Lake Populations Research Articles

Using Radiotelemetry to Inform and Guide Muskellunge Culture and Stocking Techniques in Spirit Lake, Iowa

Abstract Agencies commonly stock Muskellunge Esox masquinongy to maintain or augment populations throughout much of North America. Muskellunge poststocking survival is variable, and adult populations are vulnerable to periodic lapses in recruitment. Radiotelemetry evaluated whether changes in stocking techniques caused recruitment declines of spring-stocked yearling Muskellunge in Spirit Lake, Iowa, or whether total length, condition, or 10-d dispersal influenced poststocking survival. The workers fitted hatchery-reared Muskellunge (38–40 fish; n = 78 fish in total) with radio transmitters and stocked in May 2016–2017 by using one of two techniques: 1) fish stocked immediately following 6-h transport in a hatchery distribution truck with Edwards treatment–laden water or 2) fish provided 36-h recovery period after a hauling event and then stocked. Radiotelemetry revealed that stocking techniques did not influence Muskellunge survival or dispersal, but survival significantly improved for fish stocked at larger sizes. Using this information, production techniques in 2018–2019 included an additional 33–40-d rearing period for Muskellunge less than 330 mm when measured for total length in mid-May. We radiotagged a subset of these fish (14–16 fish/y; n = 30 fish total), and survival improved to more than 73.4%. Subsequent application of telemetry was via a side-by-side comparison in 2020 for greater than or equal to 330-mm Muskellunge fitted with radio transmitters and stocked in May (n = 17 fish) and those reared using the grow-out procedure and stocked in June (n = 21 fish). Both cohorts experienced poor survival (39.2–56.1%), resulting from both fish and great blue heron Ardea herodias predation, despite large differences in dispersal. Regardless of stocking technique, this study identified that most mortality occurred within the first 25 d poststocking. These results indicate that Muskellunge populations in natural lakes would benefit from a better understanding of poststocking survival and stocking practices that minimize predator threats during this critical period.

Chromosome-Level Genome Assembly and Whole-Genome Resequencing Revealed Contrasting Population Genetic Differentiation of Black Bream (Megalobrama skolkovii) (Teleostei: Cyprinidae) Allopatric and Sympatric to Its Kin Species.

The black bream (Megalobrama skolkovii) is an economically important species widely distributed in China, with its geographic populations potentially having undergone differentiations and local adaptations. In this study, we presented a chromosome-level genome assembly of this species and investigated genetic differentiations of its populations that are allopatric (the northern one) and sympatric (the Poyang Lake) to its kin species, the blunt-snout bream (M. amblycephala), using whole genome resequencing analysis. The results showed that the genome size of black bream was 1.13 Gb, very similar to its kin species but larger than its close relatives, the four Chinese major carps. By resequencing individuals from the northern and Poyang Lake populations, we found that the northern population showed lower genetic diversity, larger genetic differentiation, and two sharp historical declines in population size through demographic analysis, indicating the possible bottlenecks after the allopatric isolation. In contrast, the Poyang Lake population, with its higher genetic diversity, higher Tajima's D value, and lower levels of linkage disequilibrium, reflects the ancestral state of black bream. In addition, we also found that the northern population shared more alleles with its kin species, indicating it may retain more ancestral variations. This was further analyzed to be caused by incomplete lineage sorting and ancient introgression. Some key genes related to reproductive processes, body size development, and muscle metabolism were found under selection in the northern population, possibly responsible for its local adaptation. Our findings that the black bream allopatric population had a loss of genetic diversity but retained more ancestral variations can expand our knowledge on population genetic differentiation and give us hints for future genetic conservation.

