摘要:

A fossil carabid (Coleoptera) belonging to the subfamily Promecognathinae is described from Cretaceous crater lake deposits at Orapa, Botswana. The specimen, which is the first ever fossil promecognathine, is placed in a new genusPalaeoxinidium.The fossil supports aCretaceousage determination for the sediments, and it indicates that the Orapa crater was, at least in part, heavily vegetated at the time of deposition. Cladistic analysis of the fossil and extant Promecognathinae indicates that the fossil represents the sister group of the extant taxa and that the latter, in turn, comprise a pair of sister groups. It is, therefore, proposed that the Promecognathinae should be divided into two tribes: the Palaeoaxinidiini, represented by the fossil, and the Promecognathini, represented by the extant groups. The Promecognathini should be subdivided further into the subtribes Promecognathina and Axinidiina, represented by the American and African species, respectively. Three alternative zoogeographic hypotheses that explain the distributions of the fossil and extant promecognathines are discussed and tests for the hypotheses are proposed.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00603.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

A systematic revision and biological account is given of the only apoid obligate necrophages, theTrigona hypogeagroup, along with descriptions ofTrigona necrophagasp. nov. and the male ofTrigona crassipes. Trigona necrophagais endemic to eastern Panama and possibly the Chocó;T. hypogeaandT. crassipesare sympatric throughout the Amazon Basin and the Guianas. The lack of a corbicula on the hind leg and reduction of giant setae on the labial palpi, workers foraging upon carrion, lack of stored pollen in nests, and complete absence of pollen grains in larval provisions demonstrate obligate necrophagy in all three social, stingless bee species. Evolution ofT. hypogeaandT. crassipesfrom a common ancestor in the Amazon Basin is postulated, andT. necrophagais likely to be an offshoot ofT. crassipes.Morphology linksT. crassipesandT. hypogea, but nest architecture joinsnecrophagaandcrassipes.Facultative necrophagy inTrigonaprobably became obligate due to preadaptations including (1) massive forager recruitment via pheromone trails; (2) aggressive foraging on carrion exudates; (3) apical mandibular teeth; (4) rapid location of novel resources; (5) beneficial microbes in bee glandular secretions that metabolize protein and produce antibiotics, and (6) queen cells and food storage pots of the same size and close proximity. Accidental placement of regurgitated, partly‐digested carrion in queen cells may have promoted admixture of hypopharyngeal glandular secretions and microbes with harvested liquid carrion. The most derived species,T. necrophaga, may have additional mutualist microbes because only this species has distinctive grey‐green protein, and fiveBacillusspecies in food pots and brood cells. No unusual anatomical features were found in worker bees. All three species make sweet, clear honey that contains some pollen but is of unknown or

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00604.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

There are several possible explanations for the low fruit: flower ratios commonly observed in the Australian Proteaceae—some proximate and others ultimate. One of these, namely that some flowers on a plant are functionally male (andromonoecy), has recently received considerable attention. However, the term andromonoecy appears to have been misused in the pollination ecology literature. In this note, we clarify the use of the terms andromonoecy and androgyny, and suggest that they should be applied with care, only after it is clear that the flowers lack ovules or that they possess dysfunctional gynoecia. These terms should not be applied to post‐fertilization events which result in ovule abortion. Further, we review the current evidence for andromonoecy or androgyny in the Proteaceae, especially the genusBanksia, and present the results of studies on two additionalBanksiaspecies,B. spinulosaandB. ericifolia.The evidence so far fails to provide support for widespread andromonoecy in this genus as an explanation for low fruit: flower rat

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00605.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Correlations, univariate analyses, multiple group principal component analyses, canonical analyses, contours and transects arc used to describe microgeographic variation in body dimensions and scalation of the scincid lizardChalcides sexlineatuswithin the island of Gran Canaria. Patterns of geographic variation in both character systems show similar north‐east/south‐west clines, scalation variation is also altitude‐related. Canonical variate analyses showed that the generalized patterns of geographic variation in scalation and body dimensions were largely unidimensional. Four hypotheses, each one predicting a unidimensional pattern of microgeographic variation, were tested simultaneously against each described pattern using partial correlation. This method did not reject north/south differences in climate and/or vegetation as a cause of the microevolution in body dimensions. Similarly, altitude and north/south differences in climate/vegetation were not rejected for scalation. Partial correlation rejected the hypothesis that there are two species ofChalcideswith different ranges within Gran Canaria. Mantel tests rejected the altitude hypothesis alone as a cause of the generalized geographic variation in body dimensions but did not reject any of the proposed hypotheses as being causal for the generalized geographic variation in scalation. A consideration is made of how habitat variation could cause differential selection and comparisons drawn with a parallel pattern of microgeographic variation found in the colour pattern, scalation and size of a lizard on a neighbouring i

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00606.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The predictions of neutralist and selectionist hypotheses have been tested many times in the past, but mostly using data only from organisms such as vertebrates, with generally low to average heterozygosities. The more recent discovery of particularly high levels of genetic variation in marine sponges and coelenterates provides an opportunity to use data from such species to contribute further to the understanding of the determinants of heterozygosity in natural populations. Therefore, 23 species of sponges and coelenterates from temperate, tropical and boreal waters were analysed by gel electrophoresis for an average of 14.3 enzyme loci per species.Mean heterozygosity values for each species were unusually high, ranging between 0.106 and 0.401. The means and variances of the heterozygosity estimates showed reasonable correlation with neutralist predictions (with both the stepwise mutation and the infinite alleles models). Population sizes were generally difficult to estimate with any confidence, but, for one sponge species for which this was possible, levels of heterozygosity again were similar to neutralist predictions, although the same was not apparently true for three species of sea anemone. No differences were found between heterozygosity levels of tropical and temperate species of sponges and coelenterates, thus apparently contradicting the selectionist ‘trophic resource stability’ and ‘temporal environmental variation’ hypotheses. Conversely, however, the consistently high levels of genetic variation found in coelenterates and sponges may be argued to be related to common biological characteristics, such as sessile life, great evolutionary ‘age’, limited ability to disperse and probable low homoeostatic capability.Our results seem, overall, to agree well with neutralist expectations for species with large, stable population sizes. Also, the mean heterozygosities, their variances and the observed and expected proportions of polymorphic loci seem to fit well with predictions based on the neutralist hypothesis. However, the selectionist ‘environmental grain’ and the ‘shifting balance’ hypotheses fit the data equally well. As with much earlier work, the problems in distinguishing between the various predictions of selectionist or neutralist ideas make it both difficult and unwise to draw d

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00607.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1991.tb00603a.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY