摘要:

Current concepts of macroevolution–the origin and diversification of higher taxonomic categories‐are reviewed. A reductionist hypothesis, seen in the light of models based on extant species, seems to be corroborated. There appears to be no reason to think that macroevolution is a natural phenomenon distinct from a speciation event giving rise to a new phyletic lineage. Neidier is it necessary to postulate any quantum element in that speciation ev

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1979.tb00061.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Pyrrolizidine alkaloids (PA) have been identified in six species of Arctiidae reared onSenecioandCrotalaria.These include senecionine, seneciphylline, integerrimine, jacobine, jacozine, jacoline, jaconine and a metabolite (C15H25NO5) fromSenecio, and monocrotaline, trichodesmine and crispatine fromCrotalaria.The all‐red aberration ofTyria jacobaeae(var.conyi)contained much less of the metabolite than normal examples of this species. FemaleSpilosoma luteareared on the same plants ofS. jacobaeacontained markedly more jacobine and jacoline than die males.Host plant relationships and secondary plant substances are discussed. It is suggested that the Arctiid moths' own deterrent secretions, directed against vertebrate predators, pre‐adapts them for feeding on foliage likewise protected against large herbivores by toxic secondary plant substances such as cardenolides and pyrrolizidine alkaloids. These latter substances are more toxic to vertebrate than to insect herbivores, and their dual function of deterrent and insect aphrodisiac puts a premium on their sequestration and storage once a species has achieved the initial steps, and occupied the plant niche concerned. It is further suggested that the polyphagous habits of the Arctiidae result in a more equitable distribution of die secondary plant substances within the Mullerian complex concerned, thus providing a generalized warning message for the potential vertebrate preda

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1979.tb00062.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The basic features of an intensive study on the various stages of a secondary succession, from fallow Held to birch woodland, are described. The α‐β diversities of the green plants, and two orders of insects, Hetcroptera and adult Coleoptera, are described. For the vegetation, in addition to taxonotnic diversity, structural diversity, with both spatial and architectural components, was recognized. It was found that up to a successional age of 16 months, the taxonomic diversities of plants and insects rose; thereafter the diversity of the plant species declined far more than the insect species diversity. It was concluded that in the later successional stages the maintenance of a high level of taxonomic diversity of these orders of insects is correlated with the rising structural diversity of the green plants, which virtually compensates for their falling taxonomic diversity. The larger fungi appear to show a similar trend to the inse

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1979.tb00063.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The Central American Locust has previously been identified asSchistocerca paranensis(Burmeister), the Argentinian Locust, and it has been suggested thatS. americanaof North America represents its solitarious phase. Hybrids of locusts from the Yucatan peninsula of Mexico with locusts from Argentina and Florida were reared, their fertility measured and meiosis in the males examined. It was found that: (1) sex ratios in the F, hybrids were distorted; (2) hybrids had reduced fertility; (3) female hybrids were more fertile than male hybrids; (4) meiosis in hybrid males was disturbed; (5) these effects were more pronounced in die hybrids with the Argentinian Locust than in those with Florida locusts.These results are discussed in relation to Haldane's rule and the biogeography of die group. It is concluded that the Central American and Argentinian Locusts are separate species, but that the relationship of the former toS. americana americanarequires further investigation.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1979.tb00064.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1979.tb00065.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY