Exotic Populations Research Articles

Indicators of rapid adaptation of an exotic aquatic Poaceae to increased salinity

AbstractThe invasion process and the persistence of invasive species across environments can be explained by their tolerance to stressors, such as salinization. Urochloa arrecta (Poaceae) exhibits high invasive potential and has already established in various natural and artificial aquatic ecosystems. Here, we experimentally evaluate the effects of water salinity on the traits of three exotic populations of U. arrecta derived from naturally occurring populations across a salinity gradient. Specifically, we measured the difference in the number and perimeter of intercellular spaces for individuals from the different populations across three experimental treatments of salinity. Our results demonstrate that high water salinity levels affected anatomical traits in all populations. However, the traits of freshwater populations were the more significantly impacted by increasing salinity compared with populations sampled from naturally higher occurring salinity. Populations of U. arrecta established in places with certain degree of salinity can be more resistance to salt increases compared with populations established in freshwater habitats that are more distant geographically. However, the resistance of freshwater populations to certain high salinity levels suggests that these populations may exhibit rapid adaptation and to survive under some degree of salinity, demonstrating the species' high resilience across various environments.

Population genomics of the invasive Northern Giant Hornet Vespa mandarinia in North America and across its native range

The northern giant hornet Vespa mandarinia (NGH) is a voracious predator of other insect species, including honey bees. NGH’s native range spans subtropical and temperate regions across much of east and southeast Asia and, in 2019, exotic populations of the species were discovered in North America. Despite this broad range and invasive potential, investigation of the population genomic structure of NGH across its native and introduced ranges has thus far been limited to a small number of mitochondrial samples. Here, we present analyses of genomic data from NGH individuals collected across the species’ native range and from exotic individuals collected in North America. We provide the first survey of whole-genome population variation for any hornet species, covering this species’ native and invasive ranges, and in doing so confirm likely origins in Japan and South Korea for the two introductions. We additionally show that, while this introduced population exhibited strongly elevated levels of inbreeding, these signatures of inbreeding are also present in some long-standing native populations, which may indicate that inbreeding depression alone is insufficient to prevent the persistence of NGH populations. As well as highlighting the importance of ongoing monitoring and eradication efforts to limit the spread of this species outside of its natural range, our data will serve as a foundational database for future genomic studies into introduced hornet populations.

Disappearing Galaxies: The Orientation Dependence of JWST-bright, HST-dark, Star-forming Galaxy Selection

Galaxies that are invisible in deep optical–near-infrared imaging but detected at longer wavelengths have been the focus of several recent observational studies, with speculation that they could constitute a substantial missing population and even dominate the cosmic star formation rate density at z ≳ 4. The depths now achievable with JWST at the longest wavelengths probed by the Hubble Space Telescope (HST), coupled with the transformative resolution at longer wavelengths, are already enabling detailed, spatially resolved characterization of sources that were invisible to HST, often known as “HST-dark” galaxies. However, until now, there has been little theoretical work to compare against. We present the first simulation-based study of this population, using highly resolved galaxies from the Feedback in Realistic Environments project, with multiwavelength images along several lines of sight forward-modeled using radiative transfer. We naturally recover a population of modeled sources that meet commonly used selection criteria (H AB > 27 mag and H AB − F444W > 2.3). These simulated HST-dark galaxies lie at high redshifts (z = 4–7), have high levels of dust attenuation (A V = 2–4), and display compact recent star formation (R 1/2,4.4 μm ≲ 1 kpc). Orientation is very important: for all but one of the 17 simulated galaxy snapshots with HST-dark sight lines, there exist other sight lines that do not meet the criteria. This result has important implications for comparisons between observations and models that do not resolve the detailed star-dust geometry, such as semianalytic models or coarsely resolved hydrodynamical simulations. Critically, we demonstrate that HST-dark sources are not an unexpected or exotic population, but a subset of high-redshift, highly dust-attenuated sources viewed along certain lines of sight.

