Size, Scaling, and the Evolution of Complex Life Cycles

“Ontogenetic niche shifts are often determined by size (Werner 1988; Law 1991; Ebenman 1992), and rapid juvenile growth may evolve whenever competition can be escaped through growth.”

“…t a m o r pho s i s h a s b ee n d e m on s t r a t e d m a ny ti m e s ( e . g ., W il bu r 1977 , T r a v i s 1984 , A l f o r d a n d H a rr i s 1988 ) ; ou r i n t e r e s t i n m a n i p u l a ti ng f ood c on ce r n e d po ss i b l e i n t e r ac ti on s w it h t h e e ff ec t s o f t h e p…”

“Because foraging needs, predation risk, and reproductive conditions change during ontogeny (e.g., due to increases in body size), animals often shift habitats in ways that meet their changing needs (Werner and Gilliam 1984, McNamara and Houston 1986, Werner 1988, Ludwig and Rowe 1990).”

“This conforms to the model of Wilbur and Collins (1973), and it highlights the constraints imposed by a threshold.”

“In intraspecific competition, smaller individuals are often superior to larger ones because of size-dependent scaling of foraging and metabolic rates (Persson 1987; Werner 1988; Persson et al. 1998).”

“Since they are adapted to a predatory life style later on, the juvenile predators generally suffer from superior competition by individuals of their future prey species (Werner & Gilliam 1984; Werner 1986, 1988; Persson 1988).”

“Possible evidence for such methods of internal prediction comes from species with complex life cycles, where juvenile and adult ecologies can differ greatly due to ontogenetic niche shifts, dispersal, migration or prolonged offspring development [74].”

“More than 80% of animals, including most insects, have a so-called complex life cycle (CLC) with discrete larval and adult stages (112).”

“The vast majority of these organisms serve as prey to some predator and, as a result, possess inducible defenses that come with associated costs of growth and development (Werner 1988; Hall and Wake 1999; Truman and Riddiford 2002; Benard 2004).”

“Body size can have important consequences for the fitness of individuals by affecting both mortality rates and reproductive success (Werner 1988).”

“Pr cesses influencing which individuals survive to reproduce are complicated by a major transitional stage in organisms that have complex life histories (e.g. many pl nts, insects, marine invertebrates and fish, and amphibians; Werner 1988; Pechenik et al. 1998).”

“The timing of these ontogenetic niche shifts should vary with the costs and benefits accruing in each stage (Werner & Gilliam 1984; Werner 1986, 1988).”

“For instance, ontogenetic niche shifts are a major mode of life in 25 of 33 phyla, or 80% of animal taxa (Werner 1988), which could have important consequences for the structure and dynamics of ecological networks (Persson 1999; Persson et al. 2003; Lafferty et al. 2006; Rudolf 2007b; Schreiber &…”

“These include size-dependent resource utilization (Werner 1988); maximization of population growth through minimization of intraspecific conflict between life stages (Ebenman 1987); and structural specialization for different tasks at different stages in their ontogeny (Bryant 1969), such as…”

“These models ignore individual growth in body size despite that it is an important process in the life history of most species (Werner, 1988), leading to major changes in their ecology during ontogeny.”

“Werner (1988) noted that up to 80% of all animal species undergo a metan~orphosis and niche shlft during their life cycle.”

“Metamorphosis is thought to occur because individuals must possess characteristics that maximize survival in each environment (Werner 1988).”

“This is true in spite of the near taxonomic ubiquity of such phenomena across taxa (Werner 1988) and the rare and valuable opportunity they represent.”

“For this reason, there has been considerable interest in the question of how body size influences ecological capacities, such as feeding (Peters, 1983; Calder, 1984; Werner, 1988; Kooijman, 1993, 2000).”

“Ontogenetic niche shifts occur in .80% of animal taxa (Werner 1988) and a recent analysis indicates that the average resource overlap among stages of a species can range from 0% to 100% and be as low as 37% for entire ecological networks (Rudolf and Lafferty 2011).”

