Life History Research Articles

The life (history), diet and death of the blackspot shark (Carcharhinus sealei) from South-east Asia

Context The blackspot shark (Carcharhinus sealei) is a small-bodied coastal shark often incidentally caught in fisheries across South-east Asia. Aims This study aimed to document the species’ biology, ecology, fisheries and markets to inform conservation. Methods In total, 103 blackspot sharks from Indonesia (n = 101) and Singapore (n = 2) were examined to determine biological parameters (growth rate, age at maturity, reproductive traits and diet). An interview with a Singaporean seafood supplier gave insight to population trends, fisheries and markets. Key results Males attained a maximum age of 9 years, the smallest mature individual measured 709-mm stretched total length (STL), with 50% reaching maturity at 6.15 years. Females attained a maximum age of 11 years, the smallest mature individual measured 730 mm STL, with 50% reaching maturity at 6.12 years. The species has an overall growth rate (k) of 0.37 year−1. Reproduction was asynchronous, with only two pups produced per litter. Crustaceans dominated the diet of juveniles, whereas bony fishes and cephalopods dominated the diets of adult males and adult females respectively. Conclusions Blackspot sharks have a moderately fast growth rate, but a late age-at-maturity and a low fecundity. Diet differed between the sexes as well as adults and juveniles. Implications The low fecundity and late maturity of blackspot sharks increase their vulnerability to exploitation. Blackspot sharks are now listed on CITES-Appendix II, but mortality may remain high because they are reportedly often caught incidentally.

Bone microstructure analyses in ontogenetic series of Mesosaurus tenuidens from the early Permian of Brazil.

Osteohistological evidence is widely used to infer paleobiological traits of fossil vertebrates, such as ontogeny and growth rates. Mesosaurs, an enigmatic group of aquatic reptiles from the early Permian, are the most well-known Paleozoic amniotes from Africa and South America. Their fossils are abundant in South America, ranging from the central-west region of Brazil to the southernmost areas, as well as parts of Paraguay and Uruguay. In this contribution, we examined the bone microstructure of Mesosaurus tenuidens by analyzing thin sections of axial and appendicular elements of several specimens collected from various Brazilian sites. The microstructure of the bones showed minimal histological variability among elements, predominantly composed of parallel-fibered tissues, indicating slow growth rhythm, along with increased bone density attributed to pachyosteosclerosis. The cortical area consists of poorly vascularized parallel-fibered bone tissue, which was interrupted by multiple cyclical growth marks, some of them being supernumerary, suggesting a strong influence of seasonality. Moreover, the organization of growth marks suggests distinct life history trajectories among individuals collected from different outcrops, reflecting environmental heterogeneity throughout the basin. Internally, the endosteal domain exhibits greater vascularization compared to the cortices and frequently contained calcified cartilage. In the ontogenetic series, there was a progressive filling of the medullary region from small to large individuals. The presence of the External Fundamental System (a proxy indicating somatic maturity) was observed in femora and ribs, suggesting that determinate growth was already occurring in Permian mesosaurs and may not be an exclusive specialization of crown amniotes.

Adaptive divergence in reproductive seasonality and underlying physiological features fit Rattus norvegicus to live as opportunistic breeders.

How organisms respond to complex environments is one of the unsolved problems in ecology. Life history patterns of a species provide essential information on how different populations may respond and adapt to environmental changes. Compared to typical seasonal breeders, which have limited distributions, the worldwide distribution of brown rats (Rattus norvegicus) across highly complex and divergent habitats suggests they exhibit exceptional adaptiveness. However, the difference in physiological mechanisms by which brown rats respond and adapt to markedly different environments is seldom investigated. Here, we reveal a significant divergence in reproductive seasonality and environmental responses between two brown rat subspecies: one subspecies, R. n. caraco, lives in the temperate zone, and another subspecies, R. n. norvegicus, lives in the subtropical region. Although R. n. caraco displayed a significantly higher reproductive seasonality than R. n. norvegicus, both subspecies adapted to sub-optimal breeding conditions mainly by regulating the seminal vesicle rather than testis development. Especially in responding to severe winter conditions in high-latitude regions, bodyweight-dependent recovery of testicular development in adults enables R. n. caraco to initiate reproduction more rapidly when conditions are suited. These findings elucidate a regulatory process of how brown rats live as opportunistic breeders by benefiting from enhanced semen production.

Influence of Longitudinal Fragmentation on Length–Weight Relationships of Fishes in the Someșul Cald River, Romania

Romania has a rich hydrographic network, which permitted the construction of over 80 large dams on its water courses, estimating a number between 545 and 674 hydropower plants that were either built or were in a different construction stage on the rivers of Romania in 2021. These hydropower plants were often built outside specific legislation regarding ecological impacts, especially before 1990. Longitudinal fragmentation of rivers causes severe ecological impacts on biodiversity, food chains, and nutrient cycles. Someșul Cald River is the main tributary of Someșul Mic River, the most important water source for the northwestern region of Transylvania. On its course, several dams and reservoirs were built from 1968 to 1980 for electricity production and population freshwater supply. The present study aimed to analyze the length–weight relationships (LWRs) and condition factors occurring in the longitudinally fragmented Someșul Cald River. The LWRs, relative condition factor Kn, and Fulton condition factor K were determined based on total length and wet body weight. Comparisons of LWRs, Kn, and K across river sections constrained by dams showed that some fish species exhibited similar growth patterns and physiological conditions, while others differed significantly. Freshwater fish physiology is altered by longitudinal fragmentation, both natural and artificial. Barriers such as dams influence the energy gradient, limiting feed availability and, consequently, the life history of fish species. Long-term management plans regarding conservation should take into consideration existing fish species population dynamics, along with their physiological and somatic status.

Chromosome Structural Rearrangements in Invasive Haplodiploid Ambrosia Beetles Revealed by the Genomes of Euwallacea fornicatus (Eichhoff) and Euwallacea similis (Ferrari) (Coleoptera, Curculionidae, Scolytinae).

Bark and ambrosia beetles are among the most ecologically and economically damaging introduced plant pests worldwide. Life history traits including polyphagy, haplodiploidy, inbreeding polygyny, and symbiosis with fungi contribute to their dispersal and impact. Species vary in their interactions with host trees, with many attacking stressed or recently dead trees, such as the globally distributed Euwallacea similis (Ferrari). Other species, like the Polyphagous Shot Hole Borer Euwallacea fornicatus (Eichhoff), can attack over 680 host plants and is causing considerable economic damage in several countries. Despite their notoriety, publicly accessible genomic resources for Euwallacea Hopkins species are scarce, hampering our understanding of their invasive capabilities as well as modern control measures, surveillance, and management. Using a combination of long and short read sequencing platforms, we assembled and annotated high quality (BUSCO > 98% complete) pseudo-chromosome-level genomes for these species. Comparative macrosynteny analysis identified an increased number of pseudo-chromosome scaffolds in the haplodiploid inbreeding species of Euwallacea compared to diploid outbred species, due to fission events. This suggests that life history traits can impact chromosome structure. Further, the genome of E. fornicatus had a higher relative proportion of repetitive elements, up to 17% more, than E. similis. Metagenomic assembly pipelines identified microbiota associated with both species including Fusarium fungal symbionts and a novel Wolbachia strain. These novel genomes of haplodiploid inbreeding species will contribute to the understanding of how life history traits are related to their evolution and to the management of these invasive pests.

Models of Science Teacher Identity: The Multiple Representations of Pre-Service Elementary Science Educators

ABSTRACT Experiences in pre-service teacher education can have a lasting effect within the professional life histories of classroom teachers. Investigating the ways in which pre-service elementary teachers (PSETs) represent themselves as science teachers before, during, and after methods course experiences can inform best practices of elementary science teacher pre-service and inservice development as well as further highlight the concerns and objectives of PSETs. Therefore, as a pre-service science teacher educator, I seek to understand the ways in which PSETs represent themselves as future science teachers and the experiences within the methods courses that influence those representations. This study relies on quantitative pre- and post-survey data and qualitative course artifact data completed as part of regular undergraduate course assignments. PSETs representations of self within this study tend to shift from a traditional approach to science teaching toward constructivist, student-centered pedagogical practices and show reduced anxiety toward teaching science and increased science teaching self-efficacy.

