scholarly journals Population dynamics of the sea snake Emydocephalus annulatus (Elapidae, Hydrophiinae)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Richard Shine ◽  
Gregory P. Brown ◽  
Claire Goiran
Keyword(s):  
Density Dependence ◽  
Population Biology ◽  
Reproductive Output ◽  
New Caledonia ◽  
Abiotic Factors ◽  
Weather Conditions ◽  
Sea Snakes ◽  
Reduced Body ◽  
Windy Weather ◽  
Population Sizes

AbstractFor sea snakes as for many types of animals, long-term studies on population biology are rare and hence, we do not understand the degree to which annual variation in population sizes is driven by density-dependent regulation versus by stochastic abiotic factors. We monitored three populations of turtle-headed sea snakes (Emydocephalus annulatus) in New Caledonia over an 18-year period. Annual recruitment (% change in numbers) showed negative density-dependence: that is, recruitment increased when population densities were low, and decreased when densities were high. Windy weather during winter increased survival of neonates, perhaps by shielding them from predation; but those same weather conditions reduced body condition and the reproductive output of adult snakes. The role for density-dependence in annual dynamics of these populations is consistent with the slow, K-selected life-history attributes of the species; and the influence of weather conditions on reproductive output suggests that females adjust their allocation to reproduction based on food availability during vitellogenesis.

Variation in reproductive output as a function of maternal age and weather conditions in the cultured Asian yellow pond turtle, Mauremys mutica

2020 ◽  
Vol 70 (3) ◽  
pp. 309-320
Author(s):  
Yakun Wang ◽  
Jian Zhao ◽  
Xiaoli Liu ◽  
Qing Shangguan ◽  
Wei Li ◽  
...  
Keyword(s):  
Clutch Size ◽  
Maternal Age ◽  
Reproductive Output ◽  
Abiotic Factors ◽  
Weather Conditions ◽  
Egg Mass ◽  
Stock Management ◽  
Artificial Breeding ◽  
Asian Yellow Pond Turtle ◽  
Mauremys Mutica

Abstract Biotic factors (e.g., maternal age) and abiotic factors (e.g., weather) play vital roles in reproduction. However, there is little information about the combined effects of maternal age and weather on the reproductive output of cultured Asian yellow pond turtles, Mauremys mutica. To address this issue, we surveyed and compared the reproductive output of 13-year-old and 25-year-old female turtles on non-rainy and rainy days. The results showed that older females produced larger eggs than younger females regardless of the weather conditions. Females laid larger clutch sizes (number of eggs per nest) under non-rainy conditions compared with those under rainy conditions. However, the variation in clutch frequency (number of clutches per day) was independent of maternal age and weather. There was no effect of an interaction between maternal age and weather on egg mass, clutch size or clutch frequency. Our results suggest that maternal age and weather had significant effects on egg mass and clutch size, respectively. These results imply that maternal age, together with weather conditions (mainly conditions of rain), can affect the reproductive output of M. mutica. Our results provide useful information for the artificial breeding and stock management of M. mutica.

Characterizing the impact of recovering sea otters on commercially important crabs in California estuaries

2020 ◽  
Vol 655 ◽  
pp. 123-137
Author(s):  
TM Grimes ◽  
MT Tinker ◽  
BB Hughes ◽  
KE Boyer ◽  
L Needles ◽  
...  
Keyword(s):  
Abiotic Factors ◽  
Sea Otter ◽  
Dungeness Crab ◽  
Sea Otters ◽  
Elkhorn Slough ◽  
Enhydra Lutris Nereis ◽  
Crab Abundance ◽  
Population Sizes ◽  
Commercially Important ◽  
The Impact

