimal temperatures for anchovy Engraulis japonicus and sardine Sardinops melanostictus larvae differ by around six degrees centigrade. When climate-induced oceanic regime shifts warm the seas, anchovies do well but sardines collapse. At a distinctly chillier 16.2 degrees, the boot is on the other foot, giving sardines the edge. However, the fish harvest is important in allowing stocks to recover as part of their natural 50-year basin-wide ups and downs. Source: Takasuka A, Oozeki Y & Aoki I (2007) Optimal growth temperature hypothesis: why do anchovy flourish and sardine collapse or vice versa under the same ocean regime? Canadian Journal of Fisheries and Aquatic Sciences DOI: 10.1139/F07-052

Related story in Conservation magazine: Point of No Return

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