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Media type:
E-Article
Title:
Reproductive Isolation? Interannual Variability in the Timing of Reproduction in Sympatric Sea Urchins, Genus Pseudechinus
Contributor:
McClary, Dan;
Barker, Mike
Published:
American Microscopical Society, Inc., 1998
Published in:
Invertebrate Biology, 117 (1998) 1, Seite 75-93
Language:
English
ISSN:
1077-8306;
1744-7410
Origination:
Footnote:
Description:
Reproductive cycles of 3 sympatric species of the echinoid genus Pseudechinus, found in southeastern New Zealand, were examined over 27 months from October 1989 to December 1991. Analysis of periodic changes in relative gonadal size was used to help define the reproductive cycle of each species. Although P. huttoni reproduced primarily during the early (austral) summers of 1990 and 1991 (December-January), mature gametes were present in the gonads throughout much of the year. Conversely, P. novaezealandiae reproduced primarily during the autumn and early winter (May-July). P. albocinctus had an extended reproductive period in 1990, which peaked in late spring/early summer (December-January), followed by a gradual spawn-out to late autumn (May-June). The pattern was different in 1991, with a secondary peak in reproductive potential noted in late autumn (June). For all 3 species, males tended to be competent to spawn gametes for a longer period than were females. These observations were all corroborated by analysis of changes in overall gonad histology and in the distribution of oocyte sizes in the ovaries of each species throughout the year. P. huttoni and P. novaezealandiae thus appeared to exhibit temporal reproductive isolation from each other. Intraspecific as well as interannual variability in the timing of reproduction, however, suggests that such temporal isolation may not always be complete. In contrast, P. albocinctus was not temporally isolated from either of its 2 sympatric congeners. These results were examined in the context of seasonally variable environmental conditions.