Although viviparous reproduction is employed by species in at least six different animal phyla it is rarely common. The phylum Onychophora is exceptional as most of the species are viviparous. Limited information is available on reproductive biology of this group. The current study provides information on parental investment and sex allocation in natural populations of Neotropical Plicatoperipatus jamaicensis. Gravid females of this onychophoran showed an average maternal effort of 12.6% (maximum 34.0%) and carried from 1-4 embryos of varying developmental stage, suggesting that offspring are born individually rather than in clutches. There was considerable overlap in the size distributions of freeliving juveniles and embryos, indicating that the period of embryonic care is variable. There was a positive correlation between embryo and maternal size, suggesting that large females release larger offspring which can more quickly attain maturity. Males of this species were sexually mature shortly after birth. Females were inseminated while small, but then had to undergo substantial growth before reproduction. Sex ratios of juveniles and adults were significantly female-biased, but embryos showed a 1:1 sex ratio. Sex ratios of broods approximated binomial expectations, and there was no shift in sex ratio with female size, suggesting that offspring gender is not maternally controlled.
Oikos is a journal issued by the Nordic Ecological Society and is one of the leading peer-reviewed journals in ecology. Oikos publishes original and innovative research on all aspects of ecology. Emphasis is on theoretical and empirical work aimed at generalization and synthesis across taxa, systems and ecological disciplines. Papers should be well founded in ecological theory and contribute to new developments in ecology by reporting novel theory or critical experimental results. Confirming or extending the established literature is given less priority. Synthesis of new and emerging fields in ecology and beyond is encouraged. Papers of review character should should strive for conceptual unification and being a point of departure for future work rather that restrospective summaries of established fields or topics.
Wiley is a global provider of content and content-enabled workflow solutions in areas of scientific, technical, medical, and scholarly research; professional development; and education. Our core businesses produce scientific, technical, medical, and scholarly journals, reference works, books, database services, and advertising; professional books, subscription products, certification and training services and online applications; and education content and services including integrated online teaching and learning resources for undergraduate and graduate students and lifelong learners. Founded in 1807, John Wiley & Sons, Inc. has been a valued source of information and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. Wiley has published the works of more than 450 Nobel laureates in all categories: Literature, Economics, Physiology or Medicine, Physics, Chemistry, and Peace. Wiley has partnerships with many of the world’s leading societies and publishes over 1,500 peer-reviewed journals and 1,500+ new books annually in print and online, as well as databases, major reference works and laboratory protocols in STMS subjects. With a growing open access offering, Wiley is committed to the widest possible dissemination of and access to the content we publish and supports all sustainable models of access. Our online platform, Wiley Online Library (wileyonlinelibrary.com) is one of the world’s most extensive multidisciplinary collections of online resources, covering life, health, social and physical sciences, and humanities.
This item is part of a JSTOR Collection.
For terms and use, please refer to our
Oikos
© 1989 Nordic Society Oikos