01616nas a2200157   4500008004100000245009400041210006900135300001400204490000800218520108700226100001801313700002801331700002101359700002401380856005401404       1997                        eng d00aJaw muscle development as evidence from embryonic repatterning in direct-developing frogs0 aJaw muscle development as evidence from embryonic repatterning i  a1349-13540 v2643 aThe Puerto Rican direct-developing frog Eleutherodactylus coqui (Leptodactylidae) displays a novel mode of jaw muscle development for anuran amphibians. Unlike metamorphosing species, several larval-specific features never form in E. coqui; embryonic muscle primordia initially assume an abbreviated, mid-metamorphic configuration that is soon remodelled to form the adult morphology before hatching. Also lacking are both the distinct population of larval myofibres and the conspicuous, larval-to-adult myofibre turnover that are characteristic of muscle development in metamorphosing species. These modifications are part of a comprehensive alteration in embryonic cranial patterning that has accompanied life history evolution in this highly speciose lineage. Embryonic ’repatterning’ in Eleutherodactylus may reflect underlying developmental mechanisms that mediate the integrated evolution of complex structures. Such mechanisms may also facilitate, in organisms with a primitively complex life cycle, the evolutionary dissociation of embryonic, larval, and adult features.1 aHanken, James1 aKlymkowsky, Michael, W.1 aAlley, Keith, E.1 aJennings, David, H.  uhttps://africanamphibians.myspecies.info/node/46201951nas a2200145   4500008004100000245008900041210006900130300001200199490000700211520147100218100001801689700002401707700002001731856005401751       1997                        eng d00aMechanistic basis of life-history evolution in anuran amphibians: Direct development0 aMechanistic basis of lifehistory evolution in anuran amphibians   a160-1710 v373 aThe primitive, or ancestral reproductive mode for Recent amphibians involves a complex, biphasic life history. Yet evolutionarily derived, alternate modes are seen in all three living orders and predominate in some clades. Analysis of the consequences and mechanistic bases of one such mode-direct development-can provide insights into the evolutionary opportunities and constraints conferred by the ancestral metamorphic ontogeny. Direct development in the anuran genus Eleutherodactylus involves fundamental alterations to many features of embryonic and posthatching development. At hatching, young emerge as fully formed, albeit tiny versions of the adult; most larval features are absent. Pervasive changes in ontogenetic timing, in particular the precocious (embryonic) formation of many adult structures, appear to be correlated with early development of the thyroid axis, although responsiveness to exogenous thyroid hormone is diminished or even lacking in at least some peripheral tissues. Changes in cranial patterning are likely mediated by the embryonic neural crest, although many gross features of crest biology are highly conserved. Laboratory-based analyses of direct development and other derived reproductive modes in amphibians, using contemporary methods developed for more standard, "model" organisms, may contribute important insights into life-history evolution that complement those derived from analyses of morphology, ecology and phylogeny.1 aHanken, James1 aJennings, David, H.1 aOlsson, Lennart  uhttps://africanamphibians.myspecies.info/node/463