Additions to the checklists of helminth and protozoan parasites of terrestrial mammals and birds in New Zealand

A combined list of additions to previously published checklists of helminth and protozoan parasites of terrestrial mammals and birds in New Zealand is provided. These additions include a total of 21 new host parasite records (11 helminth, 10 protozoan) from 12 mammalian hosts and 82 new records (26 helminth, 56 protozoan) from 43 birds.     

Optimal age of sexual maturity and limitations of juvenile survival in mammals

Although the life history evolution of small- and large-bodied mammals seems to be governed by different factors, the both shows relative neonate size and juvenile survival to be slightly dependent on body mass. I propose a hypothesis that natural selection simultaneously maximizes a time to maturity (minimizes somatic growth rate) and a number of newborn survived to reproduction. In this case optimal juvenile survival of large-bodied mammals must be close to e-beta and that of small-bodied approximately e-(1 + beta), where beta is the slope of the regression of log annual fecundity on log annual juvenile mortality. Analysis of vital characters for 71 mammal species revealed the slope to be close to unity. As a result frequency distribution of log juvenile survival shows bimodality which coincides well with predicted optimal survival for large- and small-bodies species. It is shown that the relative neonate size can be directly proportional to the juvenile survival and inversely proportional to the lifetime offspring production irrespective of mortality factors.     

Introduced species: domestic mammals are more significant transmitters of parasites to native mammals than are feral mammals

The study of parasitism related to biological invasion has focused on attributes and impacts of parasites as invaders and the impact of introduced hosts on endemic parasitism. Thus, there is currently no study of the attributes of hosts which influence the invasiveness of parasites. We aimed to determine whether the degree of domestication of introduced mammalian species – feral introduced mammals, livestock or pets, hereafter ‘D’ – is important in the spillover of introduced parasites. The literature on introduced parasites of mammals in Chile was reviewed. We designed an index for estimating the relevance of the introduced host species to parasite spillover and determined whether the D of introduced mammals predicted this index. A total of 223 introduced parasite species were found. Our results indicate that domestic mammals have a higher number of introduced parasites and spillover parasites, and the index indicates that these mammals, particularly pets, are more relevant introducers than introduced feral mammals. Further analyses indicated that the higher impact is due to higher parasite richness, a longer time since introduction and wider dispersal, as well as how these mammals are maintained. The greater relevance of domestic mammals is important given that they are basically the same species distributed worldwide and can become the main transmitters of parasites to native mammals elsewhere. This finding also underlines the feasibility of management in order to reduce the transmission of parasites to native fauna through anti-parasitic treatment of domestic mammals, animal-ownership education and the prevention of importing new parasite species.     

Ultrastructure adaptations of symbiotic bacteria associated with freshwater fish and their cestode parasites

The ultrastructure of symbiotic bacteria colonizing the mucous membrane of the gut of freshwater fish and the tegument surface of their cestodes was studied. A comparative analysis of published and original data made it possible to define the ultrastructure peculiarities promoting the adaptation of bacteria to the digestive transport surfaces of fish and their intestinal parasites. The studied peculiarities may be split into three groups: (1) the structure and composition of the bacterial cell surface, which allows the colonization of gut epithelia and cestode tegument; (2) the intracellular ultrastructure of the bacteria; and (3) the reorganization of cell types, i.e., the formation of the dormant cells and nanobacteria.     

Ascorbic acid in buffalo ovary in relation to oestrous cycle.

Concentration of ascorbic acid was determined in different parts of buffalo ovary at four different stages of oestrous cycle viz. early luteal, mid luteal, late luteal and follicular. The stages were decided from the physical and morphological examinations of corpora lutea. The ovary was dissected in three components viz. corpus luteum, follicular fluid and ovarian stromal tissue for ascorbic acid assay. Corpus luteum showed significant change in concentration of ascorbic acid with the advancement of oestrous cycle, value being highest in late- luteal stage. Follicular fluid and ovarian stromal tissue did not show significant changes in ascorbic acid at any stage of the oestrous cycle. Small follicles, irrespective of the stage of oestrous cycle had, however, significantly higher ascorbic acid content than large follicles.     

