FIGURE 3.

Examples of semelparous organisms and their senescent pathologies. (A) Pacific salmon O. nerka. Top left: sexually mature adults (photo courtesy of Georgia Strait Alliance, www.georgiastrait.org© Olga Vasik—Adobe Stock). Bottom left: Immunoreactivity to Aβ₁–₄₂ antibody in the brain of spawning kokanee salmon (Maldonado et al., 2000), c.f. amyloid plaques associated with Alzheimer’s disease. Bar, 20 μm. Right: cross section of normal coronary artery (top); L, lumen, filled with nucleated red blood cells; MSM, medial layer of vascular smooth muscle; EM, elastic membrane; ISM; or (bottom) from mature adult with severe arteriosclerotic lesion, containing mainly intimal smooth muscle cells (ISM) (Farrell, 2002). Bars, 50 μm. (B) Lamprey (genus Lampetra). Top, European river lamprey (L. fluviatilis) (photo by Tiit Hunt, distributed under a CC BY-SA 3.0 license). Bottom: stages of intestinal atrophy during spawning in L. japonica. Diameters of (a) 3.9 mm, (b) 1.5 mm (b), and (c) 1 mm. Arrows, intestinal villi; arrowheads, typhosole (internal intestinal fold) (Higashi et al., 2005). (C) Examples of reproductive death in semelparous plants. Left, Spinacia oleracea 45 days after full bloom; reproductive death (right) has been suppressed by flower removal (left) (Leopold et al., 1959) (© American Society of Plant Biologists, reprinted with permission). Right, Agave americana during and after flowering (photos by Gerhard Bock, reproduced with permission). Century plants typically live 10–30 years, and death follows rapidly after a single massive reproductive event.