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It seems that evolutionary features have been more important in defining the asteroid fauna that inhabit this zone. The diverse ecological and environmental features of this zone and the mixed origin of the species allow them to have different reproductive features according to their specific necessities regarding, feeding, population conditions and phylogenetic constraints. Young (2003) considered that as in shallow water, the deep sea contains enough spatial and temporal variability to allow exploitation by species with various strategies of energy allocation. Below 3000 m a trend is observed that is possibly influenced strongly by environmental factors such as temperature and food quality and quantity, which affect the adults and the larvae. High latitudes and deep waters are characterized by low temperatures. Therefore in these environments there is a tendency to produce larger eggs reducing fecundity in order to provide the offspring with energy sufficient for a longer developmental time (King and Butler, 1985; MacDonald and Thompson, 1985; Lonsdale and Levinton, 1986, 1989; Barber et al., 1988; Mauchline, 1988; Clark and Gore, 1992; Gorny et al., 1992). Conversely, metabolic rates are also reduced and consequently physiological processes demand less utilization of energy. Of the 9 species found below 3000 m in this study, 6 belong to the Porcellanasteridae, a family found entirely in the deep sea. Six of the genera of Porcellanasteridae live in the abyssal depths, and only two genera (Porcellanaster and Eremicaster) occur at depths less than about 2500 m. One species of Eremicaster reaches down into the hadal zone, to a depth of about 7200 m (Madsen, 1961). Therefore it is possible that the reproductive features at this zone are also related to historical factors affecting evolutionary pathways (Vinogradova et al., 1959). This would explain why Porcellanaster ceruleus was the only porcellanasterid grouped into another cluster by the analysis as this genus is presumably the youngest abyssal type of porcellanasterid 91
which has penetrated into the great depths and its features enable this species to inhabit depths above 3000 m where the environmental conditions are different. The base of the continental slope in the NE Atlantic occurs at ~ 3300 m (Rice et al., 1991). Howell et al. (2002) proposed that this may represent a barrier to abyssal species. They also found a tenuous relation between the depth at which abyssal fauna starts to appear and the depth at which North Atlantic Deep Water (NADW) and Modified Antarctic Bottom Water (MABW) meet between 3000 and 3500 m. Rogers (2000) provided evidence; which suggest that many abyssal groups have originated in the Southern Ocean, where Antarctic Bottom Water originates. The abyssal zone is inhabited by asteroid species with reproductive features indicative of equilibrium K strategists (Winemiller and Rose, 1992), which have low fecundity, large egg size and expected high juvenile survivorship, although their large body size makes them more comparable to the classical K strategists (MacArthur and Wilson, 1967; Pianka, 1970), and they are characteristic inhabitants of constant environments (Winemiller and Rose, 1992; McCann and Shuter, 1997). As Ramirez-Llodra (2002) concluded, the species that have colonized the different deep-sea environments have to be well adapted to their habitat in order to be successful and persistent. In the deep NE Atlantic the habitat has selected for species with specific reproductive traits, which provide them with successful and advantageous life history strategies (Eckelbarger, 1994; Eckelbarger and Watling, 1995) as can be clearly observed in the upper bathyal zone between 700 and 1100 m, where the environmental conditions have selected for small species with low fecundity and large eggs, plus habits related directly or indirectly with suspension feeding. This species exhibit reproductive features associated to the opportunistic 92
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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
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Although larval dispersal and settl
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larvae of shallow water echinoids f
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few hours, whereas other species su
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een defined as a unique sequence of
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therefore a developing form may wel
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adults” that have the definitive
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The dipleurula is the hypothetical
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among tunicate tadpoles, sponge and
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Fig.2.4. Bipinnaria larvae of the a
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In marine invertebrates there is a
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independent of habitat or mode of n
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whether juveniles derived from larv
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and the northern Mediterranean have
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Wares (2001) performed phylogenetic
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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 and 74: CHAPTER FOUR- REPRODUCTIVE FEATURES
Page 75 and 76: In 1973, Vance proposed a theoretic
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 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
Page 124 and 125: David, B., A. Guille, J-P. Féral a
Page 126 and 127: Grant, A. 1983. On the evolution of
Page 128 and 129: Inaba, D. 1934. On some holothurian
Page 130 and 131: of the 6 th International Echinoder
Page 132 and 133: Lieberkind, I. 1926. Ctenodiscus au
Page 134 and 135: McEdward, L.R. and S.F. Carson. 198
Page 136 and 137: Minchin, D. 1987. Sea-water tempera
Page 138 and 139: Pawson, D.L. 1976. Some aspects of
Page 140 and 141: Pingree. R.D., B. Sinha and C.R. Gr
Page 142 and 143: Savidge, G., H.J. Lennon, and A.D.
Page 144 and 145: Shilling, F.M. and D.T. Manahan. 19
Page 146 and 147: Turner, R.L. and J.M. Lawrence. 197
Page 148 and 149: Vickery, M.S. and J.B. McClintock 2
Page 150 and 151: (Eds.): Reproduction Genetics and D
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