“Introduction Most organisms have complex life cycles, with one or more abrupt ontogenetic changes in their morphology, physiology and behaviour, often associated with a change in habitat (Wilbur, 1980; Werner, 1988).”

“We look at a particularly important stage of the amphibian life cycle that has a strong influence on the individual fitness, namely metamorphic timing (Wilbur & Collins 1973; Werner 1988; Day & Rowe 2002).”

“Typical examples are hatching, metamorphosis and maturity of fish (Reznick 1990; Jones et al. 2003), holometabolous insects (Werner 1988), amphibians (Wilbur 1980), marine invertebrates (Twombly 1996; Hentschel and Emlet 2000) and parasites (Esch 1977).”

“It is now widely recognized that most multicellular organisms undergo complex life cycles (Werner 1988) with a series of stages that can differ dramatically in habitat and functional traits (defined here as aspects of the phenotype that underlie organismal performance).”

“[Behav Ecol 10:251–262 (1999)] Growth and development profoundly influence predator–prey interactions (Polis, 1984; Polis et. al, 1989; Werner, 1988; Werner and Gilliam, 1984).”

“Most organisms undergo major changes in size and basic morphology over their ontogeny and high growth rates in early life stages have been suggested to increase individual survival (Werner 1988, Wilbur 1988, Post et al. 1999).”

“Specialization in one niche should be associated with costs in competitive ability in other niches (Persson 1988, Werner 1988).”

“Most marine organisms have a stage-structured life history consisting of a relatively sedentary benthic stage (usually juveniles and adults) and a pelagic larval stage capable of long-distance dispersal (for review, see Werner 1988).”

“It has been estimated that 80% of metazoan animal species have complex life-cycles (Werner, 1988), and one of the most critical life-history events for these animals is the transition to the adult stage.”

“These organisms, which span a large range of body sizes during their ontogeny, often alter their habitat and diet as they grow in order to obtain optimal growth rates while minimizing predation mortality (Werner & Gilliam 1984, Werner 1988, Dahlgren & Eggleston 2000).”

“However, no natural population is truly homogeneous, and developmental changes in size usually entail changes in the foods and predators of the individuals in question (Metz and Diekmann, 1986; Ebenman and Persson, 1988; Werner, 1988).”

“Werner and Gilliam 1984 theory and its extensions Ž . e.g., Werner, 1986, 1988; Rowe and Ludwig, 1991 is a comparison of the patterns of metamorphosis across copepod taxa with different life styles.”

“In size-structured populations, growing consumers are generally expected to change their ecological niche with respect to prey type, prey size, or habitat type to meet their increasing basic metabolic demands and to optimise their ecological foraging performance over ontogeny (e.g., Werner and Gilliam 1984; Persson 19…”

“Werner (1988) estimated that ∼80% of all animal species have complex life cycles.”

“Most animals have a complex life cycle with morphologically distinct stages, typically a larval and an adult stage (Buss 1987; Werner 1988).”

“For example, Werner (1988) argued that the size at which organisms should switch habitats could be predicted from the ratio of growth rates to mortality rates in the potential habitats.”

“While the importance of considering the entire life cycle has long been recognized in evolution (Bonner, 1965; Werner, 1988), an adult-centric view has nonetheless persisted in developmental biology (Minelli, 2003, 2015).”

“Many organisms show ontogenetic niche shifts, e.g. insects and amphibians shift from an aquatic to a terrestrial habitat, and some fish species shift from a littoral to a pelagic habitat (Werner 1988).”

“Despite not understanding all the factors that influence metamorphosis in marine fishes, a general conclusion is that the timing is not a haphazard process, as the existence of a complex life cycle is indicative of selective pressures that change with the size or age of an organism (Werner 1988).”

“…reef organisms (i.e., molluscs, fish, and crustaceans) have stage-structured life histories with 2 distinct stages: a relatively sedentary benthic stage (usually juveniles and adults) and a pelagic larval stage capable of long-distance dispersal that can last for weeks or months (Werner 1988).”

“Plasticity in life history switch points is favoured when there is a trade-oV of stage-speciWc risks or opportunities, and environmental variation in one or both stages (Werner 1986; Werner 1988).”