Population Fluctuations Research Articles

Examining Population Fluctuation During the Korean Neolithic Period Using Radiocarbon Dates

Examining Population Fluctuation During the Korean Neolithic Period Using Radiocarbon Dates

Natural History of Nonhuman Primates After Oral Exposure to Ebola Virus Variant Makona.

The primary route of infection by Ebola virus (EBOV) is through contact of mucosal surfaces. Few studies have explored infection of nonhuman primates (NHPs) via the oral mucosa, which is a probable portal of natural infection in humans. To further characterize the pathogenesis of EBOV infection via the oral exposure route, we challenged cohorts of cynomolgus monkeys with low doses of EBOV variant Makona. Infection with 100 or 50 PFU of EBOV Makona via the oral route resulted in 50% and 83% lethality, respectively. Animals that progressed to fatal disease exhibited lymphopenia, marked coagulopathy, high viral loads, and increased levels of serum markers of inflammation and hepatic/renal injury. Survival in these cohorts was associated with milder fluctuations in leukocyte populations, lack of coagulopathy, and reduced or absent serum markers of inflammation and/or hepatic/renal function. Surprisingly, 2 surviving animals from the 100- and 50-PFU cohorts developed transient low-level viremia in the absence of other clinical signs of disease. Conversely, all animals in the 10 PFU cohort remained disease free and survived to the study end point. Our observations highlight the susceptibility of NHPs, and by extension, likely humans, to relatively low doses of EBOV via the oral route.

Population fluctuations of grape leafhopper, Arboridia kermanshah (Hemiptera: Cicadellidae), under natural conditions of Kermanshah grapes

Population fluctuations of grape leafhopper, Arboridia kermanshah (Hemiptera: Cicadellidae), under natural conditions of Kermanshah grapes

POTENTIAL IMPACT OF NITROGEN ON POPULATION FLUCTUATION OF APHID AND YIELD PARAMETERS IN BARLEY

The present study was carried out on the farmer field under the supervision of the Department of Plant Protection and Quality Control of Pesticides during 2020 and 2021. Barley cultivar ‘Haider-93’ was sown in a randomized complete block design (RCBD) with three replications to examine the effect of two levels ofnitrogen fertilizer, 50 and 100 kg/ha along with control (no fertilizer), on population fluctuation of aphid and on barley yield components like grain protein (%), 1000-grain weight and the barley grain yield. Aphid incidence was recorded throughout the cropping season. The results revealed that peak infestation of aphids per tiller were recorded in the 3rd week of February in successive year. The study indicated a significant relationship between nitrogen fertilizer and aphid population density per tiller. The mean aphid population per tiller was recorded a significantly higher (34.12 ± 0.81 and 28.65 ± 0.17 for the years 2020 and 2021, respectively) at 100 kg/ha of nitrogen level while lowest infestation (14.51 ± 0.20 and 12.30 ± 0.10 aphids per tiller for the year 2020 and 2021, respectively) was recorded at 0 kg/ha of nitrogen fertilizer. Nitrogen fertilizer level at 100 kg/ha gave significantly higher grain protein (12.80 ± 0.17 and 13.70 ± 0.26% for the years 2020 and 2021, respectively) and grain yield (2758.75 ± 60.82 and 2673.79 ± 61.88 kg/ha produce for the year 2020 and 2021, respectively) of the barley crop. However, treatment differences for 1000-grain weight (g) were recorded as non-significant. These findings suggest that the nitrogen fertilizer at 100 kg/ha level produced significantly higher grain protein (%) and grain yield at the same time, also supported the higher infestation of aphids per tiller. Still, this aphid density did not affect the accumulation of grain protein (%) and grain yield of the barley crop. The results of this study might be used for decision-making to apply nitrogen fertilizer for better grain yield of barley crop but at the same time considering the colonizing aphid population.

