Flowery advertising, tempting toilets for shrews, bat beacons and more in this week’s news

Flowers rely on advertising
Some unusual graffiti has demonstrated just how important advertising signs are among flowers in the wild. Six white streaks on the dark flower of a kind of South African wild iris point to the vital “insert proboscis here” opening for sipping nectar. Scribbling ink over some or all of those guide marks did not make much difference in whether pollinators approached a flower. But few pollinators sipped from defaced flowers, and pollen spread dropped as low as zero, report Dennis Hansen and colleagues at the University of KwaZulu-Natal in South Africa in an upcoming Proceedings of the Royal Society B. —Susan Milius

SWEET SPOT Flowers dress for success, not just style: a study of white marks on the petals of a wild iris species in Africa, shown here with a Prosoeca fly, supports the long-standing idea that petal patterns encourage insect visits. Dennis Hansen

Hope for cod comeback
A new crunching of four decades of data suggests that predatory fishes such as cod may finally have an opportunity to increase their numbers. So far, the overfished Scotian Shelf off Canada’s east coast has not bounced back despite a virtual fishery shutdown beginning in the early 1990s. For 15 years, numbers of cod and other predatory fish species have stayed low while plankton-eating fish and larger invertebrates boomed. Now, plankton eaters appear to have outpaced their food supply, and their decline gives predators like cod a chance, Kenneth Frank of the Bedford Institute of Oceanography in Nova Scotia and his colleagues argue online July 27 in Nature. —Susan Milius

Fruit of the loo
One of nature’s toilets uses fruity odors to lure furry critters to its dangerous rims. In Borneo, the carnivorous pitcher plant Nepenthes rajah is a favorite throne for tree shrews and rats. While perched on the pot, animals simultaneously lick the plant’s lid and deliver a nutrient-rich poopy present. And they occasionally drown in the bowl, which is filled with soupy digestive juices, insects and fecal matter. Now, scientists from Germany and Malaysia think they know what keeps small mammals coming back to these toilets: the lid exudes hydrocarbons, esters, ketones and alcohols — compounds that produce a tempting fruity or flowery fragrance, the team reports in July’s Journal of Tropical Ecology. —Nadia Drake

Leafy beacons beckon bats
Even though they’re not as flashy as their floral neighbors, plain old leaves can attract pollinators, too. Bats bounce echolocation signals off leaves growing on the bat-pollinated Cuban rainforest vine Marcgravia evenia, scientists from Germany and the U.K. report July 29 in Science. An odd, dish-shaped leaf hangs above the vine’s ring of flowers. Shooting simulated echolocation calls at the leaf produced a strong, multidirectional and invariant reflection. Removing the leaf doubled the foraging time of nectar-feeding bats, suggesting that it is indeed an echo-acoustic beacon for nocturnal pollinators. The leaf’s strange shape and orientation affects its photosynthetic efficiency, but scientists think that the cost is balanced by the benefits of aiding bat pollination. —Nadia Drake

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