Variation In Body Size Research Articles

Limited population and community effects of hatching asynchrony in a pond‐breeding salamander

AbstractUnderstanding attributes of phenology beyond the mean date of a life history event, such as variability among individuals within a population, is critical to predict how climate‐induced phenological shifts may alter population dynamics. Identifying how phenological variability impacts organisms is especially needed to better understand how phenological shifts affect trophic dynamics (e.g., shifts in variability of top predators affecting primary production). To better understand the effects of phenological variability on both populations and communities, we examined how variation in egg hatching synchrony of predatory marbled salamanders (Ambystoma opacum) impacted intraspecific interactions at the larval stage, ultimately affecting demographic traits and survival through metamorphosis. We also examined how hatching synchrony affected overall trophic dynamics (e.g., primary consumers and producers) in pond food webs. We experimentally manipulated the degree of hatching synchrony of embryonicA. opacumand subsequently reared larvae in outdoor mesocosms. We monitored demographic traits such as larval growth, size at and time to metamorphosis, and survival. To assess trophic dynamics, we monitored zooplankton abundance and phytoplankton biomass during the experiment. Larvae exhibited greater variability in body size in medium and low hatching synchrony treatments compared to high synchrony treatments. Larval body size variation diminished over time to ultimately result in no differences in most life history traits at metamorphosis or survival among hatching synchrony treatments. We also found no differences among treatments in zooplankton abundance or phytoplankton biomass, likely because of minimal variation inA. opacumsurvival among treatments that would induce top‐down changes. Overall, we found that phenological variation may be context dependent in its influence on demography and overall community structure. Because of concerns for how phenological shifts will affect species interactions, greater scrutiny into conditions that would promote changes in population and community dynamics is needed.

Seasonality rather than average temperature explains body size variation in a Neotropical fruit‐eating bat

AbstractWe investigated variation in body size of the widely distributed Neotropical bat Chiroderma villosum across its entire range. Our objective was to verify if the size‐related geographic variation in the species is related to environmental variables. We took 13 measurements of 410 specimens from 198 localities in Mesoamerica and South America, and collected information on latitude, longitude, altitude, precipitation, and temperature, totalling 22 variables. We detected clinal variation in size related to latitude and longitude, with a pattern that conforms to the Bergmann's rule. Clinal variation of size along longitude was influenced by the taxonomic component, with subspecies C. v. jesupi being smaller than C. v. villosum. In contrast the latitudinal cline was explained by temperature seasonality and precipitation, with a 14% increase in size between the north and south extremes of the range. In other words, size of individuals is larger in areas with more seasonal oscillations in temperature and with lower precipitation. Our results support the notion that low temperatures alone do not explain large size of mammals in high latitudes. One hypothesis is that large size is favoured in more seasonal climates because somatic growth is faster when resources are abundant, and also larger animals can endure food scarcity better than small ones. We also postulate that pressures related to interspecific competition and resource use may be more intense in more areas marked by seasonal climatic variations. Specifically, a larger size in seasonal areas may allow individuals to explore a wider niche. We suggest that future approaches, refining regional variation in the diet of C. villosum may serve as a further test to this hypothesis.

Increases in intraspecific body size variation are common among North American mammals and birds between 1880 and 2020.

Many studies have documented the average body size of animals declining over time. Compared to mean body size, less is known about long-term changes in intraspecific trait variation (ITV), which is also important to understanding species' ability to cope with environmental challenges. On the basis of 393,499 specimen records from 380 species collected in North America between 1880 and 2020, we found that body size ITV increased by 9.59% for mammals (n = 302) and 30.67% for birds (n = 78); human-harvested species had higher probability of ITV increase. The observed increasing ITV in many species suggests possible niche expansion and potential buffering effects against downsizing but it risks increased maladaptation to rapidly changing environments. The results demonstrate that trait mean and variance do not necessarily respond in similar ways to anthropogenic pressures and both should be considered.

Increasing body-size variation in many downsizing North American mammals and birds.

Increasing body-size variation in many downsizing North American mammals and birds.

Can transport costs explain the near absence of marmot bones at shoreline archaeological sites on Vancouver Island? Finding input values for central place modelling with biological scaling

Central place models test economic optimization hypotheses about resource processing and transport in archaeological contexts. These models require input values for the weights of resource portions, values that are typically found through the empirical measurement of one or a few specimens of a taxon of interest. This method is limited by the availability of specimens for measurement and often relies on small sample sizes that cannot account for body size variation due to factors such as age, sex, health, and genetics. As an alternative, biological scaling equations are introduced with which mammalian resource portion weight averages with standard deviations can be estimated across a range of body sizes in a mammalian taxon. A case study from the Northwest Coast of North America operationalizes this approach. The study asks if economic factors can account for a difference in the relative abundance of marmot (Marmota vancouverensis) bones at high-elevation archaeological sites compared with shoreline middens on Vancouver Island. Results indicate that abundant marmot skeletal elements at high-elevation sites are consistent with the economic benefit of processing these small mammals close to capture sites. Transport costs can explain the near absence of marmot bones at shoreline sites in the study area, a conclusion that does not preclude alternative explanations. This study demonstrates that biological scaling equations are useful for estimating mammalian resource portion input values in theoretical modelling.

Abstract IA021: Studies of aging, morphology, and cancer in the domestic dog

Abstract Each of the nearly 450 domestic dog breeds in existence today has a unique history and genetic profile. Early in the domestication process, dogs were bred to perform specific tasks such as herding, guarding and hunting. Later, fanciers developed hundreds of breeds, often displaying variation in body morphology, including shape and size, in addition to coat color, skull shape, leg length, etc. We are interested in understanding the genetic underpinnings of that variation, and applying those results to studies of growth regulation, normal and abnormal behavior and disease susceptibility. Dogs are a naturally-occurring model for many complex human disorders, including cancer. One in two dogs that live to be ten or older will develop cancer in their lifetimes, with most common human cancers occur spontaneously in dogs. This offers unique opportunities to study cancer susceptibility, progression and treatment response. The high rate of single types of cancer in some breeds, such as histiocytic sarcoma in Bernese Mountain Dogs or invasive bladder cancer in Scottish Terriers offers specific advantages for genetic studies that do not exist in human population studies. As with cancer, domestic dogs present interesting opportunities for studies of aging. Surprisingly, small breeds typically live longer than larger breeds, offering the chance to study the interaction between morphology and lifespan. To take advantage of these opportunities, we have assembled the largest and most diverse dataset of dog breeds and other canines to date, with canines originating from six continents, reflecting the extensive phenotypic variation and heritage that coalesce in modern dogs, and identified over 90 million single nucleotide variants. In this presentation we explore the genetics of cancer and aging in dogs, drawing parallels to the human condition. Citation Format: Elaine A. Ostrander. Studies of aging, morphology, and cancer in the domestic dog [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr IA021.

An integrative paleobiological study of woolly mammoths from the Upper Paleolithic site Kostenki 14 (European Russia)

This paper presents a thought-out protocol for an integrative analysis of woolly mammoth (Mammuthus primigenius) bone accumulation in the upper (I) cultural layer of the famous Upper Paleolithic site Kostenki 14 (Markina gora) using Haynes’ concept of a “demographic health measure,” the advanced concept of the “last glacial body size decrease,” and precise taphonomic analysis. We apply linear regression analysis to further reveal the complex structure of mammoth size variation, complementary to univariate measures of body size used in previous studies: body size variation in woolly mammoths is predominantly accounted for by sexual dimorphism, size differences between smaller “East” and larger “West” mammoth populations, and two types of allometry (ontogenetic and static). Our analysis indicated natural formation of the bone assemblage in the cultural layer I at the Kostenki 14 site: this formation is based on the L-shaped age-sex profile obtained via depositional-time averaging of recurring nonselective death events, also confirmed by the taphonomic analysis. Our results suggest that the mammoth bone assemblage accumulated under local conditions of varying moisture in deposits at a mammoth watering place. We can hypothesize relatively long-term inhabitation of this area by mammoths and permanent visitation of the site featuring an available source of water (a spring) and possibly salt.