Features of the Structure and Nutrition of the Fish Population in Mountain Glacial Lakes on the Western Slopes of the Urals

The paper analyzes the modern structure and food relations of the fish population of the small glacial lakes of the Urals. The features that are expressed primarily in the reduction of the species richness of the local ichthyofauna and the predominance of a single-species fish population are revealed. The number of fish species inhabiting these reservoirs correlates with the height of their location above sea level, the area and the value of the redox potential of water. It is shown that the fish population of many small Ural lakes of the Pechora River basin is formed by a single species. It is established that the single-species fish part of the aquatic communities of mountain lakes can be represented by Arctic char, Siberian and European grayling, pike, lake and common minnow, roach and perch. The maximum number of such lakes was found in the highest mountainous region of the Circumpolar Urals. The relative abundance of fish and shifts in the trophic structure of the fish part of aquatic communities are considered. Fish-ichthyophages mainly switch to eating invertebrates, while cases of cannibalism are rare. The data obtained are analyzed from the standpoint of modern ideas about the glacial history of the Urals.

Functional traits and adaptation of lake microbiomes on the Tibetan Plateau

BackgroundTibetan Plateau is credited as the “Third Pole” after the Arctic and the Antarctic, and lakes there represent a pristine habitat ideal for studying microbial processes under climate change.ResultsHere, we collected 169 samples from 54 lakes including those from the central Tibetan region that was underrepresented previously, grouped them to freshwater, brackish, and saline lakes, and generated a genome atlas of the Tibetan Plateau Lake Microbiome. This genomic atlas comprises 8271 metagenome-assembled genomes featured by having significant phylogenetic and functional novelty. The microbiomes of freshwater lakes are enriched with genes involved in recalcitrant carbon degradation, carbon fixation, and energy transformation, whereas those of saline lakes possess more genes that encode osmolyte transport and synthesis and enable anaerobic metabolism. These distinct metabolic features match well with the geochemical properties including dissolved organic carbon, dissolved oxygen, and salinity that distinguish between these lakes. Population genomic analysis suggests that microbial populations in saline lakes are under stronger functional constraints than those in freshwater lakes. Although microbiomes in the Tibet lakes, particularly the saline lakes, may be subject to changing selective regimes due to ongoing warming, they may also benefit from the drainage reorganization and metapopulation reconnection.ConclusionsAltogether, the Tibetan Plateau Lake Microbiome atlas serves as a valuable microbial genetic resource for biodiversity conservation and climate research.9n3SXpnTm6EbgSwcGAa_6cVideo

Рост окуня Perca fluviatilis L., 1758 (Percidae) в казахстанской части бассейна Ишима

The growth of Eurasian perch in water bodies within the Ishim River system in the Republic of Kazakhstan has been investigated. Data from 29 samples from various water bodies of the Ishim watershed and some adjacent watersheds are presented. The most extensive age series were found in specimens from Lake Lobanovo (National Park “Kokshetau”) – up to sixteen years (15+). River populations had a shorter lifespan. Comparison of growth rate patterns indicates the presence of two conditional “units”: the first includes the majority of lake populations, while the second includes Karatomarskoe Reservoir and Lake Lobanovo. Some samples are located outside of these groupings. The examined chronological samples show significant differences in growth for some. This is typical for Lake Karakol and, partialy, – the Ishimskoe Reservoir, where positive hydrological changes occurred between perch catches years, resulting in increased growth rates. These samples exhibit a low level of correlation in growth indicators between adjacent ages, indicating disruption in growth rate “canalization” and the acquisition of opportunities for individuals in a renewed unbalanced habitat environment. In relatively stable conditions of most other water bodies, the correlation level of these data indicators is high for the majority of comparison pairs. When comparing Ishim populations with previously published data on the Nura and Sarysu river watersheds re-garding growth rates, one can empirically conclude about the more successful growth of perch in the Nura-Sarysu watershed. However, it should be noted that mainly water bodies without commercial fishing and with developed recreational fishing were studied in the Ishim watershed. In contrast, water bodies with predominant commercial fishing were surveyed in the Nura-Sarysu system. The different impacts of these types of fishing may determine both the growth rates and the lifespan of perch.