RESISTANCE OF CORN (ZEA MAYS L.) GENOTYPES TO NATURAL INFESTATION OF FALL ARMYWORM (SPODOPTERA FRUGIPERDA) (J. E. SMITH, 1797) (LEPIDOPTERA: NOCTUIDAE) IN MOZAMBIQUE

This work aimed to evaluate the resistance of maize genotypes under natural infestation of fall armyworm, known as Spodoptera frugiperda, a polyphagous and highly mobile pest of migratory insects, it causes considerable economic losses in several important crops, has more than 350 hosts of plants, due to its migratory and devastating nature, the fall armyworm is considered to be the main pest of the corn crop, being responsible for causing production losses from 17.7 to 55.6% of the grain yield, which The main control method for this pest insect species is the use of synthetic insecticides, whose incorrect use has been changing the number of applications and decreasing their efficiency, allowing the emergence of populations of resistant insects and negatively affecting the environment, the use of resistant varieties is an agroecological management strategy, for this purpose a field experiment was conducted, using a randomized block design (DBC), with 10 treatments and three replications. The damage of S. frugiperda was evaluated using a visual scale of notes and the monitoring of population fluctuation was carried out weekly, there was a significant difference regarding the level of damage in the samples taken at 21, 28, 35, 42 and 49 days after emergence, the highest pest densities were observed in the Gema, ZM523, SY644, SY5944 and SC403 genotypes, the Namuli, PAN53 and SC403 genotypes showed better grain yield.

MOLECULAR IDENTIFICATION OF INSECT INTERMEDIATE HOSTS WITH POTENTIAL PARASITE TRANSMISSION TO THE DEFINITIVE HOST NORTHERN BOBWHITE (COLINUS VIRGINIANUS).

Grassland birds have been declining substantially for the past several years. Habitat loss, degradation, and fragmentation as well as climate change are all thought to be the main drivers of the decline. However, as the declines continue to accelerate, it is becoming imperative to examine other factors that may contribute to population fluctuations. The nematodes Oxyspirura petrowi, Aulonocephalus pennula, and Physaloptera sp. are commonly found infecting northern bobwhite (Colinus virginianus), a game species of economic importance, and all 3 nematodes use insects as an intermediate host. Here we used polymerase chain reaction techniques to determine the occurrence of the 3 nematodes in 7 insect orders to uncover epidemiological patterns of the greatest potential for transmission to northern bobwhite. Insects were collected from March through September using sweep nets and pitfall traps. An R × C chi-squared test with Monte Carlo simulation was used to determine differences in the occurrence of the parasites across taxa and time. The results of the statistical analysis showed the nematodes are predominantly found in the order Orthoptera, and A. pennula and Physaloptera sp. showed epidemiological patterns in insects. However, no such pattern was observed with O. petrowi. An explanation for the lack of epidemiological pattern in O. petrowi is proposed and the diversity of known insect hosts of the 3 nematodes is increased.

POPULATION FLUCTUATION OF SUCKING INSECTS IN IRRIGATED AND NON-IRRIGATED COTTON CROPS

In the cotton crop (Gossypium hirsutum L.), there is a complexity of pests that appear systematically, thus significantly reducing crop yield; and their population fluctuation is strongly influenced by meteorological conditions that result in a greater or lesser density of these insects. Thus, this work aimed to evaluate the population fluctuation of insect pests with sucking feeding behavior in an area with and without irrigation in the cotton plant under second-harvest conditions. The experiment was developed at the State University of Maringá - Campus of Umuarama. In the experimental area, grid meshes of 10 × 10 m were demarcated, forming plots of 100 m², resulting in a total of 64 points in the irrigated area and 42 points in the non-irrigated area. The sampling points were demarcated in the center of each grid where three randomly selected plants were sampled. Samplings were carried out weekly, from 37 to 122 days after the emergence (DAE) of cotton, examining the aerial part of the plant, to observe the presence of aphids (Aphis gossypii), thrips (Frankliniella schultzei), and whitefly (Bemisia tabaci). The non-irrigated area provided the highest population peaks of whiteflies and thrips. On the other hand, the irrigated area had a higher incidence of aphids. However, with the increase in the population of ladybugs, the incidence of pests reduced significantly, showing the efficiency and importance of the control carried out by natural predators.

