92 posts · 39,182 views
Mennonite, evolutionary biologist, cat-4 cyclist. Not necessarily in that order.
Denim and Tweed
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- February 25, 2010
- 10:05 AM
- 71 views
Invasive species runs out of evolutionary "steam" as it invades
by Jeremy Yoder in Denim and Tweed
For invasive plants, flowering time is a trait that may often be under selection during colonization—when a plant flowers determines its climatic tolerances, its vulnerability to herbivores, and its compatibility with the local pollinator community. In a study just released online at Proceedings of the Royal Society B, Colautti and coauthors examined the evolution of this trait in a plant that has swept across eastern North America since its introduction from Europe: purple loosestrife, and fo........ Read more »
Colautti, R., Eckert, C., & Barrett, S. (2010) Evolutionary constraints on adaptive evolution during range expansion in an invasive plant. Proc. R. Soc. B. DOI: 10.1098/rspb.2009.2231
Phillips, B., Brown, G., Webb, J., & Shine, R. (2006) Invasion and the evolution of speed in toads. Nature, 439(7078), 803. DOI: 10.1038/439803a
Phillips, B., & Shine, R. (2006) An invasive species induces rapid adaptive change in a native predator: cane toads and black snakes in Australia. Proc. R. Soc. B, 273(1593), 1545-50. DOI: 10.1098/rspb.2006.3479
Vellend, M., Harmon, L., Lockwood, J., Mayfield, M., Hughes, A., Wares, J., & Sax, D. (2007) Effects of exotic species on evolutionary diversification. Trends in Ecology , 22(9), 481-8. DOI: 10.1016/j.tree.2007.02.017
- February 17, 2010
- 10:05 AM
- 45 views
Caught between birds and squirrels, limber pines go both ways
by Jeremy Yoder in Denim and Tweed
Responding to natural selection often means compromising between different selective forces. A brief paper published online early at Evolution documents one such case – limber pine trees' compromise between protecting their seeds from squirrels, and making them accessible to the birds that disperse them. Pulled between these conflicting selective sources, some limber pine populations grow cones in a wider variety of shapes [$a].
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Siepielski, A., & Benkman, C. (2007) Convergent patterns in the selection mosaic for two North American bird-dispersed pines. Ecological Monographs, 77(2), 203-20. DOI: 10.1890/06-0929
Siepielski, A., & Benkman, C. (2009) Conflicting selection from an antagonist and a mutualist enhances phenotypic variation in a plant. Evolution. DOI: 10.1111/j.1558-5646.2009.00867.x
- February 11, 2010
- 10:05 AM
- 72 views
Bats can hold their liquor
by Jeremy Yoder in Denim and Tweed
A new paper in PLoS ONE tests the alcohol tolerances of nectar-eating bats. Believe it or not, there is a scientific purpose.
Alcohol isn't a vice exclusive to humans. Animals that eat fruit or nectar may accidentally imbibe if they eat past-ripe fruit or nectar that has had time to ferment. Some species, like the pentail treeshrew, have evolved tolerances that surpass our own capacities – and some, like cedar waxwings, get distinctly tipsy after a few bad berries. Alcohol tolerance effective........ Read more »
Orbach, D., Veselka, N., Dzal, Y., Lazure, L., & Fenton, M. (2010) Drinking and flying: Does alcohol consumption affect the flight and echolocation performance of Phyllostomid bats?. PLoS ONE, 5(2). DOI: 10.1371/journal.pone.0008993
- February 3, 2010
- 10:05 AM
- 84 views
Dethroning the Red Queen?
by Jeremy Yoder in Denim and Tweed
Regular readers of Denim and Tweed know that I'm fascinated by the evolution of species interactions: interactions between plants and nitrogen-fixing bacteria, Joshua trees and yucca moths, parasitoid wasps and butterflies, and between ants and the trees they guard. I tend to think that coevolutionary interactions not only determine the health of natural populations, but shape their evolutionary history. But would I feel that way if I were a paleontologist?
