SCIENCE@home

REPRODUCTIVE RELATIONSHIPS BETWEEN HOMOSEQUENTIAL SPECIES OF HAWAIIAN DROSOPHILA

E. Craddock

Published 1974 in Evolution; international journal of organic evolution

ABSTRACT

The acquisition of reproductive isolation is the most significant event in the speciation process. A knowledge of the nature of the reproductive barriers between species and of the ways in which these barriers evolve is therefore critical to any analysis of speciation mechanisms. The Drosophilidae in the Hawaiian Islands have undergone explosive speciation giving rise to some 650 to 700 endemic species (Carson et al., 1970). In view of the substantial isolation of these oceanic islands from continental land masses, it is believed that the present-day fauna may have been derived from a single successful founder, or perhaps from two separate introductions (Throckmorton, 1966). In spite of their morphological and behavioral diversity, the species constitute a closely knit evolutionary group. The geological recency of the Islands (Macdonald and Abbott, 1970) further implies that evolutionary processes in the group have been exceptionally rapid. All of these features render the Hawaiian Drosophila particularly suitable for studies of the speciation process. Many of the species are very young in evolutionary terms and some may show only partial reproductive isolation, since speciation is most often a slow, continuous process rather than an instantaneous event. Study of the reproductive relationships between such forms should therefore offer the possibility of identifying the primary reproductive barriers formed, thereby obtaining some information on the sequence of events which lead to full speciation. This was the aim of this investigation. Accordingly, it was decided to study a set of homosequential species in the planitibia subgroup of the picture-winged flies. Homosequential species have an identical banding sequence in their polytene salivary gland chromosomes (Carson et al., 1967), and are presumptively very closely related. Furthermore, some homosequential species are, in addition, very recently evolved. Two of the species used in this study are endemic to the island of Hawaii, the youngest in the chain (McDougall, 1964), and must be very recent evolutionary products. This study therefore utilizes species which are judged to be amongst the most closely related and the most recently evolved. The reproductive barriers which isolate them have been analysed initially by the method of interspecific laboratory hybridizations, since this approach has previously proved relatively successful with Hawaiian Drosophila (Yang and Wheeler, 1969). This paper presents the data obtained on their reproductive relationships, and discusses the patterns of species formation which these data suggest.

PUBLICATION RECORD

CITATION MAP

EXTRACTION MAP

CLAIMS

  • No claims are published for this paper.

CONCEPTS

  • No concepts are published for this paper.

REFERENCES

Showing 1-14 of 14 references · Page 1 of 1

CITED BY

Showing 1-44 of 44 citing papers · Page 1 of 1