摘要:

The stability of a clinal pattern geographic variation in relation to character number was investigated by the random selection of real characters. The characters used were selected from a set of 18 significant characters, drawn from four different character systems, and had a low within‐group correlation. Principal component/coordinate analysis was used to elucidate the main pattern of geographic variation and the first principal coordinate was plotted against a geographical transect to illustrate this pattern. The existence of ‘clinal’ or ‘monotically clinal’ variation was assessed by the rank correlation between geographic position and coordinate score and the congruence between patterns of geographic variation was assessed by the correlation between the first principal coordinates of the appropriate analyses.Two procedural models were used: A, the congruence between completely independent character sets based on 1–9 characters, and B, congruence between the ‘total’ analysis and those analyses based on 1–16 characters. The frequency of the types of pattern of geographic variation shown by these Model B analyses was also determined. Congruence is asymptotic in relation to character number and is described by various mathematical models, depending upon parameter and procedure. A broad pattern of clinal variation occurred in all analyses based on six or more characters and appears to be a stable feature of the racial affinities that is unlikely to be influenced by character choice. The details of the clinal pattern cannot be shown to be stable and may be influenced by the choice of character. This study had several findings in common with a previous study of categorical variation, e.g. the approximately hyperbolic relationship between character number and congruence in Model B, which may prove to be generally true in comp

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb01632.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The multivariate analysis of a set of significant characters portrays a simple geographic cline which is evident even when very few characters are used. The effect of adding insignificant characters to the set of significant characters is studied, as is the effect of replacing significant characters by insignificant characters. The former (addition) causes only a slight decline in congruence between patterns of geographic variation but the latter (replacement) causes a substantial decline in congruence. The congruence between patterns of geographic variation obtained by multivariate analysis of independent character sets is plotted against character number and gives an S‐shaped relationship when insignificant or significant plus insignificant characters are used. This is distinct from the convex asymptotic curve obtained when only significant characters are used. In spite of the reduction in congruence caused by the use of insignificant characters, multivariate analysis of insignificant characters consistently revealed the ‘same’ geographic pattern (i.e. ‘cline’) as the set of significant characters. However, it required 10 times as many insignificant characters to ach

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb01633.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Callimorpha quadripunctaria(Lepidoptera, Arctiidae) is both genetically polymorphic for hindwing colour and well protected from predators. Polymorphic populations are, however, only found in the extreme northwest of its extensive distribution in Europe and Asia Minor. Use of a colour analyser confirmed the existence of three reasonably discrete colour classes: bright red, orange and yellow. These could each be subdivided into two further groupings of phenotypes, one of moths of pure colour and the other with a secondary colour. The species is polymorphic in SW England, where it became well established in villages and towns around the Exe estuary in the late 19th century. It now extends about 30 km east and west along the south coast of Devon and up to a similar distance inland along the river valleys. The rate of spread is consistent with the substantial dispersal of up to 500 m detected in a capture‐recapture experiment performed at Exeter over the whole flight period in August 1984. This experiment also found no differences in timing of emergence, survivorship or within‐habitat movement between the sexes or the colour classes. Males may show a higher rate of emigration than females. The species is polymorphic throughout S Devon. Its stronghold to the west of the Exe basin is characterized by a comparatively uniform morph frequency with 5045% red, 20–40% orange and 10–20% yellow. Yellow moths have their highest frequency in this area, red moths in the east and west and orange to the north. Adult activity is concentrated in the 2–3 h after dusk. Air temperatures of higher than 15°C are probably critical to pairing which involves sex pheromones released by females. This may be an important factor limiting the species' range. Our results suggest that climatic selection pressures involving non‐visual differences in fitness account for the geographical variation. The lack of daytime activity of moths in comparison to that found by other workers on Rhodes and which is likely in other warmer climates suggests the hypothesis that expression of the polymorphism is favoured in the marginal populations of NW Europe by a relaxation of the stabilizing influence on the warning coloration exerted by visu

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb01634.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

It is argued that groups of similarly coloured species of coccinellids are Müllerian mimicry rings. This is based on a synthesis of the literature about the nature of their biology and aposematic colour patterns, their highly developed chemical defence and the responses of bird predators to them. The system of multiple mimicry ‘rings’ is illustrated for the Dutch coccinellid fauna. Some polymorphic species, includingAdalia, exhibit red forms and black melanic forms which are apparently components of different putative mimicry rings. A similar reasoning is put forward with regard to the orange and the black forms of the soldier beetleCuntharis livida. Hypotheses involving spatial variation in comimics, as have been developed to account for some other cases of polymorphic Miillerian mimicry, predict that sympatric polymorphic species exhibiting similar sets of phenotypes will show parallels in their geographical variation. This is tested forA. bipunctataandA. decempunctatain The Netherlands. On this local scale there is no parallel variation;A. bipunctataexhibits marked geographical differentiation whereasA. decempunctatashows a general uniformity in morph frequency. Observations on their population biology show that only inA. bipunctatais there a major spring period of adult reproduction on shrubs exposed to direct sunshine. Previous work has demonstrated an influence of thermal melanism in this period of the life cycle. It is suggested that local responses in species such asA. bipunctatamay reflect a partial ‘escape’ from stabilizing aposematic selection. The basis of a steep cline found inC. livida, which opposes one inA. bipunctata, is unknown and unlikely to be related to mimicry. There is some evidence that the polymorphism is influenced by non‐random mating. When species and communities of coccinellids are considered on a wide geographical scale many observations about their colour patterns and spatial variation, especially those of Dobzhansky, support an interaction between selection favouring mimetic resemblance and forms of climatic selection, especially thermal melanism. The polymorphism inAdaliais discussed in relation to a system of multiple mimicry rings and to Thompson's recent theoretical treatment of the maintenance of some polymorphisms for warning coloration by a balance between aposematic and apostatic selection. This becomes more tenable in coccinellids because of evidence that bird predators show a variable response to them. Frequency‐independent selection arising from thermal melanism can provide the basis of spatial variation in equilibrium points. An alternative to such a hypothesis is one in which differences in unpalatability between species of coccinellids are emphasized (after experiments of Pasteels and colleagues). Some less unpalatable species such asAdaliamay have responded to periods of prolonged disruptive selection acting in a frequency‐dependent way to promote polymorphic mimicry associated with different modal colour patterns and intermediate in nature between classical Batesian and Müllerian mimicry. The likely occurrence of a supergene controlling polymorphism in some coccinellids is consistent with such

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb01635.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Two subspecies of the grasshopperChorthippus parullelushave distributions that abut in the Pyrenees. We have studied morphological and electrophoretic variation in II populations near Mont Louis, Pyrénées‐Orientales, France. The two subspecies differ in several morphological characters and at one enzyme locus, esterase‐2, and in this area they hybridize forming a cline in morphology less than 5 km wide. Examination of museum specimens suggests that this hybrid zone extends for most of the length of the Pyrenees, possibly breaking down in the extreme west. As the two subspecies are known to differ in mating behaviour this hybrid zone is well suited to the study of reinforc

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb01636.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Two subspecies of the grasshopperChorthippus parallelushave ranges that abut in the Pyrenees. Males produce two types of song—calling song and courtship song. We have examined the use and structure of these songs in males from nine sites near Mont‐Louis, Pyrénées‐Onentales, France. These sites were previously used to identify the position of the hybrid zone on morphological characters. The subspecies differ in the use and structure of both types of song. Clines in these characters correspond in position with the morphological cline. At least one character may be relevant to mate choice but none of the characters show evidence of reinfo

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb01637.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY