Complex offspring size effects: variations across life stages and between species

Ecology and Evolution

Zhao Sun¹  Jean-François Hamel²  Christopher C. Parrish¹ 

[1] Department of Ocean Sciences, Memorial University, St. John's, Newfoundland and Labrador, Canada;Society for the Exploration and Valuing of the Environment (SEVE), Portugal Cove-St. Philips, Newfoundland and Labrador, Canada

关键词: Benthic environment;    carry‐over effect;    cnidarian;    life history;    offspring performance;    parental care;    size–number trade‐off;    viviparity;   

DOI  :  10.1002/ece3.1320

来源: Wiley

【 摘 要 】

Abstract

Classical optimality models of offspring size and number assume a monotonically increasing relationship between offspring size and performance. In aquatic organisms with complex life cycles, the size–performance function is particularly hard to grasp because measures of performance are varied and their relationships with size may not be consistent throughout early ontogeny. Here, we examine size effects in premetamorphic (larval) and postmetamorphic (juvenile) stages of brooding marine animals and show that they vary contextually in strength and direction during ontogeny and among species. Larger offspring of the sea anemone Urticina felina generally outperformed small siblings at the larval stage (i.e., greater settlement and survival rates under suboptimal conditions). However, results differed when analyses were conducted at the intrabrood versus across-brood levels, suggesting that the relationship between larval size and performance is mediated by parentage. At the juvenile stage (15 months), small offspring were less susceptible than large ones to predation by subadult nudibranchs and both sizes performed similarly when facing adult nudibranchs. In a sympatric species with a different life history (Aulactinia stella), all juveniles suffered similar predation rates by subadult nudibranchs, but smaller juveniles performed better (lower mortalities) when facing adult nudibranchs. Size differences in premetamorphic performance of U. felina were linked to total lipid contents of larvae, whereas size-specific predation of juvenile stages followed the general predictions of the optimal foraging strategy. These findings emphasize the challenge in gathering empirical support for a positive monotonic size–performance function in taxa that exhibit complex life cycles, which are dominant in the sea.

【 授权许可】

CC BY   
© 2014 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.