Protective legislation and management have led to an increase in California’s sea otter Enhydra lutris nereis population. While sea otter recovery has been linked to ecosystem benefits, sea otter predation may negatively affect commercially valuable species. Understanding the potential influence of sea otters is of particular importance as their range expands into estuaries that function as nurseries for commercially valuable species like Dungeness crab Metacarcinus magister. We consider how sea otter predation has affected the abundance and size of juvenile Dungeness crab in Elkhorn Slough, California, USA, and analyzed cancrid crab abundance and size across 4 California estuaries with and without sea otters to understand how biotic and abiotic factors contribute to observed variation in crab size and abundance. We compared trends in southern sea otters relative to Dungeness crab landings in California to assess whether increasing sea otter abundance have negatively impacted landings. In Elkhorn Slough, juvenile Dungeness crab abundance and size have declined since 2012, coinciding with sea otter population growth. However, the impact of sea otters on juvenile Dungeness crab size was habitat-specific and only significant in unvegetated habitat. Across estuaries, we found that cancrid crab abundance and size were negatively associated with sea otter presence. While abiotic factors varied among estuaries, these factors explained little of the observed variation in crab abundance or size. Although we found evidence that sea otters can have localized effects on cancrid crab populations within estuaries, we found no evidence that southern sea otters, at recent population sizes, have negatively impacted Dungeness crab landings in California from 2000-2014.

scholarly journals Isolation of entomopathogenic nematodes in an apple orchard in Southern Brazil and its virulence to Anastrepha fraterculus (Diptera: Tephritidae) larvae, under laboratory conditions

2017 ◽  
Vol 77 (1) ◽  
pp. 22-28 ◽  
Author(s):  
E. Foelkel ◽  
M. Voss ◽  
L. B. Monteiro ◽  
G. Nishimura
Keyword(s):  
Entomopathogenic Nematodes ◽  
Abiotic Factors ◽  
Integrated Control ◽  
Weather Conditions ◽  
Apple Orchard ◽  
Soil Samples ◽  
Similar Frequency ◽  
Promising Alternative ◽  
Climate Conditions ◽  
Anastrepha Fraterculus

Abstract Entomopathogenic nematodes (EPNs) are a promising alternative to integrated control in many fruit pests. Few studies were made on the relationship of Anastrepha fraterculus natural population with native EPNs population and other biotic and abiotic factors. The aim of this work was to verify the occurrence of endemic nematodes in an apple orchard, concerning environmental conditions and technical procedure, and access isolates virulence to A. fraterculus larvae. The experiment was conducted during a year taking monthly soil samples from an apple orchard, with and without fallen fruits just above the soil. Samples were baited with Tenebrium molitor and A. fraterculus larvae in laboratory. Canopy and fallen fruits were sampled to access the pest infestation. Seventy three EPN isolates were captured, in 23.2% soil samples, more with T. molitor than with A. fraterculus baits. From the 20 isolates tested against A. fraterculus, only five were pathogenic, and they were identified as Oscheius sp. The nematodes were captured during all seasons in a similar frequency. Soil and weather conditions, presence of fruit over the orchard soil, and A. fraterculus pupae in the fruits had no significant influence on the capture. As a conclusion, nematodes of the genera Oscheius are found in an apple orchard of Porto Amazonas constantly along the year, independently of fluctuations in A. fraterculus population, climate conditions and presence of fruit over the soil. Some of the isolates are pathogenic to A. fraterculus.

scholarly journals Models of mitochondrial DNA transmission genetics and evolution in higher eucaryotes

1982 ◽  
Vol 40 (1) ◽  
pp. 41-57 ◽  
Author(s):  
Robert W. Chapman ◽  
J. Claiborne Stephens ◽  
Robert A. Lansman ◽  
John C. Avise
Keyword(s):  
Mitochondrial Dna ◽  
Population Biology ◽  
Sequence Information ◽  
Random Allocation ◽  
Cell Lineages ◽  
Daughter Cells ◽  
Mtdna Sequence ◽  
Population Sizes ◽  
Future Value ◽  
Mtdna Evolution

SUMMARYThe future value of mitochondrial DNA (mtDNA) sequence information to studies in population biology will depend in part on understanding of mtDNA transmission genetics both within cell lineages and between animal generations. A series of stochastic models has been constructed here based on various possibilities concerning this transmission. Several of the models generate predictions inconsistent with available data and, hence, their assumptions are provisionally rejected. Other models cannot yet be falsified. These latter models include assumptions that (1) mtDNA's are sorted through cellular lineages by random allocation to daughter cells in germ cell lineages; (2) the effective intracellular population sizes (nM's) of mtDNA's are small; and (3) sperm may (or may not) provide a low level ‘gene-flow’ bridge between otherwise isolated female lineages. It is hoped that the models have helped to identify and will stimulate further empirical study of various parameters likely to strongly influence mtDNA evolution. In particular, critical experiments or measurements are needed to determine the effective sizes of mtDNA populations in germ (and somatic) cells and to examine possible paternal contributions to zygote mtDNA composition.

scholarly journals Population biology of shrimp Macrobrachium jelskii (Miers, 1778) (Decapoda, Palaemonoidea) at the Grande River at northwest of the state of Minas Gerais, Brazil

2012 ◽  
Vol 24 (3) ◽  
pp. 266-275 ◽  
Author(s):  
Samara de Paiva Barros-Alves ◽  
Ariádine Cristine Almeida ◽  
Vivian Fransozo ◽  
Douglas Fernandes Rodrigues Alves ◽  
José Carlos da Silva ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Frequency Distribution ◽  
Population Biology ◽  
Abiotic Factors ◽  
Mesh Size ◽  
Minas Gerais ◽  
Reproductive Period ◽  
Length Frequency Distribution ◽  
Length Frequency ◽  
Monthly Basis

AIM: The population biology of the freshwater shrimp Macrobrachium jelskii was investigated here emphasizing the length-frequency distribution, sex ratio, reproductive period and juvenile recruitment. In addition, the abundance of individuals was correlated with the abiotic factors. METHODS: Samples were collected on a monthly basis from July 2005 to June 2007 along the river margin in shallow water of Grande River, at Planura region, State of Minas Gerais, Brazil (20º 09' S and 48º 40' W), using a trawl net (1.0 mm mesh size, and 2.0 m × 0.5 m wide). The fishing gear was handled by two people along the marginal vegetation of the Grande River in a course of 100 m, covered for one hour. In the laboratory, the specimens were identified, measured and sexed. RESULTS: A total of 2,789 specimens was analyzed, which corresponded to 1,126 males (549 juveniles and 577 adults) and 1,663 females (1,093 juveniles, 423 adults non-ovigerous and 147 ovigerous). The sex ratio differed significantly in favor of the females of M. jelskii (1:1.48; χ² = 103.95; p < 0.0001). The mean size of carapace length (CL) of females (6.32 ± 1.84 mm CL) was statistically higher than of males (5.50 ± 1.07 mm CL) (p < 0.001). The length-frequency distribution of the specimens revealed an unimodal pattern and non-normal distribution for males and females (W = 0.945; p < 0.01). No significant relationship between the abundance of M. jelskii and the environmental variables was observed (p = 0.799). CONCLUSION: The presence of ovigerous females and juveniles in the population suggests a continuous reproduction pattern and recruitment for M. jelskii at Planura region.

Growth, sexual dimorphism, and population biology of the olive sea snake, Aipysurus laevis, on the Great Barrier Reef of Australia

2000 ◽  
Vol 21 (3) ◽  
pp. 289-300 ◽  
Author(s):  
Glen Burns ◽  
Harold Heatwole
Keyword(s):  
Sexual Dimorphism ◽  
Great Barrier Reef ◽  
Population Biology ◽  
Sexual Maturity ◽  
Reproductive Behaviour ◽  
Barrier Reef ◽  
Sea Snake ◽  
Sea Snakes ◽  
Equivalent Length ◽  
Reef Edge

AbstractThe olive sea snake, Aipysurus laevis (Lacépède) grows at a rate of 0.22-0.95 cm/month, with young animals growing faster than older ones. Males reach sexual maturity in their third year and females in their fourth or fifth year. There is sexual dimorphism in size, with females larger than males; at snout-vent lengths greater than 80 cm, females are heavier than males of equivalent length. Small snakes were uncommon. Apparent sexratio favours males in winter but moves toward equality or even a preponderance of females in summer, probably reflecting changes in reproductive behaviour. Numbers of snakes are approximately 0.70-0.86 snakes per metre of reef edge. Olive sea snakes live to about 15 years or older.