Reconstructing half a century of coregonine recruitment reveals species-specific dynamics and synchrony across the Laurentian Great Lakes

Abstract Understanding how multiple species and populations vary in their recruitment dynamics can elucidate the processes driving recruitment across space and time. Lake Whitefish (Coregonus clupeaformis) and Cisco (C. artedi) are socioecologically important fishes across their range; however, many Laurentian Great Lakes populations have experienced declining, poor, or sporadic recruitment in recent decades. We integrated catch and age data from 38 long-term surveys across each of the Great Lakes and Lake Simcoe, resulting in a combined time series spanning 1960–2019. We estimated Lake Whitefish and Cisco year-class strength (YCS) in each lake using longitudinal mixed-effects regressions of relative cohort abundance. We subsequently quantified interspecific, spatial, and temporal synchrony in YCS using correlation and dynamic factor analyses. Lake Whitefish YCS was positively spatially synchronous on average, and YCS in all six lakes was elevated during the 1980s–1990s. In contrast, Cisco YCS was sporadic, not spatially synchronous, and highly variable around long-term, lake-specific means. YCS was not synchronous between species in any lake. Collectively, our analyses demonstrate that these species exhibit differential recruitment dynamics that may be regulated by species-specific factors. Results from this study can be leveraged in future research on the causes and consequences of cross-species, cross-basin recruitment variability.

Emergence and persistence of Cyvirus cyprinidallo 2 (CyHV-2) in Prussian carp in Serbian lakes

Between 2018 and 2021, significant die-offs of Prussian carp (Carassius gibelio) occurred in five lakes in eastern, central and northern Serbia. In all cases, Cyvirus cyprinidallo 2, formerly named Cyprinid herpesvirus 2 (CyHV-2) infection was suspected, based on initial diagnostic observations. To determine the cause of these mass mortalities, real-time PCR assays targeting CyHV-2, CyHV-3, and SVCV were conducted. CyHV-2 DNA was detected in the affected populations, while SVCV and CyHV-3 were negative in the assay. The CyHV-2 was also detected in asymptomatic Prussian carp. Sequence analysis of the CyHV-2 DNA polymerase and helicase genes revealed high similarity to previously reported strains from Serbia and other countries. The occurrence of these outbreaks in Prussian carp populations in lakes indicates the probable spread of the virus within freshwater ecosystems in Serbia, potentially impacting the degradation of aquatic habitats.

Prickly postglacial pioneers: freshwater plankton community composition influences fatty acid desaturase (FADS2) copy number in southern Greenland threespine sticklebacks

The adaptation of marine fish to freshwater environments includes prodigious examples of rapid evolution.Given the scarcity of ω‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA) in freshwater, we expect selection to be strong on fish transitioning to freshwater habitats and yet the underlying ecological causes of genomic and phenotypic differentiation are poorly understood for traits associated with lipid content and composition. Threespine stickleback Gasterosteus aculeatus have repeatedly colonized, and adapted to, freshwater habitats across the Northern Hemisphere. These freshwater populations often show elevated copy number of the fatty acid desaturase 2 gene (FADS2), which increases the biosynthetic capacity of LC‐PUFA. The starkly lower content of LC‐PUFA in freshwater compared to marine prey, especially docosahexaenoic acid (DHA), likely imposes strong positive selection on freshwater fish for either increased biosynthesis or greater dietary acquisition of LC‐PUFA. The recently colonized and relatively undisturbed threespine stickleback populations in postglacial coastal lakes of southern Greenland offer an exceptional opportunity to study how variation in the copy number of FADS2 is related to abiotic and biotic conditions of lakes and their morphometry. As expected, given its position on the stickleback X chromosome, we found strong sexual dimorphism in FADS2 copy number in all populations (19 freshwater, 1 marine and 1 brackish), and an increased dimorphism in some freshwater populations. We also found that FADS2 copy number was negatively correlated, for both males and females, with the abundance of copepods, which are a DHA‐rich food source in the zooplankton community. Overall, our results suggest that the prey community context of lakes might influence the process of metabolic adaptation of marine fish colonizing freshwater ecosystems.

Virulence and transmission biology of the widespread, ecologically important pathogen of zooplankton, Spirobacillus cienkowskii.

Spirobacillus cienkowskii is a bacterial pathogen of zooplankton, first described in the 19th century and recently placed in a new family of bacteria, the Silvanigrellaceae. Spirobacillus causes large epidemics in lake zooplankton populations and increases the probability that zooplankton will be eaten by predators. However, little is known about how Spirobacillus transmits among hosts, to what extent it reduces host survival and reproduction (i.e., how virulent it is), and what role virulence plays in Spirobacillus' life cycle. Here, we experimentally quantified Spirobacillus' virulence and showed that Spirobacillus must kill its host to transmit horizontally. We also found evidence that Spirobacillus may transmit vertically via Daphnia's seed-like egg sacks. Our work will help scientists to (i) understand Spirobacillus epidemics, (ii) use Spirobacillus as a model pathogen for the study of host-parasite interactions, and (iii) better understand the unusual group of bacteria to which Spirobacillus belongs.

Altai Osmans of the Genus Oreoleuciscus and African Barbs of the Barbus intermedius Complex: the Common Patterns of Morphological Differences Between Piscivorous and Non-Piscivorous Forms under Sympatry Conditions

In populations of fish species of the same and of different systematic groups living in lakes of the same and of different continents the patterns of differences in factor loadings of the considered parameters of the morphology of the jaw apparatus and neurocranium on the main vectors of variability in comparison of piscivorous and non-piscivorous ecological forms almost coincides. It is shown that in the Altai osmans of the Oreoleuciscus potanini species in two lakes of the Central Asian Closed Basin, the structure of differences is almost identical to the structure of differences between the piscivorous and non-piscivorous forms of the barbs of the Barbus intermedius complex sensu Banister (1973) complex in the African Lake Tana. At the same time, the structure of the differences between the piscivorous and non-piscivorous forms of another species of Altai Osmans Oreoleuciscus humilis in a lake located in another part of the Central Asian Closed Basin differs significantly from the structure of differences in ecological forms of both the O. potanini species and the B. intermedius complex. It is assumed that the following explanation may be given for the revealed difference in the variability of Osmans in the studied water bodies. In the African lake Tana and Mongolian lakes Bayan and Khar-Us, the structure of differences reflects the already established situation of stationary coexistence of piscivorous and non-piscivorous forms in one water body. Whereas the structure of variability in the periodically drying Mongolian lake Lake Orog reflects not an established situation, but an incomplete process of its formation, interrupted over and over again by the death of the lake population in the next drought period.

Examining Bald Eagle Contaminant Exposure and Reproductive Risk Above and Below Dams on Great Lakes Tributaries

Removing lowermost dams can reestablish fish passage on Great Lakes tributaries. This can increase the transfer of contaminants from anadromous fish to piscivorous wildlife upstream; however, concentrations of bioaccumulative contaminants in Great Lakes fish have decreased over the last several decades. We analyzed concentrations of PCBs and the toxic equivalence (TEQs) calculated from PCBs, DDTs, other organochlorine pesticides, and PBDEs in the plasma of bald eagle nestlings above and below lowermost dams on five river systems in Michigan from 1999 to 2013. We examined relationships between contaminants and metrics of reproductive success from 1997 to 2018, including the effects of year and location relative to the lowermost dam. Σ20PCB and p,p’-DDE were important in characterizing differences in contaminant mixtures above and below dams. Concentrations of contaminants were generally greater below dams than above. There were generally greater nest success and more nestlings per nest below dams, but nest location explained little variability (R2 values = 0.03–0.15). Neither Σ20PCB nor p,p’-DDE was a significant predictor of 5-year productivity means by river reach despite concentrations exceeding previously established effects thresholds for healthy bald eagle populations in the Great Lakes (≥ 1 nestling/nest). Our study indicates that dams may continue to reduce the upstream movement of contaminants to bald eagles, but at the measured concentrations, contaminants did not impair productivity and reproductive success as indicated by nestlings per nest. Additional information about population dynamics could clarify population-level effects of contaminants on bald eagles and to what degree these populations are self-sustaining throughout the Great Lakes.

Spatio-temporal variation in reproductive characteristics of invasive fish Pseudorasbora parva (Temmick & Schlegel, 1846) in the lakes region of Türkiye.

