摘要:

Pseudis paradoxahas an extremely large tadpole with a long, deep tail‐ These features are also found in overwintering tadpoles of temperate species where low temperatures delay development and prolong prolactin exposure.Pseudis paradoxadoes not occur in localities with marked seasonal temperature fluctuations. Low temperature cannot be implicated in the development of the tadpole. However, the parallels in shape betweenPseudistadpoles and those of temperate overwintering species suggest thatPseudistadpoles may have a prolonged exposure to prolactin, higher levels of prolactin during development or an increased sensitivity to prolacti

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb01951.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Colony genetic structure was studied in natural populations of three fire ant taxa,Solenopsis richteriForel,S. geminata(Fabr.), and hybridS. invicta/richteri, using allozyme markers. All colonies studied exhibited arrays of female genotypes predicted under a model of monogyny (single functional queen) and monoandry (single insemination of queens). Males produced in the colonies appear to originate exclusively from the foundress queen, rather than from any virgin females present in the colonies. Thus these social insect colonies represent simple, albeit enormous, family groups. Single insemination and foundress parentage of males appear to be conserved reproductive traits in the subgenusSolenopsis, whereas another major determinant of colony genetic structure, the number of functional queens, is evolutionarily labile in this group.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb01952.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Polygala vulgarisis a widespread perennial plant species of basic to neutral grassland throughout Britain. It is variable in flower colour and some vegetative characters in most populations. Gene flow is restricted in all populations since the plants are normally self‐pollinating (up to 20% outcrossing, calculated from figures of heterozygosity) and seeds are normally dispersed only up to 2 m from the parent plant. Examination of several enzyme systems, using starch gel electrophoresis, showed that all enzyme loci appeared to have been duplicated, probably owing to the fact thatP. vulgarisis a tctraploid in a genus which has primarily diploid members in Europe. Polymorphisms were found at both of the duplicated loci in four enzyme systems and at one locus in each of two further systems.Fifty‐one populations from a diversity of habitats were sampled in southern Britain. In most populations from the typical habitat of lowland calcareous grassland, polymorphisms occurred at five or more loci, and the alleles were distributed throughout the populations. In all these sites there was a diversity of microhabitat and, in one area, marked differences in microhabitat distribution between different enzyme morphs. It is likely that differential selection is an important factor in the maintenance of the polymorphisms in all these areas. These populations were divided, genetically, into two main groups, those from the Gower peninsula, South Wales, and those from the English chalk. Within each group the populations were quite closely related genetically, though some large differences at particular loci occurred even between adjacent populations. Diffuse clumps of alleles occurred within all these populations, and it is likely that limited gene flow has affected the genetic structure of the populations, particularly since cycles of local extinction and recolonization are likely to be recurring. The genetic structure of each population, at the allozyme loci examined, is likely to be the consequence of a balance between differential selection and restricted gene flow. The number of heterozygotes was small, though higher than expected from an analysis of experimental progeny, suggesting a hcterozygotc advantage. Few strong multilocus associations were found despite the predominance of self‐pollination.In the populations from sand dunes, roadsides, submontane grassland and water meadows there was, in general, much less polymorphism than in those from lowland calcareous grassland and some populations were entirely monomorphic; in most others there were large, entirely monomorphic groups of plants. Genetic distances between these populations were variable, even within one habitat and area, and they did not appear to show any particular relationship to each other. It is likely that the genetic structure of these populations, at the loci studied, has arisen largely through chance colonizations and genetic

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb01953.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A marked morphological and genetical discontinuity among the greater galagos points to the existence of two genetical species within the taxon,Galago crassicaudatusE. Geofl'roy 1812. This contribution investigates the conditions surrounding this speciation event, and places it within a phylogenetic context. Information pertaining to body size, litter size, sexual dimorphism, locomotor mode and karyotypic structure is assessed. It is hypothesized thatG. crassicaudatusdiverged from its more gracile sibling,G. garnettii, approximately 2 million years ago, in respotise lo the increasing aridification of Africa that accompanied the Northern Hemisphere Pleistocene glaciations.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb01954.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

A series of morphologieal and locomotor performance variables was measured in a population of newborn garter snakes to determine whether performance capacity has a significant morphological basis in these animals. Morphological traits measured were body length and mass, number of body and tail vertebrae and numbers of vertebral abnormalities. Locomotor performances included burst and mid‐distance speed and distance and time crawled before anti‐predator displays were assumed. All performance variables were repeatable in daily replicate trials (P<0.001). Individual burst speed, mid‐distance speed, and distance crawled were significantly correlated pairwise (P<0.01). Most morphological and performance variables had a significant mass dependence (static allometry), although the effects were rather weak (r2<0.1, except for body length): larger animals performed better and had fewer abnormalities. There were significant associations between some morphological traits and locomotor performance. Morphological factors accounted for 19% of the variation in mid‐distance speed and 14% of the variation in antipredator behavior by multiple regression analysis. Canonical correlation of all performance and morphological variables simultaneously accounted for 24% of the observed variation in performance. Numbers of body and tail vertebrae (assayed by scale counts) had an interactive effect on speed of loc

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1988.tb01955.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY