Variation in the life History of Diadromous and Lanlocked populations of the Spotted Galaxias, Galoxias truttaceus Valenciennes, in Tasmania

1989 ◽  
Vol 40 (5) ◽  
pp. 501 ◽  
Author(s):  
P Humphries
Keyword(s):  
Life History ◽  
Egg Size ◽  
Reproductive Investment ◽  
Gonadal Development ◽  
Early Spring ◽  
First Year ◽  
Age Class ◽  
Large Numbers ◽  
History Of ◽  
Spawning Time

Variations in life history traits such as age class distribution, growth, gonadal development, reproductive investment and spawning time were studied in two stream-dwelling diadromous and two landlocked freshwater lake populations of the spotted galaxias, Galaxias truttaceus, in Tasmania. Whereas stream populations were dominated by 0+, I+ and 2+ age-class fish, lake populations had a smaller proportion of these younger individuals and a larger proportion of age classes older than 2 +. Growth in both lake and stream populations was slow over winter and more rapid during spring and summer. The majority of fish of both sexes matured at age two, irrespective of size, although some lake-dwelling males matured in their first year. Gonadal development commenced at the beginning of summer (December) in all populations. Spawning in stream-dwelling populations occurred before winter (May) and was associated with decreasing water temperature and photoperiod. By contrast, landlocked populations spawned in early spring (September), at which time both temperature and photoperiod were increasing. At spawning, landlocked females invested more energy in reproduction than did riverine females. This appeared to be a function of larger egg size in females from one lake population and greater fecundity in females from the other. Although G. truttaceus fits the general life-history model for diadromous galaxiids, having relatively large numbers of small eggs, the shift in spawning time for landlocked populations, and the inter-population variations in egg size and fecundity suggest considerable flexibility in the characteristics of this species' life history.

scholarly journals The biology of Limacina retroversa

1954 ◽  
Vol 33 (2) ◽  
pp. 297-312 ◽  
Author(s):  
J. E. Morton
Keyword(s):  
Life History ◽  
Breeding Season ◽  
Detailed Account ◽  
Larval Stages ◽  
Large Numbers ◽  
History Of ◽  
Clione Limacina

The Plymouth Fauna List contains records of two genera of pteropods, Limacina and Clione. Of the first, Limacina retroversa (Flem.) is by far the better-known species, apparently occurring regularly at Plymouth in large numbers in townettings from outside, and sometimes inside, the Sound. It breeds at Plymouth from June to August, and Lebour (1932) has given a detailed account of its breeding and larval stages and has discussed its role in the plankton. The second species of Limacina at Plymouth is lesueuri (d'Orbigny), which has been observed from time to time since 1906, when it was very common. The last record in the Fauna is off the Breakwater in 1920. Of the gymnosomatous pteropods, Clione limacina Phipps is the only species regularly occurring. Lebour (1931) has described the life history of this form, and mentions February to August as its months of greatest abundance. Its breeding season is June to August. Another gymnosome, tentatively referred to as Clionina longicauda, is reported by Russell (1936), and from the specimen department at Plymouth Laboratory the writer obtained some preserved specimens, not easily identifiable, of a Pneumodermopsis taken locally; its species is perhaps ciliata, recorded by Massy (1917) from the Irish Coast.

The effects of egg size and incubation conditions on life history of vendace (Coregonus albula L.)

1991 ◽  
Vol 24 (4) ◽  
pp. 2418-2423
Author(s):  
M. Viljanen ◽  
J. Koho
Keyword(s):  
Life History ◽  
Egg Size ◽  
Coregonus Albula ◽  
History Of

The life history of shoots of Carex lacustris

1975 ◽  
Vol 53 (3) ◽  
pp. 256-260 ◽  
Author(s):  
John M. Bernard
Keyword(s):  
Life History ◽  
Water Level ◽  
Early Spring ◽  
Basal Diameter ◽  
Late Autumn ◽  
History Of ◽  
Carex Lacustris

Most shoots of Carex lacustris live for about 12–14 months, emerging in autumn, overwintering as shoots of up to 50 cm in length, and maturing during the next summer. Others emerge in early spring but both groups die in late autumn. A third class emerges in late July or August, grow to be over 50 cm in length, and die in late autumn, living only 2 or 3 months.Flower initials in this species begin growth in the September–October period and overwinter while about 1.0 cm in length. The shoots that develop inflorescences are in general longer, heavier, and have a greater basal diameter than those shoots which do not flower. More shoots flower if the water level in the marsh was high the previous year.

