Odd Couples: Extraordinary Differences between the Sexes in the Animal Kingdom
Daphne J. Fairbairn
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While we joke that men are from Mars and women are from Venus, our gender differences can't compare to those of many other animals. For instance, the male garden spider spontaneously dies after mating with a female more than fifty times his size. And male blanket octopuses employ a copulatory arm longer than their own bodies to mate with females that outweigh them by four orders of magnitude. Why do these gender gulfs exist?
Introducing readers to important discoveries in animal behavior and evolution, Odd Couples explores some of the most extraordinary sexual differences in the animal world. Daphne Fairbairn uncovers the unique and bizarre characteristics of these remarkable species and the special strategies they use to maximize reproductive success. Fairbairn also considers humans and explains that although we are keenly aware of our own sexual differences, they are unexceptional within the vast animal world.
Looking at some of the most amazing creatures on the planet, Odd Couples sheds astonishing light on what it means to be male or female in the animal kingdom.
this among invertebrates are the colonial termites and hymenopterans (ants, wasps, and bees) in which the larvae are tended and fed by cadres of sterile female workers until they metamorphose into adults.30 This is all to say that female reproductive roles sometimes extend beyond egg laying to include protecting and sometimes providing nutrition for offspring until the offspring are able to fend for themselves. Although the same can be said for males in a few lineages, commitment to parental care
about 16 percent just prior to egg laying, and they depend on the spring flush of annual herbaceous vegetation to do so.24 When winter rainfall is above average the density of herbaceous vegetation is high, and more females attempt to breed. Females breeding in those years also lay more eggs, and the eggs have higher hatching success. Abundant winter rain also increases the density of the annual grasses, and these provide food for the grasshoppers and crickets that become the main food for great
focus on success in attracting females. In many species females actively choose their mates, and males compete by displaying themselves to females in hopes of being chosen. The type of display that males use depends to some extent on the medium in which they are displaying (i.e., in the air, on the ground, or in the water) and on the sensory capabilities of their females, but in all cases the display is tailored to attract female attention, often through multiple sensory modalities. For example,
is larger in the majority of species. bParasitic species only. SOURCES: 1, Poulin and Morand (2000); 2, Foellmer and Moya-Laraño (2007); 3, Gilbert and Williamson (1983); 4, Fairbairn (1997), Blanckenhorn et al. (2007); 5, Clarke (1983), Schultz and Taborsky (2000), Pietsch (2009); 6, Kupfer (2007) and personal communication, Kraus (2008); 7, Székely et al. (2007); 8, Sims (2005); 9, Cox et al. (2007); 10, Pearson et al. (2002); 11, Gibbons and Lovich (1990); 12, Lindenfors et al. (2007),
eggs. For example, many females in the class Malacostraca (crabs, lobsters, and shrimp) use modified swimming appendages (called pleopods) or specialized plates called oostigites for brooding eggs, whereas in another arthropod class, the sea spiders (Pycnogonida), males have specialized legs called ovigera for this task. Male appendages are also modified in phyla other than the Arthropoda, most commonly for grasping females during mating. For example, many male reptiles and amphibians have front