Population Fluctuations of the Deer Mouse (Peromyscus maniculatus) in Old-Field and Bunchgrass–Sagebrush Habitats: The Role of Agricultural Setting and Optimum Habitat

In semiarid regions, the deer mouse (Peromyscus maniculatus) is a major small mammal species occupying perennial grassland habitats that include old-fields, native bunchgrass–sagebrush, and some agricultural settings. We investigated population changes in deer mouse populations in perennial grasslands, both natural and old-field, from 1982 to 2003 in southern British Columbia, Canada. Hypotheses (H) predicted that P. maniculatus populations will have (H1) multiannual fluctuations in abundance driven by population increases from extended breeding in summer and winter; (H2) relaxed spring reorganization events in some years leading to higher overall recruitment and survival; and (H3) interspecific competition with montane voles that causes deer mice to be lower in density when voles are higher. P. maniculatus populations in old-field and grass–sagebrush sites had clearly defined periods of high “peak” mean numbers (32–52/ha) and other times of low mean numbers (20–22/ha). Based on mean annual peak density in autumn, deer mouse populations exhibited fluctuations of 3–4 years in both habitats, but this pattern was not always present. The greater numbers of P. maniculatus in high than low years was directly related to population increases from extended breeding seasons and an increased number of lactating females, thereby supporting H1. Spring breeding season declines occurred but were similar or less in high than low years of mean abundance and were relaxed in comparison to forest populations of deer mice in other studies. Thus, H2 was supported for recruitment with high numbers of young-of-the-year breeding and total number of juvenile recruits but for survival was equivocal. Total summer survival was consistently higher in high than low population years but juvenile productivity in all years was poor. Mean abundance of P. maniculatus and M. montanus in old-field sites were highly correlated, and hence H3 was not supported. This latter result is the first, to our knowledge, of P. maniculatus coexisting in a similar pattern of population fluctuations with a Microtus species in a mainland grassland habitat. Higher than average precipitation in the year preceding a peak population of deer mice may have enhanced herbaceous vegetation and contributed to population increases in both habitats. We conclude that the old-field habitat associated with this agricultural setting provides optimum habitat for P. maniculatus and facilitates multiannual population fluctuations in this species.

Should I Stay or Should I Go? Seasonal Fluctuations of Wood Mouse Populations in Fields Surrounded by Woodlands.

The wood mouse Apodemus sylvaticus is common in woodlands and open areas of the Western Palearctic. Despite extensive research, little is known about its population ecology in fields in the Mediterranean area, where the climate involves great seasonal changes in environmental features. Here, we investigated wood mice seasonal fluctuations in the number of captures and population structure by sampling long-fallow fields and woodlands, i.e., oak forest and conifer plantation, in a heterogeneous landscape of central Italy. Mice were live-trapped every two months for three years (23.814 trap-days). The number of captures, mice body weight, and proportion of adult, residents and breeding individuals were analyzed. Mice dynamics changed across seasons and habitats. In fields, we recorded more captures, more reproductive individuals, and fewer non-adults and resident individuals in the warmer months compared to the colder months; mice were heavier in warmer months. During the cold season, the captures and adult proportion in fields were lower than in resource-rich woodlands. Breeding and non-resident mice were more abundant in fields than in woodlands in warmer months. Overall, the seasonal demographic variations we recorded provide evidence that fields can represent a suboptimal habitat in Mediterranean heterogeneous landscapes, acting nonetheless as a source of food resources, cover, and mates for mice in spring-summer.

A Great Escape: resource availability and density‐dependence shape population dynamics along trailing range edges

Populations along geographical range limits are often exposed to unsuitable climate and low resource availability relative to core populations. As such, there has been a renewed focus on understanding the factors that determine range limits to better predict how species will respond to global change. Using recent theory on range limits and classical understanding of density dependence, we evaluated the influence of resource availability on the snowshoe hareLepus americanusalong its trailing range edge. We estimated variation in population density, habitat use, survival, and parasite loads to test the Great Escape Hypothesis (GEH), i.e. that density dependence determines, in part, a species' persistence along trailing edges. We found that variability in resource availability affected density and population fluctuations and led to trade‐offs in survival for snowshoe hare populations in the northeastern USA. Hares living in resource‐limited environments had lower and less variable population density, yet higher survival and lower parasitism compared to populations living in resource‐rich environments. We suggest that density‐dependent dynamics, elicited by resource availability, provide hares a unique survival advantage and partly explain persistence along their trailing edge. We hypothesize that this low‐density escape from predation and parasitism occurs for other prey species along trailing edges, but the extent to which it occurs is likely conditional on the quality of matrix habitat. Our work indicates that biotic factors play an important role in shaping species' trailing edges and more detailed examination of non‐climatic factors is warranted to better inform conservation and management decisions.

Frugivorous Flies of the Drosophilidae, Lonchaeidae and Tephritidae and Their Parasitoids in Brazil

Objective: Brazil is one of the leaders in the production of fruit in temperate climates but is still plagued by pests, particularly frugivorous flies. The damage caused by these insects results in reduced yields and difficulties in exporting due to quarantine barriers imposed by importing countries. The objective of this study was to investigate the main species of frugivorous flies of the Drosophilidae, Lonchaeidae and Tephritidae and their parasitoids in Brazil. Methods: The collected fruits (orange, star fruit, guava, mango, and pitanga) were deposited on a layer of fine sand, in plastic containers, cylindrical, transparent, and open at the top. Each week, the pupae were separated from the substrate by flotation. They were removed and placed in glass flasks with fine sand at room temperature until the emergence of dipterans and/or their parasitoids. Results: In Goiás, Doryctobracon areolatus (Szepligeti, 1911) (Hymenoptera: Braconidae) was the most frequent with 65.0%, and in Minas Gerais, Trichopria anastrepha Costa Lima, 1940 (Hymenoptera: Diapriidae) accounted for 44.4%. In Goiás, Doryctobracon areolatus presented the highest percentage of parasitism with 4.3%, and in Minas Gerais the percentage of parasitism in Trichopria anastrepha was 5.7%. In both states, Zaprionus indianus Gupta, 1970 (Diptera: Drosophilidae) the largest species with the highest percentage of parasitism was Pachycrepoideus vindemmiae (Rondani, 1875) (Hymenoptera: Pteromalidae) with 96.7%. In Psidium guajava, L. (Myrtaceae) the percentage of natural parasitism was 16.7%, being 0.9% by Aganapis pelleranoi (Brèthes, 1924) 8.0%. Conclusion: In Brazil, frugivorous flies are important pests of fruits and vegetables. Knowledge of the population fluctuation of these species in each biome is an important requirement for the adoption of pest control.

Explaining population booms and busts in Mid-Holocene Europe

Archaeological evidence suggests that the population dynamics of Mid-Holocene (Late Mesolithic to Initial Bronze Age, ca. 7000–3000 BCE) Europe are characterized by recurrent booms and busts of regional settlement and occupation density. These boom-bust patterns are documented in the temporal distribution of 14C dates and in archaeological settlement data from regional studies. We test two competing hypotheses attempting to explain these dynamics: climate forcing and social dynamics leading to inter-group conflict. Using the framework of spatially-explicit agent-based models, we translated these hypotheses into a suite of explicit computational models, derived quantitative predictions for population fluctuations, and compared these predictions to data. We demonstrate that climate variation during the European Mid-Holocene is unable to explain the quantitative features (average periodicities and amplitudes) of observed boom-bust dynamics. In contrast, scenarios with social dynamics encompassing density-dependent conflict produce population patterns with time scales and amplitudes similar to those observed in the data. These results suggest that social processes, including violent conflict, played a crucial role in the shaping of population dynamics of European Mid-Holocene societies.

Breeding biology of Red-backed Shrikes (Lanius collurio): distribution, performance and post-fledging survival in Denmark

Agricultural intensification and habitat degradation across Europe have caused declines since the 20th century in populations of birds adapted to open landscapes, such as the Red-backed Shrike (Lanius collurio). Effective conservation strategies require knowledge on species’ breeding biology. To understand the status of the Danish breeding population better, we investigate which factors affect their breeding parameter (i.e. distribution, performance, post-fledging survival and behaviour). Our focus on the post-fledging period addresses present knowledge gaps due to the importance of this, yet under-studied, phase of passerines’ breeding cycle. We studied breeding pairs on different habitat types with Denmark-wide Citizen Science data, complemented by data of local projects in Northern Zealand and Northern Jutland (Denmark). Significantly fewer pairs were found in agricultural habitats and more in forests, semi-natural open habitats and synanthropic habitats. Pairs in forests had a significantly higher breeding productivity compared to agricultural or semi-natural open habitats for data from the years 2000 to 2021. Some project sites showed significantly higher number of fledglings compared to others, indicating that these sites are potential core areas for breeding productivity. Over the last two decades, the mean breeding productivity across Denmark was stable with 2.3 fledglings per successful pair. The survival rate of ringed fledglings increased during the post-fledging period, likely due to their increase in more active and independent behaviour. The relatively low breeding productivity found in this study calls for further studies including detailed data from potentially secondary habitats like agricultural areas to understand the effects of habitat on population fluctuations.

Mites associated with Vitis labrusca (Vitaceae) in southern Brazil: Population dynamics and ecology

Viticulture is one of the main economic activities in Rio Grande do Sul (RS), Brazil, with emphasis on the American grape varieties, Vitis labrusca L. (Vitaceae), used in producing juices and wines. The present work aimed to identify the mite species associated with American grapevines (V. labrusca), their possible natural enemies, and their population fluctuations. The selected varieties were: Bordô (Bd) and Couderc (Cc and Cd) in Dois Lajeados (RS), Bordô (Bi) in Imigrante (RS) and Bordô (Bp), in Putinga (RS). The study was conducted monthly between March 2017 and March 2018, evaluating 20 randomly selected plants from each municipality. We found 5,452 mites belonging to 13 families, distributed across 29 genera and 42 species, or belonging to the suborder Oribatida. Higher mite richness was observed on Cc (12 species) and higher abundance on Cd (2,812 specimens), Cc (868) and Bi (799). Among the predatory mite families, Stigmaeidae had the highest abundance (896 specimens), followed by Phytoseiidae (746). The most abundant species observed were Euseius mesembrinus (Dean), Agistemus riograndensis Johann & Ferla, Tydeus californicus (Banks), Polyphagotars-onemus latus (Banks) and Tarsonemus sp. This is the first study in southern Brazil that evaluates and reports the mite fauna and its ecology on American grape varieties, with high abundance and frequency of predatory mites. This work is important to assist in implementing management techniques that promote the maintenance of predatory mite species in these vineyards.