A contribution to the morphology and life history of Proteocephalus niloticus (Beddard, 1913) from Varanus niloticus (L.) in Ghana

Parasitology ◽  
1963 ◽  
Vol 53 (1-2) ◽  
pp. 201-215 ◽  
Author(s):  
Gwendolen Rees
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Technical Staff ◽  
Large Numbers ◽  
History Of ◽  
The University ◽  
University Of Ghana ◽  
Zoology Department

1. A plerocercoid of ‘Acanthotaenia’ has been found in large numbers in ‘cysts’ in the pancreas of Rana occipitalis (Günther) in Ghana.2. ‘Cysts’ containing plerocercoids were fed to Varanus niloticus (L.). Adults of Proteocephalus niloticus (Beddard) were recovered from the intestine 3 weeks later.3. It is suggested that the life cycle involves three hosts, the first being a copepod.4. The morphology of the larva and adult is described.I wish to express my sincere gratitude to the authorities of the University of Ghana for inviting me to spend some time in the Zoology Department there. I am most grateful, also, to Professor R. D. Purchon for his kindly interest and for the facilities which he placed at my disposal. It is a pleasure to thank Dr J. D. Thomas and the technical staff for their assistance in the collection of material.

scholarly journals The relationship between egg size and helper number in cooperative breeders: a meta-analysis across species

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4028 ◽  
Author(s):  
Tanmay Dixit ◽  
Sinead English ◽  
Dieter Lukas
Keyword(s):  
Life History ◽  
Social Environment ◽  
Group Size ◽  
Egg Size ◽  
Reproductive Investment ◽  
Maternal Investment ◽  
Differential Allocation ◽  
The Social ◽  
Cooperatively Breeding ◽  
The Relationship

BackgroundLife history theory predicts that mothers should adjust reproductive investment depending on benefits of current reproduction and costs of reduced future reproductive success. These costs and benefits may in turn depend on the breeding female’s social environment. Cooperative breeders provide an ideal system to test whether changes in maternal investment are associated with the social conditions mothers experience. As alloparental helpers assist in offspring care, larger groups might reduce reproductive costs for mothers or alternatively indicate attractive conditions for reproduction. Thus, mothers may show reduced (load-lightening) or increased (differential allocation) reproductive investment in relation to group size. A growing number of studies have investigated how cooperatively breeding mothers adjust pre-natal investment depending on group size. Our aim was to survey these studies to assess, first, whether mothers consistently reduce or increase pre-natal investment when in larger groups and, second, whether these changes relate to variation in post-natal investment.MethodsWe extracted data on the relationship between helper number and maternal pre-natal investment (egg size) from 12 studies on 10 species of cooperatively breeding vertebrates. We performed meta-analyses to calculate the overall estimated relationship between egg size and helper number, and to quantify variation among species. We also tested whether these relationships are stronger in species in which the addition of helpers is associated with significant changes in maternal and helper post-natal investment.ResultsAcross studies, there is a significant negative relationship between helper number and egg size, suggesting that in most instances mothers show reduced reproductive investment in larger groups, in particular in species in which mothers also show a significant reduction in post-natal investment. However, even in this limited sample, substantial variation exists in the relationship between helper number and egg size, and the overall effect appears to be driven by a few well-studied species.DiscussionOur results, albeit based on a small sample of studies and species, indicate that cooperatively breeding females tend to produce smaller eggs in larger groups. These findings on prenatal investment accord with previous studies showing similar load-lightening reductions in postnatal parental effort (leading to concealed helper effects), but do not provide empirical support for differential allocation. However, the considerable variation in effect size across studies suggests that maternal investment is mitigated by additional factors. Our findings indicate that variation in the social environment may influence life-history strategies and suggest that future studies investigating within-individual changes in maternal investment in cooperative breeders offer a fruitful avenue to study the role of adaptive plasticity.