Invasive species present a serious peril to aquatic ecosystems worldwide, thus it is essential to have a comprehensive understanding of the reproductive dynamics, spreading characteristics, and biological properties of these species in order to effectively manage their population structure and mitigate both the ecological damage and economic loss they can cause. For this reason, we delved into the reproductive dynamics of Pseudorasbora parva, an invasive species of inland water fish found in Türkiye. We focused on three populations inhabiting Beyşehir (Konya, Isparta) and Eğirdir Lakes (Isparta) and Onaç Reservoir (Burdur). Sampling was carried out on a monthly basis from March 2021 to June 2022, utilizing a variety of tools such as multimesh nets, seine nets, and electrofishing. The developmental stages of gonads and reproductive cells were determined through morphological and microscopic examinations. A total of 1186 P. parva individuals were captured from all three lakes. Our results showed that the Beyşehir Lake population spawned from March to July, while the Eğirdir Lake population did so between May and October, and the Onaç Reservoir population laid their eggs from June to August. Female individuals in Beyşehir Lake, Eğirdir Lake, and Onaç Reservoir had initial breeding lengths of 3.49, 4.89, and 5.35 cm, respectively. In comparison, male individuals measured 5.56, 4.80, and 5.40 cm. Interestingly, the Beyşehir Lake population exhibited the highest egg fecundity, with each individual at 2 years producing a remarkable 2949 eggs. The present findings provide valuable information for us to further understand the reproductive biology and dynamics of P. parva, which could be useful in managing and preventing the spread of this invasive species in inland aquatic ecosystems.

Incorporating ecological heterogeneity and intraspecific variation differentiates complex interactions between apex predators and stocked fish

Ecological heterogeneity and intraspecific variation can impact energy flow from the base of the food web to top predators. We evaluated the effect of intraspecific variation on estimates of lake trout ( Salvelinus namaycush) consumption of stocked kokanee (lacustrine sockeye salmon, Oncorhynchus nerka) in a 390 ha oligotrophic lake with two distinct basins. Lake trout stomach content analyses, stable isotope niche space, and catch rates indicated high intraspecific variation in resource use across habitats and basins. Intraspecific variation and ecological heterogeneity were incorporated into two bioenergetics modeling approaches: one lake-wide model, and one partitioned model that accounted for differences in lake trout diet composition and population size across habitats. The ecologically partitioned model highlighted that lake trout consumption was primarily in the epilimnion of one basin, while the lake-wide, unpartitioned model performed similarly but failed to provide ecological context for where that consumption occurred. Incorporating ecological heterogeneity and intraspecific variation into bioenergetic models can more accurately represent top predators foraging patterns across habitats and inform management actions to mitigate impacts to stocked fish.

Phenotypic covariation predicts diversification in an adaptive radiation of pupfishes.

Phenotypic covariation among suites of traits may constrain or promote diversification both within and between species, yet few studies have empirically tested this relationship. In this study, we investigate whether phenotypic covariation of craniofacial traits is associated with diversification in an adaptive radiation of pupfishes found only on San Salvador Island, Bahamas (SSI). The radiation includes generalist, durophagous, and lepidophagous species. We compared phenotypic variation and covariation (i.e., the P matrix) between (1) allopatric populations of generalist pupfish from neighboring islands and estuaries in the Caribbean, (2) SSI pupfish allopatric lake populations with only generalist pupfish, and (3) SSI lake populations containing the full radiation in sympatry. Additionally, we examine patterns observed in the P matrices of two independent lab-reared F2 hybrid crosses of the two most morphologically distinct members of the radiation to make inferences about the underlying mechanisms contributing to the variation in craniofacial traits in SSI pupfishes. We found that the P matrix of SSI allopatric generalist populations exhibited higher levels of mean trait correlation, constraints, and integration with simultaneously lower levels of flexibility compared to allopatric generalist populations on other Caribbean islands and sympatric populations of all three species on SSI. We also document that while many craniofacial traits appear to result from additive genetic effects, variation in key traits such as head depth, maxilla length, and lower jaw length may be produced via non-additive genetic mechanisms. Ultimately, this study suggests that differences in phenotypic covariation significantly contribute to producing and maintaining organismal diversity.

