Titlebook: Larvae and Evolution; Toward a New Zoology Donald I. Williamson Book 19921st edition Springer Science+Business Media B.V. 1992 animals.arth

輕快來事

habile

Near-Trochophorate Animals: Flatworms, Nemertines, Bryozoansugh I claim that the evidence has been wrongly interpreted. Much the same applies to larvae resembling trochophores and the phyla in which they occur (the near-trochophorate phyla). I shall confine myself to larvae whose affinities to trochophores are widely accepted, thus limiting myself to three p

妨礙

敘述

Toward Confirmation of the Hypothesesryonic and larval forms have occasionally been transferred between distinct evolutionary lineages, and the second is the suggestion that such transfers have resulted from cross-fertilizations. Distinction should be made between the series of postulated historical events, which is the subject of the

不在灌木叢中

Toward a New Zoologyarely discusses. It seeks to explain a number of anomalies in larval form and methods of metamorphosis, but it adds nothing to existing theories on the origins of larvae. It emphasizes the evolutionary distinction between radial and bilateral symmetry but adds nothing to our knowledge of the origins

食料

Echinoderms: Adults and Larvaethin the echinoderms, and, finally, of several pairs of species within the same class. I hope to show that these inconsistencies are resolved by the suggestion that some larval forms were acquired from animals in distinct evolutionary lineages. Before this, however, let us consider what the animals are like, both as adults and larvae.

exclamation

Near-Trochophorate Animals: Flatworms, Nemertines, Bryozoans(the near-trochophorate phyla). I shall confine myself to larvae whose affinities to trochophores are widely accepted, thus limiting myself to three phyla, but I would point out that there are a number of other larval types that various authors have regarded as being related to trochophores.

CLIFF

Horizontal Genetic Transferrvae in distantly related groups are not the result of chance, convergent evolution, or inheritance from a remote common ancestor. I believe they have resulted from transfers of genetic material between species on different branches of the phylogenetic tree, and in the present chapter I wish to discuss four questions relating to these transfers.

浪費時間

in of embryos and larvae, replacing the discredited ‘recapitulation‘ theory of Haeckel (1866). Metamorphosis, previously unexplained, represents a change in taxon during development..978-94-015-8077-9

效果

Decapod Crustaceansr phyla I found no shortage of paradoxes that could be explained as examples of the transfer of embryonic and larval forms from distinct lineages. For some of the paradoxes no other explanation has been offered, and for others I regard the accepted explanations as weak or flawed.