Abstract
We examined the multivariate life-history trajectories of age 0 and age 1 female Gambusia affinis to determine relative effects of age-based and environment-based cues on reproductive investment. Age 0 females decreased reproductive investment prior to the onset of fall and winter months, while age 1 females increased reproductive investment as the summer progressed. The reproductive restraint and terminal investment patterns exhibited by age 0 and age 1 females, respectively, were consistent with the predictions from the cost of reproduction hypothesis. Age 0 females responded to environment-based cues, decreasing reproductive investment to increase the probability of overwinter survival and subsequent reproductive opportunities in the following summer. Age 1 females responded to age-based cues, or the proximity of death, increasing investment to current reproduction as future reproductive opportunities decreased late in life. Thus, individuals use multiple cues to determine the level of reproductive investment, and the response to each cue is dependent on the age of an individual.
Highlights
Patterns of reproductive allocation are influenced by an individual’s age and environmental conditions (Fisher 1930; Williams 1966; Roff 2002)
Gambusia affinis was introduced into Utah in the early 1930s and likely dispersed into Utah Lake between 1934 and 1945 after it was introduced into freshwater springs near the northwest shore of the lake (Rees 1934, 1945)
We documented how the interaction of agebased and environment-based cues affect the pattern of reproductive investment in G. affinis
Summary
Patterns of reproductive allocation are influenced by an individual’s age and environmental conditions (Fisher 1930; Williams 1966; Roff 2002). The prominent age-based hypothesis, the cost of reproduction hypothesis, predicts the level of reproductive allocation based on future reproductive opportunities assuming that reproduction comes at a cost (e.g., reduction in body condition or survival) that reduces future reproductive opportunities (Williams 1966; Clutton-Brock 1984; Reznick 1985). The cost of reproduction hypothesis predicts that young individuals that have a high reproductive value, or high future reproductive potential (Fisher 1930), should allocate less to current reproduction to ensure future reproductive opportunities. Old individuals that have low reproductive values should allocate more to current reproduction (i.e., terminal investment; Clutton-Brock 1984), accepting the greater costs of reproduction because future opportunities may not be available (Williams 1966). Reproductive patterns that support the predictions of the cost of reproduction hypothesis have been reported in organisms that have seasonal reproduction (P€art et al 1992; Berteaux and Boutin 2000; Descamps et al 2007) and in short-lived organisms that reproduce multiple times in a single reproductive season (Poizat et al 1999, 2002; Baker et al 2008; Creighton et al 2009)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