中国大陆鸟类和兽类物种多样性的空间变异

生物多样性科学的研究重心之一是大尺度生物多样性空间分布规律及其形成机制。中国是世界上物种特丰富国家之一,了解我国物种多样性在空间上的变异情况,对于进一步认识大尺度上的生物多样性有重要意义。我们收集了全国205个自然保护区的鸟类和兽类物种分布信息,以G-F指数作为物种多样性的测度指标,利用地统计学方法分析了大陆鸟类和兽类物种多样性的空间变异特征。G-F指数是一种基于香农-威纳指数的信息测度,测度了研究地区环境分化程度和实际利用这种生态环境分化的生物类群多样性, 是一种对共同起源,相似生境需求的物种类群多样性的标准化多样性测度。结果发现,在东部季风区、西北干旱区和青藏高寒区内我国大陆鸟类多样性变异大部分都是由随机因素所引起的。兽类多样性的分布,在东部季风区和西北干旱区内是由随机因素所产生的,而在青藏高寒区,兽类多样性的总变异中99.9%是由空间依赖性所引起的,主要表现在71,492~1,020,000m空间尺度上,其分布表现出了强空间相关性。据此,大尺度上的物种多样性空间分布具有特定的规律,在生物多样性的保护行动中应加以考虑。     

Life history patterns in birds and mammals and their evolutionary interpretation

Summary It is argued that allometric principles account for most of the observed variation in the life history patterns amongst birds. To test this contention it is shown that traits such as incubation time, growth rates, age at first reproduction, lifespan, clutch weight and egg weight all scale to body weight with exponents similar to those found for analogous traits in mammals. It is then shown that most of the variation amongst bird taxa and between birds and mammals based on body weight allometry can be explained by variations in brain size, body temperature and metabolic rate, consistent with theories of growth and ageing derived from mammalian studies. Finally, it is suggested that the evidence for life histostory allometry is sufficiently strong that it argues for a more epigenetic view of life history patterns and their evolution than is generally conceded in most adaptation theories.     

Hypothalamic expression of thyroid hormone-activating and -inactivating enzyme genes in relation to photorefractoriness in birds and mammals

Photorefractoriness is the insensitivity of gonadal development to the stimulatory effects of long photoperiods in birds and to the inhibitory effects of short photoperiods in small mammals. Its molecular mechanism remains unknown. Recently, it has been shown that reciprocal expression of thyroid hormone-activating enzyme [type 2 deiodinase (Dio2)] and -inactivating enzyme [type 3 deiodinase (Dio3)] genes in the mediobasal hypothalamus is critical for photoperiodically induced gonadal growth. Since thyroid hormones are required not only for photoinduction, but also for the induction of photorefractoriness, we examined the expression of these genes in relation to photorefractoriness in birds and mammals. Transfer of birds to long photoperiods induced strong expression of Dio2. This was maintained in tree sparrow when they later became photorefractory, but decreased somewhat in quail. In hamsters, transfer to long photoperiods also induced strong expression of Dio2. High values were not maintained under long photoperiods, and, indeed, expression decreased at the same rate as in animals transferred to short photoperiods. There was no renewed expression of Dio2 associated with testicular growth as animals became refractory to short photoperiods. Expression of Dio3 was high under short photoperiods and low under long photoperiods in all the animals examined, except for the short photoperiod-refractory hamsters. Our present study revealed complex regulation of deiodinase genes in the photoinduction and photorefractory processes in birds and mammals. These gene changes may be involved in the regulation of photorefractoriness, as well as photoinduction.     

Follicular fluid steroid levels in relation to oocyte maturity and in vitro fertilization

Steroid levels in follicular fluid (FF) obtained from stimulated ovaries in patients undergoing in vitro fertilization (IVF) were measured by capillary gas chromatography. The correlation between these levels and the maturity of the oocyte, judged from the morphology of the oocyte corona cumulus complex (OCCC) and the fertilizability of the oocytes was analysed. Oocyte maturity was associated with higher FF levels of progesterone, 17-hydroxyprogesterone, 16 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone. Follicular fluids containing oocytes that became fertilized had significantly higher levels of 20 alpha-dihydroprogesterone and progesterone and lower levels of androstenedione. Of all the steroids determined, 20 alpha-dihydroprogesterone provides the most significant group differences. Enhanced 20 alpha-dihydrogenation in the presence of decreased 16 alpha- and 17-hydroxylation appears to be an important characteristic of the ultimate ripening stages and early luteinization, at least in stimulated cycles.     

Re-introduction of birds and mammals to the British Isles

Large and exciting raptors like white-tailed eagle and red kite have been restored to the skies of Scotland and England, and now there are advanced plans to return the beaver. These successes encourage debate on other missing animals, with the elusive Eurasian lynx as the next best candidate.     

