McAlister JS and Moran AL (2012), Relationships among egg size, composition, and ...

ECB-ART-42546

PLoS One 2012 Jan 01;77:e41599. doi: 10.1371/journal.pone.0041599.

Show Gene links Show Anatomy links

Relationships among egg size, composition, and energy: a comparative study of geminate sea urchins.

McAlister JS , Moran AL .

???displayArticle.abstract???
Egg size is one of the fundamental parameters in the life histories of marine organisms. However, few studies have examined the relationships among egg size, composition, and energetic content in a phylogenetically controlled context. We investigated the associations among egg size, composition, and energy using a comparative system, geminate species formed by the closure of the Central American Seaway. We examined western Atlantic (WA) and eastern Pacific (EP) species in three echinoid genera, Echinometra, Eucidaris, and Diadema. In the genus with the largest difference in egg size between geminates (Echinometra), the eggs of WA species were larger, lipid rich and protein poor compared to the smaller eggs of their EP geminate. In addition, the larger WA eggs had significantly greater total egg energy and summed biochemical constituents yet significantly lower egg energy density (energy-per-unit-volume). However, the genera with smaller (Eucidaris) or no (Diadema) differences in egg size were not significantly different in summed biochemical constituents, total egg energy, or energy density. Theoretical models generally assume a strong tradeoff between egg size and fecundity that limits energetic investment and constrains life history evolution. We show that even among closely-related taxa, large eggs cannot be assumed to be scaled-up small eggs either in terms of energy or composition. Although our data comes exclusively from echinoid echinoderms, this pattern may be generalizable to other marine invertebrate taxa. Because egg composition and egg size do not necessarily evolve in lockstep, selective factors such as sperm limitation could act on egg volume without necessarily affecting maternal or larval energetics.

???displayArticle.pubmedLink??? 22911821
???displayArticle.pmcLink??? PMC3402426
???displayArticle.link??? PLoS One

Genes referenced: LOC100887844 LOC115925415 LOC590297

???attribute.lit??? ???displayArticles.show???

References [+] :

Bolton, Maternal energy investment in eggs and jelly coats surrounding eggs of the echinoid Arbacia punctulata. 2000, Pubmed, Echinobase

	Figure 1. Egg volume.Average (1± SE) egg volume for Eastern Pacific (green) and Western Atlantic (blue) species of sea urchins in the genera Diadema, Echinometra, and Eucidaris.
	Figure 2. Mean biochemical constituent content of eggs.Average (±1 SE) summed total amounts (ng) of biochemical constituents per egg per species. Average protein (blue), lipid (yellow), and carbohydrate (red) content per egg per species are indicated.
	Figure 3. Average energy and energy density of eggs.Left vertical axis and non-patterned bars: Average (±1 SE) total energy content (mJ) per egg per species. Enthalpic energy equivalents of 39.5 µJ/ng (lipid), 24 µJ/ng (protein), and 17.5 µJ/ng (carbohydrate) were used to calculate energy content. Right vertical axis and patterned bars: Average (±1 SE) energy density (mJ nl−1) per egg per species. Western Atlantic species (blue) and Eastern Pacific species (green) are indicated.