摘要:

Many scattered lizard groups have small skin invaginations in such places as the neck, axilla, groin and postfemoral region. These frequently contain feeding chiggers (the larvae of trombiculid mites) which, in general, are much commoner on species with pockets than on those without. Mite pockets appear to have evolved many times, being found in at least five families (Iguanidae, Chamaeleonidae, Gekkonidae, Lacertidae, Scincidae) and are most abundant in warm areas that are not extremely dry. They are present in newly hatched animals and embryos of viviparous forms and so cannot be produced in direct response to the mites. Typically, the epidermis of infested pockets is hyperplastic and resilient, rapidly repairing damage caused by feeding mites, and the dermis contains dense concentrations of lymphoid cells. It is suggested that mite pockets have evolved in forms prone to trombiculid infestation and ameliorate the damage that this causes by concentrating chiggers in places that are equipped to minimize the harm they do.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb01767.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

We estimated heritabilities, and genetic and phenotypic correlations between beak and body traits in the song sparrow (Melospiza melodia). We compared these estimates to values for the same traits in the Galápagos finches,Geospiza(Boag, 1983; Grant, 1983). Morphological variance is low in the song sparrow, and our results show that genetic and phenotypic correlations are considerably lower than correlations in the morphologically more variable Geospiza. Comparison using a larger sample of Galapagos populations confirms the existence of an association between variance and correlation for phenotypic values. We suggest two possible explanations for this association. First, most traits studied are functionally related, and the joint evolution of variance and correlation may have resulted from stabilizing selection about a line of optimal allometry between traits. Alternatively, introgression between populations and species could have caused correlation and variance to evolve jointly. Both selection and introgression were probably influential in producing the observed pattern, but it is not possible to estimate their relative importance with current data. Genetic and phenotypic correlations were correlated in the song sparrow, but heritabilities of traits varied greatly. As a result, the genetic variance‐covariance matrix for traits is not simply a constant multiple of the phenotypic matrix. Evolutionary response to natural selection cannot, therefore, be predicted from the measurement of phenotypic characteristics alo

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb01768.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Phenotypic plasticity is an important mode of adaptation to temporal and spatial environmental variability, particularly in plants. Although data are available concerning interspecific differences in the sizes and shapes of characters, there is little information concerning differences between taxa for the plastic responses of those characters. We have measured: (1) the mean value of a character, (2) the amount of character plasticity, and (3) the pattern of phenotypic plasticity for species in five genera, and calculated the divergences among species for each of these three measures. We compared the divergences of these measures to address the question of whether there is a relationship between the evolution of the character means of species and the evolution of the plasticities of those characters. We found that the evolutionary divergence of character plasticities could be independent of the interspecific divergence of character means. There was, however, a tendency for the divergence of amounts and patterns of plasticity to be related.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb01769.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb01770.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Aciurina bigeloviae(Cockerell) (Diptera: Tephritidae) is a gall‐forming tephritid fly associated with rubber rabbitbrush,Chrysothamnus nauseosus(Pallas) Britton (Compositae), throughout the western United States. Two distinct gall morphologies were found amongA. bigeloviaepopulations, each associated with its own morphologically distinct group of subspecies ofC. nauseosus. Adults emerging from these galls can be distinguished on the basis of wing morphology and pronotal colour. Electrophoretic analysis of these two morphs suggested limited, unidirectional gene flow between them. Results of several other investigations were consistent with a restricted gene flow hypothesis. Heterotypic matings occurred in the laboratory, but at a depressed level. Host plant preferences, ovipositional success on the different host plant groups, and two life history parameters differed between the two fly types. Based on these multiple lines of evidence, we concluded that these two morphs ofAciurinarepresent two species:A. bigeloviaeandA. trixaCurran. Reasons why these flies might be more appropriately viewed as host races are discussed as are scenarios which might account for their divergenc

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb01771.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1986.tb01767a.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY