Phylogeny, biogeography and reproductive trends in the Onychophora Artículo académico Valor fecha/hora uri icon

Abstracto

  • A cladistic analysis places the Onychophora between Polychaeta and Arthropoda. The 'Uniramia' concept is not supported. No justification was found for either onychophoran family to be considered ancestral. A cladogram of fossil genera indicates the common ancestor to have long oncopods, armoured plates and an annulated body. Later forms show adaptations to life in reduced spaces. Physiological data suggest that the Onychophora became adapted to land via the littoral zone, before the Late Ordovician. Adhesive glands evolved for defence on land. Peripatopsidae and Peripatidae were distinct by the late Triassic. The occurrence of onychophorans probably dates from post-Pliocene in New Guinea and southern Australia, and post-Early Cretaceous in Chile, the southern half of Southeast Asia, Mesoamerica and the Caribbean. After the Early Cretaceous, the peripatids of tropical Africa lost terrestrial contact with those of South America. A new biogeographic technique, formalized here under the name retrovicariance, indicates that the Peripatidae of Equatorial Africa and the Neotropics are sister-groups. Typical inbreeding adaptations found in some onychophorans include: female-biased sex ratios; gregarious development; relatively constant time of development and number of offspring in each clutch; male polygamy and shorter life span; frequent sibmating in the microhabitat of development, and sperm storage by females, so that a single insemination fertilizes all ova. © 1995 The Linnean Society of London.

fecha de publicación

  • 1988