Population genomics unveils the century-old invasion of the Seagrass Halophila stipulacea in the Mediterranean Sea

The tropical seagrass Halophila stipulacea invaded the Eastern Mediterranean Sea in the late nineteenth century and progressively spread throughout the basin ever since. Its spread is expected to continue north-westward as the Mediterranean Sea becomes warmer, potentially changing the seagrass biogeography of the basin. Given the power of genomics to assess invasion dynamics in non-model species, we report the first ddRAD-seq study of H. stipulacea and small-scale population genomic analysis addressing its century-old Mediterranean invasion. Based on 868 SNPs and 35 genotyped native (Red Sea) and exotic (from Cyprus, Greece, and Italy) samples, results suggest that genetic structure was high, especially between major geographic discontinuities, and that exotic populations maintain comparably lower genetic diversity than native populations, despite 130 years of invasion. The evidence of high heterozygosity excess, coupled with previously reported male-dominated and rare flowering records in the exotic range, suggests that clonal propagation likely played a pivotal role in the successful colonization and spread of H. stipulacea in the Mediterranean. This shift in reproductive strategy, particularly evident in the Italian populations located closest to the western boundary and representing more recent establishments, underscores the importance of this cost-effective mode of reproduction, especially during the initial stages of invasion, raising questions about the species future expansion trajectory. Our findings serve as a catalyst for future research into the species’ invasion dynamics, including deciphering the intricate roles of acclimatization and rapid adaptation, important for a comprehensive assessment of invasion risks and improving management strategies aimed at conserving seagrass ecosystems.

UOCS-XII. A study of open cluster NGC 6940 using UVIT/AstroSat cluster properties and exotic populations

ABSTRACT We study an open cluster NGC 6940 using AstroSat/UVIT (Ultraviolet Imaging Telescope) data and other archival data. This is an intermediate age cluster (∼1 Gyr), located at about 770 pc distance, harbouring several exotic populations apart from normal single and binary stars. We identify members of this cluster using a machine learning algorithm, ML-MOC and identify 492 members, including one blue straggler star (BSS), two yellow straggler stars (YSS), 11 blue lurker (BL) candidates, and two red clump (RC) stars. The cluster shows the effect of mass segregation, with massive stars segregated the most into the cluster, followed by the equal-mass binary members and the single low-mass stars. We report the presence of an extended main-sequence turn-off (eMSTO) feature in this cluster and suggest that the age spread may be a contributing factor behind it. However, the effect of stellar rotation, and the dust absorption needs to be examined more comprehensively with a larger fraction of MSTO stars. All the sixteen sources mentioned above have a counterpart in the UVIT/F169M filter. In order to characterize them, we construct multi-wavelength spectral energy distributions (SEDs) of 14 of these objects having no nearby sources within 3 arcsec. The BSS is successfully fitted with a single-component SED. We find that three BLs, two YSS, and one RC star have UV excess greater than 50 per cent and successfully fit two-component SEDs having hot companions. The parameters derived from the SEDs imply that the hot companions of BLs and the RC star are low-mass and normal-mass white dwarfs, whereas the hot companions of YSS are likely to be subdwarf B stars. We suggest that at least 6 out of 14 stars (∼42 per cent) are formed via mass transfer and/or merger pathways.

Modeling the habitat suitability of two exotic freshwater crayfishes in Mesoamerica and the Caribbean:Cherax quadricarinatus(von Martens, 1868) andProcambarus clarkiiGirard, 1852 (Decapoda: Astacidea: Parastacidae, Cambaridae)

