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patterns—electric blue in the westernCaribbean, lemon yellow in the Northern Why Gobies Are Like Hobbits
Caribbean—might be local signals to preda-tors that these gobies are the valet service As Bilbo Baggins famously warned, trav- genetic breaks between island groups that rather than the entrée. If this is true, then the live relatively close together. These breaks wrong color pattern of an “immigrant” goby coincide with well-established color-pattern ing where you might be swept off to” (1). For differences among goby fish—for example, the better part of a century, marine biologists the white and blue forms in the Caribbean have assumed the roads of ocean currents are waters around Puerto Rico are genetically goby populations remain remarkably distinct distinct populations even though they reside from island to island, so this explanation can- within 23 km of each other (see the figure). not suffice. The other possibility is that the and larvae and rafting content/full/299/5603/51 propagules of many that is, they have a hidden level of drift far from their homes, on distant shores.
Now, on page 107 of this issue, Taylor and Hellberg (2) help to overturn this notion. They provide further evidence that at least some marine species whose larvae have the potential the larvae of other reef fishes. But this to disperse over long distances, instead show and low dispersal. Mantis shrimp in Indonesia show genetic differences similar in spatial scale and genetic depth to the gobies studied contained in larval structures (3).
In living color. The white
(top) and blue (middle)
other, yet remain genetically separate. Even though their Mexico and the west Atlantic (6), or between pelagic larvae could be dispersed over large distances by the Mediterranean and the east Atlantic (7).
ocean currents, the larvae prefer to remain close to home.
These genetic results are paralleled by new (Bottom) A cleaner goby (also called a sharknose goby) cleans
information gleaned from the chemical signa- the parasites from a red hind (Epinephelus guttatus).
ture of fish otoliths (calcareous components of the inner ear) or mollusk statoliths (calcareous genetic data, the implications are strong that The gobies studied by Taylor and Hellberg very little population exchange has taken place.
have high dispersal potential—their larvae hard structures of calcium carbonate grow like remain adrift in ocean currents for about 3 tiny pearls within the animal, depositing a Taylor and Hellberg study (2). They show layer for each day of life—including the days that there are remarkably strong patterns of buoys to travel hundreds of kilometers (2).
spent as pelagic larvae. As larvae pass through genetic structure in the mitochondrial genes Two types of explanations are possible for different trace-metal environments, the hard of a small Caribbean reef goby fish (see the sharp genetic distinctions in the face of such parts act as a sort of flight recorder that can be figure). Such patterns demonstrate not only dispersal potential. First, there might be read after the larvae settle in their final loca- that distant islands harbor genetically distinct strong selection against the wrong genotypes.
tion. The information thus gleaned differs in populations, but also that there are sharp These gobies are cleaners—that is, they make significant ways from that obtained through their living picking the parasites off larger genetic analysis. It reflects an individual’s his- S. R. Palumbi is in the Department of Biological fish, often the same fish that any rational tory since birth, including the pelagic pathway Sciences, Stanford University, Pacific Grove, CA 93950, goby would consider a dangerous predator.
taken as a larva, and potentially provides much USA. E-mail: R. R. Warner is in Yet the large fish hold their appetites at bay more fine-scale spatial data. But the results are the Department of Ecology, Evolution, and Marine while the tiny gobies dart about them, picking Biology, University of California, Santa Barbara, CA similar to those obtained by genetic analysis.
93106, USA E-mail: their skin clean of parasites. The variable color For example, populations of fish on tropical islands are capable of seeding themselves uncharacteristic in that they are almost all 3. S. E. Swearer et al., Bull. Mar. Sci. 70, 251 (2002).
despite having larvae that survive for weeks from island populations (9). Yet these exam- 4. P. H. Barber, S. R. Palumbi, M. V. Erdmann, M. K. Moosa, with the potential for long-distance dispersal ples of fine-scale patterns in genetic or chem- Nature 406, 692 (2000).
5. S. Planes, P. Romans, R. Lecomte-Finiger, Coral Reefs (3). Whelk populations along the California ical signatures tell us that the conventional 17, 9 (1998).
coast also appear to be colonized by locally wisdom of marine biology—that the ocean 6. J. C. Avise, Phylogeography (Harvard Univ. Press, road is a long one for larvae—may prove to be 7. H. Quessada, C. Zapata, G. Alvarez, Mar. Ecol. Progr.
a coarse generalization (10). It turns out that Ser. 116, 99 (1995).
using two very different approaches are telling 8. D. Zacherl, thesis, University of California, Santa us the same thing: that in some times and either—Bilbo was an exception—and in the 9. C. Mora, P. F. Sale, Trends Ecol. Evol. 17, 422 (2002).
places, marine larvae are capable of maintain- end gobies and hobbits like to stay at home.
10. The extent of marine larval dispersal will be one of ing close links to home despite their proximity the subjects of a symposium at the upcoming AAAS to the ocean highways of the sea. Of course, References and Notes
meeting in Denver, CO: “Opening the Black Box: 1. J. R. R. Tolkien, The Lord of the Rings: The Fellowship Understanding Ecosystem Dynamics in the Coastal many other marine species seem to disperse of the Ring (Houghton Mifflin, Boston, 1994), p. 72.
Ocean” (B. Menge, R. Warner, and J. Lubchenco, co- broadly, and the examples cataloged here are 2. M. S. Taylor, M. E. Hellberg, Science 299, 107 (2003).
P E R S P E C T I V E S : C H E M I S T R Y form. Thus, there are 3 C22H28 tetraman-tanes, 6 isomeric C26H32 pentamantanes,and as many as 17 possible C Diamondoid Hydrocarbons—
Delving into Nature’s Bounty
ferences between their relative thermody-namic stabilities decrease, and the com- plexity of the potential-energy surface con- elucidated in 1913 (1), consists of forming a tetracyclic cage system. Shortly thereafter it was recognized that a series of posed on this diamond lattice. The simplest of these “diamondoids,” with the common In a report by Dahl et al. (5) higher “adamantologs” of adamantane (see cules. They could neither be isolated from doids (6, 7). Such functionalized Diamond in miniature. The structures of adamantane
(left), diamantane (center), and triamantane (right) are seg-
interest in these molecules and their chem- Schleyer reported that endo-trimethyle- tane (C14H20) (see the figure). This com- nenorbornane (which can be prepared read- which is used extensively as an antidyski- cal antiviral agent to treat Type A influenza in humans (6). Polyalkyladamantanes have tane (3). The third member of the dia- jet fuel blends (810). There is also particularly in the area of microelectron- mula C(4n+6)H(4n+12), where n = 0, 1, 2, 3, … Dahl et al. (5) have isolated and charac- terized several previously unknown higher first three members of the series (adaman- diamondoid hydrocarbons from crude oil.
tane, diamantane, and triamantane) exists In addition, they have developed improved The author is in the Department of Chemistry, as a single isomer, higher members of the University of North Texas, Denton, TX 76203, USA.
E-mail: series can exist in more than one isomeric



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