scholarly journals Discrete Spawning Aggregations of the Loliginid Squid Doryteuthis gahi Reveal Life-History Interactions of a Dwarf Morphotype at the Center of Its Distribution Range

2021 ◽  
Vol 7 ◽  
Author(s):  
Sergio A. Carrasco ◽  
Macarena Bravo ◽  
Christian M. Ibáñez ◽  
Germán Zapata-Hernández
Keyword(s):  
Life History ◽  
Soft Tissues ◽  
Trophic Position ◽  
Egg Laying ◽  
Distribution Range ◽  
Small Scale ◽  
Humboldt Current ◽  
Central Chile ◽  
Egg Capsules ◽  
Loliginid Squid

Heterogeneous environmental conditions along the Humboldt Current System (HCS) influence the life-history strategy of a variety of species in different ways. There is limited information on latitudinal traits of coastal cephalopods as part of the interacting species in pelagic and benthic environments. The present study used the loliginid squid Doryteuthis gahi as a model organism to: (1) evaluate latitudinal traits on egg laying patterns, (2) characterize a particular spawning ground, (3) quantify the isotopic variation from different tissues, (4) evaluate potential trophic ontogenetic changes, (5) determinate trophic position, and (6) isotopically estimate the relative importance of putative preys in the squid’s assimilated diet. Results evidenced that egg-masses collected between 2014 and 2020 presented similar patterns along northern-central Chile (27–36°S), with females attaching small egg-capsules (10–50 mm length) through the year and over a variety of anthropogenic and natural substrates. At a small scale (Coquimbo; 29°S), early life history traits showed distinct patterns depending on SST, with warmer collection periods (∼18°C) evidencing larger capsules and smaller embryos, although small paralarvae were obtained over the 4-year sampling period. In this site, sampling of older ontogenetic stages supported the constant presence of small-sized squids (19–77 mm ML). Males had larger mean sizes compared to females and undetermined specimens, with a high proportion of mature stages. Observations in captivity were extended for up to 110 d, validating that small females (45–64 mm ML) spawn the small egg-capsules typically observed in the field. Differences in stable isotope composition between beaks and soft tissues of adult squids were lower for δ13C values (1.1 vs. 1.4‰, respectively) and higher for δ15N values (5.3 vs. 4.7‰, respectively). Isotopic composition through ontogeny found similar δ13C and δ15N values, suggesting that carbon sources (pelagic origin) and trophic position did not change significantly, with copepods, euphausiids and nereid polychaetes being the most important preys. This study unveils the permanent occurrence of a small reproductive morphotype of D. gahi in shallow coastal habitats of northern-central Chile (i.e., center of the distribution range), providing the first insights for understanding the species’ potential adaptations to heterogeneous conditions in the HCS and the unexplored distribution gap between the two centers of abundance (Peru and the Falkland/Malvinas islands).

scholarly journals GENETICS OF LIFE HISTORY IN DROSOPHILA MELANOGASTER. II. EXPLORATORY SELECTION EXPERIMENTS

Genetics ◽  
1981 ◽  
Vol 97 (1) ◽  
pp. 187-196 ◽  
Author(s):  
Michael R Rose ◽  
Brian Charlesworth
Keyword(s):  
Life History ◽  
Egg Laying ◽  
Small Scale ◽  
Female Reproduction ◽  
Direct Response ◽  
Indirect Response ◽  
Three Generations ◽  
Selection Experiments ◽  
Selection For ◽  
Early Fecundity

ABSTRACT Two types of small-scale selection experiments were performed. (1) Artificial selection experiments were performed on age-specific female fecundity. Selection for early fecundity over three generations produced a statistically detectable direct response. There was no detectable indirect response in other life-history characters. Selection for late fecundity over three generations did not produce any detectable direct response. Indirect responses were detected: early egg-laying decreased and longevity increased. (2) Natural selection for late-age fitness components increased late fecundity, female longevity, and the duration of female reproduction, while early fecundity and mean egg-laying rate decreased.