AbstractBiological invasions are among the main threats to the diversity of freshwater ecosystems, particularly invasions of freshwater crayfishes, which have negatively impacted native populations and ecosystem functions. Various invasions of freshwater crayfishes have been relatively well documented, allowing the use of Ecological Niche Modeling (ENM) techniques to forecast their potential invasive distribution. Modeling the most environmentally suitable areas for exotic species can provide guidelines to allocate resources, thus contributing to the control and management of invasions. We modelled the potential distribution of Cherax quadricarinatus (von Martens, 1868) and Procambarus clarkiiGirard, 1852 in Mesoamerica and the Caribbean using global occurrence data and ten environmental variables to ensemble a model using nine different algorithms. Our models showed that C. quadricarinatus has a high probability of invasion in tropical lowland areas, with the presence of exotic populations of this species already reported. Our results support that P. clarkii has a higher probability of invasion in some of the mountain ranges and plateaus of the study region, where this species has already established non-native populations. These models visualize the high-risk areas of invasion of these two non-native crayfish species in Mesoamerica and the Caribbean. A regional approach for monitoring and control of the invasive populations is encouraged as well as regulations for trade and aquaculture of freshwater crayfishes.

The identity of Tokays (Squamata: Gekkonidae: Gekko) from Hong Kong.

The Tokay gecko (Gekko gecko), found throughout Southeast Asia and India, is a heavily harvested species of high commercial value. Recent studies have supported the elevation of the black morph of Tokay gecko, found only in southern China and northern Vietnam, to the species Gekko reevesii. Previous genetic studies focused on specimens of G. reevesii from southwestern populations. Hong Kong, in southeastern China, has native populations of G. reevesii. To verify the identity of G. reevesii in Hong Kong, we employed three mitochondrial genes (COI, Cytb & ND2) and constructed a matrilineal genealogy using other specimens from Guangxi (southwestern China) and northern Vietnam, as well as G. gecko from a wide range of Southeast Asian countries. Our study confirmed that G. reevesii occurs naturally in Hong Kong, but one exotic population of G. gecko, likely a translocation from international trade, was also revealed. Our study did not reject the species ranking of G. reevesii. Moreover, like previous studies, we recovered a paraphyletic G. gecko, which may reflect a species complex, hybridization or incomplete lineage sorting. More extensive sampling of the two species over a broader range of their asserted distribution together with the use of both mitochondrial and nuclear DNA are required to better investigate their biogeography.

Karyotypic and Molecular Analysis of Pterygoplichthys pardalis (Castelnau 1855) from the Lower Amazon River.

Pterygoplichthys pardalis is an armored catfish native to South America and an important resource for the ornamental fish industry. Recently, several exotic populations have been introduced into rivers on five continents. Despite its commercial and environmental importance, P. pardalis is poorly studied from a genetic perspective. In this study, we analyzed the karyotype of P. pardalis from the Amazon River and molecular variations in the mitochondrial gene Cytochrome oxidase I (COI) between native and exotic populations. The karyotype presented diploid number 2n = 52 and NF = 100 without cytogenetic variation between males and females. Nucleolus organizer regions (Ag-NOR) in the distal region of the long arm of pair 12 coincided with the 18S hybridization signal, whereas 5S was syntenic to this chromosome but localized in the short arm. The constitutive heterochromatin was restricted in the distal regions of pairs 4, 12, 25, and 26. Telomeric probes showed only distal hybridization signals. The karyotype of P. pardalis diverged from that of its congeners, and COI molecular variation revealed four haplotypes. The Philippine population revealed the greatest diversity with three haplotypes, while haplotype H1 was the most abundant and observed in both native and exotic populations. This new genetic data contributes to species management and provides useful information from an aquaculture perspective.

Reaching new environments through illegal trade: evidence of a widely traded turtle in Colombia

A major threat to biodiversity is illegal trade, with many unwanted wildlife pets released into exotic environments outside their native distribution. Therefore, many potential invasive species have established in new ecosystems. Ecological niche modeling (ENM) has been used to predict and compare the environmental conditions of natural and exotic population in many groups. We used ENM to compare the climatic niche between natural and exotic areas of Trachemys venusta callirostris, one of the most traded turtles in Colombia. We generated a niche model using the MaxEnt algorithm through the R package kuenm to test several parametrizations and four sets of fresh water environmental predictors. Models were calibrated in the native distribution and projected to non-native zones in Colombia to identify suitable areas for the species. Further, we use a niche similarity test to compare native and exotic environmental space. We found few suitable areas within the projected zone even when using extrapolation; there was a greater suitability in the Magdalena River basin than in the Cauca River basin. Low similarity was detected between the niche comparison of native and exotic areas, suggesting that exotic populations have reached different environmental conditions than the native zone through ilegal trade. Although there was low extrapolation in the exotic area, the models projected ideal conditions in localities with new records for this turtle. The generalist strategies for feeding, thermoregulation, and reproduction in changing conditions may help this T. v. callirostris establish in new ecosystems, and with no current knowledge on dynamics between this exotic species and local fauna, its effects on aquatic communities are unpredictable.

Low genetic diversity in a widespread whistling alien: A comparison of Eleutherodactylus johnstonei Barbour, 1914 (Eleutherodactylidae) and congeners in native and introduced ranges

There is no clear empirical evidence to support the general assumption that genetic diversity favours successful invasions. Many invading species disperse and establish successfully despite low genetic diversity, a phenomenon known as the genetic paradox of biological invasion. Model systems that allow comparison of genetic patterns between exotic and native source populations are still scarce. This is particularly true for amphibians. Here we compare genetic patterns of the widely introduced Johnstone’s Whistling Frog, Eleutherodactylus johnstonei, with its successful alien congener E. antillensis and the single island endemic E. portoricensis. Genetic diversity and population differentiation in native and introduced populations of the three taxa were inferred from mitochondrial D-loop sequences (235 bp). Our results reveal that exotic populations of the two alien taxa, E. johnstonei and E. antillensis, are not only genetically impoverished due to founder effects, but that, moreover, their native range source-populations exhibit low genetic diversity and inter-population differentiation in the first place. Populations of the endemic E. portoricensis, on the other hand, are genetically more diverse and show marked inter-population differentiation. These observed genetic patterns are consistent with geological processes and invasion histories. We argue that the establishment success of the alien taxa in our model system is better explained by ecological factors and anthropogenic drivers than by genetic diversity. As these factors provide more parsimonious explanations, they should be given priority in management decisions. However, molecular studies with higher resolution are needed to fully test possible genetic and epigenetic components that could promote the invasion process.

Evidence for the ∼ 1.4 Ga Picuris orogeny in the central Colorado Front Range

We present the first evidence for sedimentation and new evidence for penetrative deformation and metamorphism in the central Colorado Front Range associated with the ∼ 1.48–1.35 Ga Picuris orogeny. This orogeny has recently been recognized in New Mexico, Arizona and southern Colorado and may be part of a larger active accretionary margin that includes the ∼ 1.51–1.46 Ga Pinware and Baraboo events, in eastern Canada and central US respectively, that preceded the amalgamation of the Rodinian supercontinent. We demonstrate that in addition to ∼ 1.4 Ga reactivation of northeast-trending Paleoproterozoic shear zones, regional folding occurred in an area south of Mt. Evans, away from these shear zones.Detrital zircon from one quartzite yielded U–Pb laser ablation inductively coupled mass spectrometry (LA-ICPMS) major age populations of ∼ 1.81–1.61 Ga and ∼ 1.49–1.38 Ga, and minor ones of ∼ 1.90 Ga and ∼ 1.56 Ga. The Paleoproterozoic and ∼ 1.49–1.38 Ga populations have numerous local and regional sources. The ∼ 1.56 Ga age population may represent a minor exotic population as recognized in Defiance, Arizona the Yankee Joe and Blackjack Formations in Arizona, the Four Peaks area in Arizona, and the Tusas and Picuris Mountains in New Mexico. Alternatively it may be a result of mixing between zircon age domains reflecting the older and younger populations, or Pb loss from 1.81 to 1.61 Ga zircon.In-situ LA-ICPMS U–Pb analysis on monazite from four biotite schist samples yielded ∼ 1.74 Ga and ∼ 1.42 Ga age populations, and separate populations that show ∼ 1.68–1.47 Ga and ∼ 1.39–1.33 Ga age spreads. The ∼ 1.74 Ga and ∼ 1.68–1.47 Ga populations may be detrital or metamorphic. Monazite ages between ∼ 1.6 Ga and ∼ 1.5 Ga may be due to the mixing of age domains or Pb loss, because metamorphism during that time has not been recognized in Laurentia. The ∼ 1.42 Ga and ∼ 1.39–1.33 Ga populations are most likely metamorphic and consistent with the age of the ∼ 1.48–1.35 Ga Picuris orogeny. The evidence for ∼ 1.4 Ga sedimentation, and especially regional folding and metamorphism in the central Colorado Front Range indicate that the impact and extent of the Picuris orogeny in the southwestern U.S. are larger than previously thought.

Plant community and native primate as drivers of habitat use by an exotic primate (Saimirispp. Linnaeus, 1758) in an Atlantic Forest fragment

AbstractUnderstanding how and why exotic species use their habitats is crucial for defining effective conservation strategies. We aimed to investigate habitat use by an exotic population of squirrel monkeys living in an Atlantic Forest fragment and identify factors associated with their habitat preferences. Over 6 months of scan sampling observations, we collected data on native and exotic plants consumed by the squirrel monkeys, food availability, and interactions between the squirrel monkeys and the native common marmosets. We also georeferenced the estimated centroid point of the study group during each scan. Squirrel monkeys used Secondary Old Forest habitats more often than the other habitats available. The consumption of native and exotic plants and the association with common marmoset appear to have influenced the habitat use of the exotic squirrel monkeys; however, the choice habitat did not demonstrate to be associated with food availability. The exotic squirrel monkeys preferred to use less disturbed habitats to consume a high amount of food (often associated with the common marmoset), potentially optimizing their food intake. Our findings demonstrated the adaptive success of an exotic primate in its non-natural habitat and the key role of the plant community in maintaining this population.

Environmental stress determines the colonization and impact of an endophytic fungus on invasive knotweed

There is increasing evidence that microbes play a key role in some plant invasions. A diverse and widespread but little understood group of plant-associated microbes are the fungal root endophytes of the order Sebacinales. They are associated with exotic populations of invasive knotweed (Reynoutria ssp.) in Europe, but their effects on the invaders are unknown. We used the recently isolated Sebacinales root endophyte Serendipita herbamans to experimentally inoculate invasive knotweed and study root colonisation and effects on knotweed growth under different environmental conditions. We verified the inoculation success and fungal colonisation through immunofluorescence microscopy and qPCR. We found that S. herbamans strongly colonized invasive knotweed in low-nutrient and shade environments, but much less under drought or benign conditions. At low nutrients, the endophyte had a positive effect on plant growth, whereas the opposite was true under shaded conditions. Our study demonstrates that the root endophyte S. herbamans has the potential to colonize invasive knotweed fine roots and impact its growth, and it could thus also play a role in natural populations. Our results also show that effects of fungal endophytes on plants can be strongly environment-dependent, and may only be visible under stressful environmental conditions.

Detecting gravitational lenses using machine learning: exploring interpretability and sensitivity to rare lensing configurations