On the Life History of the Lungworm, Synthetocaulus abstrusus, hitherto confused with that of Ollulanus tricuspis in Cats

1926 ◽  
Vol 4 (2) ◽  
pp. 53-60 ◽  
Author(s):  
Thomas W. M. Cameron
Keyword(s):  
Life History ◽  
Intestinal Tract ◽  
Trichinella Spiralis ◽  
Posterior Extremity ◽  
Original Description ◽  
Domestic Cat ◽  
Internal Organs ◽  
Large Numbers ◽  
History Of ◽  
Enclosed Space

In 1865, Leuckart described from the stomach of the domestic cat, a minute bursate worm which he named Ollulanus tricuspis. His original description was somewhat scanty, but it was amplified in later years (1867–1876). As this work is scattered throughout many pages, the following is a brief resumé of Leuckart's theory.He was struck by the fact, that being viviparous in habit, it resembled Trichinella spiralis, but recognised that several fundamental differences existed between them. Ollulanus never produced more than three larvae at a time from relatively large eggs, about 60μ to 120μ long; whereas Trichinella produced numerous larvae with small eggs about 35μ long. He found what he believed were the free larvae of Ollulanus, which measured about 320μ long by 15μ wide, had a truncated oral extremity and a short tail which ended in a short S-shaped tip (Fig. 1, a). The oesophagus was between one third and one half of the total length of the intestine; several transparent vesicles could be seen at its clubshaped posterior extremity. Although there are seldom more than three embryos inside the female, larvae were usually, found in large numbers throughout the whole intestinal tract of the host, as well as encysted (in cysts ·15 to ·2 mm. in diameter) on various internal organs. The cyst wall had a connective tissue-like structure of such thickness that it might be three or four times the diameter of the enclosed space.

Effect of body size, age and timing of breeding on clutch and egg size of female Eastern Gray Treefrogs, Hyla versicolor

2021 ◽  
pp. 1-11
Author(s):  
Gerlinde Höbel ◽  
Robb Kolodziej ◽  
Dustin Nelson ◽  
Christopher White
Keyword(s):  
Life History ◽  
Egg Size ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Ecological Factors ◽  
Hyla Versicolor ◽  
Growth And Survival ◽  
Factors Affecting ◽  
Trade Offs ◽  
Gray Treefrogs

Abstract Information on how organisms allocate resources to reproduction is critical for understanding population dynamics. We collected clutch size (fecundity) and egg size data of female Eastern Gray Treefrogs, Hyla versicolor, and examined whether observed patterns of resource allocation are best explained by expectations arising from life history theory or by expected survival and growth benefits of breeding earlier. Female Hyla versicolor showed high between-individual variation in clutch and egg size. We did not observe maternal allocation trade-offs (size vs number; growth vs reproduction) predicted from life history theory, which we attribute to the large between-female variation in resource availability, and the low survival and post-maturity growth rate observed in the study population. Rather, clutches are larger at the beginning of the breeding season, and this variation in reproductive investment aligns with seasonal variation in ecological factors affecting offspring growth and survival.

scholarly journals Considerations on the Life-history of Tapeworms of the Genus Moniezia

Parasitology ◽  
1922 ◽  
Vol 14 (3-4) ◽  
pp. 268-281 ◽  
Author(s):  
F. W. Flattely
Keyword(s):  
Life History ◽  
Intermediate Host ◽  
Intermediate Stage ◽  
Early Spring ◽  
Early Summer ◽  
The Body ◽  
Domestic Sheep ◽  
Complete Control ◽  
History Of ◽  
Series Of Experiments

