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ooding pterasterid, Pteraster militaris (O.F. Müler) (Kaufman, 1968; McClary & Mladenov, 1990) based on similarities with P. tesselatus. Strict direct development is extremely rare in asteroids. Direct development involving feeding has not been reported for asteroids. Given the predatory nature of most juvenile and adult asteroids, it is unlikely that transitional developmental stages (mesogens) could acquire particulate food without the use of specialized (i.e. larval) feeding structures. Direct development, with feeding seems to be an unlikely evolutionary option for starfish (McEdward & Janies, 1993). 2.7. Larval cloning in asteroids Larval cloning is known to occur in all echinoderm classes except crinoids. This supports an earlier conjecture that it might be an ancestral ability of echinoderms (Eaves & Palmer, 2003). The developmental stage of clones at separation ranges from blastulae to fully formed larvae and some clones may not separate until just after the primary larva has begun metamorphosis. This indicates either that larval cloning evolved independently on several occasions or that its mechanisms have diverged extensively from an ancestral mode. Knott et al. (2003) were the first to identify fieldcollected cloning asteroid larvae, and provided evidence that larval cloning is phylogenetically extensive within the Asteroidea. Furthermore cloning occurs regularly and in multiple ways within species that are capable of cloning. Three distinct modes of larval cloning have been observed in planktotrophic asteroid larvae collected from the field and reared in laboratory including 1) paratomy of the posterolateral arms, 2) autotomization of the preoral lobe, and 3) budding from the larval body and arm tips (Jaeckle, 1994; Knott et al., 2003). Clones are able to develop to metamorphosis and may themselves exhibit further larval cloning (Vickery & McClintock, 2000; Kitazawa & Komatsu, 2001). Nevertheless it is not known 43
whether juveniles derived from larval cloning will develop until they reach sexual maturity, or if larval cloning has only fitness consequences for either the primary or cloned larvae (Knott et al., 2003). Balser (2004) stated that cloned larvae also reproduce asexually creating a potential perpetual cycle of cloning, this author suggests that the ecological and evolutionary connotations of this incident is to increase the number of original offspring produced and in consequence to enhance the potential advection of larvae spawned in a single event. Larval cloning signifies an interesting new element for the life histories of invertebrates. This process presents three potential ecological advantages for the cloning species: 1) an increased fecundity when the conditions are appropriate for optimal growth, 2) an increased probability of settlement after a prolonged larval life, and 3) recycling of otherwise unused or reabsorbed larval tissue (Eaves & Palmer, 2003). 44
Page 1 and 2: University of Southampton Research
Page 3 and 4: Graduate School of the National Oce
Page 5 and 6: UNIVERSITY OF SOUTHAMPTON ABSTRACT
Page 7 and 8: Marthasterias glacialis (ECHINODERM
Page 9 and 10: Acknowledgments I know everybody sa
Page 11 and 12: Prière de l’étoile de mer Seign
Page 13 and 14: species of asteroid Patiriella para
Page 15 and 16: embryonic tolerances could determin
Page 17 and 18: dispersed over great distances and
Page 19 and 20: lecithotrophic development. The pre
Page 21 and 22: 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: independent of habitat or mode of n
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 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 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
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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