Archive for January, 2007

Jan

31

2007
 
 

Bug uses germ warfare



Whitefly...eugh!Invasive whitefly carries a virus to make its conquest easier

In just twenty years a strain of whitefly Bemisia tabaci — known as “biotype B” — has all but taken over the world. The waves of tiny bugs, which feed on the phloem of their host plants, were transported across the globe by the international flower trade (“spread it with flowers”?). How they have managed to bump out the local strain has until now remained a mystery, but according to the authors of a study published this week, the key to success lies in a neat evolutionary arrangement with a group of viruses. A team led by Shu-Sheng Liu at Zhejiang University, China, found that tobacco curly shoot virus and tomato yellow leaf curl China virus, which have devastated their respective crops in the wake of the whitefly invasion, also allow the biotype B strain to live much longer and produce more eggs. Such a terrible partnership is certainly one way to cut down global cigarette consumption, but what harm have tomatoes ever done?

Source: Jiu, M, Zhou, X-P, Tong, L, Xu, J, Yang, X, Wan, F-H & Liu, S-S (2007) Vector-virus mutualism accelerates population increase in an invasive whitefly. PLoS ONE DOI: 10.1371/journal.pone.0000182

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Jan

31

2007
 
 

Surgin’ sturgeon



Hudson RiverEndangered fish is no longer… but in a good way

The road to extinction is steep, with travel being much easier in one direction than the other. So findings reported by Main Bain and colleagues at Cornell University, provide welcome news: the shortnose sturgeon Acipenser brevirostrum is alive and well in the Hudson River. With population numbers up by a factor of four since the 1970s, an estimated 60000 fish now do their fishy thing in the river that flows past one of the world’s largest, busiest cities. This is the first time a fish with US Endangered Species Act protection has qualified to be taken off the list for the right reasons. Let’s hope it’s not the last.

Source: Bain, MB, Haley, N, Peterson, DL, Arend, KK, Mills, KE & Sullivan, PJ (2007) Recovery of a US endangered fish. PLoS ONE DOI: 10.1371/journal.pone.0000168

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Jan

30

2007
 
 

Chips down for battered cod



cod...pieces!Genetic response to selective fishing hampers stock recovery from collapse

Evolution is a two-edged sword — just ask any Atlantic cod. Having withstood the ravages of decades of overfishing, collapsed populations have been slow to recover, and a study published this week shows why. Cod numbers in the Gulf of St Lawrence dwindled in the 1960s and 1970s but recovered well during the 1980s, only to crash again in the 1990s, since when they have remained at low densities. So why no second cod comeback? Gulf Fisheries Centre, New Brunswick, marine biologist Douglas Swain and colleagues think the increase in mesh size around the late 1970s was crucial, bringing about a fast evolutionary shift in the cod. The change was intended to allow fish stocks to build, but instead seems to have selected for slow growth and thus delayed maturity and reproduction. Swain’s findings show how rapid genetic changes can be: fishermen should ignore the warning at their peril!

Source: Swain, DP, Sinclair, AF & Hanson, JM (2007) Evolutionary response to size-selective mortality in an exploited fish population. Proceedings of the Royal Society of London, Series B. DOI: 10.1098/rspb.2006.0275

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Jan

30

2007
 
 

Who’s afraid now?



Grey_wolfSurvey suggests Scots would welcome wolves back to the fold

Plans to reintroduce grey wolves to Scotland haven’t rattled the natives, according to a study published this week. The idea of putting wolves – hunted to extinction in the 18th Century – back into the Highlands has been mooted for many years but failed to become a reality. The study, led by Erlend Nilsen at the University of Olso, Norway, combined a survey of public opinion with computer models to predict the impact of wolf packs on Scotland’s red deer population. The virtual wolves dutifully went on the rampage, producing a suitably satisfying degree of digital carnage. The desolate real-world hills of Northern Britain are all but overrun by red deer, and the annual cull is a costly exercise. However, the wolf’s fate in Scotland is intertwined with sheep, which are somewhat easier to catch than nervy deer. But leaving aside the ethical and animal rights issues, sheep predation need not raise too much concern: most farms operate at a loss and survive on agricultural subsidies. The big bad wolf might just turn out to be the Scottish sheep farmer’s best friend.