Effect of Temperature on Black Carp (Mylopharyngodon piceus) Age at Sexual Maturity

ABSTRACTBlack Carp (Mylopharyngodon piceus) is one of the four invasive Asian Carp species (Bighead Carp, Hypophthalmichthys nobilis; Grass Carp, Ctenopharyngodon idella; and Silver Carp, Hypophthalmichthys molitrix) in North America. As benthic predators, Black Carp poses ecological risks to unionids within the Great Lakes and could bring other changes to local benthic communities. One means of assessing invasion risk and potential impact is to determine how critical life history characteristics depend on environmental conditions in new regions. Age at sexual maturity is negatively correlated to the maximum per capita population growth rate and thus can be used to estimate potential population growth for invasive species. Previous studies have found a significant negative relationship between age at maturity and temperature for all three other Asian Carp species, but not for Black Carp. With a more comprehensive dataset, we demonstrate that the same relationship exists for Black Carp. Winter duration is the best predictor of Black Carp age at maturity, followed by average winter air temperature. This significant relationship between age at maturity and temperature was not altered in artificial growing environments. Our results suggested that for Black Carp, temperatures in the winter months are more important for its energy accumulation and maturation and may determine invasion risk in northern locations, such as tributaries of the Great Lakes.

Bottom-up effects of nutrient solutions on grape-grape phylloxera (Daktulosphaira vitifoliae) interaction.

Fertilizers generally influence the nutritional quality or defense ability of the plants, which can indirectly cause an increase in populations of herbivorous insect pests such as grape phylloxera, Daktulosphaira vitifoliae (Homoptera: Phylloxeridae, Fitch). The effects of nutrient solutions on grape-grape phylloxera interactions were analyzed using five concentrations (nitrogen content: 15, 30, 60, 120, and 180mg/L) of Hoagland's nutrient solution to irrigate Vitis vinifera L. × Vitis labrusca L. (Kyoho). Life table variables and life history variables showed a hump-shaped or an inverted hump-shaped curve as nutrient input level increased. Sixty microgram per liter treatment resulted in the greatest longevity and egg incubation, shortened the nymph duration and significantly increased the adult lifespan. Overall, both excessive and insufficient nutrient inputs curbed growth and multiplication of D. vitifoliae. These results provide a theoretical basis for vineyards for amending fertilizer inputs to prioritize the prevention and control of this pest.

Insect responses to seasonal time constraints under global change are facilitated by warming and counteracted by invasive alien predators.

In seasonal environments, organisms with complex life cycles not only contend with seasonal time constraints (TC) but also increasingly face global change stressors that may interfere with responses to TC. Here, we tested how warming and predator stress imposed during the egg and larval stages shaped life history and behavioural responses to TC in the temperate damselfly Ischnura elegans. Eggs from early and late clutches in the season were subjected to ambient and 4°C warming temperature and the presence or absence of predator cues from perch and signal crayfish. After hatching, larvae were retained at the same thermal regime, and the predator treatment was continued or not up to emergence. The late eggs decreased their development time, especially under warming and when not exposed to predator cues. However, the late eggs increased their development time when exposed to predator cues, especially to crayfish cues. The TC decreased survival of late larvae that were as eggs exposed to crayfish cues, indicating a carry-over effect. The TC and warming additively reduced late larvae development time to emergence. Independent of the TC, predator cue effects on development time were stronger during the egg than during the larval stage. The late individuals expressed lower mass at emergence, which mirrored the size difference between field-collected mothers. Warming caused a higher mass at emergence. The late individuals increased their boldness and showed a higher number of moves, whereas warming caused a decreased boldness. There was no predator cue effect on larval behaviour. The results indicate that late individuals compensate for late season egg laying, which is facilitated under warming but counteracted under predation risk, especially when imposed by the crayfish.

Monitoring the genetic diversity in holothurian populations from the Italian coasts with mitochondrial DNA sequences

Sea cucumbers are deposit feeding members of marine benthic communities. The over-exploitation of sea cucumber natural stocks, especially in the Mediterranean basin, is having negative impacts on the marine ecosystem. This concerns had led the Italian government to take legal actions to preserve these important marine resources. The aim of this study was to evaluate the level of genetic diversity and population structures within two sympatric Holothuria sea cucumber species, H. polii and H. tubulosa, across ten Mediterranean areas along Italy. A 323 bp portion of the COI mitochondrial gene was sequenced in a total of 441 holothurians (251 H. polii, 177 H. tubulosa and 13 from other species). Genetic diversity analyses and analysis of molecular variance (AMOVA) suggest that H. polii and H. tubulosa species are distinct, but within and among populations are homogeneous, indicating active gene flows across the Mediterranean areas investigated. H. polii showed a lower genetic diversity than H. tubulosa, probably related to differences in life history traits. Phylogenetic analyses showed a clear differentiation between the two species, even if six specimens morphologically assigned to a species clustered within the other species, indicating a possible occurrence of hybridization events. These data will be useful in implementing conservation actions for these holothurian genetic resources.

