Production of Eggs and Young Snails by Adult Theba-Pisana (Muller) and Cernuella-Virgata (Da Costa) (Mollusca, Helicidae) in Laboratory Cultures and Field Populations

1991 ◽  
Vol 39 (6) ◽  
pp. 673 ◽  
Author(s):  
GH Baker
Keyword(s):  
Breeding Season ◽  
South Australia ◽  
Shell Size ◽  
Shell Diameter ◽  
Laboratory Cultures ◽  
Theba Pisana ◽  
Positive Correlations ◽  
Breeding Seasons

The fecundities of two terrestrial helicid snails, Theba pisana and Cernuella virgata, were measured in laboratory cultures. The breeding seasons of both species extended from autumn to spring, with most eggs and largest clutches being laid in autumn. Significant positive correlations between shell size and total number of eggs produced, numbers of clutches and clutch sizes were demonstrated for both species, but these correlations were generally weak and not consistently significant for snails collected from different habitats. In field populations in pastures in South Australia, the numbers of juvenile T. pisana and C. virgata (> 6 mm in shell diameter) produced per adult were inversely related to the densities of adults at the start of the breeding season. Possible reasons for this variation in production are discussed. Previous studies with other species of helicid snails have suggested that crowding can reduce the sizes of adults and hence their production of young. Such an explanation is inadequate in this case.

Patterns of movement in the small dasyurid (Ningaui yvonneae)

2007 ◽  
Vol 55 (5) ◽  
pp. 299 ◽  
Author(s):  
Darren G. Bos ◽  
Susan M. Carthew
Keyword(s):  
Breeding Season ◽  
Site Fidelity ◽  
Average Distance ◽  
South Australia ◽  
Home Ranges ◽  
Movement Behaviour ◽  
Population Composition ◽  
Short Term ◽  
Time Of Year ◽  
Breeding Seasons

The movement behaviour of a small dasyurid (Ningaui yvonneae) was investigated using mark–recapture data collected over 28 months from a population in the Middleback Ranges, South Australia. We were particularly interested in assessing variability in patterns of movement between the sexes and across seasons, as this has potentially important implications for population composition and dynamics. The species was found to be fairly mobile, with frequent and sometimes large movements relative to the size of the animal (up to 900+ m). Average distances moved between recaptures within and between trap sessions were 84 m and 160 m respectively, with nearly half of all recorded movements being between trapping grids (i.e. >80 m). Relatively high recapture rates (many separated by more than 100 days) and measures of site fidelity indicated that the species was not particularly transitory, but probably establishes large and/or drifting home ranges. However, patterns of movement varied considerably according to sex and the time of year. Female N. yvonneae were generally more sedentary than males, with few females moving between trapping grids, and most short-term movements (<100 days apart) being less than 70 m. Movements of females for which the records were separated by more than 100 days tended to be larger, with an average between-capture distance >200 m. In contrast, males often moved between trapping grids, even over short periods. Some short-term movements were more than 600 m in length, and the average distance moved within trapping sessions was >100 m. During the breeding season, males more than doubled the average distances moved between recaptures, when they were presumably roaming in search of females. For females, movement distances were similar during the prebreeding and breeding seasons, but were significantly smaller in the postbreeding season, when they were caring for young.

Population ecology of the Australian frog Crinia signifera: adults and juveniles

1996 ◽  
Vol 23 (3) ◽  
pp. 249 ◽  
Author(s):  
CM Bull ◽  
I Williamson
Keyword(s):  
Breeding Season ◽  
Population Ecology ◽  
South Australia ◽  
Adult Mortality ◽  
Large Size ◽  
Early Emergence ◽  
The Common ◽  
Males And Females ◽  
A Site ◽  
Breeding Seasons

A population of the common Australian frog Crinia signifera Girard, 1853 was studied over a 3.5 year period at a site near Bridgewater in South Australia. In this population, C. signifera are long lived and iteroparous, with some individual males and females participating in at least four consecutive breeding seasons. Adult survivorship was high (up to about 70% per annum) for both males and females. Metamorphosis occurred from October to January and some individuals reached maturity within a year. However, most individuals reached maturity in the second breeding season following metamorphosis. Survival of juveniles ranged from 5 to 72% per annum, with individuals emerging early having higher survival than those that metamorphosed late. However, it was not clear whether increased survival was associated with early emergence or large size at emergence. The data support the argument that iteroparity is favoured in situations in which preadult mortality is higher and less predictable than adult mortality.

