Line | In the Sonoran Desert of northwestern Mexico and |
southern Arizona, the flowers of several species of | |
columnar cacti—cardon, saguaro, and organ | |
pipe—were once exclusively pollinated at night by | |
(5) | nectar-feeding bats, as their close relatives in arid |
tropical regions of southern Mexico still are. In these | |
tropical regions, diurnal (daytime) visitors to columnar | |
cactus flowers are ineffective pollinators because, | |
by sunrise, the flowers’ stigmas become unreceptive | |
(10) | or the flowers close. Yet the flowers of the Sonoran |
Desert cacti have evolved to remain open after sunrise, | |
allowing pollination by such diurnal visitors as bees and | |
birds. Why have these cacti expanded their range of | |
pollinators by remaining open and receptive in daylight? | |
(15) | This development at the northernmost range of |
columnar cacti may be due to a yearly variation in the | |
abundance—and hence the reliability—of migratory | |
nectar-feeding bats. Pollinators can be unreliable | |
for several reasons. They can be dietary generalists | |
(20) | whose fidelity to a particular species depends on |
the availability of alternative food sources. Or, they | |
can be dietary specialists, but their abundance may | |
vary widely from year to year, resulting in variable | |
pollination of their preferred food species. Finally, they | |
(25) | may be dietary specialists, but their abundance may |
be chronically low relative to the availability of flowers. | |
Recent data reveals that during spring in the | |
Sonoran Desert, the nectar-feeding bats are | |
specialists feeding on cardon, saguaro, and | |
(30) | organpipe flowers. However, whereas cactus-flower |
abundance tends to be high during spring, bat | |
population densities tend to be low except near | |
maternity roosts. Moreover, in spring, diurnal cactus- | |
pollinating birds are significantly more abundant in | |
(35) | this region than are the nocturnal bats. Thus, with bats |
being unreliable cactus-flower pollinators, and daytime | |
pollinators more abundant and therefore more reliable, | |
selection favors the cactus flowers with traits that | |
increase their range of pollinators. While data suggest | |
(40) | that population densities of nectar-feeding bats are |
also low in tropical areas of southern Mexico, where | |
bats are the exclusive pollinators of many species | |
of columnar cacti, cactus-flower density and bat | |
population density appear to be much more evenly | |
(45) | balanced there: compared with the Sonoran Desert’s |
cardon and saguaro, columnar cacti in southern Mexico | |
produce far fewer flowers per night. Accordingly, | |
despite their low population density, bats are able to | |
pollinate nearly 100 percent of the available flowers. |
Sports Association
Statement by sports association spokes-person:
Our sports association issues contracts to television networks for the exclusive right to broadcast our sporting events. For this right, the networks pay the association substantial fees, which help finance our leagues. We also provide free media passes to our events for journalists so that they can effectively report on sports news, including final scores. Now, however, some news organizations are posting video clips, audio clips, digital photographs, and live score updates from our events on their websites. Conditions must be placed on these practices, which go beyond mere sports news reporting; they harm the value of our broadcasting contracts and violate our rights as the owners of the sports leagues. News organizations that wish to post such information on their websites should therefore sign contracts with the sports association that stipulate what postings will be allowed and how much they will cost. As we have in the past, we will deny media passes to journalists from news organizations that do not comply with our requirements.
News Organizations
Statement by news organizations spokesperson:
me news business has largely shifted (rom print media to the Internet, where readers expect text to be accompanied by audio and Images To charge news organizations for providing online sports coverage or to place unnecessary conditions on that coverage is to deny news organizations their right to cover the news. Online news sites are not asking to broadcast sporting events In their entirety, and their sports reporting does not detract from the value of the sports leagues or their events. On the contrary—free, engaging sports reporting generates interest in sports and thus benefits readers and the sports association alike. News organizations must be allowed to report freely about sports on their websites, in any timeframe, using any type of online medium they deem effective.