Source: Nilsen, EB, Milner-Gulland, EJ, Schofield, L, Mysterud, A, Stenseth, N-C & Coulson, T (2007) Wolf reintroduction to Scotland: public attitudes and consequences for red deer management. Proceedings of the Royal Society of London, Series B. DOI: 10.1098/rspb.2006.0369

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Jan

29

2007
 
 

Stuff the cuckoo



Cuckoo chick -- big bird!New Zealand’s introduced birds no longer recognize nest parasites

Being away from one’s enemies isn’t always a good thing: recognizing the bad guys usually means being familiar with them too. Katrina Hale and James Briskie, both at the University of Canterbury, Christchurch, provide a striking case in point this week. The European song thrush, blackbird and chaffinch got lucky the day European settlers decided to take them to New Zealand, because they were freed from the unwanted attentions of the cuckoo Cucuclus canorus. And how quickly they’ve forgotten their old adversary! In less than 140 years since their introduction to the islands, all three species have lost their aggressive response to the presence of a cuckoo at the nest. Whereas their European counterparts will readily attack an intruder, Hale and Briskie found that the New Zealand birds barely gave a stuffed cuckoo a second glance. They were much better at spotting model “eggs”: however, that could be down to the researchers’ skill – or lack – with Styrofoam, clay, and paint.

Source: Hale, K & Briskie, JV (2007) Response of introduced European birds in New Zealand to experimental brood parasitism. Journal of Avian Biology DOI: 10.1111/j.2007.0908-8857.03734.x

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Jan

25

2007
 
 

Good and bad news for turtles



loggerhead turtles...ahhhTwo reports reveal different aspects of longline fisheries

Replacing traditional “J-hooks” with so-called circle hooks will greatly reduce sea turtle bycatch, according to a review paper published this week. Duke University’s Andrew Read crunched data from 1.5 million fishing lines and reached the conclusion that circle hooks are good for turtles. Lightsticks, on the other hand, are not. In controlled behavioral experiments, University of Hawaii — Manoa marine biologist John Wang and collaborators showed that loggerhead turtles are attracted to tiny underwater lights: green, blue, yellow, orange — any colour as long as it’s on. Given the widespread use of lightsticks in longline fisheries, the future for sea turtles is perhaps not too bright after all.

Source: Read AJ (2007) Do circle hooks reduce the mortality of sea turtles in pelagic longlines? A review of recent experiments. Biological Conservation DOI: 10.1016/j.biocon.2006.10.030

Source: Wang, JH, Boles, LC, Higgins, B & Lohmann, KJ (2007) Behavioral responses of sea turtles to lightsticks used in longline fisheries. Animal Conservation DOI: 10.1111/j.1469-1795.2006.00085.x

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Jan

24

2007
 
 

Big mammas hit hardest



common snooksSex-changing fish species could be vulnerable to size-selective fishing

When fish evolved their neat sex-changing strategy they weren’t being driven to extinction by humans. And for those commercially important species that change sex only once, that could turn out to be a very bad thing. Using a computer model equipped with some really fishy (er, real fish ;)) data, Simon Fraser University’s Phil Molloy and colleagues analyzed the effects of sex-changing in fish populations. The model showed that species changing just once are most vulnerable because fisheries target the largest (i.e. female) fish. The timing of the sex-change is important, however, and if fish can control that they might be able to adjust to the sudden disappearance of all the females.

Source: Molloy, PP, Goodwin, NB, Côté, IM, Gage, MJG & Reynolds, JD (2007) Predicting the effects of exploitation on male-first sex-changing fish. Animal Conservation DOI: 10.1111/j.1469-1795.2006.00065.x

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