Running just to stay in place
The id........ Read more »
Benton, M. (2010) Evolutionary biology: New take on the Red Queen. Nature, 463(7279), 306-7. DOI: 10.1038/463306a
Futuyma, D. (1987) On the role of species in anagenesis. The American Naturalist, 130(3), 465-73. DOI: 10.1086/284724
Stenseth, N., & Maynard Smith, J. (1984) Coevolution in ecosystems: Red Queen evolution or stasis?. Evolution, 38(4), 870-80. DOI: 10.2307/2408397
Van Valen, L. (1973) A new evolutionary law. Evolutionary Theory, 1(1), 1-30. info:/
Venditti, C., Meade, A., & Pagel, M. (2009) Phylogenies reveal new interpretation of speciation and the Red Queen. Nature, 463(7279), 349-52. DOI: 10.1038/nature08630
- January 27, 2010
- 10:05 AM
- 106 views
"Chemical camouflage" lets leafhoppers hide from their own bodyguards
by Jeremy Yoder in Denim and Tweed
Many insects in the order Hemiptera – the "true" bugs – have evolved a way to hire their own protection by excreting sugary "honeydew." Honeydew attracts ants, who tend honeydew-producing bugs like livestock, protecting them from predators and even disease. Honeydew is cheap to make because honeydew producers typically make a living sucking the sap of their host plants; they're trading sugar and water, which they have in abundance, for safety.
.flickr-photo { }.flickr-frameright { float: ri........ Read more »
Silveira, H., Oliveira, P., & Trigo, J. (2010) Attracting predators without falling prey: Chemical camouflage protects honeydew‐producing treehoppers from ant predation. The American Naturalist, 175(2), 261-8. DOI: 10.1086/649580
- January 19, 2010
- 10:05 AM
- 132 views
Evolving from pathogen to symbiont
by Jeremy Yoder in Denim and Tweed
Recently the open-access PLoS Biology published a really cool study in experimental evolution, in which a disease-causing bacterium was converted to something very like an important plant symbiont. The details of the process are particularly interesting, because the authors actually used natural selection to identify the evolutionary change that makes a pathogen into a mutualist.
Life as we know it needs nitrogen – it's a key element in amino acids, which mean proteins, which mean structural ........ Read more »
Amadou, C., Pascal, G., Mangenot, S., Glew, M., Bontemps, C., Capela, D., Carrere, S., Cruveiller, S., Dossat, C., Lajus, A.... (2008) Genome sequence of the beta-rhizobium Cupriavidus taiwanensis and comparative genomics of rhizobia. Genome Research, 18(9), 1472-1483. DOI: 10.1101/gr.076448.108
Gitig, D. (2010) Evolving towards mutualism. PLoS Biology, 8(1). DOI: 10.1371/journal.pbio.1000279
Marchetti, M., Capela, D., Glew, M., Cruveiller, S., Chane-Woon-Ming, B., Gris, C., Timmers, T., Poinsot, V., Gilbert, L., Heeb, P.... (2010) Experimental evolution of a plant pathogen into a legume symbiont. PLoS Biology, 8(1). DOI: 10.1371/journal.pbio.1000280
- January 13, 2010
- 01:05 PM
- 146 views
Why make your own food when it doesn't pay?
by Jeremy Yoder in Denim and Tweed
We humans like to think we're pretty complex – what with having invented the wheel, wars, New York, and so on – so we tend to forget that evolution doesn't care about complexity. All that matters to natural selection is who makes the most babies, and sometimes complex adaptations can get in the way of that criterion. A study recently published on the always open-access PLoS ONE provides a good example of this principle in action – given the right selective pressures, photosynthetic organis........ Read more »
de Castro, F., Gaedke, U., & Boenigk, J. (2009) Reverse evolution: Driving forces behind the loss of acquired photosynthetic traits. PLoS ONE_id, 4(12). http://dx.plos.org/10.1371/journal.pone.0008465
Hansen, B., P. K. Bjornsen, & P. J. Hansen. (1994) The size ratio between planktonic predators and their prey. . Limnology and Oceanography, 395-403. info:/
McFadden, G. (2001) Chloroplast Origin and Integration. Plant Physiology, 125(1), 50-3. DOI: 10.1104/pp.125.1.50
- January 7, 2010
- 10:05 AM
- 142 views
Masquerading caterpillars hide in plain sight
by Jeremy Yoder in Denim and Tweed
Insects that have evolved elaborate mimicry of inanimate objects – leaves, twigs, even bird droppings – to hide from predators are a staple of nature documentaries. But do these masquerades work because they help insects blend into the background, or because predators actually see the insects and then dismiss them as inedible leaves, twigs, or bird droppings? It's a tricky question to answer, but a brief paper in this week's Science presents an experiment that tries to do just that [$a].