Study of the patterns of variations in ice lakes and the factors influencing these changes on the southeastern Tibetan plateau

The ice lakes in the southeastern Qinghai–Tibet Plateau have exhibited a pronounced expansion against the backdrop of global warming, consequently amplifying the local risk of ice lake outburst disasters. However, surveys of ice lake changes in the entire region have consistently been incomplete due to the prevalent high cloud density. On the basis of Landsat remote sensing images and the Google Earth Engine (GEE) cloud computing platform, in this study, the full convolution segmentation algorithm is utilized to accurately and comprehensively map the regional distribution of ice lakes in southeastern Tibet at consistent time intervals in 1993, 2008, and 2023. Furthermore, the formation, distribution, and dynamic changes in these ice lakes are investigated. The numbers of ice lakes discovered in 1993, 2008, and 2023 were 2520, 3198, and 3877, respectively. These lakes covered areas of approximately 337.64 ± 36.86 km2, 363.92 ± 40.90 km2, and 395.74 ± 22.72 km2, respectively. These ice lakes are located primarily between altitudes of 4442 m and 4909 m. The total area experienced an annual growth rate of approximately 0.57 % from 1993 to 2023. In the present study, the long-term variations in ice lakes in each district and county are examined. These findings indicate that between 1993 and 2023, the expansion of ice lakes was more pronounced in regions with a large number of marine glaciers. Notably, Basu County presented the highest annual growth rate of the ice lake population, at 6.23 %, followed by Bomi County, at 4.28 %, and finally, Zayul County, at 2.94 %. The accelerated shrinkage of marine glaciers induced by global warming is the primary driver behind the expansion of ice lakes. The results obtained from this research will enhance our overall understanding of the complex dynamics and mechanisms that govern the formation of ice lakes while also offering valuable perspectives on the potential risks linked to their expansion in this particular area.

Historical and morphological evidence for a remnant population of Lake Erie cisco Coregonus artedi (albus) in Crystal Lake, Pennsylvania

The cisco (Coregonus artedi) population in Crystal Lake, Pennsylvania, is of great scientific interest as it either originated from Lake Erie or Lake Ontario. Cisco in Lake Erie once supported the largest freshwater fishery in the world, but populations were extirpated by 1960. We conducted a morphological analysis of Crystal Lake cisco to determine whether it was consistent with a distinctive Lake Erie form (albus), which was also historically documented, albeit rarely, in western Lake Ontario. Using principal component analysis, we compared eight morphometric ratios and one meristic from our Crystal Lake cisco collection with historical and contemporary collections of cisco from Lakes Erie and Ontario. Maximum likelihood ellipse overlaps between Crystal Lake cisco and presumed albus (the dominant Lake Erie form prior to extirpation) collections averaged 54%. For all groups, the greatest morphological overlap (73.9%) occurred between Crystal Lake and 1957 Lake Erie cisco, which only differed from Crystal Lake cisco in dorsal fin length. Alternatively, overlap between Crystal Lake cisco and all other Lake Ontario collections averaged 3.2%. Our results demonstrate that Crystal Lake cisco are likely an albus form; furthermore, historical documentation and our morphological results suggest a Lake Erie origin. Substantial overlap between Crystal Lake cisco and Lake Ontario albus collected in 1917 is likely explained by continuous entrainment of Lake Erie larvae into Lake Ontario. We suspect this created an albus metapopulation spanning Lakes Erie and Ontario, yet albus are no longer observed in either lake today.

Unlocking Nile tilapia (Oreochromis niloticus Linn., 1758) selective breeding programmes in Uganda through geographical genetic structure mapping