ABSTRACT Forthcoming large imaging surveys such as Euclid and the Vera Rubin Observatory Legacy Survey of Space and Time are expected to find more than 105 strong gravitational lens systems, including many rare and exotic populations such as compound lenses, but these 105 systems will be interspersed among much larger catalogues of ∼109 galaxies. This volume of data is too much for visual inspection by volunteers alone to be feasible and gravitational lenses will only appear in a small fraction of these data which could cause a large amount of false positives. Machine learning is the obvious alternative but the algorithms’ internal workings are not obviously interpretable, so their selection functions are opaque and it is not clear whether they would select against important rare populations. We design, build, and train several convolutional neural networks (CNNs) to identify strong gravitational lenses using VIS, Y, J, and H bands of simulated data, with F1 scores between 0.83 and 0.91 on 100 000 test set images. We demonstrate for the first time that such CNNs do not select against compound lenses, obtaining recall scores as high as 76 per cent for compound arcs and 52 per cent for double rings. We verify this performance using Hubble Space Telescope and Hyper Suprime-Cam data of all known compound lens systems. Finally, we explore for the first time the interpretability of these CNNs using Deep Dream, Guided Grad-CAM, and by exploring the kernels of the convolutional layers, to illuminate why CNNs succeed in compound lens selection.

MOLECULAR DIFFERENTIATION BETWEEN NATIVE AND VIETNAM ORIGINATED STRIPED SNAKEHEADS (CHANNA STRIATA) IN BANGLADESH USING MITOCHONDRIAL CYTOCHROME B GENE

The freshwater striped snakehead, Channa striata, is widely distributed in several Asian countries such as China, Vietnam, Indonesia, Malaysia, India, Myanmar, and Bangladesh. The present study investigated various C. striata populations sequentially by the mitochondrial cytochrome b gene. Native populations (136) were collected from nine geographically different locations and the Vietnamese populations (50) from two other fish farms in Bangladesh. The partial sequence of Cyt b (836bp) was analyzed, and the results have identified five haplotypes from nine natives and a single haplotype from two Vietnamese populations. This demonstrated that Vietnam-originated populations in Bangladesh had the same origin. In contrast, the pairwise highest Fst value observed between Native and Vietnamese populations shows a substantial genetic variation between them. The phylogenetic tree separated both the native and exotic populations, whereas five native haplotypes formed a cluster with the Indian C. striata. In contrast, the Vietnam haplotype formed a clade with the East Asian C. striata suggesting possible cryptic genetic diversity. Finally, the mitochondrial cytochrome b gene can also be used to identify native and Vietnam-originated C. striata strain available in Bangladesh, beneficial to broodstock development and conservation issues. Besides, a detailed morphological study of Vietnam-originated C. striata needs to be required to identify the exact morphotype available in Bangladesh.

Searching for a sign of exotic Aedes albopictus (Culicidae) introduction in major international seaports on Kyushu Island, Japan.

BackgroundThe Asian tiger mosquito, Aedes albopictus, has spread around the world. The migration was mainly mediated by maritime transportations. This species is known as an efficient vector for arboviruses, and it was responsible for the recent dengue outbreak in Tokyo, Japan. As the vector competence varies among geographical populations, and insecticide resistant populations have emerged, it is important to reveal their movements. The present study uses molecular techniques to search for a sign of introduction of an exotic population in three major international seaports on Kyushu Island.Methodology/principal findingsAdults of Ae. albopictus were sampled around the international seaports of Fukuoka, Kitakyushu, and Nagasaki. Pairwise fixation indexes were estimated between the sampled populations based on 13 microsatellite markers. There was no clear genetic differentiation between distant and port populations in Kitakyushu and Nagasaki. However, the analysis found one distinct group near the container terminal in Fukuoka, which handles international freight containers mainly from adjacent countries. DNA samples were also obtained from Goto, Tsushima, Honshu, Ryukyu, Thailand, and the Philippines; and a cluster analysis and discriminant analysis revealed that the distinct group in Fukuoka did not belong to these groups. Combined with the results of phylogenetic analysis based on CO1, these results implied that this group originated from one Asian temperate region outside of Japan. Neutrality test and mismatch distribution analysis suggested that the establishment of this group was not recent.Conclusions/significanceThe present study found a sign of Ae. albopictus introduction from a temperate region of Asia through maritime freight container transportation. The genetically distinct group found in Fukuoka likely originated from a temperate region outside of Japan. Maritime container transportation may introduce to Japan mosquitoes with greater vector competence/insecticide resistance. This is the first study to describe the spatial population structure of Ae. albopictus in Japan using molecular techniques.