T........ Read more »
Skelhorn, J., Rowland, H., Speed, M., & Ruxton, G. (2010) Masquerade: Camouflage without crypsis. Science_id, 327(5961), 51-51. http://www.sciencemag.org/cgi/doi/10.1126/science.1181931
- December 30, 2009
- 10:05 AM
- 187 views
Escaping the "poverty trap" of infectious disease
by Jeremy Yoder in Denim and Tweed
Even in the twenty-first century, infectious diseases such as malaria, dengue fever, cholera, and AIDS remain widespread in much of the developing world, at tremendous cost to human life and economic productivity. Poorer nations lack the resources for more effective public health measures; but widespread infectious disease may slow or prevent the economic development that can provide those resources. A new paper in Proceedings of the Royal Society tries to sort out this chicken-and-egg problem, ........ Read more »
Bonds, M., Keenan, D., Rohani, P., & Sachs, J. (2009) Poverty trap formed by the ecology of infectious diseases. Proc. R. Soc. B. DOI: 10.1098/rspb.2009.1778
- December 23, 2009
- 10:05 AM
- 197 views
Why aren't there more sickle-cell anemics in the Mediterranean?
by Jeremy Yoder in Denim and Tweed
The story of sickle-cell anemia and its malaria-protective effects is a textbook case how environmental context determines the fitness of a given genetic profile. However, the evolution of human blood disorders in response to selection from malaria parasites might be more complicated than that textbook story.
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Malaria-cau........ Read more »
Penman, B., Pybus, O., Weatherall, D., & Gupta, S. (2009) Epistatic interactions between genetic disorders of hemoglobin can explain why the sickle-cell gene is uncommon in the Mediterranean. Proc. Nat. Acad. Sci. USA, 106(50), 21242-6. DOI: 10.1073/pnas.0910840106
- December 16, 2009
- 10:05 AM
- 190 views
Cuckholding crows don't necessarily have fitter chicks
by Jeremy Yoder in Denim and Tweed
Birds are bad at monogamy. There are a number of good evolutionary reasons to cheat on your mate, and it's not clear which one is the most likely explanation. A new study of American crows, however, suggests that, for females, cheating isn't necessarily the best choice [$-a].
Avian infidelity isn't obvious, because many birds are socially monogamous, forming couples for one or more breeding seasons to raise chicks. However, DNA-based paternity testing has overturned this intuition -- a 2002 rev........ Read more »
Arnqvist, G., & Kirkpatrick, M. (2005) The evolution of infidelity in socially monogamous passerines: The strength of direct and indirect selection on extrapair copulation behavior in females. The American Naturalist, 165(s5). DOI: 10.1086/429350
Griffith, S.C., Owens, I.P.F., & Thuman, K.A. (2002) Extrapair paternity in birds: A review of interspecific variation and adaptive function. Molecular Ecology, 2195-212. info:/10.1046/j.1365-294X.2002.01613.x
Townsend, A., Clark, A., & McGowan, K. (2010) Direct benefits and genetic costs of extrapair paternity for female American Crows (Corvus brachyrhynchos). . The American Naturalist, 175(1). DOI: 10.1086/648553
- December 10, 2009
- 10:05 AM
- 172 views
Picky eating, not genetics, splits leaf beetles
by Jeremy Yoder in Denim and Tweed
Many different factors can conspire to create reproductive isolation between populations and, ultimately, separate species. Disentangling them is often tricky, but a study recently published in PNAS takes a crack, and demonstrates that two populations of leaf beetles are divided by food preferences, not genetics [$-a]
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N........ Read more »
Bikard, D., Patel, D., Le Mette, C., Giorgi, V., Camilleri, C., Bennett, M., & Loudet, O. (2009) Divergent evolution of duplicate genes leads to genetic incompatibilities within A. thaliana. Science, 323(5914), 623-6. DOI: 10.1126/science.1165917
Egan, S., & Funk, D. (2009) Ecologically dependent postmating isolation between sympatric host forms of Neochlamisus bebbianae leaf beetles. Proc. Nat. Acad. Sci. USA, 106(46), 19426-19431. DOI: 10.1073/pnas.0909424106
- December 2, 2009
- 10:05 AM
- 182 views
For yucca moths, does (flower) size matter?
by Jeremy Yoder in Denim and Tweed
In a paper just released online at Molecuar Ecology ahead of publication, genetic tests on moth larvae provide the latest piece to the puzzle of why there are two kinds of Joshua tree -- because the tree's pollinators need to match its flowers [PDF].