AbstractNile tilapia (Oreochromis niloticus), native to Africa and the Levant, is an important species for both aquaculture and capture fisheries. Despite these attributes, Nile tilapia has been negatively impacted by anthropogenic activities ranging from overfishing and habitat destruction to translocations. These human‐mediated activities have threatened the genetic evolutionary integrity of native populations of Nile tilapia and congeneric species through admixture, demographic bottlenecks and introgressive hybridization. In this context, the genetic contrast between farmed/bred strains and wild Nile tilapia populations in the major lakes of Uganda remains understudied. Understanding the genetic structure of Nile tilapia populations in the major water bodies of Uganda (lakes Victoria, Kyoga, Edward, George, Albert and Nile River) is a key resource to guide selective breeding programmes, thus minimizing the effects of maladaptation under both aquaculture and natural stocks. Although the population genetics of Nile tilapia in Uganda's major lakes have been studied, this was based on limited sampling scope, especially in the wild, and the key information on the species could have been overlooked. We fill this knowledge gap by genotyping 756 Nile tilapia individuals from multiple populations for each major water body of Uganda using a panel of 34 microsatellite loci based on the microsatellite genotyping‐by‐sequencing (SSR‐GBS) technique. The results indicate two discrete gene pools/stocks: the Edward‐George system and the Albert‐Kyoga system‐Victoria. Evidence of loss of genetic diversity and admixture of some Nile tilapia stocks was found, most likely resulting from anthropogenic perturbations. This study contributes useful information key for understanding the potential Nile tilapia broodstock sources for selective breeding programmes, aimed at improving aquaculture production in Uganda.

Interactive effects shape the dynamics of Chydorus sphaericus (O.F. Müller, 1776) population in a shallow eutrophic lake

Interactive effects shape the dynamics of Chydorus sphaericus (O.F. Müller, 1776) population in a shallow eutrophic lake

Parallel evolution of integrated craniofacial traits in trophic specialist pupfishes.

Populations may adapt to similar environments via parallel or non-parallel genetic changes, but the frequency of these alternative mechanisms and underlying contributing factors are still poorly understood outside model systems. We used QTL mapping to investigate the genetic basis of highly divergent craniofacial traits between the scale-eater (Cyprinodon desquamator) and molluscivore (C. brontotheroides) pupfish adapting to two different hypersaline lake environments on San Salvador Island, Bahamas. We lab-reared F2 scale-eater x molluscivore intercrosses from two different lake populations, estimated linkage maps, scanned for significant QTL for 29 skeletal and craniofacial traits, female mate preference, and sex. We compared the location of QTL between lakes to quantify parallel and non-parallel genetic changes. We detected significant QTL for six craniofacial traits in at least one lake. However, nearly all shared QTL loci were associated with a different craniofacial trait within each lake. Therefore, our estimate of parallel evolution of craniofacial genetic architecture could range from one out of six identical trait QTL (low parallelism) to five out of six integrated trait QTL (high parallelism). We suggest that pleiotropy and trait integration can affect estimates of parallel evolution, particularly within rapid radiations. We also observed increased adaptive introgression in shared QTL regions, suggesting that gene flow contributed to parallel evolution. Overall, our results suggest that the same genomic regions may contribute to parallel adaptation across integrated suites of craniofacial traits, rather than specific traits, and highlight the need for a more expansive definition of parallel evolution.

Geographically driven shifts in land use influence phytoplankton community patterns in the Inner Mongolian Plateau lakes

Abstract Phytoplankton play an irreplaceable role as producers in maintaining lake ecosystems. Nevertheless, scant attention has been given to investigating the dispersion of phytoplankton communities and the factors influencing them across expansive areas. In this study, we present the results of a survey on the distribution of phytoplankton community and the effects of different driving factors in 11 lakes along Inner Mongolia in July–August 2020. Non-metric multidimensional scaling analysis and variance decomposition (VPA) were used to elucidate the distribution of phytoplankton communities and the response of drivers. A total of 169 species of phytoplankton from 8 phyla were detected. Both the abundance and diversity of phytoplankton in the Inner Mongolia lakes showed a trend of high in the east and low in the west (with Daihai Lake as the boundary). The Margalef index of phytoplankton significantly negatively correlated with salinity (r = −0.707, P < 0.05) and total dissolved solids (r = −0.720, P < 0.05), and both density and biomass highly significantly positively correlated with the suspended solids, Chlorophyll a and trophic level index. The VPA explained 38.9% of the changes in the phytoplankton community with the highest rate of explanation of land use. Therefore, preventing anthropogenic impacts, as well as reducing nutrient loads, can effectively ensure the ecological diversity of lake phytoplankton in lake populations with large geographical spans and varying levels of nutrients.