Ecological details mediate different paths to the evolution of larval competitive ability in drosophila

Abstract

For most of their historical development as distinct fields of biology, population ecology and population genetics have remained largely separate (Kingsland 1995, Mueller 1997), even though they have had obvious overlaps as reflected in Fisher’s (Fisher 1930) equation of the Malthusian parameter of population growth with Darwinian fitness (henceforth, fitness). The two major areas where theory in population genetics and population ecology has meaningfully intersected are the dynamics of age-structured populations (Fisher 1930, Hamilton 1966, Charlesworth 1970, 1994, Charlesworth & Williamson 1975, Charlesworth and Hughes 1996) and density-dependent selection (MacArthur 1962, MacArthur & Wilson 1967, Gadgil & Bossert 1970, Roughgarden 1971, Clarke 1972, Asmussen 1983, Anderson & Arnold 1983). The latter is especially significant, as selection at high densities is essentially selection for increased competitive ability (Joshi et al 2001), and competition is an important factor shaping not just evolution but also population dynamics and stability, and community structure, as well as affecting the ecological and evolutionary outcomes of other species interactions (Arthur 1982, Case 1999, Dey et al 2012). Indeed, competition between organisms was an important component of Darwin’s conception of the ‘struggle for existence’ (Darwin 1859).