Through the looking glass
30-11-2009 19:25
Today we had a one-day
symposium at Naturalis, „Through the looking glass”,
about asymmetry, handedness, and mirror images in
nature.
Richard Palmer (University of Alberta), who is a visiting professor at the moment, did the key-note lecture on „Learning, developmental plasticity and evolution”.
Evolution by natural selection requires three steps. New variants of organisms: must arise, must have an impact on fitness (survival or fecundity), and must (ultimately) be heritable. The first step - how new variants arise - remains controversial. Traditionally, new phenotypes are attributed to novel genotypes (mutants or recombinants). But developmental plasticity may be a more important source of new variants than generally recognized.
The absence of heritable variation for direction of asymmetry in species that show a random mixture of asymmetric forms (i.e., equal numbers of right- and left-handed forms), identifies a unique phenotype - "direction of asymmetry" - for which there is no genotype. A wide-ranging survey of asymmetry variation within and among species of animals and plants offers some of the strongest evidence to date for a 'phenotype-precedes-genotype' mode of evolution. In addition, the tendency of many animals to learn (e.g., handed behavior) may facilitate both the origin and the amplification of right-left morphological differences via developmental plasticity. Such an interplay between learning and developmental plasticity might greatly enhance the rate of morphological evolution.
There were also lectures by Menno Schilthuizen and Edi Gittenberger on malacological subjects.
Menno talked about „A negative spiral: sex and body shape in tropical tree snails”, in which he showcased the work being doing on Amphidromus. The Malaysian species with which he is working, shows dimorphism and he concluded that probably aspects of the reproduction can explain why dimorphism does occur in this taxon. The coiled spermatophore plays an important role.
Edi Gittenberger eloborated „A very unlikely event”, in which he showed that although e.g. sinistrality is not rare in Japanese land snails, this can be traced back to three evolutionary events. And, as such, these may be considered rare events in evolutionary timeframe.
Richard Palmer (University of Alberta), who is a visiting professor at the moment, did the key-note lecture on „Learning, developmental plasticity and evolution”.
Evolution by natural selection requires three steps. New variants of organisms: must arise, must have an impact on fitness (survival or fecundity), and must (ultimately) be heritable. The first step - how new variants arise - remains controversial. Traditionally, new phenotypes are attributed to novel genotypes (mutants or recombinants). But developmental plasticity may be a more important source of new variants than generally recognized.
The absence of heritable variation for direction of asymmetry in species that show a random mixture of asymmetric forms (i.e., equal numbers of right- and left-handed forms), identifies a unique phenotype - "direction of asymmetry" - for which there is no genotype. A wide-ranging survey of asymmetry variation within and among species of animals and plants offers some of the strongest evidence to date for a 'phenotype-precedes-genotype' mode of evolution. In addition, the tendency of many animals to learn (e.g., handed behavior) may facilitate both the origin and the amplification of right-left morphological differences via developmental plasticity. Such an interplay between learning and developmental plasticity might greatly enhance the rate of morphological evolution.
There were also lectures by Menno Schilthuizen and Edi Gittenberger on malacological subjects.
Menno talked about „A negative spiral: sex and body shape in tropical tree snails”, in which he showcased the work being doing on Amphidromus. The Malaysian species with which he is working, shows dimorphism and he concluded that probably aspects of the reproduction can explain why dimorphism does occur in this taxon. The coiled spermatophore plays an important role.
Edi Gittenberger eloborated „A very unlikely event”, in which he showed that although e.g. sinistrality is not rare in Japanese land snails, this can be traced back to three evolutionary events. And, as such, these may be considered rare events in evolutionary timeframe.