Effect of Incorporating Early Feather Restriction Gene (KS) From Native Chicken to Purebred Chicken

Fast growing chicken suffers more in a hot humid condition than a slow growing one. The slow feathering affects the insulation mechanism of the chicken, thus enhance birds ability to dissipate heat during heat stress to a greater extent. As a consequence, slow feathered birds are more adaptive to hot humid environmental conditions. This study was undertaken to investigate the effect of incorporating early feather restriction gene (KS) in exotic population. A total of 34 slow feathered (SF) native chicks with KS gene of 28-day-old were collected from different villages and markets and were reared up to sexual maturity. After attaining sexual maturity, 2 males and 8 females of SF native chicken were randomly chosen to make a di-allelic cross with rapid feathered (RF) Rhode Island Red (RIR) and Fayoumi (FY). The crossbred progeny of each cross were reared up to 105 days to assess growth, survivability, heat tolerance and carcass yield under hot humid Bangladeshi condition. The collected data were arranged in a 3(genotype)×2(feather pattern)×9(age) factorial experiment in a Completely Randomized Design (CRD) and analyzed by SAS. Among genotypes, the highest survivability was obtained in Desi×Fayoumi (96.7%) and in SF chicks (96.1%) and the lowest in Desi×RIR (91.5%) and in RF chicks (90.5%). The SF chicks exhibited an average 8% heavier live weight than that of their RF counterparts. The cloacal temperature varied among genotypes and between feathering patterns (FP); being highest in Desi×RIR (430C) and in RF chicks (41.60C) and lowest in RIR×Desi (400C) and in SF chicks (41.40C). In case of Desi×RIR, RIR×Desi and Desi×Fayoumi, cloacal temperature increased linearly by 0.047, 0.044 and 0.0320C for each gram of live weight increase. Further, the cloacal temperature increased linearly by 0.036 and 0.0440C for the increase of each gram of live weight gain in case of RF and SF chicks, respectively. There was no significant (P>0.05) difference of dressing percentage for the effect of either genotype or FP (55.4% for SF vs. 46.6% for RF birds). Genotype and FP had significant effects (P<0.05; P<0.01) on total meat yield; being highest in Desi×RIR (24.6%) and in SF birds (26.2%) and lowest in Desi×Fayoumi (21.4%) and in RF birds (20.6%). Breast meat yield of SF birds (9.2%) was significantly (P<0.01) higher than that of RF birds (7.1%). The highest thigh meat yield was obtained in Desi×RIR (7.6%) and in SF birds (8.3%) and the lowest in Desi×Fayoumi (6.7%) and in RF counterparts (6.0%). The highest drumstick meat yield was obtained in RIR×Desi (5.6%) and in SF birds (5.9%) and the lowest in Desi×Fayoumi (5.0%) and in RF birds (4.8%). Genotype and FP had significant interaction effect on total meat yield as well as fractional meat yields. The study revealed that incorporation of ‘Ks’ gene in the exotic one by crossing with native chicken and rearing under hot humid environment may be a means of improving growth, survivability, heat tolerance and carcass yield.

Major locus for spontaneous haploid genome doubling detected by a case-control GWAS in exotic maize germplasm.

A major locus for spontaneous haploid genome doubling was detected by a case-control GWAS in an exotic maize germplasm. The combination of double haploid breeding method with this locus leads to segregation distortion on genomic regions of chromosome five. Temperate maize (Zea mays L.) breeding programs often rely on limited genetic diversity, which can be expanded by incorporating exotic germplasm. The aims of this study were to perform characterization of inbred lines derived from the tropical BS39 population using different breeding methods, to identify genomic regions showing segregation distortion in lines derived by the DH process using spontaneous haploid genome doubling (SHGD), and use case-control association mapping to identify loci controlling SHGD. Four different sets were used: BS39_DH and BS39_SSD were derived from the BS39 population by DH and single-seed descendent (SSD) methods, and BS39 × A427_DH and BS39 × A427_SSD from the cross between BS39 and A427. A total of 663 inbred lines were genotyped. The analyses of gene diversity and genetic differentiation for the DH sets provided evidence of the presence of a SHGD locus near the centromere of chromosome 5. The case-control GWAS for the DH set also pinpointed this locus. Haplotype sharing analysis showed almost 100% exclusive contribution of the A427 genome in the same region on chromosome 5 of BS39 × A427_DH, presumably due to an allele in this region affecting SHGD. This locus enables DH line production in exotic populations without colchicine or other artificial haploid genome doubling.

