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Sex differences in age-dependent telomere length with no relation in (a) females, but a curvilinear decline of telomere length with age in (b) males in the red-sided garter snake (Thamnophis sirtalis parietalis). Females show a much less active reproductive strategy. In picture (c), a passive female (the large, central head) is surrounded by smaller heads of energetically courting males. (© CRF, From Rollings et al. [84]). (Online version in colour.)
