Size, Scaling, and the Evolution of Complex Life Cycles

“In marine organisms that have a relatively sedentary stage and dispersive propagules, the size of adult stocks is set by a dynamic balance between input of propagules (recruitment success) and their subsequent loss by death.(15) In coral reef fish, the mortality of recruited larvae may eliminate up to 90% of the total…”

“The metamorphosis of insects (Werner 1988) and amphibians (Wilbur 1980) and the migration of diadromous fishes between freshwater and seawater systems (Gross et al. 1988) are the typical examples of ontogenetic niche shifts involving drastic habitat changes (i.e., complex life cycles; Wilbur 1980).”

“Most organisms undergo substantial growth and development during their life cycle (Sebens 1987; Werner 1988).”

“Any differences in the growth due to size are captured by the exponents, b1 and b2, which are scale factors that affect growth as a function of size (Sebens, 1982, 1987; Uchmański, 1985; Werner, 1988; Brown et al., 2004).”

“Life history stages respond differently to changes in their habitat (Werner 1988), and this response may be independent of size.”

“…distinct life stages (Moran 1994; Wilbur 1980). complex life cycles exist, at least in part, because selection changes with body size; how life cycles are partitioned across stages reflects how costs and benefits in each stage scale with size (Werner 1986, 1988; Werner and gilliam 1984).”

“The majority of animal species have complex life cycles (Werner 1988), and for those species metamorphosis from the juvenile to adult form represents a critical period of transformation (Wilbur 1980).”

“Such ontogenetic modifications may affect the ecology of the organism (Calder, 1984; Werner, 1988; Stearns, 1992) and may provide insight into the evolution of form and function, yet they are often neglected in studies of functional morphology and comparative biomechanics.”

“Complex life-cycle theory postulates that different habitats utilised for foraging by different life stages play an important role in growth and maturation and might obviate intraspecific competition between life stages (Wilbur & Collins, 1973; Werner, 1988).”

“Ontogenetic niche shifts, which include habitat or ecosystem shifts (depending on the spatial scale at which this occurs) with changing life phase, are pervasive and found in ~80% of animal taxa (Werner 1988).”

“While SLCs have evolved repeatedly in a wide array of taxa (Werner, 1988), the transition from CLC to SLC is difficult to study on the proximate level.”

“Post-embryonic change in musculoskeletal systems is common in animals (e.g. Goldspink, 1983; Kelly, 1983; Werner, 1987; Kier, 1996).”

“Most marine organisms have life histories with 2 distinct phases: a relatively sedentary benthic phase and a dispersive, mobile pelagic phase (Werner 1988).”

“In particular, body 175 mass is expected to reflect trade-offs between growth and developmental rates (Werner 1988; 176 Heyland, Degnan & Reitzel, 2011).”

“From an evolutionary prospective, virtually all life-history traits covary with body size (Peters 1983; Werner 1988; Reznick et al. 1990).”

“It is known that swarming has a cost due to a reduced amount of food within the swarms (Jakobsen & Johnsen, 1988a), but animals minimizing the ratio between death rate and growth rate (a minimization of µ/g) will maximize fitness (Werner, 1988).”

“The course of development for nearly 80 % of all animal taxa is divided into discrete ontogenetic stages that exhibit different morphological, physiological, behavioral, or ecological attributes (Werner 1988, Moran 1994).”

“This is particularly relevant given that more than 80% of animal species show such ontogenetic shifts (Werner 1988).”

“These assumptions are partly supported by Werner (1988) who argued that an increase in body size often necessities a shift in ecological niche.”

“Most insects exhibit different phenotypes across their lifespan that differ radically in form and function [1].”

“Changes in size during development cause scaling issues between an organism’s morphology and environmental processes (Werner 1988).”

“For example, populations are often structured by body size as a consequence of age structure, survivorship and food availability (which affects both growth rate and asymptotic body size) (Werner 1988).”

“At the same time, individual growth depends on the density and quality of available resources (de Roos and Persson 2013), and feeding on small or large prey can affect ontogenetic growth trajectories differently (Werner 1988; Shuter et al. 2016).”