scholarly journals Accurate age estimation in small-scale societies

2017 ◽  
Vol 114 (31) ◽  
pp. 8205-8210 ◽  
Author(s):  
Yoan Diekmann ◽  
Daniel Smith ◽  
Pascale Gerbault ◽  
Mark Dyble ◽  
Abigail E. Page ◽  
...  
Keyword(s):  
Life History ◽  
Bayesian Approach ◽  
Age Estimation ◽  
Human Life ◽  
The Philippines ◽  
Monte Carlo Algorithm ◽  
Small Scale ◽  
Hunter Gatherers ◽  
Cultural Life ◽  
Ranking Order

Precise estimation of age is essential in evolutionary anthropology, especially to infer population age structures and understand the evolution of human life history diversity. However, in small-scale societies, such as hunter-gatherer populations, time is often not referred to in calendar years, and accurate age estimation remains a challenge. We address this issue by proposing a Bayesian approach that accounts for age uncertainty inherent to fieldwork data. We developed a Gibbs sampling Markov chain Monte Carlo algorithm that produces posterior distributions of ages for each individual, based on a ranking order of individuals from youngest to oldest and age ranges for each individual. We first validate our method on 65 Agta foragers from the Philippines with known ages, and show that our method generates age estimations that are superior to previously published regression-based approaches. We then use data on 587 Agta collected during recent fieldwork to demonstrate how multiple partial age ranks coming from multiple camps of hunter-gatherers can be integrated. Finally, we exemplify how the distributions generated by our method can be used to estimate important demographic parameters in small-scale societies: here, age-specific fertility patterns. Our flexible Bayesian approach will be especially useful to improve cross-cultural life history datasets for small-scale societies for which reliable age records are difficult to acquire.

Initial Results On Medium Frequency Electromagnetic Field Penetration In Biological Soft Tissue

2012 ◽  
Author(s):  
Zulkarnay Zakaria ◽  
Mohd Fahajumi Jumaah ◽  
Mohd Saiful Badri Mansor ◽  
Khairi Mat Daud ◽  
Mohd Hafiz Fazalul Rahiman ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Soft Tissue ◽  
Soft Tissues ◽  
Low Cost ◽  
The Body ◽  
Small Scale ◽  
Medium Frequency ◽  
Magnetic Field Penetration ◽  
Magnetic Induction Tomography ◽  
Field Penetration

Terapi merupakan antara teknik perubatan tertua dalam mengekalkan kesihatan badan terutama daripada aliran darah yang tidak baik, strok dan beberapa penyakit yang lain. Teknik ini termasuklah akupuntur, guasa dan juga urutan. Terdapat juga teknik terapi moden seperti terapi warna, terapi ozon, terapi dadah dan banyak lagi. Kertas kajian ini akan mengetengahkan penjana terapi elektromagnet, satu alat yang mempunyai potensi aplikasi terapi dalam bidang perubatan. Alat ini menghasilkan medan magnet berfrekuensi sederhana sebagai sumber terapi. Perkakasan yang berskala kecil berfrekuensi sederhana dan berkos rendah ini telah dibangunkan dan telah diuji pada tisu biologi bagi mengukur tahap ketembusan medan magnet. Ujian ini telah membuktikan bahawa medan magnet yang telah dihasilkan mampu menembusi tisu lembut bersaiz sehingga 2 cm dengan jarak 7 cm daripada sumber. Kebolehan penembusan sistem ini terhadap tisu lembut memberikan peluang yang cerah kepada kajian ini memandangkan medan magnet telah menunjukkan potensi sebagai sebahagian daripada terapi untuk memulihkan migraine, strok, kekejangan dan beberapa yang lain selain boleh diaplikasikan dalam pengimejan tomografi induksi magnet. Kata kunci: Terapi elektromagnet, medan magnet, penembusan, tisu lembut, aplikasi perubatan Therapy is among the oldest medication technique in maintaining the health of the body especially from bad blood circulation, stroke and several others. This technique includes acupuncture, guasa and also massage. There are also modern therapy techniques like colour therapy, water therapy, ozone therapy, drug therapy and others. This paper will highlight electromagnetic therapy generator, a device which has the potential of therapy application in medical field. This device produce medium frequency magnetic field as a therapy source. This small scale medium frequency and low cost hardware that has been developed was tested on the biological tissue for the purpose of measuring the magnetic field penetration. The testing has proven that the generated magnetic field is able to penetrate the soft tissue up to 2 cm with distance from the source up to 7 cm. The capability of the system penetrations through the soft tissues provide the bright future of this research since magnetic field have shown the potential as being part of the therapy for curing migraine, stroke, cramp and several others besides the application in the magnetic induction tomography imaging. Key words: Electromagnetic therapy, magnetic field, penetration, soft tissue; medical applications