Gnawing pressure led to the expansion of JAZ genes in angiosperms

A long-standing problem in evolutionary biology is why some populations differentiate into many species while the majority do not. Angiosperms is an excellent group for investigating this problem because their diversity is unevenly distributed in space and phylogeny. Plant hormone participates in growth, development and defense. However, jasmonic acid (JA) was the only hormone response to bites. We first searched jasmonate ZIM-domain (JAZ), AUXIN/INDOLE ACETIC ACID (IAA / aux), PYR/PYL/RCAR (PYL), DELLA, and SUPPRESSOR OF MAX2 1-like (SMAX) in 272 plant species. We found the gene number change trends were consistent with origination rates and species numbers of angiosperms. So, 26 representative species were selected as an example for further analysis. The results showed JAZ had experienced two lineage-specific gene expansion events in angiosperms, which coincided with increases in mammalian body size and dental diversity. The proliferation of large herbivores as a results of mammalian prosperity after dinosaur extinction may be related to angiosperm evolution and bursting. The proliferation of large herbivores as the result of mammalian prosperity after the extinction of the dinosaurs was related to angiosperm evolution and bursting. Overall, our study uncovered a previously unknown co-evolution mechanism in terrestrial plants exposed to extreme environmental conditions.

The selected genes NR6A1, RSAD2-CMPK2, and COL3A1 contribute to body size variation in Meishan pigs through different patterns.

The high-fertility Meishan pig is currently categorized into medium sized (MMS) and small sized (SMS) based on body size. To identify causal genes responsible for the variation in body size within the two categories, we sequenced individuals representing the entire consanguinity of the existing Meishan pig. This enabled us to conduct genome selective signal analysis. Our findings revealed the genomes of MMS and SMS are stratified, with selective sweep regions formed by differential genomic intervals between the two categories enriched in multiple pig body size related quantitative trait loci (QTLs). Furthermore, the missense mutation c.575T > C of candidate causal gene NR6A1, accounting for the variation in lumbar vertebrae number in pigs, was positively selected in MMS only, leading to an increase in body length of MMS at 6 months of age. To precisely identify causal genes accounting for body size variation through multi-omics, we collected femoral cartilage and liver transcription data from MMS and SMS respectively, and re-sequencing data from pig breeds exhibiting varying body sizes. We found that two selected regions where the RSAD2-CMPK2 and COL3A1 genes are located, respectively, showed different haplotypes in pig breeds of varying body size, and was associated with body or carcass length in hybridized Suhuai pig. Additionally, the above three hub genes, were significantly greater expressed in SMS femoral cartilage and liver tissues compared to MMS. These three genes could strengthen the pathways related to bone resorption and metabolism in SMS, potentially hindering bone and skeletal development and resulting in a smaller body size in SMS. These findings provide valuable insights into the genetic mechanism of body size variation in Meishan pig population.

Ecological mechanisms generating variable first-year growth in Paralichthys lethostigma, a coastal flatfish

Determining the relative influence of, and possible synergistic relationships among, environmental and biotic processes on individual growth rates can identify key mechanisms that contribute to variation in body size observed among similar-aged individuals. The timing of ontogenetic shifts in diet or habitat, which themselves can be size-dependent, can have considerable impacts on individual growth trajectories, survival, and year class formation. The southern flounder Paralichthys lethostigma is a coastal flatfish species with juvenile cohorts that occupy diverse estuarine settlement habitats and commonly display 2-3 fold variation in body size by the end of the first growing season. We examined abiotic and biotic factors contributing to differences in early juvenile growth for the 2018 year-class of southern flounder in a North Carolina estuary. Following peak larval settlement (Febuary/March), flounder body sizes began to diverge by April, with differences between settlement habitats contributing to roughly 3-fold variation by August. Stomach content analyses indicated a greater occurrence of fish prey in the diets of southern flounder recovered in mesohaline versus oligohaline settlement habitats. Increased piscivorous foraging in mesohaline habitats was linked to nitrogen (δ15N)-enriched tissues and faster growth rates relative to fish collected in oligohaline habitats. Results from a controlled laboratory experiment provided evidence for the strong effects of diet, with only minor direct effects of salinity on juvenile southern flounder growth. Our findings support the critical role of ontogenetic shifts to piscivorous feeding for growth in young-of-the-year southern flounder and highlights the potential for growth-mortality tradeoffs to exist among estuarine settlement habitats.

Phenotypic extremes or extreme phenotypes? On the use of large and small-bodied "phenocopied" Drosophila melanogaster males in studies of sexual selection and conflict.

In the fruit fly, Drosophila melanogaster, variation in body size is influenced by a number of different factors and may be strongly associated with individual condition, performance and success in reproductive competitions. Consequently, intra-sexual variation in size in this model species has been frequently explored in order to better understand how sexual selection and sexual conflict may operate and shape evolutionary trajectories. However, measuring individual flies can often be logistically complicated and inefficient, which can result in limited sample sizes. Instead, many experiments use large and/or small body sizes that are created by manipulating the developmental conditions experienced during the larval stages, resulting in "phenocopied" flies whose phenotypes resemble what is seen at the extremes of a population's size distribution. While this practice is fairly common, there has been remarkedly few direct tests to empirically compare the behaviour or performance of phenocopied flies to similarly-sized individuals that grew up under typical developmental conditions. Contrary to assumptions that phenocopied flies are reasonable approximations, we found that both large and small-bodied phenocopied males frequently differed from their standard development equivalents in their mating frequencies, their lifetime reproductive successes, and in their effects on the fecundity of the females they interacted with. Our results highlight the complicated contributions of environment and genotype to the expression of body size phenotypes and lead us to strongly urge caution in the interpretation of studies solely replying upon phenocopied individuals.

Nuclear Cytoplasmic Conflict in Hybrids of Roach <i>Rutilus rutilus</i> and Bream <i>Abramis brama</i> as a Consequence of the Divergence Species in Body and Genome Sizes

Species divergence in body size is often associated with changes in genome size and the rate of evolution of mitochondrial DNA (mtDNA), which can lead to problems of nuclear-cytoplasmic compatibility and embryonic genome activation and reduce the fitness of hybrids. The bream Abramis brama (L.) is larger than the roach Rutilus rutilus (L.) in body and genome sizes. In the first generation of hybrids according to the ITS1 region of ribosomal DNA, a change in the donor genome of male to the level of the maternal species was previously established, which can affect the inheritance of traits from the male and, in particular, body size. Body length and height, a complex of diagnostic morphological characters, and genotyping (ITS1 rDNA and cyt b mtDNA) of underyearlings and mature individuals of bream, roach, F1 hybrids and underyearlings of backcrosses (Fb) were analyzed. Sexually mature hybrids of both directions of crossing are close in body length to R. rutilus, which indicates a violation of the paternal effect when inheriting the body length of a larger of species. Violation of the inheritance of bream body length in hybrids of cross R. rutilus × A. brama (♀ ♂, RA) is considered as a developmental deviation, which, obviously, can affect the adaptation of hybrids and determines the rarity of this variant in nature. At the same time, alloplasmic ARR backcrosses restore the body length of the bream even in the presence of the roach nuclear genome, which indicates the influence of mitochondrial genes on the development of this trait. The observed decrease in the fitness of first-generation hybrids with roach mtDNA may be associated with to an insufficient level of transcription of ribosomal genes due to a decrease in the number and variability of copies of the donor bream rDNA. Moreover, the high level of changes of mtDNA roach indicate a suboptimal mitochondrial-nuclear correspondence of respiratory a complexes in hybrids RA, which negatively affects key physiological processes, including growth and development of a large body size. Presumably, the development of large body size, as a complex trait with high aerobic fitness, is blocked in RA hybrids for energy reasons. The paper shows that differences families of repeated sequences rDNA and mtDNA in terms of the number and variability of copies in genome of R. rutilus and A. brama can lead to regulatory nuclear-cytoplasmic incompatibility of genomes and affect the fitness of hybrids already in the first generation.

Resource availability modulates the effect of body size on reproductive development.

Within-species variation in animal body size predicts major differences in life history, for example, in reproductive development, fecundity, and even longevity. Purely from an energetic perspective, large size could entail larger energy reserves, fuelling different life functions, such as reproduction and survival (the "energy reserve" hypothesis). Conversely, larger body size could demand more energy for maintenance, and larger individuals might do worse in reproduction and survival under resource shortage (the "energy demand" hypothesis). Disentangling these alternative hypotheses is difficult because large size often correlates with better resource availability during growth, which could mask direct effects of body size on fitness traits. Here, we used experimental body size manipulation in the freshwater cnidarian Hydra oligactis, coupled with manipulation of resource (food) availability to separate direct effects of body size from resource availability on fitness traits (sexual development time, fecundity, and survival). We found significant interaction between body size and food availability in sexual development time in both males and females, such that large individuals responded less strongly to variation in resource availability. These results are consistent with an energy reserve effect of large size in Hydra. Surprisingly, the response was different in males and females: small and starved females delayed their reproduction, while small and starved males developed reproductive organs faster. In case of fecundity and survival, both size and food availability had significant effects, but we detected no interaction between them. Our observations suggest that in Hydra, small individuals are sensitive to fluctuations in resource availability, but these small individuals are able to adjust their reproductive development to maintain fitness.

Variability in bat morphology is influenced by temperature and forest cover and their interactions.

Multiple climatic and landscape drivers have been linked to variations in bat body size and wing functional traits. Most previous studies used proxies rather than actual climate and land-use data, and their interactions are rarely explored. We investigate whether higher summer average temperatures are driving decreasing bat body size as predicted by Bergmann's rule or increasing appendage size as per Allen's rule. We also explore whether temperature or resource availability (namely forest cover) is responsible for changes in wing functional traits. Using land-use data from historical maps and national statistics combined with climatic data, we assessed the effect of temperature and resource availability on bat morphology. We used 464 museum specimens of three bat species (Eptesicus nilssonii, Pipistrellus pygmaeus, and Plecotus auritus), spanning 180 years, across a 1200 km latitudinal gradient. We found no evidence of higher summer average temperatures driving decreases in body size in bats. Jaw sizes of P. auritus and P. pygmaeus changed over time but in different directions. The geographical variation of forest cover was also related to differences in wing functional traits in two species. Crucially, there was a significant antagonistic interactive effect of forest and temperature on tip index in P. pygmaeus whereby above 14.5°C the relationship between forest and tip index actually reversed. This could indicate that higher temperatures promote more pointed wings, which may provide energetic benefits. Our results show the importance of including both climatic and land-use variables when assessing trends in bat morphology and exploring interactions. Encouragingly, all three species have shown an ability to adapt their body size and functional traits to different conditions, and it could demonstrate their potential to overcome future negative impacts of climate and land-use change.

Body size, maturation and motor performance in young soccer players: relationship to technical actions in small-sided games

The objective of this study was to investigate the relative contributions of body size, skeletal age, and motor performance variables with technical actions through an ecological model during small-sided soccer games, and the interaction of biological maturation with technical and motor performance in young players. In this cross-sectional study, eighty-two young players (14.4 ± 1.1 years), belonging to state-level soccer teams and divided by category (U-13 and U-15), were included. Players having an injury in the evaluation period were not included in the study. Measurements of body size, skeletal age (SA), motor tests, and technical actions in small-sided games (SSG) were performed (3 × 3 plus goalkeeper) in two periods (halves) of four minutes. Differences between age groups were found for SA (ES = -2.36), chronological age (ES = -3.89), body mass (ES = -2.09), height (ES = -1.90), and fat-free mass (ES = -2.09). Positive associations were found between body size (R = 0.43 to R = 0.48) and manipulation (R = 0.50 to R = 0.52) indicators and numbers of technical actions (CB and SS), except for stature with LB (R = -0.42) in the U-13 age group. In the U-15 category, skeletal age (R = -0.29 to R = -0.30) and body mass (R = -0.28 to R = -0.29) were negatively associated with the number of technical actions (RB, NB, LB, and OB) (P > 0.05) and positively with the balance with LB (R = 0.26). In conclusion, body size, SA, and motor performance influenced technical actions in SSG differentially in each category. U-13 heavier players and those with a better motor performance presented higher involvement due to the higher.

Out of the tropics: Macroevolutionary size trends in an old insect order are shaped by temperature and predators

AbstractAimGlobal interspecific body size distributions have been suggested to be shaped by selection pressures arising from biotic and abiotic factors such as temperature, predation and parasitism. Here, we investigated the ecological and evolutionary drivers of global latitudinal size gradients in an old insect order.LocationGlobal.TaxonOdonata (dragonflies and damselflies).MethodsWe compiled data on interspecific variation in extant and extinct body sizes of Odonata, using an already existing database (The Odonate Phenotypic Database) and fossil data (The Paleobiology Database). We combined such body size data with latitudinal information and data on biotic and abiotic environmental variables across the globe to investigate and quantify interspecific latitudinal size‐gradients (“Bergmann's Rule”) and their environmental determinants. We used phylogenetic comparative methods and a global published phylogeny of Odonata to address these questions.ResultsPhylogenetic comparative analyses revealed that global size variation of extant Odonata taxa is negatively influenced by both regional avian diversity and temperature, with larger‐bodied species in the suborder Anisoptera (dragonflies) showing a steeper size‐latitude relationship than smaller‐bodied species in the suborder Zygoptera (damselflies). Interestingly, fossil data show that the relationship between wing size and latitude has shifted: latitudinal size trends had initially negative slopes but became shallower or positive following the evolutionary emergence and radiation of birds.Main ConclusionsThe changing size‐latitude trends over geological and macroevolutionary time were likely driven by a combination of predation from birds and maybe pterosaurs and high dispersal ability of large dragonflies. Our study reveals that a simple version of Bergmann's Rule based on temperature alone is not sufficient to explain interspecific size‐latitude trends in Odonata. Our results instead suggest that latitudinal size gradients were shaped not only by temperature but also by avian predators, potentially driving the dispersal of large‐sized clades out of the tropics and into the temperate zone.

Interactions between life history and the environment on changing growth rates of Chinook salmon

Fish in all the world's oceans exhibit variable body size and growth over time, with some populations exhibiting long-term declines in size. These patterns can be caused by a range of biotic, abiotic, and anthropogenic factors and impact the productivity of harvested populations. Within a given species, individuals often exhibit a range of life history strategies that may cause some groups to be buffered against change. One of the most studied declines in size-at-age has been in populations of salmon; Chinook salmon in the Northeast Pacific Ocean are the largest-bodied salmon species and have experienced long-term declines in size. Using long-term monitoring data, we develop novel size and growth models to link observed changes in Chinook size to life history traits and environmental variability. Our results identify three distinct trends in size across the 48 stocks in our study. Differences among populations are correlated with ocean distribution, migration timing, and freshwater residence. We provide evidence that trends are driven by interannual variation in certain oceanographic processes and competition with pink salmon.

Egg size-dependent embryonic development in the desert locust, Schistocerca gregaria

Phenotypic plasticity in body size is a product of modification of the developmental pathway. Although hatchlings of the desert locust, Schistocerca gregaria, show egg size-dependent plasticity in body size, it remains unclear how embryogenesis during egg development regulates final embryonic body size. To determine the developmental pathway causing body size variation at hatching, we examined egg and embryonic development at the early, middle, and late egg developmental stages in S. gregaria by comparing small and large eggs. Crowd-reared females produced larger eggs than isolated-reared females. The daily egg developmental rate was similar between small and large eggs: eggs dramatically absorbed external water after days 3 to 7 and nearly doubled the initial egg weight at the late stage of day 12. Morphological measurements of eggs and embryos at different days after oviposition revealed that large eggs were longer than small eggs throughout developmental stages. However, embryo length was similar between small and large eggs at the early stage (anatrepsis). Embryos begin to absorb yolk into their bodies after blastokinesis. The size of large-egg embryos increased significantly from the middle stage (katatrepsis) due to absorption of more yolk than small eggs. Egg length and embryo length were conspicuously larger in large eggs than in small eggs on day 12 of late katatrepsis. These results suggest that egg size did not influence the egg developmental rate and initial embryo size. Large eggs had more yolk and space, resulting in larger final embryos than small eggs. The amount of yolk and size of eggshells during katatrepsis could play a key role in determining hatchling body size in S. gregaria.

Genome-wide association study analysis to resolve the key regulatory mechanism of biomineralization in Pinctada fucata martensii.

Biomineralization-controlled exo-/endoskeleton growth contributes to body growth and body size diversity. Molluscan shells undergo ectopic biomineralization to form the exoskeleton and biocalcified "pearl" involved in invading defence. Notably, exo-/endoskeletons have a common ancestral origin, but their regulation and body growth are largely unknown. This study employed the pearl oyster, Pinctada fucata marntensii, a widely used experimental model for biomineralization in invertebrates, to perform whole-genome resequencing of 878 individuals from wild and breeding populations. This study characterized the genetic architecture of biomineralization-controlled growth and ectopic biomineralization. The insulin-like growth factor (IGF) endocrine signal interacted with ancient single-copy transcription factors to form the regulatory network. Moreover, the "cross-phylum" regulation of key long noncoding RNA (lncRNA) in bivalves and mammals indicated the conserved genetic and epigenetic regulation in exo-/endoskeleton growth. Thyroid hormone signal and apoptosis regulation in pearl oysters affected ectopic biomineralization in pearl oyster. These findings provide insights into the mechanism underlying the evolution and regulation of biomineralization in exo-/endoskeleton animals and ectopic biomineralization.

Geographical Variation in Body Size and the Bergmann's Rule in Andrew's Toad (Bufo andrewsi).

Environmental variation likely modifies the life-history traits of vertebrates. As ectothermic vertebrates, it is possible that the body size of amphibians is impacted by environmental conditions. Here, we firstly quantified age and body size variation in the Andrew's toad (Bufo andrewsi) across the Hengduan Mountains. Then, we examined the environmental correlates of this variation based on the literature and our unpublished data on the age and body size of the Andrew's toad from 31 populations distributed in southwestern China. Although our analysis revealed significant variations in age and body size across B. andrewsi populations, neither latitude nor altitude correlated with this variability in age and body size. We found that age at sexual maturity, mean age, and longevity increased with decreasing annual mean temperature, whereas age at sexual maturity increased with decreasing temperature seasonality, implying that temperature was a crucial habitat characteristic that modulated age structure traits. Moreover, we revealed positive associations between age structure and UV-B seasonality, and negative relationships between both mean age and longevity and precipitation seasonality. We also found that body size increased with increasing precipitation in the driest month and UV-B seasonality. However, body size did not covary with temperature, signifying no support for Bergmann's rule. These findings help us to understand amphibians' abilities to adapt to environmental variation, which is particularly important in order to provide a theorical basis for their conservation.