Condition‐dependent reproductive tactics in male smallmouth bass: evidence of an inconsistent birthdate effect on early growth and age at first reproduction

Abstract

Many animals exhibit alternative forms of reproductive behavior, the expression of which depends on individual condition or status. For instance, male smallmouth bass Micropterus dolomieu that are large early in life often build a nest and spawn for the first time at a young age and small body size, while males that are small early in life delay reproduction, invest in growth and spawn when they are older and larger, tactics referred to as α and β, respectively. The observation that larger males also tend to spawn earlier within a season led to a hypothesis that birthdate – more specifically, dispersal date – may control which tactic is adopted. Here, we examined the individual growth and reproductive histories of 184 male M. dolomieu of three cohorts for evidence of a birthdate effect on early life condition and the subsequent expression of tactics, namely whether a long first‐year growth period tends to induce the α tactic and whether variability in the timing of reproduction by parents within a season contributes to body size differences in progeny at the end of their first‐year growth period. The extent to which male condition early in life influences the expression of tactics was also evaluated. Evidence of a birthdate effect on progeny condition and subsequent tactic choice was observed for only one of the three cohorts and, in another cohort, tactic choice and individual condition were largely unrelated. The seasonal variability in birthdates and growth histories suggest that a broad range of swim‐up dates may be necessary to generate differences in condition early in life that are sufficiently large to control future reproductive decisions. Potential impacts of various physical, environmental and biotic factors that may mediate the seasonal timing of reproduction by parents or individual growth early in life are discussed.

Hatch date and growth rate drives reproductive success in nest-guarding males of a temperate reef fish

“…Variation in growth rate can influence longevity (reviewed by Metcalfe & Monaghan 2003) and/or timing of maturation (Rowe & Thorpe 1990). Similarly, variation in hatch dates can affect timing of maturation (Uller & Olsson 2010), vulnerability to predators (Karban 1982) and/or future reproductive tactics (Fagundes et al 2015, Welsh et al 2017.…”

Environmental influence on life-history traits in male squid Uroteuthis edulis with alternative reproductive tactics

“…For short-lived species with ARTs in the temperate area, date of birth can influence ART expression, because individuals born at different periods experience different growth conditions before maturation (the birthdate effect: Pastres et al 2002;Fagundes et al 2015;Welsh et al 2017). The high proportion of consorts appearing in the JWSG could be accounted for by the large number of consorts comprising the Jwarm cohort.…”

Environmental Influence on Life-History Traits in Male Squid Uroteuthis Edulis With Alternative Reproductive Tactics

“…For short-lived species with ARTs in the temperate area, date of birth can in uence ART expression, because individuals born at different periods experience different growth conditions before maturation (the birthdate effect: Pastres et al, 2002;Fagundes et al, 2015;Welsh et al, 2017). The high proportion of consorts appearing in the JWSG could be accounted for by the large number of consorts comprising the Jwarm cohort.…”