Density and genetic diversity of grizzly bears at the northern edge of their distribution

AbstractSpecies at the periphery of their range are typically limited in density by poor habitat quality. As a result, the central–marginal hypothesis (CMH) predicts a decline in genetic diversity of populations toward the periphery of a species' range. Grizzly bears (Ursus arctos) once ranged throughout most of North America but have been extirpated from nearly half of their former range, mainly in the south. They are considered a species at risk even in Canada's remote North, where they occupy the northernmost edge of the species' continental distribution in a low‐productivity tundra environment. With climate change, one of their main prey species in the tundra (caribou), which has always shown yearly fluctuations, is declining, but simultaneously, grizzlies appear to be expanding their range northward in the same tundra environment. Yet, a lack of population density estimates across the North is hindering effective conservation action. The CMH has implications for the viability of peripheral populations, and the links between population fluctuations, potential bottlenecks, and genetic diversity need to be determined to contribute to species' conservation. Using noninvasive genetic sampling from 2012 to 2014 and autosomal DNA genotyping (via microsatellites), we estimated bear density using a spatial capture–recapture framework and analyzed genetic diversity using observed heterozygosity (Ho), allelic richness (AR), and expected heterozygosity (He). We compared our findings to other studies that used comparable methodologies on grizzly bears and a related species (black bears; Ursus americanus). We found densities of grizzly bears that were low for the species but characteristic for the region (5.9 ± 0.4 bears/1000 km2), but with high Ho (0.81 ± 0.05), AR (7 ± 0.78), and He (0.71 ± 0.03), despite a signal of recent bottlenecks. In both species, peripherality was not correlated with Ho but was negatively correlated with density. We suggest that the apparent growth of this expanding population of grizzlies offsets the negative impacts of recent bottlenecks on Ho. Indigenous knowledge provides historical context (on the order of centuries, e.g., arctic large mammal fluctuations, grizzly bear bottlenecks) for the current bear population dynamics (on the order of decades, e.g., climate change, northern grizzly bear expansion).

Spatial Heterogeneity Effects on Meta-Community Stability of Annual Plants from a Coastal Dune Ecosystem.

Spatial heterogeneity affects plant community composition and diversity. It is particularly noticeable in annual plant communities, which vary in space and time over short distances and periods, forming meta-communities at the regional scale. This study was conducted at the coastal dune ecosystem in Nizzanim nature reserve, Israel. This study aimed to analyze the effect of the spatial heterogeneity, which is expressed in differences in the fixation levels of the dunes and patches outside and beneath the dominant Artemisia monosperma shrubs, on the characteristics of the annual plant meta-community and its temporal stability, considering the mechanisms that may affect it. Thirteen dunes were studied: three mobile, seven semi-fixed, and three fixed dunes. Data on the annual plants were collected during the spring seasons of 2006, 2007, 2009, 2014, 2015, and 2016. For each dune, 72 quadrats of 40×40 cm were sampled yearly, with 24 quadrats per slope aspect (windward, leeward, and crest), 12 under the shrub, and 12 in the open. The results indicate that the transition from mobile dunes through semi-fixed to fixed dunes is characterized by an increase in annual plant cover, species richness, species diversity, changes in plant communities, and stability driven by the asynchrony of species population fluctuations. Asynchrony affected the stability of the meta-community of this ecosystem in patches beneath the shrubs but not in the open patches.

Ancient Maya movement in the Rio Bravo Conservation and Management Area, NW Belize

Population pressure and migration are often central features of many hypotheses related to ancient Maya population declines, abandonment episodes, settlement, and sociopolitical organization. The Rio Bravo Conservation and Management Area (RBCMA) in northwest Belize shows archaeological evidence for several depopulation and resettlement events. Working hypotheses for the region suggested that the population resettlement and apex of the Late Classic included high numbers of external immigrants. In this paper, we assess movement across ancient Maya settlements from the RBCMA to gauge whether rates of movement overlap with population fluctuations, as garnered by the archaeological record. We present strontium and oxygen isotope data from the dental enamel of 47 ancient Maya individuals recovered from five sites in the RBCMA. We identified seven individuals as being non-local to the region and show potential short-distance movements, where three individuals were local to the RBCMA but not the site from which they were recovered. Our research suggests that movement into and around the RBCMA was steady through time and indicates that rural spaces experienced more movement than their urban counterparts. This may be related to changing regional sociopolitical issues in more urban areas. These data provide insight into both the consistency of movement for the ancient Maya of northwest Belize and the role political activities may have played in prompting movement to more rural areas.

