Tradeoffs between somatic and gonadal investments during development in the African clawed frog (Xenopus laevis)

Abstract

Tradeoffs between time to and size at metamorphosis occur in many organisms with complex life histories. The ability to accelerate metamorphosis can increase survival to the next life stage, but the resulting smaller size at metamorphosis is often associated with lower post-metamorphic survival or reduced fecundity of adults. Reduced fecundity is thought to be because of reduced energy reserves, longer time to maturity, or reduced capacity to carry eggs or compete for mates. This pattern could also be explained by a shift in allocation to somatic growth that further retards the growth or development of reproductive tissues. The main goal of this study was to determine if the relationship between growth and development of somatic and gonadal tissues depends on environmental conditions. We address this question through two experiments in which we quantify the development and growth of the body and gonads of Xenopus laevis reared in different resource environments. First, tadpoles were reared communally and development and growth were evaluated over time. Restricted food reduced somatic and gonadal growth rate, but did not affect the developmental rate of either tissue type. Second, tadpoles were reared individually and evaluated at metamorphosis. Restricted food reduced somatic development and growth, but only influenced size, and not developmental stage of testes at metamorphosis. This work demonstrates that environmental conditions influence tradeoffs between growth and development of somatic and gonadal tissues, apparently in a sex-specific manner. These tradeoffs may contribute to phenotypic correlations between small size and reduced fitness.

Highly plastic resource allocation to growth and reproduction in females of an African annual fish

“…Within species, the relative allocation to growth and reproduction generally appears to remain in stable proportion across wide levels of resource availability (Wootton ; McCoy et al. ; Inness & Metcalfe ; Zeng et al. ).…”

“…Within species, the relative allocation to growth and reproduction generally appears to remain in stable proportion across wide levels of resource availability (Wootton 1977;McCoy et al 2007; Inness & Metcalfe 2008;Zeng et al 2012). However, conditions experienced early in life may determine lifetime patterns in allocation to reproduction, while adult growth reflects prevailing conditions with deviations from a stable allocation ratio (Taborsky 2006a).…”

Effects of plastic hatching timing carry over through metamorphosis in red‐eyed treefrogs

“…Although studies of plasticity in hatching are still relatively few, studies of plasticity in metamorphosis spanning more than 70 years have revealed that there are carryover effects of the larval environment even after crossing this life-history switchpoint (Pechenik 2006). Many taxa respond to larval conditions by altering their metamorphic phenotype (e.g., size, morphology, larval period duration; Werner and Gilliam [1984], Benard [2004]), which can have important consequences for post-metamorphic growth (Van Allen et al 2010), lifetime fitness (Semlitsch et al 1988, McCoy et al 2007, and population and community dynamics (Beckerman et al 2002, McCoy et al 2009). Such carryover effects have been demonstrated in bryozoans, gastropods, polychaetes, crustaceans, echinoderms, urochordates, insects, and amphibians (reviewed in Pechenik 2006).…”

Carry-over effects of the larval environment on post-metamorphic performance in two hylid frogs

“…Development during the larval period and sweeping changes in the internal anatomy of organisms during metamorphosis provide an opportunity for individuals in good habitat to invest in higher quality tissues (Zera and Harshman 2001;Ishizuya-Oka and Shi 2005;Brown and Cai 2007). For example, Xenopus larvae reared at higher food levels metamorphosed with larger and more developed gonads (McCoy et al 2007). This is likely due to a portion of increased larval food being used for reproductive rather than somatic growth.…”