The butterflies and birds of Madeira and La Gomera: taxon cycles and human influence

Analyses of the habitat distributions and densities of Madeiran and La Gomeran butterflies and birds are used to test the predictions of the taxon cycle hypothesis. The predictions are as follows: recent colonists should occupy more habitats and be found at higher densities than endemic species or sub-species; colonists should predominate in the marginal habitats on the islands.
The distributions of Madeiran and La Gomeran birds and butterflies do not conform to those predicted by the taxon cycle. Neither do the densities of the bird and butterfly species on either island. There is some evidence that recent colonizers occupy marginal habitats but we suggest that it is difficult to draw conclusions when man has greatly influenced the nature of the islands' habitats.     

Functional and Evolutionary Relationships Among the RPCH-AKH Family of Peptides

SYNOPSIS. The RPCH-AKH peptide family is a group of structurallysimilar peptides which are apparently widely distributed inarthropods, and which serve a variety of functions in differentsettings. The first three recognized members of this familywere detected and purified based on endocrine activities includingcolor change in crustaceans (RPCH) and effects on energy metabolismin insects (AKH and Compound II). The most recently identifiedfamily members, MI and Mil, were found on the basis of neuromuscularactivity as well as endocrine effects, and a combination ofhistological and physiological evidence strongly suggests thatat least some of these peptides are localized in neurons includingmotor neurons which use them as transmitters. Thus this is oneof several neuropeptide families with highly conserved structures,but diverse endocrine and neural functions. The significanceof structural similarities between family members is unclear.Fortunately the arthropod preparations in which these peptideshave been identifiedlend themselves to detailed developmental,anatomical, and physiological analysis, so there is every reasonto suppose that molecular biological and physiological investigationscurrently inprogress will shed significant light on the meaningof the phenomenon of structurally conservative peptide families.