Pleomerism, the Widespread Tendency Among Related Fish Species for Vertebral Number to be Correlated with Maximum Body Length

1975 ◽  
Vol 32 (12) ◽  
pp. 2453-2469 ◽  
Author(s):  
C. C. Lindsey
Keyword(s):  
Body Length ◽  
Fish Species ◽  
Population Biology ◽  
Maximum Size ◽  
Maximum Length ◽  
Latitudinal Gradients ◽  
Vertebral Number ◽  
Sea Snakes ◽  
The Relationship ◽  
Maximum Body

Data for 3137 fish species were analyzed for possible correlations, among related species, between mean vertebral number (V) and maximum recorded body length (L). Of 118 families having counts for over 4 species, 90 show a positive correlation; statistically significant correlations are positive in 45 and negative in only 2 families. The relationship can be expressed by the power function V = CLm, in which C and m are constants characteristic of each family or taxon. Among families with a significant correlation between V and L, the median value of m is 0.12 (representing about 10% vertebral increase for each doubling of length) but m ranges widely, from −0.033 to +0.416. Families with high mean vertebral counts tend to have high m values. The phenomenon, termed pleomerism, occurs within genera as well as within families, and sometimes between races, between populations, or even between the sexes. It exists in widely different shapes of fishes (e.g. sharks, mackerels, sea horses, sand lances, and lumpfish), and in caecilians and in sea snakes. Latitudinal gradients in vertebral number (Jordan’s rule) are often reinforced by pleomerism coupled with latitudinal gradients in maximum length, but gradients in vertebral numbers persist even when effect of maximum length is removed. Although its cause is unknown, pleomerism is taxonomically useful in predicting adult sizes of species known only from young specimens, and in unmasking synonymies of "species" based on young of other named species. Vertebral number considered in conjunction with maximum size is more reliable for making taxonomic judgments at all levels than is vertebral number alone. Moreover, if the cause of pleomerism is functional, it may provide information on locomotory mechanisms and on population biology, since mean vertebral number in each population may be matched to that body size at which selection operates most significantly.

Density dependence in establishment, growth and worm fecundity in intestinal helminthiasis: the population biology ofTrichuris muris(Nematoda) infection in CBA/Ca mice

Parasitology ◽  
1989 ◽  
Vol 98 (3) ◽  
pp. 451-458 ◽  
Author(s):  
E. Michael ◽  
D. A. P. Bundy
Keyword(s):  
Density Dependence ◽  
Worm Burden ◽  
Population Biology ◽  
Positive Association ◽  
Significant Positive Association ◽  
Trichuris Muris ◽  
Heligmosomoides Polygyrus ◽  
Density Dependent ◽  
Faecal Egg Counts ◽  
Helminth Fecundity

SUMMARYThe results are presented of an experimental study of the population biology of chronicTrichuris muris(Nematoda) infection in cortisone-treated CBA/Ca mice. Attention is focused upon both the validity of the common use of faecal egg counts to demonstrate density dependence in helminth fecundity, and the identification of other possible density-dependent mechanisms that may regulate worm numbers in chronic trichuriasis. The results show that faecal egg counts, although demonstrating high daily variation, are not an artefact of host faecal output but a significant density-dependent function of worm burden. This finding contrasts with the observations onHeligmosomoides polygyrusinfection in outbred MF1 mice, but accords with similar studies in a wide variety of host - helminth systems. Worm establishment in the murine host is found to be a density related function of infection dose. This is attributed to the probable existence of a physical gut-carrying capacity in the murine host forT. muris. Worm distribution in the gut is also shown to be density dependent, with worms being displaced from the caecum to the colon at increasing intensities of infection. The sex ratio of the adult parasites, however, is found to be both unitary and independent of worm burden. Evidence for a significant density-dependent decline in femaleT. murisgrowth or size is presented. The results also show a significant positive association between femaleT. murisweight andper capitafecundity. These findings indicate that the stunted growth of individual worms at high parasite densities may be a potential mechanism underlying density dependence in helminth fecundity.

scholarly journals Succession within the prokaryotic communities during the VAHINE mesocosms experiment in the New Caledonia lagoon

2016 ◽  
Vol 13 (8) ◽  
pp. 2319-2337 ◽  
Author(s):  
Ulrike Pfreundt ◽  
France Van Wambeke ◽  
Mathieu Caffin ◽  
Sophie Bonnet ◽  
Wolfgang R. Hess
Keyword(s):  
N2 Fixation ◽  
Temporal Dynamics ◽  
New Caledonia ◽  
Abiotic Factors ◽  
Niche Partitioning ◽  
16S Rrna Gene Sequencing ◽  
Inorganic Phosphorus ◽  
Shannon Index ◽  
Rrna Gene ◽  
South Pacific Ocean

