Size-specific reproductive parameters in red algae: a comparative analysis for two sympatric species from Central Chile

Ahnfeltia durvillaei and Gymnogongrus furcellatus, two intertidal red algae from central Chile, often grow sympatrically and their gametophytic phases are dominant in the field, but recruitment is low. A shortterm comparative analysis of the reproductive behavior of their gametophytes was carried out to determine quantitative levels of reproduction and their degree of functional similarity. Size, rather than age, was evaluated as predictor of fecundity. Both species showed the same qualitative patterns, although maintaining quantitative differences. Reproductive plants were recorded throughout the size range, and fecundity increased continuously and directly with size. A size-independent threshold in reproductive effort was found for each species, and the variance of effort values decreased inversely with size. Vertical, size-specific life tables revealed low dependence of survivorship with size, and reproductive values exhibited a maximum at the same size class for both species. This last pattern, and a negative relationship found between fecundity and survivorship, suggest the existence of costs or trade-offs operating at the phenotypic level, but they would not be supported in a selective context.     

Habitat preferences of four chironomid species associated with aquatic macrophytes in an irrigation reservoir

Habitat preferences of four chironomid species associated with aquatic macrophytes were studied during the vegetation season from April to October at an irrigation reservoir located in Nagoya, Japan.The two smaller sized species,Corynoneura cuspis Tokunaga andPentapedilum tigrinum Hashimoto, were found to be abundant in two floating-leaved plants,Nymphoides indica O. Kuntze andTrapa japonica Flerov. Phytophages,C. cuspis larvae were observed freely moving on the surfaces of leaves and stems within both of these floating-leaved plant communities. Although found within both plant communities,P. tigrinum larvae, as facultative leaf miners, were more concentrated on the surfaces and within the leaves ofN. indica, which have a thin epidermis and thick mesophyll layer.The two larger sized species,Glyptotendipes viridis (Macquart) andPentapedilum sordens (van der Wulp), were found to be living principally within the stems ofN. indica and the petioles ofT. japonica. These parts of the plants, with thin epidermis and many lacunae in the parenchyma, are favorable for miners.     

Terrestrial Chironomidae: Contribution of local emergence to global aerial flow in a heterogeneous environment

Terrestrial Chironomidae were studied for one year in four closely related habitats (pondbanks, woodland, grassland, heathland). Community structure and emergence phenology are analysed and compared with the aerial flow composition and timing. The contribution of local emergence to aerial flow is estimated using Principal Component Analysis with Instrumental Variables (PCAIV). Results are discussed, taking in account larval capabilities, adults behaviour and landscape heterogeneity.     

Plasticity,political economy,and physical growth status of Guatemala Maya children living in the United States

Migration of Maya refugees to the United States since the late 1970s affords the opportunity to study the consequences of life in a new environment on the growth of Maya children. The children of this study live in Indiantown, Florida, and Los Angeles, California. Maya children between 4 and 14 years old (n = 240) were measured for height, weight, fatness, and muscularity. Overall, compared with reference data for the United States, the Maya children are, on average, healthy and well nourished. They are taller and heavier and carry more fat and muscle mass than Maya children living in a village in Guatemala. However, they are shorter, on average, than children of black, Mexican-American, and white ethnicity living in Indiantown. Children of Maya immigrants born in the United States tend to be taller than immigrant children born in Guatemala or Mexico. Families that invest economic and social resources in their children tend to have taller children. More economically successful families have taller children. Migration theory and political economy theory from the social sciences are combined with plasticity theory and life history theory (parental investment) from biology to interpret these data. Am J Phys Anthropol 102:17–32, 1997. © 1997 Wiley-Liss, Inc.     

The evolution of parental care in freshwater leeches

Summary The life-history strategies of a selection of the most common European freshwater leeches (Euhirudinea) are described. On the basis of this information and results from the literature, the probable phylogenetic development of parental care in the Euhirudinea is reconstructed. The jawless worm leeches (Erpobdellidae) secrete a protective cocoon, cement it to the substrate and sometimes ventilate it before they leave the egg capsules. This behaviour represents the most ancient state in leech evolution. Members of the jawed Hirudinidae deposit desiccation-resistant cocoons on land. All known Glossiphoniidae (leeches equipped with a proboscis) have evolved the habit of brooding the eggs and young. These unique parental care patterns within one family of extant freshwater leeches can be arranged schematically in a series of increasing complexity which may reflect the evolution of brooding behaviour. Glossiphoniid leeches of the genus Helobdella, which have a world-wide distribution, display the most highly developed parental care system: they not only protect but also feed the young they carry. This results in the young being much larger when they leave the parent and, presumably, in higher subsequent survival. Isolated cocoons of all aquatic leeches are rapidly destroyed by predators, primarily water snails. In erpobdellids (but not glossiphoniids, which protect the cocoons) a large portion of the cocoons are lost due to predatory attacks. We conclude that the major selective pressure driving the evolution of parental care in leeches may have been predation on eggs and juvenile stages. Dedicated to Professor Dr. G. Osche on the occasion of his 75th birthday     

Constitutive immune defences correlate with life-history variables in tropical birds

1. It has been suggested that immune defences are shaped by life history and ecology, but few general patterns have been described across species. We hypothesized that 'fast' life-history traits (e.g. short development times, large clutch sizes) would be associated with developmentally inexpensive immune defences, minimizing the resource demands of young animals' immune systems during periods of rapid growth. Conversely, 'slow' life histories should be associated with well developed antibody-mediated defences, which are developmentally costly. 2. We therefore predicted that 'fast-living' species would exhibit higher levels of complement proteins, a component of non-specific innate defence, but lower levels of constitutive ('natural') antibodies. Additionally, we predicted that constitutive immune defences in general would be higher in species with ecological characteristics that might increase exposure to pathogens, such as open nests, omnivorous diets, gregariousness, and closed forested habitat. 3. Across 70 Neotropical bird species, we found a strongly positive relationship between incubation period and natural antibody levels in adult birds, suggesting that longer developmental times might allow the production of a more diverse and/or more reactive adaptive immune system. Complement activity was positively, although weakly, correlated with clutch size, providing some support for the hypothesis that faster-living species rely more on innate defences, such as complement. Unexpectedly, solitary species had higher natural antibody titres than species that frequently join flocks. 4. Our results suggest that, despite probably widespread differences in the intensity and diversity of pathogen exposure, species-level variation in constitutive immune defences is understandable within the context of life-history theory.     

