Delta Smelt (Hypomesus transpacificus) Exhibit Wide Variation in Spawning Behavior: An Investigation of Substrate Type, Diel Timing, and Participants

AbstractStudies of cultured populations can be invaluable to the conservation of imperiled species for which little is known and whose very low abundance in the wild can preclude studies with robust sample sizes. For example, in endangered delta smelt (Hypomesus transpacificus), conservation measures developed to mitigate population decline are hindered by a lack of knowledge regarding spawning behavior. However, the availability of a cultured population allows important questions about spawning to be addressed experimentally. We examined the effect of substrate type on spawning behavior and egg fertilization success in cultured H. transpacificus under laboratory conditions. We also examined the diel frequency of spawning and the sex and number of spawning participants. We found that the frequency of spawns and resulting egg fertilization success did not differ between sand, gravel, and control (acrylic) substrates. We also demonstrated that spawning was predominantly nocturnal, though rare diurnal spawns were observed. Of the five mature males and five ripe females available within a given trial, spawns included up to seven participants, but most frequently occurred between a single female and one or two males. Our results highlight the wide behavioral variation exhibited by H. transpacificus during spawning, particularly in terms of substrate use, diel timing, and participants. These findings provide the most detailed and experimentally robust data regarding H. transpacificus spawning behavior to date and thereby provide ongoing conservation efforts with much-needed information.

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Characterization of spawning behavior in cultured Delta Smelt ( Hypomesus transpacificus )

North American Journal of Aquaculture ◽

10.1002/naaq.10182 ◽

2021 ◽

Author(s):

Yi‐Jiun Jean Tsai ◽

Samantha Chase ◽

Evan W. Carson ◽

Leanna Zweig ◽

Tien‐Chieh Hung

Keyword(s):

Spawning Behavior ◽

Delta Smelt ◽

Hypomesus Transpacificus

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A possible stimulus to induce SPAWNING in Ezo abalone Haliotis discus hannai during stormy weather: Fenton reaction induces spawning behavior

10.1101/2020.10.30.356469 ◽

2020 ◽

Author(s):

Yukio Matsumoto ◽

Kousuke Yatsuya

Keyword(s):

Fenton Reaction ◽

Fertilization Success ◽

Ocean Bottom ◽

Haliotis Discus Hannai ◽

Spawning Behavior ◽

External Fertilization ◽

Synchronous Spawning ◽

In The Wild ◽

Stormy Weather ◽

Haliotis Discus

AbstractSynchronous spawning is an important behavior to increase fertilization success of invertebrates with external fertilization. Previous work has shown that it is possible to induce spawning behavior using free radicals in tank experiments, but the stimulus for spawning in the wild is not fully understood. Ezo abalone Haliotis discus hannai mainly spawn during stormy weather. Rainwater contains H2O2 and iron (II) ions (Fe2+). We propose that during stormy weather water layers in the ocean are mixed and the surface layer containing H2O2 and Fe2+ interacts with the ocean bottom; this leads to conditions suitable for the Fenton reaction to occur. Hydroxyl radicals (·OH) are generated during the oxidization of Fe2+ by H2O2 and we hypothesized these induce spawning behavior of abalone in the wild. This study observed that H. discus hannai released eggs after salinity decreased due to the rainfall during stormy conditions. In addition, our tank experiment demonstrated that ·OH generated by the Fenton reaction induced synchronous spawning behavior between the sexes. This study provides a new hypothesis about control of synchronous spawning in H. discus hannai and the results could be applicable to other invertebrates.

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Microsatellite analysis reveals low genetic diversity in managed populations of the critically endangered gharial (Gavialis gangeticus) in India

Scientific Reports ◽

10.1038/s41598-021-85201-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Surya Prasad Sharma ◽

Mirza Ghazanfarullah Ghazi ◽

Suyash Katdare ◽

Niladri Dasgupta ◽

Samrat Mondol ◽

...