Estimating pup production in a mammal with an extended and aseasonal breeding season, the Australian sea lion (Neophoca cinerea)

2012 ◽  
Vol 39 (2) ◽  
pp. 137 ◽  
Author(s):  
Rebecca R. McIntosh ◽  
Simon D. Goldsworthy ◽  
Peter D. Shaughnessy ◽  
Clarence W. Kennedy ◽  
Paul Burch
Keyword(s):  
Breeding Season ◽  
South Australia ◽  
Rate Of Change ◽  
Estimation Methods ◽  
Sea Lion ◽  
Mark Recapture ◽  
Australian Sea Lion ◽  
Rate Of Decline ◽  
Breeding Seasons ◽  
Pup Mortality

Context The Australian sea lion population at Seal Bay Conservation Park, South Australia, was estimated to be declining at a rate of 1.14% per breeding season, on the basis of maximum counts of live pups in each of 13 breeding seasons (Shaughnessy et al. 2006). The reliability of the pup-production estimates used to identify this decline is uncertain. Aims Our aims were to obtain representative and repeatable estimates of pup production and to assess the current rate of decline. Methods We compared four estimates of pup abundance over five breeding seasons (2002–03, 2004, 2005–06, 2007, 2008–09), including the count of cumulative new births, the maximum live-pup count, the number of pups given passive integrated transponder (PIT) tags, and mark–recapture methods using the Petersen estimate. Key results A total of 90% of pup births occurred over a mean of 124 days (s.d. = 14). Final estimates of pup production (from the largest of the four estimation methods used) in the five seasons were 227 (CL 221–239), 288 (CL 273–302), 219 (NA), 260 (CL 254–272) and 268 (CL 268–269). The average estimate of pup mortality was 28.6% (s.d. = 6.3%). The decline in the population at Seal Bay over 17 breeding seasons on the basis of maximum counts of live pups was 0.51% per year or 0.76% per breeding season. However, this trend was not based on best estimates of pup production. On the basis of final estimates for the last five breeding seasons, there is no declining trend. Conclusions The count of cumulative new births was the most reliable measure of pup production; the Petersen mark–recapture estimate provided a check for accuracy and confidence limits about the estimate. Implications The actual rate of change and the expected trajectory of the Seal Bay population remain uncertain. Ongoing monitoring is a priority for this site, using the reliable methods of estimating pup production identified in the present study.

Breeding biology and haul-out pattern of the New Zealand fur seal, Arctopehalus forsteri, at Cape Gantheaume, South Australia

1994 ◽  
Vol 21 (3) ◽  
pp. 365 ◽  
Author(s):  
SD Goldsworthy ◽  
PD Shaughnessy
Keyword(s):  
New Zealand ◽  
Sex Ratio ◽  
Breeding Season ◽  
Age Distribution ◽  
South Australia ◽  
Operational Sex Ratio ◽  
Fur Seal ◽  
Median Date ◽  
Breeding Seasons ◽  
Bay Islands

New Zealand fur seals, Arctocephalus forsteri, breed at Cape Gantheaume (36�04'S,137�28'E), Kangaroo Island, South Australia, on broken rock platforms. In 1988-89, pups were born between late November and mid-January, 90% of them over 34 days between 3 December and 6 January. The median date of birth was 21 December. A re-analysis of data for this species from three breeding seasons at the Open Bay Islands (South Island, New Zealand, 43�52'S,l68�53'E) indicates that: (i) the breeding season at Cape Gantheaume occurs 5-12 days later than at the Open Bay Islands, (ii) the period containing 90% of births was the same duration for both populations, and (iii) the median date of birth spanned seven days in three seasons at the Open Bay Islands. In addition, the timing and duration of the pupping season varied within the Cape Gantheaume colony, it being later in recently colonised areas. We suggest that this pattern is a consequence of changes in the age distribution of females through the colony. The sex ratio of pups born in the colony over four breeding seasons did not differ significantly from 1:l. Females were mated on average 7.4 days after birth and left for sea 2.3 days later. The mean date of observed matings was 29 December; copulations lasted about 13 min. The operational sex ratio (OSR) in the colony was 8.6 females per territorial male (the maximum ratio of territorial males to pups was 1:16), which was within the range reported for other southern fur seal species. In two consecutive breeding seasons, the estimated fecundity rate of adult females averaged 67%. Non-breeding animals (sub-adult males, juveniles and yearlings) occurred in areas not occupied by breeding animals. The number of juveniles ashore increased after the breeding season, but no pattern was found for sub-adults and yearlings. Yearlings were uncommon in the colony at all times; it is suggested that they are mostly pelagic and do not moult in their second year.

scholarly journals Evidence for use of both capital and income breeding strategies in the mangrove tree crab, Aratus pisonii

