Morphological diversity of larval skeletons in the sea urchin family Echinometridae (Echinoidea: Echinodermata)

Kinjo, Sonoko; Uehara, Tsuyoshi; Yazaki, Ikuko; Shirayama, Yoshihisa; Wada, Hiroshi

doi:10.1017/s0025315406013725

Cited by 3 publications

(18 citation statements)

References 31 publications

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“…Calcified skeletal elements of adult echinoids include test plates, jaw components (including teeth and pyramids) and spines, both primary and secondary. The feeding echinopluteus larvae of most echinoids have a basketshaped endoskeleton supporting the body and arm rods that support the larval arms (Emlet 1988, Kinjo et al 2006, which can be simple or fenestrated calcite rods, with the latter being more robust (Kinjo et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Risk and resilience: variations in magnesium in echinoid skeletal calcite

Am¹,

Clark²,

Lamare³

et al. 2016

Mar. Ecol. Prog. Ser.

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Echinoids have high-magnesium (Mg) calcite endoskeletons that may be vulnerable to CO 2 -driven ocean acidification. Amalgamated data for echinoid species from a range of environments and life-history stages allowed characterization of the factors controlling Mg content in their skeletons. Published measurements of Mg in calcite (N = 261), supplemented by new X-ray diffractometry data (N = 382), produced a database including 8 orders, 23 families and 73 species (~7% of the ~1000 known extant species), spanning latitudes 77°S to 72°N, and including 9 skeletal elements or life stages. Mean (± SD) skeletal carbonate mineralogy in the Echinoidea is 7.5 ± 3.23 wt% MgCO 3 in calcite (range: 1.5−16.4 wt%, N = 643). Variation in Mg within individuals was small (SD = 0.4−0.9 wt% MgCO 3 ). We found significant differences among skeletal elements: jaw demi-pyramids were the highest in Mg, whereas tests, teeth and spines were intermediate in Mg, but generally higher than larvae. Higher taxa have consistent mineralogical patterns, with orders in particular showing Mg related to first appearance in the fossil record. Latitude was a good proxy for sea-surface temperature (SST), although incorporating SST where available produced a slightly better model. Mg content varied with latitude; higher Mg content in warmer waters may reflect increased metabolic and growth rates. Although the skeletons of some adult urchins may be partially resistant to ocean acidification, larvae and some species may prove to be vulnerable to lowered pH, resulting in ecosystem changes in coastal marine environments.

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Section: Introductionmentioning

confidence: 99%

Risk and resilience: variations in magnesium in echinoid skeletal calcite

Am¹,

Clark²,

Lamare³

et al. 2016

Mar. Ecol. Prog. Ser.

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“…we first identified characters that are not affected by growth or food supply and thus are useful in homologous comparison among the species. We compared larval skeletons between different ages within the same species (2-vs. 4-day-old larvae of Echinometra oblonga and 2-vs. 5-day-old larvae of Colobocentrotus mertensii) and found that the elements of body-skeleton did not differ between different ages although the length of postoral rod significantly increased with larval age (Kinjo et al 2006). Thus, the characters of the body-skeleton can be regarded as typical for each species and useful for the homologous comparison among the species (Fig.…”

Section: Phylogenetic Analysismentioning

confidence: 96%

“…Also, many other morphological characters are quite similar, for example, the test structure, the shape of pedicellaria, and the larval skeleton (Smith 1988;Kinjo et al 2006). Thus, molecular and morphological characters suggest a close relationship between these two genera.…”

Section: Phylogeny Of the Echinometridaementioning

confidence: 99%

“…The evolutionary patterns of larval skeletal traits can be visualized by mapping 11 morphological characters of larval skeletons (Kinjo et al 2006) onto a phylogenetic tree (Figs. 3 and 4).…”

Section: Evolutionary History Of Larval Skeletal Morphologymentioning

confidence: 99%

“…In this regard, sea urchins of the Echinometridae family provide several advantages. First, considerable morphological variation has been observed in Echinometridae larval skeletons (Onoda 1936(Onoda , 1938Thet et al 2001;Yanagisawa 2001, Kinjo et al 2006. Although it is well known that larval morphology displays phenotypic plasticity in response to the environmental conditions such as the availability of food (Strathmann et al 1992;Hart and Strathmann 1994;Orr 1999), the skeletal elements of the main body region (body rods) are not affected by diet, availability or species of algae (McEdward and Herrera 1999).…”

Section: Introductionmentioning

confidence: 99%

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Evolutionary history of larval skeletal morphology in sea urchin Echinometridae (Echinoidea: Echinodermata) as deduced from mitochondrial DNA molecular phylogeny

Kinjo¹,

Shirayama²,

Wada³

2008

Evolution and Development

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The larval skeletons of sea urchins show considerable morphological diversity, even between closely related species, although the evolutionary history and functional significance of this diversity are poorly understood. To infer the evolutionary history of the skeletal morphology, we focused on echinometrid species for which the morphological variation in larval skeletons had been investigated qualitatively and quantitatively. We reconstructed the phylogenetic relationships among 14 echinometrid species based on mitochondrial ND1 and ND2 genes and mapped the morphological characters onto the resultant trees. The monophyly of each genus in the Echinometridae was well supported by our results, as was the close affinity between Colobocentrotus, Heterocentrotus, and Echinometra. The mapping of the morphological characters of the larval skeletons indicated that the length, direction, and density of spines on the postoral rods was well conserved in each group of Echinometridae and that the abundance of spines and the size and shape of the body skeleton changed relatively frequently and hence were less conserved. In Echinometrid species, morphological variation in relatively unconserved features tends to be associated with latitudinal distributions, rather than phylogenetic relationships, indicating that the morphological diversity of larval skeletons could have been caused by adaptation to the habitat environment. Some morphological differences, however, seem to be nonfunctional and generated by the constraints on larval skeletogenesis. Thus, echinometrid species can be a good model with which to study the evolutionary history from both ecological and developmental standpoints.

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Genetic divergence and assortative mating between colour morphs of the sea urchinParacentrotus gaimardi

Calderón¹,

Ventura²,

Turon³

et al. 2010

Molecular Ecology

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Some species of sea urchins feature large variation in pigmentation. This variability may be the result of phenotypic plasticity or it may be associated with genetic divergence between morphs. Paracentrotus gaimardi exhibits five colour morphs (pink, brown, green, grey and black), which often occur side by side on the same rock. We studied genetic divergence between these morphs in three populations on the coast of Brazil. A fragment of the region encoding the mitochondrial ATPase 8 and 6 mitochondrial genes, a fragment of the intron of a nuclear histone and the entire nuclear gene coding for the sperm protein bindin were analysed. Mitochondrial DNA was differentiated between the pink and all other morphs, but the histone intron was similar in all colour morphs. In bindin, nine codons were found to be under positive selection and significant differences of allelic frequencies were observed in almost all pairwise comparisons between colour morphs. Although the molecular differentiation in bindin is not large enough to suggest reproductive isolation, some degree of assortative mating within morphs seems to be occurring in this species.

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Morphological diversity of larval skeletons in the sea urchin family Echinometridae (Echinoidea: Echinodermata)

Cited by 3 publications

References 31 publications

Risk and resilience: variations in magnesium in echinoid skeletal calcite

Risk and resilience: variations in magnesium in echinoid skeletal calcite

Evolutionary history of larval skeletal morphology in sea urchin Echinometridae (Echinoidea: Echinodermata) as deduced from mitochondrial DNA molecular phylogeny

Genetic divergence and assortative mating between colour morphs of the sea urchinParacentrotus gaimardi

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