However, in the African cichlid fish, Haplochromis burtoni (Günther), there is a socially regulated dynamic response to reproductive opportunity that depends ultimately on animal size. In these species, typically displaying indeterminate growth, the allocation of resources toward somatic growth and hence future reproductive success occurs only once in the life of an animal. Decisions about such life-history strategies may be made by changes in growth rate in some species (see, e.g., refs. For example, a male may delay reproduction if he cannot compete with currently superior/dominant animals. Because reproductive prospects depend on many factors, including changes in fecundity, longevity, and population structure, to change strategy, animals must be able to assess current reproductive opportunities and respond by changing phenotype. Shifts in strategy are thought to reflect the likelihood of present and future reproductive success ( 1, 2). Such reversible phenotypic plasticity in a crucial life-history trait may have evolved to enable animals to shift resources from reproduction to growth or vice versa, depending on present and future reproductive prospects.Īnimals can use different behavioral strategies depending on immediate social and environmental conditions. This suggests that differential growth, in interaction with environmental conditions, is a central mechanism underlying the changes in social status. Similar behavioral and physiological changes are caused by social change in animals kept in stable environmental conditions, although at a lower rate. Nonterritorial males and animals ascending in social rank showed an increased growth rate whereas territorial males and animals descending in social rank slowed their growth rate or even shrank.
Surprisingly, the induced changes in social status caused changes in somatic growth. Moreover, many fish changed social status several times. Although on average 25–50% of the males are territorial in both the stable and unstable environments, during the 20-week study, nearly two-thirds of the animals became territorial for at least 1 week. burtoni males can be either reproductively active, guarding a territory, or reproductively inactive (nonterritorial). Here we show that disruption of the habitat of a colony of African cichlid fish, Haplochromis burtoni (Günther) caused males to switch social status more frequently than animals kept in a stable environment. As a consequence, animals of many species show flexible behavioral responses to environmental and social change. I have provided these links to other websites for your convenience only I am not responsible for the availability of these other websites nor the freebies/coupons/information they offer.The life-history strategies of organisms are sculpted over evolutionary time by the relative prospects of present and future reproductive success. Please Note: I make every effort to check the validity of all outgoing links at the time of posting, but I am not responsible for any content outside of this website. NOTE: This post may contain affiliate links. Questions? Email me at catherine (at) or post to my Facebook Fan Page!Ĭheck out our Frugal Freebies Deal groups for more fun, frugal tips, freebies and money-saving deals! We have rescued two little dogs, Denny and Dexter - and Bella, the cat. I am now mom to three sons, who are all grown up - and re-married to a wonderful man. About Catherine: I have been writing frugal tips since 1982, when I was a young divorced mom of two - for my baby product company, Born to Love.
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