摘要:

Six bill dimensions, and wing, tarsus and hallux lengths were measured on almost all museum specimens ofGeospizaspecies available, and up to 20 specimens from each population of the remaining species of Darwin's finches. The data were subjected to univariate and multivariate analyses in order to provide a quantitative description of size and shape differences among populations and between species.Each species ofGeospizavaries among islands in size, and most of the remaining species do so as well. There is more variation in shape among species than among populations of the same species, especially in bill proportions. Allometric relations differ among species. Approximate morphological counterparts to the ground finch species,Geospiza, can be identified among the tree finches. There is a small amount of overlap in multivariate space between a ground finch species and a tree finch species (two cases), but no overlap between any two species within each group. Size variation among populations is not generally correlated with geographical variables such as latitude, longitude, island area or its degree of isolation. Nor do coefficients of variation show strong geographical trends. Several of the results confirm the findings of other workers from simpler and non‐statistical comparisons. In addition we have shown that the tree finches have relatively long legs (tarsi), and that these finches as well as the ground finches which spend most time scratching on the ground or climbing in cacti also have a relatively long hallux (hind toe). To interpret the various morphological patterns a knowledge is required of inter‐island variation in food supply, feeding habits and the incidence of genetic exchange between populations. Recent field studies have provided some of this needed information, which helps to explain, among other things, why several populations of Darwin's finches are so unusually varia

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb00384.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Eichhornia paniculata(Spreng.) Solms. (Pontederiaceae) is a short‐lived perennial or annual of marshes, seasonal pools and ditches of lowland tropical South America, primarily NE Brazil, and the Caribbean islands of Cuba and Jamaica. Comparisons, made under uniform glasshouse conditions, of populations originating from seed collected in the two regions revealed striking differences in their floral biology and breeding systems. The majority of populations sampled in NE Brazil are tristylous. Floral trimorphism is associated with pollen trimorphism and minor differences in anther size and pollen production among the three stamen levels. Unlike the majority of heterostylous plants the floral morphs ofE. paniculataare highly self‐fertile. Populations sampled on the island of Jamaica are composed exclusively of self‐pollinating, semi‐homostylous, mid‐styled forms. Flowers from these populations are smaller and less showy, with reduced pollen heteromorphism and significantly fewer pollen grains and ovules per flower, in comparison with trimorphic populations from Brazil. Individual genotypes from Jamaican populations display considerable developmental instability in floral expression, particularly with respect to filament elongation of the lower stamen level. It is proposed that self‐pollinating populations ofE. paniculataare evolutionarily derived from tristylous ancestors and that the shift in breeding system is favoured at low density, following population bottlenecks, where pollinator service is

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb00385.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A series of morphometric and meristic analyses conducted on specimens of sand smelt,Atherina, from populations around the British Isles, and including classicA. boyeriandA. presbyterforms, has shown that the characteristics variously used in the past to distinguish these two species are invalid. Multivariate analyses showed no significant splitting of the material into two groups which might correlate to these two species; classicA. boyeriand the very large Atlantic coastA. presbyterindividuals represent the tails of a continuum of form. From these and published data, it is concluded that theA. boyerimorphology varies under the influence of conditions of temperature and salinity during embryo development, and the isolation of populations maintains comparative morphological distinctions resulting from local selection and random genetic drift.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb00386.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The breeding behaviour of ratites and tinamous is reviewed. This group includes many of the homeothermic animals which habitually show prominent or exclusive paternal care of eggs and offspring. This unusual parental care pattern is associated with a diverse array of mating systems, ranging from monogamy to mixed polygyny/polyandry. This latter system, typical of the rhcas, is unknown among higher vertebrates outside the taxa considered herein. This diversity of mating systems, together with their great geographical and ecological range, makes ratites and tinamous a group of great potential importance in the investigation of the adaptive significance of social organization, mating systems and parental care patterns. Inadequately described features of their reproductive biology have become incorporated into various considerations of the evolution of reproductive behaviour patterns, and are in danger of assuming the status of fact through repetition. We show that these birds are very little known, in the main, and urge that caution be exercised in the use of what information is available. Directions for new research in ratite breeding biology are suggested, and an interpretation of parental care and pair‐bond patterns in these birds is offere

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb00387.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1985.tb00384a.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY