Showing papers in "Biological Journal of The Linnean Society in 1977"
TL;DR: It is suggested that the change from being planktonic macrophagous carnivores to benthic microphagous omnivores can only take place in the estuaries of the region and conditions in the inshore waters of the Indian Ocean in south-east Africa are probably too rough for substrate feeding by juvenile mullet.
Abstract: Changes in the feeding ecology of juveniles (10–59 mm standard length) of eleven species of Mugilidae were investigated in south-east African estuaries. Adults of all species spawn in the sea and juveniles enter estuaries at a length of about 10 mm. In estuaries they change their feeding habits in the following sequence: zooplankton to zooplankton in the benthos (10–15 mm), zooplankton in the benthos to meiobenthos (10–20 mm), and meiobenthos to sand particles and associated microbenthos (15–25 mm). All species show a similar pattern of change but interspecific competition is probably prevented by the rapid switch to the adult diet of microbenthos and sand particles and because species enter estuaries at different times according to spawning periods. The juveniles seek shallow quiet water areas of estuaries and it is suggested that the change from being planktonic macrophagous carnivores to benthic microphagous omnivores can only take place in the estuaries of the region. Conditions in the inshore waters of the Indian Ocean in south-east Africa are probably too rough for substrate feeding by juvenile mullet.
84 citations
TL;DR: It is concluded that chromosomals evolution in the Didelphidae proceededs from low numbers to higher numbers by a process of centromeric fissioning complemented by some pericentric inversions and/or translocations.
Abstract: One hundred and seventy-seven specimens of American didelphids, representing 9 genera and 22 species have been studied for their chromosomal constitution. Didelphids are very conservative in chromosomal complements. All of the studied species can be sorted into one of three kinds of karyotypes: 2n= 14 (three species of Didelphis, one of Lutreolina, two of Philander, and one of Chironectes), 2n = 14 (eight species of Marmosa, one of Metachirus, three of Caluromys, and one of Dromiciops), and 2n= 18 (three species of Monodelphis). These karyotypes are stable, showing only minor variations within each basic pattern. It is concluded that chromosomals evolution in the Didelphidae proceededs from low numbers to higher numbers by a process of centromeric fissioning complemented by some pericentric inversions and/or translocations. The pattern of karyotypic stability is consistent with bradytely at the organismic level of evolution. This is explained by a low rate of regulatory genetic evolution promoted by epistatic selection favouring the retention of chromosomal arrangements highly advantageous for overall adaptation.
55 citations
TL;DR: The findings of this study support the conclusions reached by Blaber (1976) with regard to the partitioning of the food resource according to inorganic particle size.
Abstract: An investigation of the feeding ecology of Mugilidae in Natal and Pondoland estuaries showed that although the diet of the eleven species is similar it varies from one estuary to another and is determined largely by the occurrence of particular food items on substrates of the preferred particle size of each species. The findings of this study support the conclusions reached by Blaber (1976) with regard to the partitioning of the food resource according to inorganic particle size. Particle sizes consumed by each species do not remain the same but vary according to locality. Within any one estuary the mullet species avoid interspecific competition by selecting particles of different sizes. The fish are always graded in the same order with regard to particle size. The relative abundance of the various species of mullet in Natal and Pondoland estuaries is probably not controlled by food or substrate requirements because most species are sufficiently flexible in their feeding ecology to cope with a wide variety of estuarine substrates.
47 citations
TL;DR: Suggestions are put forward for its management and conservation, and areas of future research are outlined on the population ecology, breeding ecology, habitat preferences and general behaviour of this snake.
Abstract: The general characteristics of the colubrid snake Coronella austriaca are described from observations made on populations examined in England. An account of the population ecology, breeding ecology, habitat preferences and general behaviour of this species is based on records collected at three study sites over a period of three years.
Level of recruitment to the populations is probably low because: 1, females do not breed usually until in their fourth year (three years old); 2, mortality of young seems to be high; 3, while gestation normally lasts about six or seven months it seems that some females may mate in alternative years. It is suggested that the location and density of C. austriaca populations is determined primarily by the topography and nature of the plant communities on the site, acting via the thermal requirements of the snakes. The abundance and location of prey species (young of small mammals and of other reptiles) may also effect the population density and local movements of this snake. The distribution of Vipera berus and C. austriaca on the study sites did not greatly overlap indicating that ecological competition may exist between these two species.
In view of the rare status of this snake, suggestions are put forward for its management and conservation, and areas of future research are outlined.
39 citations
TL;DR: Any theory which accounts for the development of a particular shape or pattern in recent animals should be able to account for the phylogenetic sequence of shapes, as illustrated by the evolution and development of patterns in dentitions.
Abstract: Studies of the fossil record indicate the sequence in which the shape of a phenotype has been modified during phylogeny. These data can provide a valuable starting point for theoretical embryology. Any theory which accounts for the development of a particular shape or pattern in recent animals should, by equivalent modifications, be able to account for the phylogenetic sequence of shapes. This argument is illustrated by the evolution and development of patterns in dentitions.
32 citations
TL;DR: The tropicalpine flora is a youthful one consisting largely of the descendants of immigrant herbs which arrived by dispersal over long distances in Plio-Pleistocene times, and several established aliens provide indications of migration ability lost to varying extents by elements within the native flora.
Abstract: Floristic elements within the tropicalpine flora of Mt Wilhelm are defined on taxonomic and distributional criteria, and are compared ecologically. The hypothesis that elements of apparently most recent immigration would retain to the largest degree characteristics appropriate to colonists of insular locations and to plants of temperate zone environments is confirmed. Good colonizing ability, rapid growth rate, continuous flowering and growth in the field, successful flowering in cultivation, vulnerability to frost, lack of preference for slopes of particular aspect, and wide and generally low altitudinal range were all present to a greater extent in more recently immigrant floristic elements. Dispersal ability was not significantly correlated with floristic elements. It is concluded that the tropicalpine flora is a youthful one consisting largely of the descendants of immigrant herbs which arrived by dispersal over long distances in Plio-Pleistocene times. A few forest plants of ancient status in New Guinea have become adapated to the tropicalpine environment, and several established aliens provide indications of migration ability lost to varying extents by elements within the native flora.
30 citations
TL;DR: The tendency for wild mice to pull more cotton wool and build better nests than laboratory mice was more pronounced among cold-treated animals, and differences in body weight did not account for the differences between wild and laboratory mice.
Abstract: Nest-building by male and virgin female wild and laboratory mice kept at a temperature of 2o C was compared with that of controls kept at 23o C. The amount of cotton wool pulled into the cage was recorded over 24 hours. Nest quality was also assessed. The tests of nest-building were conducted in both cold and warm environments. Cotton pulling was usually at a lower rate in the cold environment, but there was no corresponding decrement in final nest quality. Previous experience in the cold, compared with absence of such experience, resulted in higher scores by wild mice tested in either environment, and by laboratory mice tested in the cold environment. Wild mice that built high quality nests used less cotton wool in the cold than in the warm environment. The tendency for wild mice to pull more cotton wool and build better nests than laboratory mice was more pronounced among cold-treated animals. Differences in body weight did not account for the differences between wild and laboratory mice.
In further experiments nest-building was observed over 16 days. In the cold environment there was an initial depression of nest-building by both wild and laboratory mice, followed by a steady improvement over 6 days.
Both males and virgin females sometimes made well constructed nests even in the warm environment. In the cold environment the effect of previous cold-exposure on wild mice was the rapid construction of a good nest.
30 citations
TL;DR: Evidence is presented which indicates that Aegopinella nitidula predates other snails and that Nesovitrea hammonis is a preferred prey species, and it is suggested that the low population densities characteristic of N. hammoni in some areas might result, at least in part, from selective predation by A. Nitidula.
Abstract: The distribution and abundance of three closely related species of zonitid snails in grassland and woodland habitats at Monks Wood are described. Interspecific differences in distribution and abundance can be related to differences in climatic tolerance as shown in laboratory experiments. Evidence is presented which indicates that Aegopinella nitidula predates other snails and that Nesovitrea hammonis is a preferred prey species. It is suggested that the low population densities characteristic of N. hammonis in some areas might result, at least in part, from selective predation by A. nitidula.
25 citations
TL;DR: Ultraviolet reflectance is a widely distributed phenomenon among certain families of Coleoptera and, in some Tenebrionidae and Buprestidae, dried secretions forming patches or stripes on the pronota and elytra are reflective.
Abstract: Ultraviolet reflectance is a widely distributed phenomenon among certain families of Coleoptera. It is so far found to occur in Carabidae, Scarabaeidae, Buprestidae, Elateridae, Tenebrionidae, Cerambycidae, Anthribidae and Curculionidae. Of more than 100 species examined, 70 were found to possess UV reflectant structures. Reflection is almost always from pigments contained within microtrichia or other setae. In some Tenebrionidae and Buprestidae, dried secretions forming patches or stripes on the pronota and elytra are reflective and, in a few desert-living Tenebrionidae, reflectance is from subcuticular pigment in the elytra.
23 citations
TL;DR: Manatees probably did not occur at Rio de Janeiro or Santos, the Sao Vicente “monster” most likely being a pinnepede.
Abstract: Records of New World manatees in 16th and 17th century literature extend the former distribution of Trichechus manatus to about 20° S. Early 19th century records confirm this range, but the species has since been exterminated from these southerly localities and is now rarely found to the south of Cayenne (French Guiana). Manatees probably did not occur at Rio de Janeiro or Santos, the Sao Vicente “monster” most likely being a pinnepede. The former distribution of T. manatus seems to have been bounded by the 24° C mean annual isotherm.
20 citations
TL;DR: The apparent non-utilization of Urticaceae by H. misippus (L.), the most widespread species of the group, is discussed in terms of its possible ecological and phylogenetic relationships with H. bolina (L.).
Abstract: The 30 species of Hypolimnas butterflies recognized are divided amongst six pattern morphism classes: monomorphic, weakly dimorphic, simple dual, unimodal polymorphic, partial 9-limited polymorphic, and multiple ♀ dual polymorphic. Eighty per cent of Hypolimnas species belong to one or other of the first three categories. About 60% of the species show evidence of mimicry, some 40% being mimetic in both sexes. In the Oriental region the great majority of mimetic species within the genus are modelled on Euptoea, whilst those of the Afrotropical region are mostly modelled on Amauris. The host plants recorded for the genus strongly suggest that the Urticaceae are primitive for the group, but eleven other families of flowering plants are recorded as hosts. The apparent non-utilization of Urticaceae by H. misippus (L.), the most widespread species of the group, is discussed in terms of its possible ecological and phylogenetic relationships with H. bolina (L.). A check-list of butterflies feeding on Ipomoea (a host plant for both H. bolina and H. misippus), and on other Convolvulaceae, is included.
TL;DR: Experiments on host preference showed that in all three species, cotton (Gossypium hirsutum: Malvaceae) is either preferred or enjoys equal preference with their principal feral host plants.
Abstract: The ecology of three species of Oxycarenus, a heteropteran bug, was studied in southern Ghana. Host plants are listed. Seasonal changes in populations were followed in two species (O. fieberi and O. hyalinipennis), both of which frequent malvaceous host plants that flower throughout the year. The third species (O. dudgeoni) shows successional colonization of host plants since its hosts include trees which have restricted flowering seasons. Experiments on host preference showed that in all three species, cotton (Gossypium hirsutum: Malvaceae) is either preferred or enjoys equal preference with their principal feral host plants. The natural enemies of Oxycarenus, and the defensive mechanisms against them, are also described.
TL;DR: Of the biotic and abiotic factors which could be involved in the observed seasonal variation in the bacterial populations, only the fluctuations in the phosphate levels were found to show a significant correlation.
Abstract: The physico-chemical characteristics and the bacterial populations of three thermal springs in West Bengal have been examined. The springs range in temperature from 42o C (Saubhagya Kund) to 65o C (Agni Kur.d). The levels of carbonate and bicarbonate alkalinity, total hardness and the ppm of chloride, phosphate and silicate as well of dissolved oxygen were measured at monthly intervals. Estimates of the bacterial populations were obtained from cultures. Water samples incubated at 37oC for enumeration of mesophilic microbes, at 50o C for thermo-tolerant bacteria and at 60o for strict thermophiles. Tests for coliform organisms were carried out at 37o C and at 50o C.
All three springs show seasonal variation in their physico-chemical characteristics and in their bacterial populations. The cooler springs have large populations of mesophilic and thermotolerant bacteria but fewer thermophilic types. In the two hot springs (Saubhagya Kund and Swetganga), the differences of mean bacterial populations observed between 37o and 50“C and between 50o and 60o C are highly significant (P < 0.01), in the third (Agni Kund) the differences are also significant (P < 0.01) but the population showed a rising trend with the temperature. Of the biotic and abiotic factors which could be involved in the observed seasonal variation in the bacterial populations, only the fluctuations in the phosphate levels were found to show a significant correlation (0.001 < P < 0.01).
TL;DR: Intensely grazed downland is an unsuitable, or at best a marginal habitat for C. nemoralis, with particular reference to ‘area effects’ in the shell character polymorphism, often found in downland populations of C. Nemoralis.
Abstract: Population densities of adult Cepaea nemoralis (L.) were estimated for nine chalk grassland sites on the South Downs. Estimates of cover, species composition and height of vegetation were also obtained. The density of C. nemoralis was positively associated with Bromus erectus cover, and negatively with Festuca spp. cover. This finding, confirmed by an earlier survey, suggests that the density of C. nemoralis in chalk grassland is directly or indirectly governed by mammalian grazing pressure, and not by the availability of suitable food. Intensely grazed downland is an unsuitable, or at best a marginal habitat for C. nemoralis. This conclusion is discussed with particular reference to ‘area effects’ in the shell character polymorphism, often found in downland populations of C. nemoralis.
TL;DR: The identity of each of the 18 species of Hymenoptera described by Forster is examined in detail, particularly the nine represented by specimens, and four new synonymies and two new combinations are established.
Abstract: Type-material of 100 insect species described by J. R. Forster has always been thought lost. We present evidence that syntypic specimens of some of these species were sent by Forster to Linnaeus in 1772. Specimens of at least 27 species survive in the Linnaean collection now in Burlington House, and are listed. The identity of each of the 18 species of Hymenoptera described by Forster is examined in detail, particularly the nine represented by specimens. Lectotypes are designated for two species; four new synonymies and two new combinations are established; and three names remain nomina dubia within their genera.
TL;DR: Around the 1880s Obelia became used in teaching to illustrate and introduce the concept of alternation of generations and, alongside Hydra, as a “type” example of the Hydrozoa and of the Coelenterata.
Abstract: Although medusa-release was first seen in Obelia in the mid-18th century (Baster, 1762b), the true nature of medusa-release in any coelenterate was not understood until Sars' (1829) observations on a scyphozoan scyphistoma. A flourish of work followed during which many coelenterate life-cycles were worked out, that of Obelia being among the first (by van Beneden, 1843). The impact on some areas of zoological thought of the mid-19th century was considerable. Around the 1880s Obelia became used in teaching to illustrate and introduce the concept of alternation of generations and, alongside Hydra, as a “type” example of the Hydrozoa and of the Coelenterata. It remained important as a teaching organism for many years.
TL;DR: The characteristic features of the Opilionid suborder Cyphophthalmi are considered, and the evidence in favour of their promotion to the rank of a separate order is discussed.
Abstract: The characteristic features of the Opilionid suborder Cyphophthalmi are considered, and the evidence in favour of their promotion to the rank of a separate order is discussed.
TL;DR: Evidence is presented which suggests that later they do take the young of small mammals as do adult smooth snakes.
Abstract: In August 1976 two broods of the endangered smooth snake (Coronella austriaca) were rescued from a fire at a National Nature Reserve. This material provided a unique opportunity in which to observe the behaviour of the young animals before they were returned to nearby heathland. It soon became apparent that the young snakes have narrow food preferences because only the young of lizards were taken. However, evidence is presented which suggests that later they do take the young of small mammals as do adult smooth snakes. Observations on other aspects of their behaviour, such as burrowing, have helped to elucidate the complex day to day behaviour of the adults.
TL;DR: A transcription is given of a series of letters written in 1900 to H. M. Bernard concern an unpublished (and lost) essay by Bernard on nomenclature and the species problem.
Abstract: A transcription is given of a series of letters written in 1900 to H. M. Bernard (then working on the Catalogue of corals in the British Museum) by Ray Lankester, Sir W. Thiselton-Dyer, W. F. R. Weldon, George Murray, William Bateson, David Sharp and Alfred Russell Wallace. The letters concern an unpublished (and lost) essay by Bernard on nomenclature and the species problem. Bernard's ideas were presented in a paper read to the Linnean Society in 1901. A commentary on the letters and their writers is added.