The Humboldt Current System of Northern and Central Chile

2007 ◽  
pp. 195-344 ◽  
Author(s):  
Martin Thiel ◽  
Erasmo Macaya ◽  
Enzo Acu√±a ◽  
Wolf Arntz ◽  
Horacio Bastias ◽  
...  
Keyword(s):  
Current System ◽  
Humboldt Current ◽  
Central Chile ◽  
Humboldt Current System

scholarly journals Reproductive biology of Sympterygia bonapartii (Chondrichthyes: Rajiformes: Arhynchobatidae) in San Matías Gulf, Patagonia, Argentina

2017 ◽  
Vol 15 (1) ◽  
Author(s):  
María L. Estalles ◽  
María R. Perier ◽  
Edgardo E. Di Giácomo
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Biology ◽  
Early Spring ◽  
Egg Laying ◽  
Reproductive Pattern ◽  
Reproductive Parameters ◽  
Egg Capsules ◽  
Northern Patagonia ◽  
Total Length

ABSTRACT This study estimates and analyses the reproductive parameters and cycle of Sympterygia bonapartii in San Matías Gulf, northern Patagonia, Argentina. A total of 827 males and 1,299 females were analysed. Males ranged from 185 to 687 mm of total length (TL) and females from 180 to 742 mm TL. Sexual dimorphism was detected; females were larger, heavier, exhibited heavier livers, wider discs and matured at lager sizes than males. Immature females ranged from 180 to 625 mm TL, maturing females from 408 to 720 mm TL, mature ones from 514 to 742 mm TL and females with egg capsules from 580 to 730 mm TL. Immature males ranged from 185 to 545 mm TL, maturing ones from 410 to 620 mm TL and mature males from 505 to 687 mm TL. Size at which 50% of the skates reached maturity was estimated to be 545 mm TL for males and 594 mm TL for females. According to the reproductive indexes analysed, S. bonapartii exhibited a seasonal reproductive pattern. Mating may occur during winter-early spring and the egg-laying season, during spring and summer.

scholarly journals Stable ringed seal (Pusa hispida) demography despite significant habitat change in Svalbard, Norway

2021 ◽  
Vol 40 ◽  
Author(s):  
Magnus Andersen ◽  
Kit M. Kovacs ◽  
Christian Lydersen
Keyword(s):  
Life History ◽  
Sea Ice ◽  
Close Association ◽  
Ringed Seal ◽  
Breeding Habitat ◽  
Small Scale ◽  
Recent Period ◽  
Ringed Seals ◽  
Time Periods ◽  
Circumpolar Arctic

