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101.
Three new species, Tambocerus dentatus, T. longicaudatus and T. robustispinus spp. n. from southern China, are described and illustrated. A checklist and distribution to the Tambocerus species from China is provided together with a key for their separation. 相似文献
102.
Most adult dung beetles (Scarabaeidae: Scarabaeinae) feed on fresh, wet dung of larger herbivorous or omnivorous mammals. As refractory plant fragments are selected out before ingestion, the food is presumed easily digestible. However, members of the desert‐living scarabaeine genus Pachysoma (probably evolved from an ancestor closely related to the wet‐dung feeding genus Scarabaeus) select dry dung pellets and/or plant litter. Thus, they ingest a much higher proportion of structural plant material, which nevertheless appears to be digested rather efficiently. This study investigates morphological modifications of the gut for this digestion in adults of eight Pachysoma species, both pellet and litter feeders. To ascertain hypothesized ancestral conditions, four fresh‐dung feeding Scarabaeus species were also examined. The latter have the usual dung beetle gut consisting of a long, simple midgut, followed by an equally simple, much shorter hindgut of the same width. Lengths of midguts (M) and hindguts (H) divided by body length (B) for comparison between species of different size are: 4.9–6.3 (M/B) and 0.7–0.8 (H/B), which is normal for dung feeders. In Pachysoma, lengths are 6.3–6.5 (M/B) and 1.0–1.4 (H/B) in pellet feeders, and 4.4–5.0 (M/B) and 2.0–2.5 (H/B) for litter feeders. Hindguts are still morphologically undifferentiated and of midgut width, but clearly longer, particularly in litter feeders. Presumably, plant fragments in the food are digested, at least partly, in the hindgut. If so, the morphological adaptation is unusual: simple elongation rather than the expansion of part of the hindgut, as found in several other plant‐ or detritus‐feeding scarabaeids. J. Morphol. 2013. © 2013 Wiley Periodicals, Inc. 相似文献
103.
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105.
Distribution of chloroplast DNA diversity within and among populations in gynodioecious Beta vulgaris ssp. maritima (Chenopodiaceae) 总被引:2,自引:0,他引:2
D. FORCIOLI P. SAUMITOU-LAPRADE M. VALERO P. VERNET & J. CUGUEN 《Molecular ecology》1998,7(9):1193-1204
With the recent technical advances in molecular biology, chloroplast DNA (cpDNA) has become a marker used for the study of cytoplasmic differentiation of natural populations of plants. As chloroplasts are maternally inherited in most plant species, the seed component of gene flow is thus made accessible. We present here a study of cpDNA polymorphism within the maritima subspecies of the gynodioecious Beta vulgaris in which we try to assess the impact of such a reproductive system on seed flow. One hundred and eighty-eight wild beets were sampled from 20 hermaphroditic and 20 gynodioecious (i.e. containing both hermaphroditic and female plants) populations from the Atlantic coast of Europe. cpDNA variability in these populations was characterized with a rapid restriction fragment length polymorphism (RFLP) method. Eight cpDNA haplotypes were found. Strong differentiation among populations was observed ( F ST = 0.43) and was consistent with isolation by distance, although most of the cpDNA haplotypes were ubiquitous. Gynodioecy seems to affect the distribution of cpDNA diversity: gynodioecious populations of Beta vulgaris ssp. maritima contained a greater number of cpDNA types but were less differentiated among themselves than hermaphroditic ones. 相似文献
106.
The effect of isolation and history on colonization patterns of plant species in secondary woodland 总被引:10,自引:0,他引:10
Colonization success of woodland originating after 1850 was determined for seventeen forest plant species having different dispersal strategies. Colonization rate of the studied endo-and exozoochorous species apparently was considerable higher than that of species having short distance dispersal like myrmecochores and species lacking dispersal mechanisms. The occurrence of eight species in this young forest habitat was related to the distance to the nearest source patch (DNS), as well as to the age of the young patches and to their former land use. DNS calculated to old, existent and occupied source patches affected most analysed species. Only Ilex aquifolium L. had a significant higher occurrence in woodland originating before 1916 than in those originating after 1916. Former land use showed significant effects for three species. Although colonization rate and effects of studied parameters on occurrence were different for the studied species, no clear differences were found between different dispersal groups. The consequences of these results for the understanding of colonization processes of the species studied is discussed. 相似文献
107.
Thefirst-instar nymph and the adult female of Kermes echinatus Balachowsky (Hemiptera, Coccoidea, Kermesidae) are described and illustrated. This species is compared with Kermes vermilio Planchon, a morphologically similar species known in the Palaeractic region. 相似文献
108.
Bruce A. Young 《Biology & philosophy》1993,8(2):225-248
Morphological elements, or structures, are sorted into four categories depending on their level of anatomical isolation and the presence or absence of intrinsically identifying characteristics. These four categories are used to highlight the difficulties with the concept of structure and our ability to identify or define structures. The analysis is extended to the concept of homology through a discussion of the methodological and philosophical problems of the current concept of homology. It is argued that homology is fundamentally a similarity based concept rather than a phylogenetic concept, and a proposal is put forth to return to a comparative context for homology. It is shown that for both the concepts of structure and homology ana priori assumption of stable underlying patterns (i.e. archetypes) is essential. 相似文献
109.
《Biological reviews of the Cambridge Philosophical Society》2018,93(2):897-913
Seed dispersal by animals is a complex phenomenon, characterized by multiple mechanisms and variable outcomes. Most researchers approach this complexity by analysing context‐dependency in seed dispersal and investigating extrinsic factors that might influence interactions between plants and seed dispersers. Intrinsic traits of seed dispersers provide an alternative way of making sense of the enormous variation in seed fates. I review causes of intraspecific variability in frugivorous and granivorous animals, discuss their effects on seed dispersal, and outline likely consequences for plant populations and communities. Sources of individual variation in seed‐dispersing animals include sexual dimorphism, changes associated with growth and ageing, individual specialization, and animal personalities. Sexual dimorphism of seed‐dispersing animals influences seed fate through diverse mechanisms that range from effects caused by sex‐specific differences in body size, to influences of male versus female cognitive functions. These differences affect the type of seed treatment (e.g. dispersal versus predation), the number of dispersed seeds, distance of seed dispersal, and likelihood that seeds are left in favourable sites for seeds or seedlings. The best‐documented consequences of individual differences associated with growth and ageing involve quantity of dispersed seeds and the quality of seed treatment in the mouth and gut. Individual specialization on different resources affects the number of dispersed plant species, and therefore the connectivity and architecture of seed‐dispersal networks. Animal personalities might play an important role in shaping interactions between plants and dispersers of their seeds, yet their potential in this regard remains overlooked. In general, intraspecific variation in seed‐dispersing animals often influences plants through effects of these individual differences on the movement ecology of the dispersers. Two conditions are necessary for individual variation to exert a strong influence on seed dispersal. First, the individual differences in traits should translate into differences in crucial characteristics of seed dispersal. Second, individual variation is more likely to be important when the proportions of particular types of individuals fluctuate strongly in a population or vary across space; when proportions are static, it is less likely that intraspecific differences will be responsible for changes in the dynamics and outcomes of plant–animal interactions. In conclusion, focusing on variation among foraging animals rather than on species averages might bring new, mechanistic insights to the phenomenon of seed dispersal. While this shift in perspective is unlikely to replace the traditional approach (based on the assumption that all important variation occurs among species), it provides a complementary alternative to decipher the enormous variation observed in animal‐mediated seed dispersal. 相似文献
110.