Signals of selection beyond bottlenecks between exotic populations of the bull-headed dung beetle, Onthophagus taurus.

Colonization of new environments can lead to population bottlenecks and rapid phenotypic evolution that could be due to neutral and selective processes. Exotic populations of the bull-headed dung beetle (Onthophagus taurus) have differentiated in opposite directions from native beetles in male horn-to-body size allometry and female fecundity. Here we test for genetic and transcriptional differences among two exotic and one native O. taurus populations after three generations in common garden conditions. We sequenced RNA from 24 individuals for each of the three populations including both sexes, and spanning four developmental stages for the two exotic, differentiated populations. Identifying 270,400 high-quality single nucleotide polymorphisms, we revealed a strong signal of genetic differentiation between the three populations, and evidence of recent bottlenecks within and an excess of outlier loci between exotic populations. Differences in gene expression between populations were greatest in prepupae and early adult life stages, stages during which differences in male horn development and female fecundity manifest. Finally, genes differentially expressed between exotic populations also had greater genetic differentiation and performed functions related to chitin biosynthesis and nutrient sensing, possibly underlying allometry and fecundity trait divergences. Our results suggest that beyond bottlenecks, recent introductions have led to genetic and transcriptional differences in genes correlated with observed phenotypic differences.

ANÁLISIS DE LA VARIABILIDAD MORFOLÓGICA DE MAÍCES NATIVOS Y EXÓTICOS EN VALLES ALTOS DE MÉXICO

El maíz (Zea mays L.) de origen tropical y subtropical de México es un reservorio de alelos útiles y diferentes a los existentes en razas de valles altos de México, que ayudaría a enfrentar distintos factores adversos y a contribuir a incrementar su adaptabilidad. El objetivo del presente estudio fue identificar la variabilidad morfológica existente entre poblaciones de maíz exóticas, adaptadas y sin adaptación previa a valles altos, y entre algunas de sus cruzas interraciales. El material genético evaluado estuvo integrado por nueve poblaciones originales de maíz exótico y sus ciclos avanzados de selección en valles altos, ocho cruzas simples, dos cruzas dobles, una cruza triple, las generaciones avanzadas de las cruzas y cuatro testigos locales. Las evaluaciones se realizaron en tres ambientes, mediante un diseño de bloques completos al azar con tres repeticiones; la unidad experimental consistió de dos surcos de 6 m de longitud, separados a 0.80 m y con una distancia entre plantas de 0.5 m. Se registraron 28 caracteres cualitativos y cuantitativos. Mediante análisis de componentes principales, agrupamiento jerárquico, análisis discriminante y comparación de medias con la prueba de Tukey se identificaron seis grupos contrastantes. Las variables de estructura morfológica, precocidad de planta y características de mazorca explicaron la variabilidad y agrupación de los genotipos. Las poblaciones exóticas originales fueron de mayor altura, más tardías y disminuyeron su rendimiento en mazorca. En contraste, las poblaciones seleccionadas para adaptación a valles altos mostraron mayor rendimiento en mazorca, menos días a floración, menor altura de planta, más ramas primarias de espiga y mazorcas cónicas. Estos atributos podrían incorporarse en programas de mejoramiento de maíz para valles altos de México o combinarse con el germoplasma local para mejorar su adaptabilidad y su heterosis.