摘要:

The palatability and the ability of neotropical butterflies to escape after being detected, attacked and captured by wild kingbirds (Tyrannus melancholicusVieillot), was investigated by the release of 668 individuals of 98 butterfly species close to the birds, during their usual feeding activities. Most of the butterflies were attacked and eaten. Only the troidine swallowtails (ParitiesandBattus; Papilionidae) were consistently rejected on taste and elicited aversive behaviours in birds. Most other aposematic and/or mimetic species in the geheraDanausandLycorea(Danainae),Dione, EueidesandHeliconius(Heliconiinae),Hypothyris, MechanitisandMelinaea(Ithomfinae),Biblis, CallicoreandDiaethria(Limenitidinae) were generally eaten. Cryptic and non‐mimetic species were always attacked and, if captured, they were also eaten. All Apaturinae, Charaxinae, Nymphalinae, Hesperidae, most Limenitidinae, Heliconiinag (Agraulis, Dryas, DryadulaandPhilaethria) and Papilionidae (Eurytides, HeraclidesandProtesilaus) were in this group. Results indicate that the learning process in kingbirds may demand a large mortality in prey populations, even among species generally accepted as unpalatable and aposematic. They also support the assertion that escaping ability and unpalatability evolved in butterflies as alternative strategies to avoid predation by birds. Mimetic relationships among several species are discussed. Evidence for the evolution of aposematism not related to unpalatability, but to escaping ability, was found for two hard‐to‐catchMorphosp

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01471.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Because fish heads are densely packed with muscles, ligaments, skeletal elements and other structures, transformations in one structure may influence surrounding structures. Transformations occur during phylogeny, ontogeny and as environmentally induced alterations, i.e. phenotypic plasticity. We describe differences in intra‐ and interspecific transformations of the pharyngeal jaw apparatus of haplochromine cichlids. Using multivariate clustering techniques we trace possible correlations in transformations of anatomical characters of the pharyngeal jaws and surrounding structures. The intraspecific transformation analysis is based on two environmentally induced morphs ofAstatoreochromis alluaudi: a molluscivorous morph with a hypertrophied pharyngeal jaw apparatus and an insectivorous one with a non‐hypertrophied apparatus. For the interspecific analysis five other haplochromine species from Lake Victoria with diets ranging from insects to molluscs were investigated. Although ranges in diet are the same, the anatomical ranges differ betweenA. alluaudiand the species cline. Besides similarities in anatomical changes of the pharyngeal jaw apparatus in the intra‐ and interspecific cline, differences were also observed. Apparently there are among haplochromines multiple pathways to achieve similar performance. In A. alluaudi architectonic and intrinsic plasticity constraints limit the adaptability of the pharyngeal jaw apparatus. In the species cline, these constraints have been overcome by genetical adapt

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01472.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Organisms are tightly packed with structures so architectonic interdependency of structures is an obvious aspect of integration. This aspect of functional morphology, however, has received remarkably little attention. The present paper presents an example of the spatial relations among several apparatuses in the head of the cichlid fish, Astatoreochromis alluaudi. It investigates the transformations of these apparatuses and their functions due to a change in the pharyngeal jaw apparatus resulting from a functional shift (insect eating to snail crushing orvice versa). The volume of the pharyngeal jaw apparatus differs 55% between the insect eating‐ and the snail eating morph. The increase in volume of the pharyngeal jaw apparatus has an impressive number of spatial effects, both direct and indirect, on other structures. Reallocation of space within the pharyngeal jaw apparatus occurs. Total head volume increases 31% but a reallocation of space is still necessary as the increase of the opercular compartment where the pharyngeal jaw apparatus is situated compensates for only 59% of the volume increase of that. Not all spatial effects do impose constraints. Spatial constraints are avoided when one of the apparatuses can use a topographically different volume of space. The respiratory apparatus shows internal reallocations of space without loss of total volume. The same solution occurs for elements of the expansion apparatus and the buccal savity. The eyes are not influenced. Finally spatial effects can have positive repercussions. The muscles of the oral jaw apparatus increase in size. This may be an example of an epiphenomeno

