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The Kaneshiro model proposes a role for sexual selection in peripatric speciation. During population bottlenecks, derived males lose attractive traits and become discriminated against by ancestral females, whereas derived females are selected to be less choosy. This permits novel mate choice cues to evolve in derived populations. In a quantitative analysis of laboratory experiments, we show that bottlenecked males have indeed become less attractive, but females have not lost their ancestral preferences. Contrary to the model, mating asymmetries were not limited to bottlenecks, but regularly occurred between derived and ancestral populations. The simplest explanation for the observed mating asymmetries is loss of genetic variation and inbreeding in the derived populations. The Kaneshiro process is unlikely to isolate small daughter populations from their ancestor but with slight modifications it may become a strong candidate for speciation in allopatry manifested as isolation between daughter populations in secondary contact.

We review published records of laboratory experiments on peripatric and vicariance allopatric speciation to address the following three questions: (1) What was the true effect size of reproductive isolation? (2) Was the reproductive isolation persistent? (3) What influenced the development of isolation? Contrary to popular belief, laboratory evidence for allopatric speciation is quite weak. Assortative mating was only found among derived populations in vicariance experiments. Reproductive isolation against control populations was only intermittent, so there is reason to doubt if some cases showing significant reproductive isolation really should be attributed to speciation. The method of testing was at least as important as the speciation model. Experimental populations tested against each other were the most likely to demonstrate reproductive isolation. This study suggests that allopatric speciation experiments are more likely to yield conclusive results under divergent selection than under drift, and points to the benefits of large populations and many generations.

The development of long-term preservation methods of somatic embryos was investigated as a contribution to synthetic seed technology, Thus, cryopreservation in liquid nitrogen was attempted with somatic embryos of two species. Coffea canephora Pierre and Daucus carota L. Cryopreservation of carrot embryos simply required a 21-h sucrose pretreatment followed by a prefreezing step at -20°C. A freeze-hardening treatment consisting of embryo culture in the presence of high sucrose molarity and 1 μM ABA was developed for coffee embryos. Following desiccation at 75% relative humidity (RH) and +24°C for 7 d, embryos were frozen by rapid immersion in liquid nitrogen. Direct regrowth of frozen-thawed embryos was obtained for the majority of both carrot and coffee embryos. Even large carrot embryos were able to survive cryopreservation. The size of embryos and the age of the embryogenic strain from which the embryos originated determined their ability to develop into normal plantlets. Direct regrowth without any secondary callogenesis and/or embryogenesis is a prerequisite for practical use of preserved embryos either in a nursery or through direct planting.

ResumeLa duree du cycle et le coefficient de proliferation ont ete determines par differentes methodes de cinetique cellulaire dans les meristemes de la racine seminale de Vigna radiata cv Tai 1. L'analyse des relations entre la valeur absolue en ADN par noyau, les durees du cycle, de G1, S et M, a mis en evidence certaines caracteristiques communes a d'autres especes de Legumineuses.Les mesures des contenus en ADN des noyaux a chromocentres de Vigna radiata, standardisees par rapport a des erythrocytes de poulet ou des lymphocytes humains ont ete realisees par cytophotometrie apres reaction de Feulgen. La valeur absolue en ADN 2C a ete estimee a 1,23 ± 0,26 pg. La population cellulaire, distribuee en quatre classes, 2C, 2C-4C, 4C et 8C, est caracterisee par un mode principal de niveau 4C et par la presence de cellules a contenu en ADN superieur a 4C.