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jade Carver ◽  
Morgan Meidell ◽  
Zachary J. Cannizzo ◽  
Blaine D. Griffen
Keyword(s):  
Breeding Season ◽  
Breeding Strategy ◽  
Reproductive Period ◽  
Breeding Strategies ◽  
Mangrove Tree ◽  
Income Breeding ◽  
Aratus Pisonii ◽  
Breeding Seasons ◽  
And Storage ◽  
Capital And Income Breeding

AbstractTwo common strategies organisms use to finance reproduction are capital breeding (using energy stored prior to reproduction) and income breeding (using energy gathered during the reproductive period). Understanding which of these two strategies a species uses can help in predicting its population dynamics and how it will respond to environmental change. Brachyuran crabs have historically been considered capital breeders as a group, but recent evidence has challenged this assumption. Here, we focus on the mangrove tree crab, Aratus pisonii, and examine its breeding strategy on the Atlantic Florida coast. We collected crabs during and after their breeding season (March–October) and dissected them to discern how energy was stored and utilized for reproduction. We found patterns of reproduction and energy storage that are consistent with both the use of stored energy (capital) and energy acquired (income) during the breeding season. We also found that energy acquisition and storage patterns that supported reproduction were influenced by unequal tidal patterns associated with the syzygy tide inequality cycle. Contrary to previous assumptions for crabs, we suggest that species of crab that produce multiple clutches of eggs during long breeding seasons (many tropical and subtropical species) may commonly use income breeding strategies.

scholarly journals Density and Flock Size of the Raven (Corvus corax) In the Orawa - Nowy Targ Basin During Non-Breeding Season

Ring ◽  
2006 ◽  
Vol 28 (2) ◽  
pp. 119-125
Author(s):  
Michał Ciach ◽  
Dominik Wikar ◽  
Małgorzata Bylicka
Keyword(s):  
Breeding Season ◽  
Early Spring ◽  
Food Resources ◽  
High Density ◽  
Line Transect ◽  
Flock Size ◽  
Early Winter ◽  
Corvus Corax ◽  
Line Transect Method ◽  
Breeding Seasons

Density and Flock Size of the Raven (Corvus corax) In the Orawa - Nowy Targ Basin During Non-Breeding Season During the 2002/2003-2004/2005 non-breeding seasons the density of the Raven in the open habitats of the Orawa - Nowy Targ Basin was studied by line transect method. The results were analysed in four periods (autumn, early winter, winter and early spring). The median density of Ravens did not differ significantly between individual periods and was respectively: 3.5, 3.8, 4.8 and 3.8 indiv. / 10 km. Number of birds during particular controls varied from 1.0 to 24.8 indiv. / 10 km. However, while excluding flocks, the median density of single individuals and pairs of the Raven was considerably lower and in subsequent periods reached respectively: 2.2, 2.4, 2.2 and 1.7 indiv. / 10 km. Flock size did not differ significantly between individual periods. Single individuals and, less often, groups of two birds were recorded mostly. Small (3-5 indiv.) and medium (6-15 indiv.) flocks were recorded rarely and large flocks (16 indiv. and above) - only exceptionally. The high density and strong fluctuations of abundance of Ravens were determined by flocks presence, which was probably linked to irregular occurrence of food resources.

scholarly journals Some Morphological Variations in The Land Snail Monacha cantiana (Montagu,1803) within Baghdad Province

2013 ◽  
Vol 10 (1) ◽  
pp. 1-12
Author(s):  
Baghdad Science Journal
Keyword(s):  
Population Density ◽  
Shell Height ◽  
Calcium Content ◽  
Land Snail ◽  
Shell Morphology ◽  
Shell Size ◽  
Aperture Diameter ◽  
Morphological Variations ◽  
Shell Diameter ◽  
Soil Calcium

The present work includes investigation of some features of shell morphology; shell size, shell thickness, shell colour of the land snail Monacha cantiana, in addition to the correlation between height and diameter of shell and between shell aperture diameter and shell diameter at four sites within Baghdad Province, Iraq. Also, measurements of three environmental variables were made; soil temperature, soil moisture and soil calcium content in adition to population density. Shell Aperture Index (Ia) and Shell Index (SI) for individuals from size class ranged between (9-12)mm were measured. The results showed that the deference in shell size by using (Ia) within population related to temperature, moisture and population density but, the value of Shell Index decreased in AL-Kadhimiya site (0.81-0.97) due to increase in population density. The species was characterized by shell colour variation (creamy white, white ,creamy). Also, The results showed strong and positive correlation between shell height and diameter and between shell aperture diameter and shell diameter for all size classes.