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01473.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Understanding the relationship between effective population size(Ne)and the number of adults in a population(N)is important for predicting genetic change in small populations. In general, Neis expected to be close toN/2, i.e. in the rangeN/4‐3N/4, provided that the powerful effect of population bottlenecks on reducingNeis factored out (using the harmonic mean ofN). However, some very low published estimates ofNe/N(<0.1) raise the possibility that other factors acting to reduceNehave been underestimated. Here one such factor, variation in female fecundity, is investigated. Its effect onNedepends on the standardized variance in fecundity (per breeding season), a measure that is generally independent of mean fecundity. Empirical estimates of this standardized variance from 16 animal studies yielded an average value of 0.44, and a maximum value less than 1.5. To investigate the effect of such values, three kinds of fecundity variation were modelled: random (seasonal): individual; and age‐related. Fixed individual differences among females reduceNethe most. However, to reduceNetoN/10, the resulting standardized variance must usually be 10 or more. Random differences need to be even larger to achieve the same reduction. One possible mechanism, the random loss of whole families, requires very high family mortality (90% or more). The third model, fecundity that increases linearly with age, is ineffective at causing a marked decrease inNe. Given the finding that very unusual conditions are required to reduceNebelowNe/10, low estimates ofNe/Nneed to be examined critically: the lowest published ratio, for a natural population of oysters, was found to be questionable because of possible immigration into the population by cultivated oyst

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01474.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The distributions of 51 non‐human primate species are used for Parsimony Analysis of Endemicity (PAE) to determine the relationships among 14 interfluvial regions in the Amazon basin, South America. Two most parsimonious cladograms were found. The strict consensus tree of these cladograms suggests an early separation between Lower Amazonia (eastern) and Upper Amazonia (western). The major clusters of interfluvial regions identified in the PAE cladogram are congruent with the areas of endemism delimited for birds. When interfluvial regions are converted into avian areas of endemism, the PAE cladogram is congruent with one of the two general areas cladograms suggested for Amazonia based on phylogenies of several clades of forest birds. Our analysis suggests that PAE can be used as a tool to objectively identify areas of endemism at an intra‐continental scale as well as to make historical inferences. However, the value of a PAE cladogram in this latter application should be always evaluated by congruence with area cladograms built upon cladistic biogeography procedu

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01475.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The morphology of three colubrid snakes,Elaphe subradiata, Psammodynastes pulverulentus, Lycodon aulicus capucinus, and the viperTrimeresurus albolabris, were examined from populations throughout the Lesser Sunda islands using canonical variate analysis. The Lesser Sundas form the western part of two extensive Island chains, the Banda Arcs, that lie between the large islands on the Sunda (Asian) and Sahul (Australian) continental shelves. The snakes of the Lesser Sunda islands show considerable intraspecific variation in morphology. Populations ofTrimeresurus albolabrisfrom Wetar andPsammodynastes pulverulentusfrom Alor show the greatest morphological separation from conspecifics. The most pronounced morphological differentiation in multidimensional space occurs between populations on islands that remained separated throughout the Pleistocene, when sea levels were about 120 m lower than present. Consensus tree evaluation of Mahalanobis distance for populations of these four species andDendrelaphis pubison the islands of Lombok, Sumba, Flores, Lembata and Alor, supports the finding that populations from islands that remained isolated throughout the Pleistocene by sea barriers show the greatest morphological divergence.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01476.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The Madeiran archipelago consists of Madeira itself, Porto Santo and the Deserta islands. On Madeira, the forest arid the coastal floral associations are so different that their faunas are effectively isolated and have undergone largely independent development. There are different faunal associations on the eastern peninsula and in the SE coastal region, which may have been separated from each other in the past. On Porto Santo, western and eastern hills have different faunas. Most observations on the fauna are compatible with evolution by allopatric speciation, consequent upon isolation on different islands or mountains, as opposed to parapatric or sympatric processes following disruptive selection. Some cases where the taxonomy is difficult to unravel may, however, indicate parapatric speciation; examples belong to the generaDisculaandHeterostoma(Helicidae) andAmphorella(Ferussaciidae). Most evidence relating to species composition in communities is compatible with a balance of random immigration and extinction, rather than selective interaction, allowing clusters of similar sympatric species to accumulate. However, this impression may indicate that test procedures are insufficiently sensitive to detect interactions, and detailed ecological studies are required. Questions about speciation and distribution would be clarified if dates of divergence were established.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01477.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Book reviewed in this article:Designing Conservation Projects, by Julian Caldecott.J Social Learning in Animals. irhe roots ofculture, Cecilia M. Heyes and Bennett G. Galef, jnr, eds.Methods in Stream Ecology, F. Richard Hauer and Gary A. Lamberti, eds.Biodiversity, Science and Development. Towardr a Nm Partnership, F. di Castri and T. Younts, eds.Behauiour and Evolution, P. J. B. Slater and T. R. Halliday.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1996.tb01478.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY