38. Ens BJ, Safriel UN, Harris MP (1993) Divorce in the long-lived and monogamous oystercatcher, Haematopus ostralegus: incompatibility or choosingthe better option. Animal Behaviour 45: 1199–1217. 39. Li W, Li L, Fu R, Deng Y, Wang H (2010) Changes to the North Atlantic Subtropical High and its role in the intensification of summer rainfall variability in the southeastern United States. Journal of Climate 24: 1499–1506. 40. Karl TR, Knight RW, Plummer N (1995) Trends in high-frequency climate variability in the 20th-century. Nature 377: 217–220. 41. Pall P, Aina T, Stone DA, Stott PA, Nozawa T, et al. (2011) Anthropogenic greenhouse gas contribution to flood risk in England and Wales in autumn 2000. Nature 470: 380–384. 42. Cezilly F, Nager RG (1995) Comparative evidence for a positive association between divorce and extra-pair paternity in birds. Proceedings of the Royal Society of London Series B-Biological Sciences 262: 7–12. 43. Moller AP, Birkhead TR (1993) Cuckoldry and sociality: a comparative study of birds. American Naturalist 142: 118–140. 44. Birkhead TR, Møller AP (1996) Monogamy and sperm competition in birds. In: Black JM, ed. Partnerships in Birds. Oxford, UK: Oxford University Press. 45. Mauck RA, Marschall EA, Parker PG (1999) Adult survival and imperfect assessment of parentage: effects on male parenting decisions. American Naturalist 154: 99–109. 46. Wikelski M, Ricklefs RE (2001) The physiology of life histories. Trends in Ecology and Evolution 16: 479–481. 47. Colwell RK (1974) Predictability, constancy, and contingency of periodic phenomena. Ecology 55: 1148–1153. 48. Le Houerou HN (1989) The grazing land ecosystems of the African Sahel. Ecological Studies 75: i–x, 1–282. 49. Solomon S, Qin D, Manning M, Chen Z, Marquis M, et al. (2007) Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. 50. Nettle D (1998) Explaining global patterns of language diversity. Journal of Anthropological Archaeology 17: 354–374. 51. Le Houerou HN (2009) Bioclimatology and Biogeography of Africa. Berlin: Springer-Verlag. 52. Pagel M (1999) Inferring the historical patterns of biological evolution. Nature 401: 877–884. 53. Felsenstein J (1985) Phylogenies and the comparative method. American Naturalist 125: 1–15. 54. Lavin SR, Karasov WH, Ives AR, Middleton KM, Garland T (2008) Morphometrics of the avian small intestine compared with that of nonflying mammals: A phylogenetic approach. Physiological and Biochemical Zoology 81: 526–550. 55. Kutner M, Nachtsheim C, Neter J, William L (2005) Applied Linear Statistical Models, Fifth edition. Irwin, CA: McGraw-Hill. Fluctuating Selection and Reproductive Flexibility 56. Judge G, Griffiths W, Hill R, Lutkepohl H, Lee T (1985) The Theory and Practice of Econometrics. New York, NY: Wiley. 57. Edgar RC (2004) MUSCLE: multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Research 32: 1792–1797. 58. Smith SA, Dunn CW (2008) Phyutility: a phyloinformatics tool for trees, alignments and molecular data. Bioinformatics 24: 715–716. 59. Stamatakis A (2006) RAxML-VI-HPC: maximum likelihood-based phylogenetic analyses with thousands of taxa and mixed models. Bioinformatics 22: 2688–2690. 60. Hackett SJ, Kimball RT, Reddy S, Bowie RCK, Braun EL, et al. (2008) A phylogenomic study of birds reveals their evolutionary history. Science 320: 1763–1768. 61. Sanderson MJ (2002) Estimating absolute rates of molecular evolution and divergence times: a penalized likelihood approach. Molecular Biology and Evolution 19: 101–109. 62. Safran RJ, Neuman CR, McGraw KJ, Lovette IJ (2005) Dynamic paternity allocation as a function of male plumage color in barn swallows. Science 309: 2210–2212. 63. Charmantier A, Blondel J, Perret P, Lambrechts MM (2004) Do extra-pair paternities provide genetic benefits for female blue tits Parus caeruleus? Journal of Avian Biology 35: 524–532. 64. Williams G (1975) Sex and evolution. Princeton, New Jersey: Princeton University Press. 65. Westneat DF, Sherman PW, Morton ML (1990) The ecology and evolution of extra-pair copulations in birds. Current Ornithology 7: 331–369. 66. Petrie M, Doums C, Moller AP (1998) The degree of extra-pair paternity increases with genetic variability. Proceedings of the National Academy of Sciences of the United States of America 95: 9390–9395. 67. Poulin B, Lefebvre G, McNeil R (1992) Tropical avian phenology in relation to abundance and exploitation of food resources. Ecology 73: 2295–2309. 68. Schwinning S, Sala OE (2004) Hierarchy of responses to resource pulses in arid and semi-arid ecosystems. Oecologia 141: 211–220. 69. Schuck-Paim C, Alonso WJ, Ottoni EB (2008) Cognition in an ever-changing world: Climatic variability is associated with brain size in neotropical parrots. Brain Behavior and Evolution 71: 200–215. 70. Bennett PM, Harvey PH (1985) Relative brain size and ecology in birds. Journal of Zoology 207: 151–169. 71. Deaner RO, Nunn CL (1999) How quickly do brains catch up with bodies? A comparative method for detecting evolutionary lag. Proceedings of the Royal Society of London Series B-Biological Sciences 266: 687–694. 72. Emlen ST, Oring LW (1977) Ecology, sexual selection, and the evolution of mating systems. Science 197: 215–223. 73. Jarman PJ (1974) Social-organization of antelope in relation to their ecology. Behaviour 48: 215–267. PLoS ONE | www.plosone.org 7 February 2012 | Volume 7 | Issue 2 | e32311