Searching for a new home: decision making by dispersing brush mice

Natal dispersal occurs when young animals leave the area where they were born and reared and search the surrounding landscape for a new place to settle. Despite the importance of dispersal for both individuals and populations, search behavior by dispersers, including the decision-making process of choosing a place to settle, has not been investigated in the field. Here we draw on the mate search literature, in which the theory of decision making during search has been well developed, and ask whether there are behavioral similarities between habitat search and mate search. We used radiotelemetry to track dispersing juvenile brush mice (Peromyscus boylii) and determined whether their search behavior was consistent with any of three decision rules: threshold, best of n, and comparative Bayes. We found that search behavior by juveniles was most often consistent with comparative decision rules (best of n and comparative Bayes), suggesting that the decision-making processes involved in searching for a place to settle and searching for a mate may be quite similar.     

Gymnospermin: A new labdan triol from Gymnosperma glutinosa

The structure of gymnospermin (1), a new diterpene triol isolated from a collection of Gymnosperma glutinosa (Compositae) from Mexico, has been determined to be (?)-7β,8α,15-trihydroxy-labdan.     

Sesquiterpene lactones — insect feeding deterrents in Vernonia

Larval feeding tests were run to determine the preference of six species of Lepidoptera for two species of Vernonia which produce sesquiterpene lactones and one which has lost the ability to produce these bitter principles. Significant differences between the feeding preferences of the insect species were observed. Further feeding tests were run with a Vernonia leaf powder medium to determine how interspecific chemical differences influenced these preferences. The sesquiterpene lactone, glaucolide-A, was found to reduce larval feeding when incorporated in a Vernonia powder-agar medium. The amount of insect feeding was inversely proportional to the concentration of glaucolide-A in the medium.     

A populational survey of amino acids in Prosopis species from North and South America

Leaf extracts of 540 plants representing 24 species of the genus Prosopis from North and South America were analyzed by 2-D PC and high voltage electrophoresis for their protein and non-protein amino acids. In addition to the presence of the usual protein amino acids, most of the species examined contained high concentrations of the non-protein amino acids, pipecolic acid, 4-hydroxypipecolic acid and proline.     

A heliangolide from Chromolaena glaberrima

The investigation of Chromolaena glaberrima afforded, besides the known heliangolide chromolaenide, a new 4-dehydrochromolaenide. The structure of the new compound was elucidated by spectroscopic methods.     

Sesquiterpene lactone and diterpene constituents of helianthus annuus

One new furanoheliangolide derivative, 4,5-dihydroniveusin A, as well as the known compounds niveusin B and argophyllin A and B, were isolated from a Texas population of Helianthus annuus. Three previously characterized diterpene acids, grandifloric acid, ciliaric acid and 17-hydroxy-ent-isokaur-15(16)-en-19-oic acid were the principal constituents of this population.