Phenotypic plasticity of the montane vole (Microtus montanus) in unpredictable environments

1992 ◽  
Vol 70 (11) ◽  
pp. 2121-2124 ◽  
Author(s):  
Norman C. Negus ◽  
Patricia J. Berger ◽  
Aelita J. Pinter
Keyword(s):  
Phenotypic Plasticity ◽  
Breeding Season ◽  
Growth Rates ◽  
Adaptive Strategy ◽  
Severe Drought ◽  
Microtus Montanus ◽  
Age Cohort ◽  
Montane Meadow ◽  
Study Sites ◽  
Breeding Seasons

From 1987 to 1989, the cohort dynamics of Microtus montanus populations were studied at two montane meadow sites approximately 160 km apart, in northwestern Wyoming. The 1987 and 1988 breeding seasons differed markedly from each other. In 1987, melt off occurred in April, and the first cohort was born in May (cohort 1). The entire breeding season was favorable owing to frequent rainfall throughout the summer. Cohort 1 animals grew rapidly and females began breeding at 4–5 weeks of age. Likewise, cohort 2 (June) animals exhibited rapid growth and females were breeding at 7–8 weeks of age. Cohort 3 (July and August) animals grew more slowly and most entered the winter as prepubertal animals of subadult size. At the end of the summer, cohort 3 animals represented >70% of the voles recruited during the breeding season. In 1988, following melt off in late April, precipitation was below normal and the situation intensified to severe drought through the summer. The growth rates of cohort 1 and 2 animals were significantly lower than 1987 growth rates, and very few females attained sexual maturity. At the end of the summer, cohort 3 animals represented <25% of the total recruitment at both study sites. Such apparent phenotypic plasticity of growth and maturation appears to be an evolved adaptive strategy that is responsive to several environmental cues. Both study sites, although widely separated, exhibited virtually identical patterns throughout the study.

Flexibility of nuptial colouration in a unique ecotype of Threespine Stickleback (Gasterosteus aculeatus)

2021 ◽  
Author(s):  
Rachel Corney ◽  
Anne Haley ◽  
Laura Weir
Keyword(s):  
Breeding Season ◽  
Gasterosteus Aculeatus ◽  
Colour Change ◽  
Threespine Stickleback ◽  
Relative Role ◽  
Mate Quality ◽  
Breeding Seasons ◽  
Potential Signal ◽  
Intersexual Competition

Nuptial colouration in animals may serve as a signal of competitor and/or mate quality during breeding. In many temperate fishes, nuptial colouration develops during discrete breeding seasons and is a target of sexual selection. We examine nuptial colouration and behaviour of a unique ecotype of Threespine Stickleback (Gasterosteus aculeatus Linnaeus, 1758), wherein males turn from dull brown-grey to pearlescent white during the breeding season. The main goal of this work was to determine the relative role of white colouration in intersexual competition and mate choice. In a combination of a field and laboratory work, we found that males are brightest white when engaging in courtship activities in the presence of a female; this indicates that white colouration may be primarily related to enhancing signalling during mate attraction. White colouration intensity increased as the breeding season progressed and may be related to an influx of conspecifics. Colour change from cryptic grey to bright white occurred rapidly (< 90 seconds) and may be deployed to enhance behavioural signals. We conclude that bright white colouration in the white ecotype is a potential signal of mate quality and may have evolved from a previously existing capacity for colour plasticity in common Threespine Stickleback.

“Data for the Problem of Evolution in Man. V. On the Correlation between Duration of Life and the Number of Offspring”

1901 ◽  
Vol 35 (6) ◽  
pp. 458-479
Author(s):  
M. Beeton ◽  
G. U. Yule ◽  
Karl Pearson
Keyword(s):  
Natural Selection ◽  
Breeding Season ◽  
The Other ◽  
Similar Statement ◽  
Men And Women ◽  
Darwinian Theory ◽  
Theory Of Evolution ◽  
Biennial Plants ◽  
Long Life ◽  
Breeding Seasons

According to the Darwinian theory of evolution the members of a community less fitted to their environment are removed by death. But this process of natural selection would not permanently modify a race, if the members thus removed were able before death to propagate their species in average numbers. It then becomes an important question to ascertain how far duration of life is related to fertility. In the case of many insects death can interfere only with their single chance of offspring; they live or not for their one breeding season only. A similar statement holds good with regard to annual and biennial plants. In such cases there might still be a correlation between duration of life and fertility, but it would be of the indirect character, which we actually find in the case of men and women living beyond sixty years of age—a long life means better physique and better physique increased fertility. On the other hand, there is a direct correlation of fertility and duration of life in the case of those animals which generally survive a number of breeding seasons, and it is this correlation which we had at first in view when investigating the influence of duration of life on fertility in man. The discovery of the indirect factor in the correlation referred to above was therefore a point of much interest. For it seems to show that the physique fittest to survive is really the physique which is in itself (and independently of the duration of life) most fecund.

Sign in / Sign up

Export Citation Format

Share Document