Ringed seals, which are small phocid seals, range across the circumpolar Arctic, and have evolved in close association with sea ice and depend on it for all aspects of their life history. This research study compares age structure, reproductive parameters, body size and condition during three time periods—1981–82 (n = 277), 2002–04 (n = 272) and 2012–18 (n = 212)—to study potential changes in demography in ringed seals in western Svalbard, Norway, an area that has undergone dramatic changes in sea-ice conditions during recent decades. Age distributions for the three time periods were similar, with the exception that the most recent period had a higher proportion of young animals. Age at sexual maturity for both sexes was similar for the two most recent periods, both being lower than in the 1980s. Ovulation rates did not vary significantly among the three periods (range 0.86–0.94). Pregnancy rates were only available for the most recent study period (0.71); this value falls within the range reported from other Arctic regions. Body length showed no clear temporal patterns; males were slightly longer in the most recent period, while females were slightly longer in the first period. Data from May in all periods suggest that body condition has not varied significantly through time. In conclusion, although the ringed seal breeding habitat in Svalbard has declined significantly in recent decades, demographic parameters appear to be largely unaffected. Life-history plasticity in combination with a small-scale regional variation in environmental conditions might explain the lack of changes in demography over time.

Newly discovered parasitic Turbellaria of opisthobranch gastropods

2010 ◽  
Vol 91 (5) ◽  
pp. 1123-1133 ◽  
Author(s):  
Kosuke Sudo ◽  
Yoshiaki J. Hirano ◽  
Yayoi M. Hirano
Keyword(s):  
Life History ◽  
Obligate Parasite ◽  
Egg Capsules ◽  
Parasitic Worm ◽  
The Family

An endoparasitic platyhelminth from six species of sacoglossan opisthobranchs was collected at several localities of temperate to subtropical waters in Japan. Poecilostomatoid copepods (all species of Splanchnotrophidae and several species of Philoblennidae) and a few digenean flukes had been the only endoparasitic metazoans known for opisthobranch hosts. The newly discovered parasite was 1 to 15 mm in length and had no eyes, mouth, pharynx, or intestine. It had no external organs for parasitic life (e.g. attachment organs) and inhabited the haemocoel of the host. When mature, it emerged from the host and secreted a silky substance around itself to form a cocoon. The cocoon contained egg capsules with 19–42 eggs. Larvae, hatched from the capsule, had a ciliated body and a pair of eye spots. They were negatively phototactic and capable of invading suitable hosts. These morphological and life history features suggest this parasitic worm may belong to the family Fecampiidae (Platyhelminthes: Turbellaria), one of a few obligate parasite taxa in Turbellaria. Molluscan hosts which are common for parasitic Platyhelminthes have not previously been known for this family. The newly discovered parasite may be important for understanding the evolution of parasitism in Platyhelminthes.

scholarly journals Breaking out of the comfort zone: El Niño-Southern Oscillation as a driver of trophic flows in a benthic consumer of the Humboldt Current ecosystem

2017 ◽  
Vol 284 (1857) ◽  
pp. 20170923 ◽  
Author(s):  
José M. Riascos ◽  
Marco A. Solís ◽  
Aldo S. Pacheco ◽  
Manuel Ballesteros
Keyword(s):  
El Niño ◽  
Trophic Ecology ◽  
El Nino ◽  
Southern Oscillation ◽  
Trophic Position ◽  
Trophic Levels ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Strong Increase ◽  
Humboldt Current

The trophic flow of a species is considered a characteristic trait reflecting its trophic position and function in the ecosystem and its interaction with the environment. However, climate patterns are changing and we ignore how patterns of trophic flow are being affected. In the Humboldt Current ecosystem, arguably one of the most productive marine systems, El Niño-Southern Oscillation is the main source of interannual and longer-term variability. To assess the effect of this variability on trophic flow we built a 16-year series of mass-specific somatic production rate (P/B) of the Peruvian scallop ( Argopecten purpuratus ), a species belonging to a former tropical fauna that thrived in this cold ecosystem. A strong increase of the P/B ratio of this species was observed during nutrient-poor, warmer water conditions typical of El Niño, owing to the massive recruitment of fast-growing juvenile scallops. Trophic ecology theory predicts that when primary production is nutrient limited, the trophic flow of organisms occupying low trophic levels should be constrained (bottom-up control). For former tropical fauna thriving in cold, productive upwelling coastal zones, a short time of low food conditions but warm waters during El Niño could be sufficient to waken their ancestral biological features and display massive proliferations.

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