Reproductive endocrinology of the Wandering Albatross Diomedea exulans in relation to biennial breeding and deferred sexual maturity

The reproductive endocrinology of the Wandering Albatross Diomedea exulans was studied at South Georgia to investigate the potential endocrine correlates of biennial breeding and of the acquisition of sexual maturity. Gonads of breeding birds and of known-age immature birds of both sexes were examined by laparoscopy throughout the period that they were at the nest site. Blood samples, subsequently analysed to determine concentrations of luteinizing hormone (LH), prolactin, progesterone, testosterone and oestradiol-17/i, were obtained from samples of breeding birds of both sexes at regular intervals from first arrival until the chicks fledged nearly a year later. Before laying in December, breeding birds had mature testes and ovarian follicles and high concentrations of LH, prolactin and sex steroids. Gonadal regression and a rapid drop in hormone levels (except for LH in females) occurred in early incubation (January). Testes (and follicles to a lesser extent) enlarged in mid-incubation, coinciding with high levels of LH and increases in prolactin and testosterone. Gonads finally regressed completely near hatching time. LH, prolactin and testosterone remained at low levels throughout chick rearing (April to November), but females had several periods of active progesterone and oestradiol secretion, and progesterone was detectable in males only late in the chick-rearing period. Although some changes in hormone levels are difficult to explain, the patterns are fairly typical of temperate birds. The persistence of progesterone secretion in both female breeders and non-breeding ‘immature’ birds is viewed as part of a mechanism inhibiting an ovary from becoming vitellogenic. Although testis size and testosterone concentrations increased with age in immature males (of ages 4–10 years), birds of 5 years and older are probably physiologically mature, even though breeding does not start until they are 7 years of age and only half an age group has bred by an age of 11 years. Immature females (of age 4–7 years) had undeveloped follicles, very low oestradiol concentrations but high progesterone levels, providing further support for the role of this hormone in inhibiting gonadotropin secretion. The condition of the female is therefore probably decisive in determining when a pair first attempts to breed but it is unknown what factors initiate normal ovarian development.     

Serum antioxidant levels in wild birds vary in relation to diet, season, life history strategy, and species

Micronutrient antioxidants are thought to be generally important for health in many animals, but factors determining levels in individuals and species are not well understood. Diet and season are obvious environmental variables that might predict the degree to which species can accumulate such nutrients. We analyzed antioxidant levels [Trolox-equivalent antioxidant capacity (TEAC), uric acid (UA), vitamin E, and four carotenoids] in 95 bird species and compared these to species-level data on diet from the literature. Using compositional principal components analysis, we identified two main axes of diet variation: invertebrate consumption and seed-to-fruit ratio. We then examined associations between diet axes and antioxidant measures, with and without control for life-history variation and phylogeny. We also analyzed a subset of 13 species for which we had data on seasonality of antioxidant levels and diet, assessing the variance in antioxidant levels explained by seasonality, diet, and species. Unsurprisingly, there were strong associations between antioxidant levels and diet. TEAC and UA concentration were consistently positively associated with invertebrate consumption and seed-to-fruit ratio, and carotenoid concentrations (e.g. zeaxanthin and β-carotene) were negatively associated with invertebrate consumption. However, vitamin E was not associated with diet as measured here. Importantly, there is much variation in antioxidants that is not explained by diet, and we are able to identify diet-independent effects of species, season/breeding stage, and life history on antioxidant levels. Circulating antioxidant concentrations within and across species can therefore be viewed as a function of multiple factors, including but not limited to diet, and antioxidant metabolism appears to differ across species and seasons irrespective of diet.     

Variations in atrioventricular valve innervation in four species of mammals

In this series of studies, the innervation patterns of whole-mount preparations of bicuspid and tricuspid valves were studied by light microscopy in the mouse, rat, guinea pig, and opossum. The acetylcholinesterase-positive networks of nerve fibers showed many similarities in the basic patterns of valve innervation in all of the species studied, but several interspecies variations were observed. The basal zone of the valve adjacent to the fibromuscular atrioventricular ring displayed the most dense plexus of nerves, with acetylcholinesterase-positive fibers being seen across the width of the valve. In the intermediate zone of the valve, less dense plexuses of nerve fibers were found; and these were more numerous in the cuspal areas and less numerous in the intervening commissural areas. In the distal portions of the valve, nerve networks arborized extensively, with some of their nerve fibers extending toward the chordae tendineae and the free edges of the valve cusps. Only in the guinea pig and opossum did these fibers reach the free margin of the valve cusp, where they either ended directly as free nerve endings or lay parallel to the free edge of the cusp, often running between adjacent chordae tendineae. Although the patterns of innervation were similar in both bicuspid and tricuspid valves, the innervation density of the bicuspid valve was greater than that of the tricuspid valve for each species examined. A distinguishing feature of guinea pig and opossum tricuspid valves was that their chordae tendineae were relatively more prominent and more densely innervated than the bicuspid chordae tendineae. Free nerve endings with no light microscopic evidence of specialization were present throughout the bicuspid and tricuspid valves of all species studied. Some nerve endings in the opossum showed evidence of specialization, with brush-like arborizations leading to presumed free terminals seen chiefly in the distal zone of the valve cusps. Although some general tendencies were apparent, we have demonstrated that interspecies heterogeneity exists in the terminal networks of the atrioventricular valves of mouse, rat, guinea pig, and opossum.