Comparison of Reproductive Indicators and Analysis of the Reproductive Seasonality of the Tinfoil Barb, Puntius schwanenfeldii, in the Perak River, Malaysia

The reproductive seasonality of Puntius schwanenfeldii from the Perak River, Malaysia was investigated over a 19 month period. Females greater than 160g had mature or rematuring ovaries, and males of all sizes had mature testes throughout the study period. Analysis of female reproductive condition was based upon the presence of post ovulatory follicles (POF), the gonadosomatic index (GSI) and the volume fraction of stage IV oocytes (IV%), and GSI and presence of tubercles for males. Recrudescence followed immediately after ovulation, which allowed the use of objective thresholds to identify recently spawned females during the GSI and IV% recovery period. GSI and IV% were the best indicators of reproductive patterns as a result of their recovery period being longer than for POF. Male tubercles and GSI showed some statistically significant variation, but no clear relation with observed changes in female indicators. Reproduction was apparently aseasonal, and this pattern is likely an effect of flow regulation by dams which have virtually eliminated the dominant flood period and most seasonal flow variation. Hypothesized shifts in the reproductive seasonality due to flow regulation are consistent with predictions based on life history theory under conditions of altered environmental seasonality.     

Life cycle ofPseudodiamesa branickii (Chironomidae) in a small upland stream

The generation time ofP. branickii was studied using larval samples in conjunction with rearing experiments and continuous collection of egg masses across one year. This species produced three generations per year in a central German stream (280 m a.s.l., 50° 40 N). Its generation time was variable and obviously influenced by the photoperiod to which eggs and larvulae were subjected. It is thus concluded that two strains ofP. branickii were present in a single population, one bivoltine and the other trivoltine.     

Re-assessment of Wundsch's (1940) ‘H2S-Oscillatoria-Lake’ type using the eutrophic Lake Scharmützel (Brandenburg, NE Germany) as an example

Thienemann's 1922 biological lake classification indicates the increase in the trophic level of lakes. It is based on the sucession of the disappearance of certain benthic indicator organisms in relation to the gradient of a decreasing O₂concentration in the deep water, i.e. from O₂-sensitive Chironomidae spp. (non-biting midges) to the less sensitive Chaoboridae (phantom midges) larvae. As early as the mid 1930s, several lakes in Brandenburg, e.g. Lake Scharmützel, belonged to the last category of this classification. They were O₂-deficient in deep water during summer and lacked the Chironomidae larvae. Simultaneously, filamentous cyanobacteria (Oscillatoriales) appeared. This lead to the replacement of Thienemann's indicators, i.e. O₂ by H₂S and Chironomidae by Oscillatoriales, and to Wundsch's 1940 new H₂S-Oscillatoria-Lake type. Since H₂S and Oscillatoriales were not clearly identified as symptoms of eutrophication, it is not justified to use them to characterise a separate lake type. However, these indicators are of ecological importance, since the regional and common creeping increase in SO₄ ^2- concentration favoures the current high H₂S formation. The successive deterioration in O₂ conditions, the increase in the extent of H₂S formation related to the decrease in species diversity clearly indicates that Lake Scharmützel reached a qualitatively new state of eutrophication within 60 years.     

Wing and leg amputation induced oviposition pattern of tropical tasar silk moth,Antheraea mylitta Drury (Lepidoptera: Saturniidae) in oviposition devices – Earthen cups and paper sheets

Antheraea mylitta Drury (Lepidoptera: Saturniidae) is a tropical semi-domesticated wild tasar silkworm reared by marginal tribal farmers of India. Due to improper egg laying frequency, oviposition is generally kept for three continuous days after amputating the gravid moth wings (W^–) in earthen cups (C). In order to systematize the oviposition frequency, wing cut with leg cut (W^–L^–) was performed in ecorace Daba trivoltine (DTV) completing three life-cycles in a year. Oviposition of (C)W^–L^– was observed in all three grainages during the year 2020 and compared with (C)W^– moths. Oviposition was also accomplished on plain paper sheets (S). It is observed that (C)W^– obtained 63–67% and (C)W^–L^– obtained 72–80% egg laying on first day. Similarly, (S)W^– and (S)W^–L^– obtained 68–71% and 74–83% on first day. Further, significant high oviposition was observed within first four hours in both earthen cups and on paper sheets by W^–L^– moths laying 49–69% and 55–65% eggs compared to W^– laying 25–45% and 39–44% eggs, respectively. A total of 44–51, 47–54, 44–48 and 46–52 eggs/g moth weight was obtained in (C)W^–, (C)W^–L^–, (S)W^– and (S)W^–L^–, respectively in three consecutive grainage. Oviposition of W^– moths in earthen cups and on paper sheets are not significantly different indicating earthen cups in contemporary tasar grainage could be replaced with paper sheets. Thus, the paper demonstrates for the first time a fast, efficient and scalable cellular oviposition of A. mylitta on paper sheets comparable to Bombyx mori.