Lambs contract Moniezia infection either at or very soon after birth, since they have been observed to harbour adult worms at 2–3 months old and in one case, to pass proglottids at 4–6 weeks.The intermediate host, if such exists, must be frequent on the pasture in early spring, otherwise lambs would not be found to harbour adult tapeworms so regularly or in such numbers when slaughtered in early summer. In the small intestine of a lamb from 3–4 months old slaughtered at Aberystwyth, there occurred 75 individuals.The fact that lambs regularly harbour adult tapeworms before they are weaned suggests the possibility of their contracting the infection from the mother-ewes. No direct evidence in this direction has been obtained, however, and an attempt to produce a larval stage in the udder region of a ewe by feeding to it the eggs of a tapeworm proved abortive.Hitherto, all attempts to produce the adult tapeworms directly by feeding the eggs to sheep have failed; there is, however, the remote possibility that the eggs require to undergo some kind of maturation process outside the body of the sheep before they will develop. The fact that several species of Moniezia occur in the domestic sheep would seem to require an intermediate stage, which would occur in a corresponding number of intermediate-host species.The disease seems prevalent in flocks which are singularly free from ectoparasites.The invertebrates which seem most likely to harbour an intermediate stage are coprophagous insects, etc. (beetles, flies, mites). Attempts to infect species of Aphodius have nevertheless proved fruitless.Moisture favours the survival of the eggs of Moniezia: eggs kept in water for a period of several months seemed to remain perfectly viable. Nevertheless tapeworm is common among flocks on pastures about Rome which are characteristically dry.A comprehensive series of experiments under conditions of the most complete control would almost certainly clear up the life-history; on economic grounds alone the problem is urgent.The overwhelming majority of a quantity of worms collected from slaughter-houses in Aberystwyth, Aberdeen, Beauly (Inverness-shire) and Newcastle-on-Tyne proved to be of the species M. expansa. The only other species found were M. trigonophora and M. alba. The identification was based on anatomical characters and not on externals, which are useless.The writer intends directing his attention to coprophagous mites as carriers, viz. Gamasus coleoptratorum, G. fimetorum, Macrocheles glaber.

Aspects of the life history of Meganyctiphanes norvegica (M. Sars), Crustacea (Euphausiacea), in Passamaquoddy Bay

1974 ◽  
Vol 52 (4) ◽  
pp. 495-505 ◽  
Author(s):  
K. W. Hollingshead ◽  
S. Corey
Keyword(s):  
Life History ◽  
Life Span ◽  
Sexual Maturity ◽  
Gonadal Development ◽  
Age Group ◽  
Group I ◽  
Passamaquoddy Bay ◽  
History Of ◽  
Meganyctiphanes Norvegica ◽  
First Time

Monthly collections of Meganyctiphanes norvegica for a 19-monih period in Passamaquoddy Bay showed that these euphausiids were present in the bay in varying numbers from February to November but virtually disappeared in December and January. Sexual maturity is attained in 1 year with gonadal development taking 3 months, and spawning occurring in July and August. The resulting generation will breed and spawn for the first time the next July as age group I. Age group I grows from April until August; from September until March, very little growth occurs. After a second breeding and spawning, the animals die, having a life span of 2 years.

The life history of Thysanoessa inermis (Krøyer) in the Bay of Fundy

1978 ◽  
Vol 56 (3) ◽  
pp. 492-506 ◽  
Author(s):  
David W. Kulka ◽  
S. Corey
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Growth Pattern ◽  
Gonadal Development ◽  
Class I ◽  
Bay Of Fundy ◽  
Eye Morphology ◽  
Passamaquoddy Bay ◽  
History Of

A 4-year study of the life history of Thysanoessa inermis was conducted in Passamaquoddy Bay. A comparison of the growth pattern and eye morphology showed that Th. inermis in Passamaquoddy Bay is part of a Bay of Fundy population centered in the Grand Manan Basin. Spawning occurs in the spring and the young stages are found near the surface during the summer. Thysanoessa inermis lives for 2 years in the Bay of Fundy and spawns at the end of the 1st and 2nd years. Gonadal development is described in detail. Growth in both years is rapid during the summer months with little or no increase in size during the winter. The growth rate of the female surpasses that of the males in the 2nd year. The neglecta form of Th. inermis (year class 0 animals) lives in the middle to upper layers and is morphologically different from the inermis form (year class I animals) which lives in the deepest layers.

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