I've written extensively about the interaction between Joshua tree and its pollinators. Like all yuccas, Joshua tree is pollinated only by yucca moths. Female yucca moths collect pollen in special mouthparts and deliberately apply it to a yucca flo........ Read more »
Godsoe, W., Yoder, J.B., Smith, C., & Pellmyr, O. (2008) Coevolution and divergence in the Joshua tree/yucca moth mutualism. The American Naturalist, 171(6), 816-823. DOI: 10.1086/587757
Marr, D., & Pellmyr, O. (2003) Effect of pollinator-inflicted ovule damage on floral abscission in the yucca-yucca moth mutualism: the role of mechanical and chemical factors. Oecologia, 136(2), 236-243. DOI: 10.1007/s00442-003-1279-3
Smith, C., Godsoe, W., Tank, S., Yoder, J.B., & Pellmyr, O. (2008) Distinguishing coevolution from covicariance in an obligate pollination mutualism: Asynchronous divergence in Joshua tree and its pollinators. Evolution, 62(10), 2676-87. DOI: 10.1111/j.1558-5646.2008.00500.x
Smith, C.I., Drummond, C., Godsoe, W.K.W., Yoder, J.B., & Pellmyr, O. (2009) Host specificity and reproductive success of yucca moths (Tegeticula spp. Lepidoptera: Prodoxidae) mirror patterns of gene flow between host plant varieties of the Joshua tree (Yucca brevifolia: Agavaceae). . Molecular Ecology. DOI: 10.1111/j.1365-294X.2009.04428.x
- November 23, 2009
- 09:05 AM
- 226 views
Aphid-tending ants cull the sick from the herd
by Jeremy Yoder in Denim and Tweed
Just released online at Biology Letters: aphid-tending ants have been observed to selectively remove sick members of their "herd" [$-a].
Most aphid species produce some sort of sweet honeydew as waste while feeding on their host plants; ant-attended aphid species use this honeydew to attract ants. In many cases, the ants "milk" the aphids by stroking them to prompt release of the honeydew. While exploiting a colony of aphids, ants defend it as a food resource, protecting the aphids from predato........ Read more »
Nielsen, C., Agrawal, A., & Hajek, A. (2009) Ants defend aphids against lethal disease. Biology Letters. DOI: 10.1098/rsbl.2009.0743
Way, M. (1963) Mutualism between ants and honeydew-producing Homoptera. Ann. Rev. Entomology, 8(1), 307-44. DOI: 10.1146/annurev.en.08.010163.001515
- November 20, 2009
- 09:05 AM
- 271 views
Cost of killing nest-mates offset by benefits of killing nest-mates
by Jeremy Yoder in Denim and Tweed
Among birds, brood parasites are the ultimate freeloaders -- species like the common cuckoo and the brown-headed cowbird lay their eggs in other birds' nests, leaving the host to raise the parasite chicks at the expense of its own. But while brood parasitism is easy on the parents, it isn't so easy on their chicks, as a study recently published in PLoS ONE suggests.
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Anderson, M., Moskát, C., Bán, M., Grim, T., Cassey, P., & Hauber, M. (2009) Egg eviction imposes a recoverable cost of virulence in chicks of a brood parasite. PLoS ONE, 4(11). DOI: 10.1371/journal.pone.0007725
Hoover, J., & Robinson, S. (2007) Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs. Proc. Nat. Acad. Sci. USA, 104(11), 4479-83. DOI: 10.1073/pnas.0609710104
Lahti, D. (2005) Evolution of bird eggs in the absence of cuckoo parasitism. Proceedings of the National Academy of Sciences, 102(50), 18057-62. DOI: 10.1073/pnas.0508930102
Soler, M., Soler, J., Martinez, J., & Moller, A. (1995) Magpie host manipulation by great spotted cuckoos: Evidence for an avian mafia?. Evolution, 49(4), 770-5. DOI: 10.2307/2410329
- November 9, 2009
- 11:05 AM
- 244 views
Pollination before flowers
by Jeremy Yoder in Denim and Tweed
Which came first, the pollinator or the pollinated? An article in this week's Science suggests that a diverse group of insects may have been drinking nectar and pollinating plants millions of years before the appearance of modern flowering plants [$-a].