Life history in Caenorhabditis elegans: from molecular genetics to evolutionary ecology.

Life history is defined by traits that reflect key components of fitness, especially those relating to reproduction and survival. Research in life history seeks to unravel the relationships among these traits and understand how life history strategies evolve to maximize fitness. As such, life history research integrates the study of the genetic and developmental mechanisms underlying trait determination with the evolutionary and ecological context of Darwinian fitness. As a leading model organism for molecular and developmental genetics, Caenorhabditis elegans is unmatched in the characterization of life history-related processes, including developmental timing and plasticity, reproductive behaviors, sex determination, stress tolerance, and aging. Building on recent studies of natural populations and ecology, the combination of C. elegans' historical research strengths with new insights into trait variation now positions it as a uniquely valuable model for life history research. In this review, we summarize the contributions of C. elegans and related species to life history and its evolution. We begin by reviewing the key characteristics of C. elegans life history, with an emphasis on its distinctive reproductive strategies and notable life cycle plasticity. Next, we explore intraspecific variation in life history traits and its underlying genetic architecture. Finally, we provide an overview of how C. elegans has guided research on major life history transitions both within the genus Caenorhabditis and across the broader phylum Nematoda. While C. elegans is relatively new to life history research, significant progress has been made by leveraging its distinctive biological traits, establishing it as a highly cross-disciplinary system for life history studies.

Taxonomy of the Palearctic socially parasitic Temnothorax (Myrmoxenus) ants (Hymenoptera: Formicidae).

The ant genus Temnothorax is one of the most diverse in the Palearctic region, comprising several species with different life histories and uncertain taxonomic backgrounds. Socially parasitic Temnothorax ant species were typically described decades ago, primarily based on traditional morphological traits. In some aspects, these species have come back into the spotlight in recent years, necessitating a comprehensive taxonomic revision of the species of the genus. In this paper, we present a quantitative morphology-based taxonomic revision of the Temnothorax corsicus species group (formerly called Myrmoxenus genus) based on the analysis of 20 continuous morphometric traits collected from 394 worker and 19 traits from 473 gyne individuals belonging to 240 samples. Based on morphometric analyses, we propose junior synonymy for Temnothorax tamarae (Arnol'di, 1968) under T. ravouxi (André, 1896), and T. microcellatus (Soudek, 1925) is revived and is considered a senior synonym of T. menozzii (Finzi, 1924). Detailed descriptions, measurements, distribution, and host usage of all ten species are given. Dichotomous keys to workers, known gynes, and photographs of all species are presented.

Predicting genetic biodiversity in salamanders using geographic, climatic, and life history traits.

The geographic distribution of genetic variation within a species reveals information about its evolutionary history, including responses to historical climate change and dispersal ability across various habitat types. We combine genetic data from salamander species with geographic, climatic, and life history data collected from open-source online repositories to develop a machine learning model designed to identify the traits that are most predictive of unrecognized genetic lineages. We find evidence of hidden diversity distributed throughout the clade Caudata that is largely the result of variation in climatic variables. We highlight some of the difficulties in using machine-learning models on open-source data that are often messy and potentially taxonomically and geographically biased.