Biological differences between FIM2 and FIM3 fimbriae of Bordetella pertussis: not just the serotype

IntroductionBordetella pertussis still circulates worldwide despite vaccination. Fimbriae are components of some acellular pertussis vaccines. Population fluctuations of B. pertussis fimbrial serotypes (FIM2 and FIM3) are observed, and fim3 alleles (fim3-1 [clade 1] and fim3-2 [clade 2]) mark a major phylogenetic subdivision of B. pertussis. ObjectivesTo compare microbiological characteristics and expressed protein profiles between fimbrial serotypes FIM2 and FIM3 and genomic clades. MethodsA total of 19 isolates were selected. Absolute protein abundance of the main virulence factors, autoagglutination and biofilm formation, bacterial survival in whole blood, induced blood cell cytokine secretion, and global proteome profiles were assessed. ResultsCompared to FIM3, FIM2 isolates produced more fimbriae, less cellular pertussis toxin subunit 1 and more biofilm, but auto-agglutinated less. FIM2 isolates had a lower survival rate in cord blood, but induced higher levels of IL-4, IL-8 and IL-1β secretion. Global proteome comparisons uncovered 15 differentially produced proteins between FIM2 and FIM3 isolates, involved in adhesion and metabolism of metals. FIM3 isolates of clade 2 produced more FIM3 and more biofilm compared to clade 1. ConclusionFIM serotype and fim3 clades are associated with proteomic and other biological differences, which may have implications on pathogenesis and epidemiological emergence.

Population Fluctuations at Equilibrium and Kramers' Rate of Diffusive Barrier Crossing.

For diffusive dynamics, Kramers' expressions for the transition rates between two basins separated by a high barrier has been rederived in many ways. Here, we will do it using the Bennett-Chandler method which focuses on the time derivative of the occupation number correlation function that describes fluctuations of the basin populations at equilibrium. This derivative is infinite at t = 0 for diffusive dynamics. We show that on a slightly longer time scale, comparable to the time it takes the system to fall off the barrier, this time derivative is proportional to the spatial derivative of the committor evaluated at the barrier top. The committor or splitting probability is the probability that the system starting on the barrier ends up in one basin before the other. This probability can be found analytically. By asymptotic evaluation of the relevant integrals, we recover Kramers' result without having had to rely on his formidable physical intuition.

The rough-toothed dolphin genome provides new insights into the genetic mechanism of its rough teeth.

The rough-toothed dolphin (Steno bredanensis) is characterized by having teeth covered in finely wrinkled vertical ridges, which is a general manifestation of amelogenesis imperfecta. The rough surfaces are hypothesized to be an evolutionary morphological trait of feeding adaptation to increase the dolphin's grip on prey. Here, we assembled a rough-toothed dolphin genome and performed the comparative genomic analysis to reveal the genetic basis of the special enamel. Results showed that genes related to enamel development or dental diseases have undergone diversified adaptive changes that may shape the special enamel morphology of this dolphin species, including positive selection (CLDN19, PRKCE, SSUH2, and WDR72), rapid evolution (LAMB3), or unique amino acid substitutions (AMTN, ENAM, MMP20, and KLK4). Meanwhile, the historical demography of rough-toothed dolphin indicated several distinct population fluctuations associated with climate change. The genome-wide heterozygosity of this dolphin is in the middle of all published data for cetaceans. Although the population is considerable, there may be population or subspecies differentiation, and with the global warming and the increasing disturbance of human activities, we should pay more attention to protection in the future. Together, our study brings new insights into the genetic mechanisms that may have driven the evolution of the special enamel morphology in rough-toothed dolphins and provides the first results of genetic heterozygosity and population historical dynamics of this species, which have important guiding implications for the conservation of this dolphin species.