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elationship with egg size. Most of the studies have been performed on free-spawning species, which have planktotrophic larval development (Strathmann and Vedder, 1977; Turner and Lawrence, 1979). These data have been complemented with seven species of free-spawning echinoderms with pelagic lecithotrophic larval development by McEdward and Chia (1991). 4.1.1- Fecundity and Egg size In general terms fecundity refers to the number of offspring produced by a female in her lifetime. Consequently fecundity may be expressed as the number of oocytes, eggs or embryos produced over a certain period (breeding season, year, lifetime) (Extensively reviewed by Ramirez-Llodra, 2002). The analysis of fecundity is very important for studies on reproduction and evolution of life-history because of its relation with energy investment by the parents and other related life-history traits such as egg size. The effect that egg size has on fecundity, fertilization, energy content, parental investment and larval development has been investigated extensively. The importance of the trade-off between fecundity and egg size in life history is apparent, not only because it represents different ways of partitioning a limited energy resource into offspring production, but also to understand the evolutionary aspects. If fitness is determined as the number of surviving offspring, the fecundityegg size trade-off is affected by selective pressures through larval mortality, fertilization success, larval development time and survival (Wilbur et al., 1974; Levitan, 1993, 1996; Hadfield and Strathmann, 1996; Podolsky and Strathmann, 1996). 73
In 1973, Vance proposed a theoretical model to predict optimal egg size with a bimodal distribution corresponding to type of development of the larvae. Considering a continuous reproductive effort, there is an important trade-off between fecundity and energy content per egg; subsequently the model proposed an apparent selection for extreme egg sizes with the production of many small eggs with minimal material or production of very few large yolky eggs. Sewell & Young (1999) performed a reexamination of asteroid and echinoid egg sizes and tested the prediction of bimodality in holothuroids and ophiuroids. Eggs diameters in asteroid species were found to range from 100 to 3500 µm, and the two modes are found in the ranges of 100 to 150 µm and 700 to 1000 µm. The ranges in egg diameter for planktotrophic and lecithotrophic asteroids do not overlap, but egg sizes overlap considerably between lecithotrophic and brooding species (Emlet et al., 1987). Levitan (1993) proposed a hypothesis to explain the evolution of egg size in marine invertebrates related to the probability of egg fertilization using a model of fertilization kinetics developed by Vogel (1982). The hypothesis proposes that conditions of sperm limitation can select for larger eggs. Consequently, variation in such conditions can contribute to the observed patterns of interspecific variation in egg size, concluding that larger eggs will be fertilized at a greater rate because they provide a larger target for sperm. Podolsky and Strathmann (1996) concluded that the results of Levitan (1993) led to incorrect inferences because he used an interspecific comparison in which other gamete attributes such as egg fertilizability, sperm speed, and sperm half-life co-vary with egg size. As an example they propose that greater zygote production of the echinoid Strongylocentrotus droebachiensis relative to its congeneric species results from interspecific differences in egg fertilizability and sperm half-life, not from larger egg size. Podolsky and Strathmann (1996) also 74
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University of Southampton Research
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Graduate School of the National Oce
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UNIVERSITY OF SOUTHAMPTON ABSTRACT
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Marthasterias glacialis (ECHINODERM
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Acknowledgments I know everybody sa
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Prière de l’étoile de mer Seign
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species of asteroid Patiriella para
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embryonic tolerances could determin
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dispersed over great distances and
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lecithotrophic development. The pre
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al., 1997). In a review (Vrijenhoek
Page 23 and 24: Although larval dispersal and settl
Page 25 and 26: larvae of shallow water echinoids f
Page 27 and 28: few hours, whereas other species su
Page 29 and 30: een defined as a unique sequence of
Page 31 and 32: therefore a developing form may wel
Page 33 and 34: adults” that have the definitive
Page 35 and 36: The dipleurula is the hypothetical
Page 37 and 38: among tunicate tadpoles, sponge and
Page 39 and 40: Fig.2.4. Bipinnaria larvae of the a
Page 41 and 42: In marine invertebrates there is a
Page 43 and 44: independent of habitat or mode of n
Page 45 and 46: whether juveniles derived from larv
Page 47 and 48: and the northern Mediterranean have
Page 49 and 50: Wares (2001) performed phylogenetic
Page 51 and 52: Fig. 3.2. A. Marthasterias glaciali
Page 53 and 54: 3.2.2- Temperature/pressure effects
Page 55 and 56: Pressure was applied using an Enerp
Page 57 and 58: Fig. 3.7. Bippinaria larvae of Mart
Page 59 and 60: X Data were abnormal. At 150 and 20
Page 61 and 62: X Data all the embryos were abnorma
Page 63 and 64: X Data blastulae, at 200atm 90% of
Page 65 and 66: 50atm more than 90% of embryos were
Page 67 and 68: Those data (Young et al., 1997; Ped
Page 69 and 70: Percentage of individuals swimming
Page 71 and 72: that settling invertebrate larvae d
Page 73: CHAPTER FOUR- REPRODUCTIVE FEATURES
Page 77 and 78: Species Volume Energy Dev Class Ref
Page 79 and 80: 4.1.2- Body Size The reproductive o
Page 81: Species Depth of max. Depth range (
Page 84 and 85: arm, and the minor radius (r), from
Page 86 and 87: From Eqs.1 and 3 we obtain the esti
Page 88 and 89: Data on maximum body size, maximum
Page 90 and 91: 250 200 Body size (mm) 150 100 50 0
Page 92 and 93: Fig. 4.7. Hierarchical cluster anal
Page 94 and 95: (Hymenaster membranaceus Thomson).
Page 96 and 97: gamete production at low population
Page 98 and 99: varies depending on the vitellogeni
Page 100 and 101: size, high fecundity, small egg siz
Page 102 and 103: strategy described by Winemiller an
Page 104 and 105: It seems that evolutionary features
Page 106 and 107: strategy stablished by the Winemill
Page 108 and 109: which normal embryonic/larval devel
Page 110 and 111: Larval dispersal from eight populat
Page 112 and 113: These results are very important si
Page 114 and 115: possibility. The opportunistic spec
Page 116 and 117: hypothesis that the Mesozoic and ea
Page 118 and 119: Barnes, H. and H.T. Powell. 1951. T
Page 120 and 121: Chester, C.M. 1996. The effect of a
Page 122 and 123: Crisp, D.J. 1978. Genetic consequen
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David, B., A. Guille, J-P. Féral a
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Grant, A. 1983. On the evolution of
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Inaba, D. 1934. On some holothurian
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of the 6 th International Echinoder
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Lieberkind, I. 1926. Ctenodiscus au
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McEdward, L.R. and S.F. Carson. 198
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Minchin, D. 1987. Sea-water tempera
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Pawson, D.L. 1976. Some aspects of
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Pingree. R.D., B. Sinha and C.R. Gr
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Savidge, G., H.J. Lennon, and A.D.
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Shilling, F.M. and D.T. Manahan. 19
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Turner, R.L. and J.M. Lawrence. 197
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Vickery, M.S. and J.B. McClintock 2
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(Eds.): Reproduction Genetics and D
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