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Author Hasumi, Masato
Source SpringerLink
Content type Text
Publisher Springer US
File Format PDF
Copyright Year ©2010
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Life sciences; biology
Subject Keyword Age at maturity ♦ Age structure ♦ Growth trajectory ♦ Indeterminate growth ♦ Population structure ♦ Skeletochronology ♦ Animal Genetics and Genomics ♦ Human Genetics ♦ Developmental Biology ♦ Ecology ♦ Evolutionary Biology
Abstract In organisms with determinate growth, sexual size dimorphism (SSD) occurs before maturity during the developmental process of growing apart, an ontogenetic perspective on the evolution of SSD. If the direction of SSD (female-larger SSD) is known, patterns of growth can be tested with one-tailed statistical distributions. In indeterminate growing organisms as well, does SSD occur before maturity? If it occurs, whether is females’ larger mean body size caused by a difference in age at maturity, age-specific size, divergent growth prior to maturity, or selection on post-maturational growth? How important is biphasic, sexual shape dimorphism (BSSD) for determinants of SSD? Biphasic characteristics are those that differ between adult aquatic- and terrestrial-phase morphs, and shape is size of a characteristic relative to body size. To address those questions, I determined age and body size based on a careful description of a growth trajectory for each sex in Salamandrella keyserlingii, using 555 independent data points from skeletochronological studies. Females reached maturity at 3–4 years of age, a year later than males that reached maturity at 2–3 years of age (mean body size: males = 57.63 mm, females = 61.70 mm; delayed sexual maturity resulted in SSD). However, SSD was highly detected before maturity (SSD index = 0.097), and females after maturity continued to grow and resulted in larger asymptotic size than males. Traits of BSSD were greater in males than in females. These results suggest that when determining SSD the difference in mean adult-body size results from the difference in age-specific size and the female-larger SSD develops to resolve intersexual ontogenetic conflict by allowing small-sized males to swell their whole body during the aquatic phase as much as large-sized females.
ISSN 00713260
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2010-02-07
Publisher Place Boston
e-ISSN 19342845
Journal Evolutionary Biology
Volume Number 37
Issue Number 1
Page Count 11
Starting Page 38
Ending Page 48


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Source: SpringerLink