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Panorpis communis, a modern scorpionfly species, and a sketch of anc........ Read more »
Ollerton, J., & Coulthard, E. (2009) Evolution of animal pollination. Science, 326(5954), 808-9. DOI: 10.1126/science.1181154
Ren, D., Labandeira, C., Santiago-Blay, J., Rasnitsyn, A., Shih, C., Bashkuev, A., Logan, M., Hotton, C., & Dilcher, D. (2009) A probable pollination mode before angiosperms: Eurasian, long-proboscid scorpionflies. Science, 326(5954), 840-7. DOI: 10.1126/science.1178338
- October 29, 2009
- 02:02 PM
- 265 views
Endless forms: Oral sex by fruit bats
by Jeremy Yoder in Denim and Tweed
One of those scientific papers that seems to have been written with the blogosphere in mind: biologists have just published records of fellatio by the fruit bat Cynopterus sphinx. Apparently C. sphinx females are pretty flexible -- they lick their mate's penis during copulation, which evidently induces him to stay in longer (see the graph below, with drawing). The authors offer a handful of non-mutually-exclusive hypotheses for the adaptive benefit of the behavior, ranging from lubrication to in........ Read more »
Tan, M., Jones, G., Zhu, G., Ye, J., Hong, T., Zhou, S., Zhang, S., & Zhang, L. (2009) Fellatio by fruit bats prolongs copulation time. PLoS ONE, 4(10). DOI: 10.1371/journal.pone.0007595
- October 26, 2009
- 12:05 PM
- 259 views
How to synchronize flowering without really trying
by Jeremy Yoder in Denim and Tweed
One way plants can gain an advantage in their dealings with pollinators, seed dispersers, or herbivores is to act collectively. For instance, when oak trees husband their resources for an extra-big crop of acorns every few years instead of spreading them out, acorn-eating rodents are overwhelmed by the bumper crop, and more likely to miss some, or even forget some of the nuts they cache. These benefits of synchronized mass seed production, or "masting," are straightforward, but how it happens is........ Read more »
Crone, E., Miller, E., & Sala, A. (2009) How do plants know when other plants are flowering? Resource depletion, pollen limitation and mast-seeding in a perennial wildflower. Ecology Letters, 12(11), 1119-26. DOI: 10.1111/j.1461-0248.2009.01365.x
Janzen, D. (1971) Seed Predation by Animals. Ann. Rev. Ecol. Syst., 2(1), 465-92. DOI: 10.1146/annurev.es.02.110171.002341
Janzen, D. (1976) Why Bamboos Wait So Long to Flower. Ann. Rev. Ecol. Syst., 7(1), 347-91. DOI: 10.1146/annurev.es.07.110176.002023
Satake, A., & Iwasa, Y. (2000) Pollen coupling of forest trees: Forming synchronized and periodic reproduction out of chaos. J. Theoretical Biol., 203(2), 63-84. DOI: 10.1006/jtbi.1999.1066
- October 19, 2009
- 12:05 PM
- 297 views
Social termites team up with non-relatives
by Jeremy Yoder in Denim and Tweed
In social insects, colonies of hundreds or thousands of workers and soldiers forgo reproduction to support one or a few "reproductives" -- drones and a queen. In most cases, this isn't as selfless as it might seem. Because the workers in a colony are all offspring of the queen, they're really reproducing through her -- because the queen shares genes with the workers, when she reproduces it contributes to their evolutionary fitness.
This is called kin selection, and in many cases it's a good exp........ Read more »
SMITH, J. (1964) Group selection and kin selection. Nature, 201(4924), 1145-1147. DOI: 10.1038/2011145a0
Johns, P., Howard, K., Breisch, N., Rivera, A., & Thorne, B. (2009) Nonrelatives inherit colony resources in a primitive termite. Proc. Nat. Acad. Sci. USA, 106(41), 17452-6. DOI: 10.1073/pnas.0907961106
- October 13, 2009
- 03:30 PM
- 268 views
Video of yucca pollination
by Jeremy Yoder in Denim and Tweed
With permission from my doctoral advisor, Olle Pellmyr, I've just uploaded a unique video to Vimeo: a yucca moth laying eggs in, then pollinating, a yucca flower. I don't know why I didn't think of this earlier -- it's great footage, and deserves to be seen more widely.
A female yucca moth mates, then collects pollen from a yucca flower in specialized mouthparts. She carries it to another flower where, as shown in the video, she drills into the floral pistil with her ovipositor and lays eggs ........ Read more »
Godsoe, W., Yoder, J., Smith, C., & Pellmyr, O. (2008) Coevolution and Divergence in the Joshua Tree/Yucca Moth Mutualism. The American Naturalist, 171(6), 816-23. DOI: 10.1086/587757
Pellmyr, O. (2003) Yuccas, yucca moths, and coevolution: A review. Annals of the Missouri Botanical Garden, 90(1), 35. DOI: 10.2307/3298524
Smith, C., Godsoe, W., Tank, S., Yoder, J., & Pellmyr, O. (2008) Distinguishing coevolution from covicariance in an obligate pollination mutualism: Asynchronous divergence in Joshua tree and its pollinators. Evolution, 62(10), 2676-87. DOI: 10.1111/j.1558-5646.2008.00500.x
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