Abstract. N2 fixation fuels  ∼  50 % of new primary production in the oligotrophic South Pacific Ocean. The VAHINE experiment has been designed to track the fate of diazotroph-derived nitrogen (DDN) and carbon within a coastal lagoon ecosystem in a comprehensive way. For this, large-volume ( ∼  50 m3) mesocosms were deployed in the New Caledonian lagoon and were intentionally fertilized with dissolved inorganic phosphorus (DIP) to stimulate N2 fixation. This study examined the temporal dynamics of the prokaryotic community together with the evolution of biogeochemical parameters for 23 consecutive days in one of these mesocosms (M1) and in the Nouméa lagoon using MiSeq 16S rRNA gene sequencing and flow cytometry. Combining these methods allowed for inference of absolute cell numbers from 16S data. We observed clear successions within M1, some of which were not mirrored in the lagoon. The dominating classes in M1 were Alpha- and Gammaproteobacteria, Cyanobacteria, eukaryotic microalgae, Marine Group II Euryarchaeota, Flavobacteriia, and Acidimicrobia. Enclosure led to significant changes in the M1 microbial community, probably initiated by the early decay of Synechococcus and diatoms. However, we did not detect a pronounced bottle effect with a copiotroph-dominated community. The fertilization with  ∼  0.8 µM DIP on day 4 did not have directly observable effects on the overall community within M1, as the data samples obtained from before and 4 days after fertilization clustered together, but likely influenced the development of individual populations later on, like Defluviicoccus-related bacteria and UCYN-C-type diazotrophic cyanobacteria (Cyanothece). Growth of UCYN-C led to among the highest N2-fixation rates ever measured in this region and enhanced growth of nearly all abundant heterotrophic groups in M1. We further show that different Rhodobacteraceae were the most efficient heterotrophs in the investigated system and we observed niche partitioning within the SAR86 clade. Whereas the location in- or outside the mesocosm had a significant effect on community composition, the temporal effect was significantly stronger and similar in both locations, suggesting that overarching abiotic factors were more influential than the enclosure. While temporal community changes were evident, prokaryotic diversity (Shannon index) only declined slightly from  ∼  6.5 to 5.7 or 6.05 in the lagoon and M1, respectively, throughout the experiment, highlighting the importance of multiple and varying sources of organic matter maintaining competition.

scholarly journals Evidence for r - and K -selection in a wild bird population: a reciprocal link between ecology and evolution

2016 ◽  
Vol 283 (1829) ◽  
pp. 20152411 ◽  
Author(s):  
Bernt-Erik Sæther ◽  
Marcel E. Visser ◽  
Vidar Grøtan ◽  
Steinar Engen
Keyword(s):  
Density Dependence ◽  
Population Size ◽  
Clutch Size ◽  
Balancing Selection ◽  
Empirical Support ◽  
Small Population ◽  
Environmental Stochasticity ◽  
Fluctuating Environments ◽  
Population Sizes ◽  
Large Clutch

Understanding the variation in selection pressure on key life-history traits is crucial in our rapidly changing world. Density is rarely considered as a selective agent. To study its importance, we partition phenotypic selection in fluctuating environments into components representing the population growth rate at low densities and the strength of density dependence, using a new stochastic modelling framework. We analysed the number of eggs laid per season in a small song-bird, the great tit, and found balancing selection favouring large clutch sizes at small population densities and smaller clutches in years with large populations. A significant interaction between clutch size and population size in the regression for the Malthusian fitness reveals that those females producing large clutch sizes at small population sizes also are those that show the strongest reduction in fitness when population size is increased. This provides empirical support for ongoing r - and K -selection in this population, favouring phenotypes with large growth rates r at small population sizes and phenotypes with high competitive skills when populations are close to the carrying capacity K . This selection causes long-term fluctuations around a stable mean clutch size caused by variation in population size, implying that r - and K -selection is an important mechanism influencing phenotypic evolution in fluctuating environments. This provides a general link between ecological dynamics and evolutionary processes, operating through a joint influence of density dependence and environmental stochasticity on fluctuations in population size.

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