“For instance, over 80 % of all animal species have complex life cycles and undergo ontogenetic shifts in habitat aYnity (Werner 1988), often alternating between the use of terrestrial and aquatic systems (Wilbur 1980; Werner and Gilliam 1984).”

“Predation rate can also be a hump-shaped function of body size if, for example, smaller prey are less detectable than intermediate-sized prey (Werner 1988; Persson et al. 1998; Brose 2009; McCoy et al. 2011).”

“Background Most animals exhibit complex life cycles with distinct larval and adult life stages (linked by metamorphosis) that occupy different ecological niches and experience distinct selective pressures [1, 2].”

“Although size- dependent asymmetry is considered a population- level parameter, it ultimately arises from how the competitive ability of individuals changes during growth (Werner, 1988).”

“majority of known species (Werner, 1988) and”

“In general, the first years of life are the most dynamic phase in the life cycle of fish as (1) individuals may increase up to three orders of magnitude in size while going through dramatic morphological and functional changes and (2) mortality rates are very high but also highly variable at this stage [39, 41, 42].”

“Werner (1988) estimated that approximately 80% of all animal species have complex life-cycles and theoretical ecologists in particular are interested in understanding the fitness consequences of differences in the timing and magnitude of the life-history events that define this complexity.”

“…in body size have formed the focus of many studies in ecology, ranging from the study of individual performance to large-scale communities and ecosystems (Werner & Gilliam, 1984, Gaston & Lawton, 1988, Werner, 1988, Cohen, Johnson & Carpenter, 2003, Brown et al., 2004, Loeuille & Loreau, 2005).”

“For species that have complex life cycles, duration of the larval period and size at metamorphosis are considered key life-history traits (Werner 1988; Twombly and Tisch 2002).”

“Second, most animals have complex life cycles (Werner, 1988), and distinct stages can respond to changing environments in different ways.”

“We were interested in exploring links among metabolic, developmental, and growth rates because such rates are expected to drive body size at metamorphosis, which is a fitness-related trait (Werner 1988; Hentschel 1999; Gotthard 2001; Heyland et al.”

“Our data suggest that the evolution of a distinct cyprid form was not likely driven by an ontogenetic niche shift resulting from size increases similar to those proposed for holoplanktonic copepods [47].”

“Metamorphosis, a process that transforms the larva into an adult, is widespread in the animal kingdom ranging from Porifera to Chordata (Werner 1988).”

“Despite years of discussion, the evolutionary forces maintaining complex life histories, and the evolutionary consequences of ecologically distinct stages, remain poorly resolved (Aguirre et al., 2014 ; Istock, 1967; Marshall & Morgan, 2011 ; Moran, 1994; Slade & Wassersug, 1975; Werner, 1988).”

“However, more than 80% of animal species show ontogenetic niche shifts during their development (Werner, 1988), and it is challenging, albeit crucial, to tease apart the role of ontogenetic processes from changes in the environment and individual plasticity when studying ITV in wild populations.”

“The critical period of high mortality for marine species (fish and invertebrates) that have a bipartite life cycle with a planktonic larval stage occurs during the transition of pelagic larvae from the open ocean to a benthic habitat (i.e. settlement phase; reviewed by Werner 1988).”

“According to Werner (1988), rapid structural and functional changes occur during the larval to juvenile periods because individuals must possess characteristics that maximize survival in each environment.”

“In coral ecosystem, most marine organisms (e.g., invertebrates, fish) have stage-structured life histories with two distinct stages, a relatively sedentary benthic stage (usually juveniles and adults) and a pelagic larval stage capable of long-distance dispersal [3].”

“In some cases, the latter involve a trade-off between survival and growth opportunities, as avoiding predators may limit foraging opportunities (Werner 1988, Rowe & Ludwig 1991).”

“Body mass is a plastic trait, driven by variations in larval growth rates and developmental time, but body mass should vary within upper and lower thresholds set by fitness costs (Werner 1988; Gotthard and Nylin 1995; Hentschel and Emlet 2000; Gotthard et al.”