Keyword(s):

Genetic Diversity ◽

Indian Subcontinent ◽

Population Decline ◽

Mitochondrial Control Region ◽

Critically Endangered ◽

Term Survival ◽

Low Level ◽

Genetic Status ◽

In The Wild ◽

Gavialis Gangeticus

AbstractThe gharial (Gavialis gangeticus) is a critically endangered crocodylian, endemic to the Indian subcontinent. The species has experienced severe population decline during the twentieth century owing to habitat loss, poaching, and mortalities in passive fishing. Its extant populations have largely recovered through translocation programmes initiated in 1975. Understanding the genetic status of these populations is crucial for evaluating the effectiveness of the ongoing conservation efforts. This study assessed the genetic diversity, population structure, and evidence of genetic bottlenecks of the two managed populations inhabiting the Chambal and Girwa Rivers, which hold nearly 80% of the global gharial populations. We used seven polymorphic nuclear microsatellite loci and a 520 bp partial fragment of the mitochondrial control region (CR). The overall mean allelic richness (Ar) was 2.80 ± 0.40, and the observed (Ho) and expected (He) heterozygosities were 0.40 ± 0.05 and 0.39 ± 0.05, respectively. We observed low levels of genetic differentiation between populations (FST = 0.039, P < 0.05; G’ST = 0.058, P < 0.05 Jost’s D = 0.016, P < 0.05). The bottleneck analysis using the M ratio (Chambal = 0.31 ± 0.06; Girwa = 0.41 ± 0.12) suggested the presence of a genetic bottleneck in both populations. The mitochondrial CR also showed a low level of variation, with two haplotypes observed in the Girwa population. This study highlights the low level of genetic diversity in the two largest managed gharial populations in the wild. Hence, it is recommended to assess the genetic status of extant wild and captive gharial populations for planning future translocation programmes to ensure long-term survival in the wild.

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Linking mechanistic and behavioral responses to sublethal esfenvalerate exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae)

BMC Genomics ◽

10.1186/1471-2164-10-608 ◽

2009 ◽

Vol 10 (1) ◽

pp. 608 ◽

Cited By ~ 44

Author(s):

Richard E Connon ◽

Juergen Geist ◽

Janice Pfeiff ◽

Alexander V Loguinov ◽

Leandro S D'Abronzo ◽

...

Keyword(s):

Behavioral Responses ◽

Delta Smelt ◽

Hypomesus Transpacificus

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Influence of historical and contemporary habitat changes on the population genetics of the endemic South African parrot Poicephalus robustus

Bird Conservation International ◽

10.1017/s0959270919000315 ◽

2019 ◽

Vol 30 (2) ◽

pp. 236-259

Author(s):

WILLEM G. COETZER ◽

COLLEEN T. DOWNS ◽

MIKE R. PERRIN ◽

SANDI WILLOWS-MUNRO

Keyword(s):

Climate Change ◽

South Africa ◽

Spatial Scales ◽

Population Decline ◽

Source Population ◽

Population Bottlenecks ◽

Eastern Cape ◽

Forest Patches ◽

In The Wild ◽

Fragmented Forests

SummaryThe Cape Parrot Poicephalus robustus is a habitat specialist, restricted to forest patches in the Eastern Cape (EC), KwaZulu-Natal (KZN) and Limpopo provinces of South Africa. Recent census estimates suggest that there are less than 1,600 parrots left in the wild, although historical data suggest that the species was once more numerous. Fragmentation of the forest biome is strongly linked to climate change and exploitation of the forest by the timber industry. We examine the subpopulation structure and connectivity between fragmented populations across the distribution of the species. Differences in historical and contemporary genetic structure of Cape Parrots is examined by including both modern samples, collected from 1951 to 2014, and historical samples, collected from 1870 to 1946. A total of 114 individuals (historical = 29; contemporary = 85) were genotyped using 16 microsatellite loci. We tested for evidence of partitioning of genotypes at both a temporal and spatial scales by comparing shifts in allelic frequencies of historical (1870–1946) and contemporary (1951–2014) samples across the distribution of the species. Tests for population bottlenecks were also conducted to determine if anthropogenic causes are the main driver of population decline in this species. Analyses identified three geographically correlated genetic clusters. A southern group restricted to forest patches in the EC, a central group including birds from KZN and a genetically distinct northern Limpopo cluster. Results suggest that Cape Parrots have experienced at least two population bottlenecks. An ancient decline during the mid-Holocene (∼ 1,800-3,000 years before present) linked to climate change, and a more recent bottleneck, associated with logging of forests during the early 1900s. This study highlights the effects of climate change and human activities on an endangered species associated with the naturally fragmented forests of eastern South Africa. These results will aid conservation authorities with the planning and implementation of future conservation initiatives. In particular, this study emphasises the Eastern Cape mistbelt forests as an important source population for the species and calls for stronger conservation of forest patches in South Africa to promote connectivity of forest taxa.

