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951.
952.
DAVID S. WOODRUFF STEPHENJAY GOULD 《Biological journal of the Linnean Society. Linnean Society of London》1980,14(3-4):389-416
Cerion's exuberant morphological diversity (600 described 'species') combined with the extreme rarity of reproductive isolation among morphotypes (only one unambiguous case of sympatry in the Bahamas) has long made this genus an object of fascination for evolutionists and of frustration for taxonomists. We have pursued an integrated approach of genetic and morphometric study based on field investigations of ecology and biogeography in the Bahamas. Cerion's morphotypes are not distributed haphazardly, but show definite patterns of correlation with habitat and geography. Although all morphotypes interbreed, hybrid zones tend to be narrow and characterized by highly local genetic anomalies–unique alleles present in neither parental population. Different patterns of covariance in ontogeny, and habitat preferences, also indicate mat the morphotypes are distinctive, non-amalgamating entities (despite little difference in the frequencies of structural genes among them) that may be called species once a definition based on strict reproductive isolation is abandoned. Variation in structural genes, anatomy and morphology is non-concordant, but orderly for each criterion. Similar morphologies are often polyphyletic and evolved repeatedly as one possible ontogenetic route within a developmental program common to all Cerion. Although we cannot always distinguish among competing causes for observed patterns, we can establish genetic, morphological, anatomical, and biogeographic criteria for decisions when adequate evidence is available. The species of Cerion will be reduced by more than an order of magnitude from a list currently described. 相似文献
953.
954.
955.
ADELINE SOULIER-PERKINS DAVID OUVRARD MARC ATTIÉ THIERRY BOURGOIN 《Systematic Entomology》2007,32(2):305-311
Abstract. The association between the Lophopidae (Hemiptera, Fulgoromorpha) and their host plants was studied within a phylogenetic framework. Host plant use was optimized on Lophopidae phylogeny and the most parsimonious hypothesis is presented. This hypothesis describes the evolution of host plant use by the Lophopidae, and postulates the ancestral plant family used. This scenario is discussed within the biogeographical evolutionary context of the fulgoromorphan families, and is corroborated by information from both insect and host plant fossils. The association of the Lophopidae and their host plants is made by comparing the angiosperms and Lophopidae phylogenies, demonstrating at this level of comparison that the insects show 'taxonomic conservatism' for their host plants. 相似文献
956.
The internal phylogenetic relationships of the ichneumonid subfamily Labeninae (Hymenoptera) are re‐assessed using 136 characters for 54 species representing all currently known species‐groups. New character sets are used. These include a new form of seta (named the grossulariform setae) which are present on the inner surface of the hind coxa of some females, and the extensive structural modifications of the terminal segments of the female metasoma, which are described and structural homologies established. The monophyly of the Labeninae and of the four component tribes, Groteini, Poecilocryptini, Xenothyrini and Labenini, is demonstrated. The Groteini is shown to be the sister‐group to the Poecilocryptini + (Xenothyrini + Labenini). Monophyletic genera are established, including three new genera: Ozlabium gen. nov. Gauld & Wahl (type‐species 0. arcadium sp. nov.) in the Groteini from Australia; Torquinsha gen. nov. Gauld & Wahl (type‐species Certonotus invictus Porter) in the Labenini from Chile, and Gauldianus gen. nov. Lanfranco (type‐species Gauldianus chilensis sp. nov. Lanfranco) in the Labenini from Chile. Apechoneura is removed from synonymy and re‐instated as a valid genus for a complex of tropical American species. The biogeographic patterns shown by the Labeninae are discussed. Evidence suggests that the group radiated on Gondwanaland after the separation of Africa/India/Madagascar, but prior to the separation of Australia. Species occurring off the southern continental fragments, in North America, are shown to be members of highly derived lineages, a result consistent with the hypothesis that labenines colonized North America recently through Mesoamerica. Patterns of host utilization and mating behaviour are examined for the group. Members of the more derived lineages show progressively more female specializations for attacking hosts deeply concealed in woody substrates. Males in the more specialized lineages are shown to have a wider array of secondary sexual characteristics and genitalic ornamentations than more plesiomorphic taxa. 相似文献
957.
Devonian fossils of Spongiophyton have been identified as a terrestrial evolutionary intermediate between algae and vascular land plants on the basis of their dichotomously branched, tubular morphology, thick cuticles, and the scattered distribution of surface pores. Our understanding of their physiology is, however, severely limited, but may be increased through the use of stable carbon isotope measurements. One such study led to the hypothesis that Spongiophyton carried a carbon isotope (δ13C) signature characteristic of lichens ( Jahren et al., 2003 Geology 31 , 99–102). Here, we outline three difficulties with accepting this idea and report independent isotopic measurements of Spongiophyton fossils from Canada and Ghana. Our results show that the isotopic discrimination of analogous tissues of Spongiophyton, extant lichens, liverworts and mosses are statistically indistinguishable. We suggest therefore that claims to have definitively identified lichen metabolism are premature, and cannot be sustained. 相似文献
958.
DAVID C. HOUSTON 《Ibis》1990,132(1):36-41
Breeding by Rüppell's Griffon Vultures Gyps rueppellii is synchronized but the time of breeding of colonies in the Serengeti region of Tanzania has changed by 5 months over the period between 1969–1970 and 1985. During this interval there have been considerable changes in the ungulate populations within the feeding range of the vultures, resulting in an increase to the food supply available to the birds. It is suggested that this species may have two alternative breeding seasons, the selective value of each depending on the magnitude of the food supply. 相似文献
959.
960.
DAVID B. WAHL 《Systematic Entomology》1993,18(4):371-387
Abstract. A cladistic analysis is presented for the genera of the ichneumonid subfamily Mesochorinae. Nine genera are recognized as valid. Previous work on larval morphology is reviewed and a number of larvae are newly illustrated and discussed. Four new synonyms are proposed: Oncocotta, Piestetron, Plectochorus and Rhaibaspis are all synonymized with Mesochorus , and Stictopisthus is placed back as a synonym of Mesochorus. Four new genera are described: Artherola from South Africa, Chineater from Chile, Thamester from Japan, and Varnado from Morocco. A new key is provided to the mesochorine genera of the world. 相似文献