KARYA MUSIK LUNGUN: INTERPRETASI VOKAL ANDUNG BATAK TOBA DALAM KONSEP MUSIK KAMAR

Lungun is a musical work inspired by a tradition in the death ceremony of the Toba Batak people, called the andung tradition. Andung is a song of sadness that expresses one's feelings of grief for a loved one. Andung chanting is chanted by a pangandung (poet) using hata andung verses (Toba Batak fine literature) whose content tells the life history of someone who has died. In its current development, the andung tradition has shifted, and many cannot practice it because many younger generations can no longer speak hata andung, and andung singing which have been replacing with spiritual songs. The analysis of the andung tradition revealed distinct characteristics of the andung melody and the presentation of Gondang Sabangunan music for death ceremonies. The creation of the musical work Lungun aims to find out the musical form and its symbolic meaning. The method used is panca sthiti ngawi sani, which consist of five stages: (1) inspiration (ngawirasa), (2) exploration (ngawacak), (3) conception (ngarencana), (4) execution (ngawangun) and (4) production (ngabah). Lungun's musical work incorporates elements such as the Toba Batak scales, processed andung vocals, hata andung poems, rhythm processing, and Gondang Sabangunan playing techniques into chamber music performances. Lungun music has three parts: part I is mula-mula (beginning), part II is andung (vocal singing), and part III is poda (message). The symbolic meaning expressed in Lungun music refers to the values found in the Toba Batak community: the Dalihan Na Tolu Batak philosophy, the five levels of Toba Batak death, and the seven Toba Batak philosophies.

The role of consciousness in adaptive behaviour: A philosophy for the science of animal consciousness

What is the role of consciousness in nature? The science of consciousness has largely neglected the question through its emphasis on human experience. In this précis of A Philosophy for the Science of Animal Consciousness, I outline how we can move from a top-down approach that begins with investigations in humans to an evolutionary bottom-up approach that targets the adaptive origins of even the most minimal forms of subjective experience. I will also offer an introduction to the central thesis of the book, that is, the pathological complexity thesis, according to which consciousness evolved in order to enable animals to adaptively respond to their life history challenges.

Alien Rainbow Trout Oncorhynchus mykiss in the Balkhash Basin (Kazakhstan, Central Asia): 50 Years of Naturalization.

Rainbow trout, or mykiss (Oncorhynchus mykiss), is one of the most popular species used in aquaculture and has been naturalized worldwide, including in the Central Asian Balkhash basin, which has unique aboriginal fish fauna. Both rainbow trout from European farms and wild mykiss from Kamchatka were introduced to some mountain lakes and rivers of the Balkhash basin about 50 years ago. This study investigates the current distribution and life history traits of the alien species and its possible impact on the local fish fauna. This study showed that the rainbow trout occupies various habitats in the Ili River basin: mountain lakes, fast-flowing mountain rivers, and lowland rivers with slow currents and warm water (up to +27 °C). Rainbow trout from European fish farms dominate the mountain Middle Kolsay Lake, while the wild trout from Kamchatka occupies the small Ulken Kokpak River. Both co-occur in the Chilik River. Contrary to that in other regions, the distribution of rainbow trout in the Balkhash basin remained almost the same after their introduction. Broad intrapopulation variability in terms of size, growth rate, and maturation age was revealed, apparently as a result of adaptation to the new environment and intrapopulation competition. In particular, the growth rate has decreased, but life span, surprisingly, has increased as compared to the originally introduced fish. Intrapopulation variation in growth and maturity patterns was also noted. Differences in skin coloration between highland (cold-water) and lowland (warm-water) populations were discovered. The feeding mode of naturalized trout is insectivorous (insect imago), indicating that it occupies its own niche in the local fish communities. The largest population of rainbow trout was recorded in the Lower Kolsay Lake, lowering the population of native fish species, while in other localities, no negative impact on local fish communities was recorded.

Exploring identity work of LGBT+ volunteers in sport through personas: the advocate, the community-minded and the sportsperson

ABSTRACT Research question Sport volunteering can be a valued and meaningful way to engage in sport beyond participation, but sport volunteers lack diversity in the UK. Specifically, there has been a lack of insight into experiences and identities of LGBT+ volunteers in sport. Therefore, this research explores how LGBT+ volunteers construct, negotiate and manage their identities over time and through the use of personas. Research methods Using identity work as a theoretical lens and from a social constructionist perspective, this study employs topical life history interviews of 16 sexually diverse sport volunteers to explore identity work strategies adopted by participants to navigate their volunteer experiences. Results and findings Using constructivist grounded theory analysis, the study identifies three personas (1) advocate, (2) community-minded and (3) sportsperson – through which identity processes are expressed, illustrating the shifts in these personas as participants navigate their volunteer experiences. Implications By acknowledging the fluidity of identity processes and the influence of socio-political contexts, sport organisations can create more inclusive environments that accommodate the varying needs of LGBT+ volunteers. Theoretically, the study contributes to the broader discourse on identity work by demonstrating how personas emerge as outcomes of this work and how they are sustained over time, offering a nuanced understanding of identity processes within sport volunteering.

Self-care practices during the gender transition of Costa Rican transgender men

Relatively little is known about the unique needs and issues faced by transgender men and their self-care practices during gender transition. This study aimed to analyse self-care practices during gender transition through the life histories of a group of Costa Rican transgender men. A qualitative study with a sociohistorical design employing a thematic life history approach was conducted with fourteen participants between April and September 2022. Data were analysed using Content Analysis. Three categories were developed concerning self-care: (i) the shaping of self-care practices throughout different life stages; (ii) self-care practices related to masculinising the body; and (iii) self-care practices on the margins of a cisheteronormative society. The identified self-care practices took place with the goal of materialising men’s gender identity socially, legally and medically. While self-care plays a key role in supporting individuals throughout the transition process, it is limited in its capacity to ensure comprehensive well-being. The social prejudice and violence encountered by transgender men poses a challenge to achieving full well-being. External pressures and adversities limit the effectiveness of self-care practices, highlighting the need for broader systemic change to enhance the overall health and wellness of transgender men in Costa Rica.

Temperature and ultraviolet radiation on a high mountain daphnid: When do interactions become lethal to highly adapted populations?

ABSTRACT Aquatic organisms from high mountain lakes experience extreme influences of climate and solar radiation, especially ultraviolet radiation (UVR), manifested through alterations in physiology, life history, and phenology. Zooplankton, a pivotal component of lake ecosystems, is particularly sensitive to changes in environmental conditions because of their short life cycles and diminished mobility. In the high mountains of the tropical Andes, zooplankton populations are adapted to low temperatures and high UVR because most of the Andean lakes are >4000 m a.s.l. This study focuses on Daphnia pulicaria populations originating from high-mountain Andean lakes, investigating their responses to different temperatures and UVR exposure by means of lab experiments. Key findings indicate that temperature is the most important factor impacting population variables, with high temperatures and UVR exposure leading to unfavorable population outcomes; however, physiological variables (cell viability and pigmentation, measured as melanin) are similarly influenced by temperature and UVR exposure. Pigmentation increases with temperature and is accentuated by solar radiation, indicating an adaptive response to mitigate UVR damage. Conversely, cellular viability declines with elevated temperatures and UVR exposure, showing that higher temperatures may offset the protective effects of pigmentation. Overall, these findings underscore the vulnerability of daphnid populations in high-mountain Andean systems to anticipated climate change impacts, with potential consequences for ecological dynamics in these critical ecosystems. More importantly, they show the importance of studying temperature and UVR (and probably other environmental conditions) as interacting variables because the results will dramatically differ if each factor is considered separately.

Ecology stereotypes exist across societies and override race and family structure stereotypes.

Perceivers hold ecology stereotypes-beliefs about how the environments others live in shape their behavior. Drawing upon a life history perspective, we examine the stereotypes people hold about those who live in relatively harsh and unpredictable ecologies. First, across diverse demographic groups and societies (the United States, India, Japan, Romania, the United Kingdom), people believe that individuals who live in harsh and unpredictable environments engage in "faster" behaviors (n = 2,078; ds from .80 to 2.14)-that they are more impulsive, sexually unrestricted, opportunistic, and invest less in education and their own children (Studies 1, 2, and 3). Second, these ecology stereotypes seem to underlie certain Black/White race stereotypes held by White perceivers in the United States (Study 1) and family structure stereotypes (i.e., growing up in a single-mother home) held by perceivers in both Japan and the United States (Studies 4a and 5a). Supporting this, the application of these race and family structure stereotypes is overridden or attenuated when perceivers are presented with direct information about a specific person's ecology (Studies 1, 4A, and 5B). Third, beliefs that there is high ecological mobility within a society reduce the magnitude of ecology stereotypes (Study 3), as one would expect if ecology stereotypes function to help perceivers better predict others' behavior. Last, ecology stereotypes do not seem to be just general valence biases or to simply reflect social class stereotypes. In sum, ecology stereotypes may be an influential but relatively unexamined type of stereotype, with broad implications for thinking about other group stereotypes. (PsycInfo Database Record (c) 2024 APA, all rights reserved).