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Adaptation to extreme ambient temperatures in cold-acclimated gerbils and mice

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.253.1.r39 ◽

1987 ◽

Vol 253 (1) ◽

pp. R39-R45 ◽

Cited By ~ 8

Author(s):

S. Oufara ◽

H. Barre ◽

J. L. Rouanet ◽

J. Chatonnet

Keyword(s):

Evaporative Heat Loss ◽

Electromyographic Activity ◽

Arid Environments ◽

Nonshivering Thermogenesis ◽

Cold Night ◽

Ambient Temperatures ◽

In The Wild ◽

Colonic Temperature ◽

And Control ◽

Thermoregulatory Reactions

To explain tolerance of heat and cold in gerbils (Gerbillus campestris) in their natural environment, a comparative study was made of thermoregulatory reactions in these animals and white mice (Mus musculus) of the same body mass exposed for 2-3 h to ambient temperatures (Ta) ranging from -23 to 40 degrees C. Metabolic rate (MR), evaporative heat loss (EHL), colonic temperature (Tb), and electromyographic activity (EMG) were measured. Nonshivering thermogenesis (NST) was also evaluated from the increase in MR after norepinephrine injection. In gerbils, tolerance of cold was higher than in mice; there was no fall in Tb in cold-acclimated (CA) and control (TN) gerbils after 3 h of exposure at -20 and -10 degrees C Ta, respectively; peak MR (PMR) reached five to six times resting MR (RMR) in gerbils and four to five times in mice. In gerbils, RMR was 35% below that of mice. In TN gerbils, EHL did not increase before 38 degrees C Ta; EHL increased at 26 degrees C in mice. In both animals, cold acclimation increased cold tolerance, PMR, RMR, and NST. Low RMR, high Tb, and mainly burrowing habits preserve gerbils from overheating and save water in hot and arid environments, and a conspicuous tolerance of cold allows them to live and forage in the wild during the cold night.

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Diet, Prey Selection, and Body Condition of Age-0 Delta Smelt, Hypomesus transpacificus, in the Upper San Francisco Estuary

San Francisco Estuary and Watershed Science ◽

10.15447/sfews.2014v12iss3art1 ◽

2014 ◽

Vol 12 (3) ◽

Cited By ~ 20

Author(s):

Steven Slater ◽

◽

Randall Baxter ◽

Keyword(s):

San Francisco ◽

Body Condition ◽

Prey Selection ◽

San Francisco Estuary ◽

Delta Smelt ◽

Hypomesus Transpacificus

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Effects of behaviour selection on litter size, fetal development and plasma progesterone concentrations during pregnancy in silver fox vixens

Proceedings of the British Society of Animal Science ◽

10.1017/s175275620000781x ◽

2002 ◽

Vol 2002 ◽

pp. 125-125

Author(s):

L. V. Osadchuk

Keyword(s):

Reproductive Function ◽

Coat Colour ◽

Performance Potential ◽

Plasma Progesterone ◽

Term Selection ◽

Silver Fox ◽

In The Wild ◽

Selection For ◽

And Control

Animal domestication is a natural selection experiment the important result of which is a great increase in the rate of appearance of new forms and in the wild range of variation of organisms. Analysing different aspects of this problem, D.K. Belyaev has came to a hypothesis that the morphological and physiological reorganisation of domestic animals has been going by the way of unconscious selection of animals on their behaviour, carried out by person at the very first stages of domestication (Belyaev, 1979). To testify this hypothesis, a population of tame silver foxes has been produced in long-term selection for lack of aggression and fear towards humans (domestic behaviour) at the Institute of Cytology and Genetics in Novosibirsk, Russia. In the process of selection the genetic transformation of behaviour and morphology, and physiological functions has been observed (Trut, 1999). In particular, selected animals show no aggressiveness to man, behave amicably towards humans and have some changes in the coat colour and body constitution (Trut, 1999). The important part of Belyaev’s hypothesis was the assumption that selection for domestic behaviour could affect the reproductive function, in particular the pituitary-gonadal axis controlling reproduction and fertility. The aim of this study was to obtain information about possible changes in reproduction between control (C) and domesticated (D) vixens. Reproductive performance, potential fertility, embryonic mortality and fetal viability were analysed for vixens from domesticated and control population. In addition, plasma progesterone concentrations were determined in selected and control females during pregnancy.

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