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768 results for “sympatric species”
Data from: DNA metabarcoding diet analysis for species with parapatric versus sympatric distribution: a case study on subterranean rodents
Closely related sympatric species commonly develop different ecological strategies to avoid competition. Ctenomys minutus and C. flamarioni are subterranean rodents parapatrically distributed in the southern Brazilian coastal plain, showing a narrow sympatric zone. To gain understanding on food preferences and possible competition for food resources, we evaluated their diet composition performing DNA metabarcoding analyzes of 67 C. minutus and 100 C. flamarioni scat samples, collected along the species geographical ranges. Thirteen plant families, mainly represented by Poaceae, Araliaceae, Asteraceae and Fabaceae, were identified in the diet of C. minutus. For C. flamarioni, 10 families were recovered, with a predominance of Poaceae, Araliaceae and Asteraceae. A significant correlation between diet composition and geographical distance was detected in C. minutus, whereas the diet of C. flamarioni was quite homogeneous throughout its geographical distribution. No significant differences were observed between males and females of each species. However, differences in diet composition between species were evident according to multivariate analysis. Our results suggest some level of diet partitioning between C. flamarioni and C. minutus in the sympatric region. While the first species is more specialized on few plant items, the second showed a more varied and heterogeneous diet pattern among individuals. These differences might have been developed to avoid competition in the region of co-occurrence. Resource availability in the environment also seems to influence food choices. Our data indicate that C. minutus and C. flamarioni are generalist species, but that some preference for Poaceae, Asteraceae and Araliaceae families can be suggested for both rodents.
Data from: Human disturbance causes the formation of a hybrid swarm between two naturally sympatric fish species
Most evidence for hybrid swarm formation stemming from anthropogenic habitat disturbance comes from the breakdown of reproductive isolation between incipient species, or introgression between allopatric species following secondary contact. Human impacts on hybridization between divergent species that naturally occur in sympatry has received considerably less attention. Theory predicts that reinforcement should act to preserve reproductive isolation under such circumstances, potentially making reproductive barriers resistant to human habitat alteration. Using 15 microsatellites we examined hybridization between sympatric populations of alewife (Alosa pseudoharengus) and blueback herring (A. aestivalis) to test whether the frequency of hybridization and pattern of introgression have been impacted by the construction of a dam that isolated formerly anadromous populations of both species in a landlocked freshwater reservoir. The frequency of hybridization and pattern of introgression differed markedly between anadromous and landlocked populations. The range-wide frequency of hybridization among anadromous populations was generally 0-8%, whereas all landlocked individuals were hybrids. Although neutral introgression was observed among anadromous hybrids, directional introgression leading to increased prevalence of alewife genotypes was detected among landlocked hybrids. We demonstrate that habitat alteration can lead to hybrid swarm formation between divergent species that naturally occur sympatrically, and provide empirical evidence that reinforcement does not always sustain reproductive isolation under such circumstances.
Data from: Genetic differentiation and phylogeography of partially sympatric species complex Rhizophora mucronata Lam. and R. stylosa Griff. using SSR markers
Mangrove forests are ecologically important but globally threatened intertidal plant communities. Effective mangrove conservation requires the determination of species identity management units and genetic structure. Here we investigate the genetic distinctiveness and genetic structure of an iconic but yet taxonomically confusing species complex Rhizophora mucronata and R. stylosa across their distributional range by employing a suite of 20 informative nuclear SSR markers. Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa and potential hybridization or introgression between them. We investigated the population genetics of each species without the putative hybrids and found strong genetic structure between oceanic regions in both R. mucronata and R. stylosa. In R. mucronata a strong divergence was detected between populations from the Indian Ocean region (Indian Ocean and Andaman Sea) and the Pacific Ocean region (Malacca Strait South China Sea and Northwest Pacific Ocean). In R. stylosa the genetic break was located more eastward between populations from South and East China Sea and populations from the Southwest Pacific Ocean. The location of these genetic breaks coincided with the boundaries of oceanic currents thus suggesting that oceanic circulation patterns might have acted as a cryptic barrier to gene flow. Our findings have important implications on the conservation of mangroves especially relating to replanting efforts and the definition of ESUs in Rhizophora species. We outlined the genetic structure and identified geographical areas that require further investigations for both R. mucronata and R. stylosa. These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species determine their respective genetic structure and avoid artificially promoting hybridization in mangrove restoration programmes.
Data from: Contracting patterns of diversity and population differentiation at the innate immunity gene Toll-like receptor 2 (TLR2) in two sympatric rodent species
Comparing patterns of diversity and divergence between populations at immune genes and neutral markers can give insights into the nature and geographic scale of parasite-mediated selection. To date, studies investigating such patterns of selection in vertebrates have primarily focused on the acquired branch of the immune system, whereas it remains largely unknown how parasite-mediated selection shapes innate immune genes both within and across vertebrate populations. Here, we present a study on the diversity and population differentiation at the innate immune gene Toll-like receptor 2 (TLR2) across nine populations of yellow-necked mice (Apodemus flavicollis) and bank voles (Myodes glareolus) in southern Sweden. In yellow-necked mice, TLR2 diversity was very low, as was TLR2 population differentiation compared to neutral loci. In contrast, several TLR2 haplotypes co-occurred at intermediate frequencies within and across bank vole populations, and pronounced isolation by distance between populations was observed. The diversity and differentiation at neutral loci was similar in the two species. These results indicate that parasite-mediated selection has been acting in dramatically different ways on a given immune gene in ecologically similar and sympatric species. Furthermore, the finding of TLR2 population differentiation at a small geographical scale in bank voles highlights that vertebrate innate immune defence may be evolutionarily more dynamic than has previously been appreciated.
Data from: Genetic structure and hybridization in the species group of Ficus auriculata: can closely related sympatric Ficus species retain their genetic identity while sharing pollinators?
Obligate mutualistic nursery pollination systems between insects and plants have led to substantial co-diversification involving at least some parallel cladogenesis, as documented in Yucca, Ficus and Phyllanthaceae. In such systems pollinators are generally species specific thus limiting hybridization and introgression among interfertile host species. Nevertheless, in the three systems, cases of one insect pollinating several plant species are reported. In most cases host plants sharing pollinators are allopatric. However in the case of the species group of Ficus auriculata, forms may co-occur over large parts of their range. We show here that the species group of F. auriculata is constituted by four well-defined genetic entities that share pollinators. We detected hybrids in nature mainly when both parental forms were growing nearby. Controlled crosses showed that F1 offspring could be successfully backcrossed. Hence, despite sharing pollinators and despite hybrid viability, the different forms have preserved their genetic and morphological identity. We propose that ecological differentiation among forms, coupled with limited overlap of reproductive season has facilitated the maintenance of these inter-fertile forms. As such, establishment of pollinator host specificity may not be a prerequisite for sympatric diversification in Ficus.
Data from: Aging alters interspecific competition between two sympatric insect-parasitic nematode species
Interspecific competition can vary depending on the stage, age, or physiological state of the competitors. Competitive ability often increases with age or size; alternatively, senescence can lead to a loss of viability and reduced competitive success. Differences between species in their age-specific competitive abilities can promote coexistence in the face of substantial niche overlap. We examined two sympatric species of nematodes (genus Steinernema) to determine whether their competitive relationship changes as a function of age. These obligately killing insect parasites are known for their broad host ranges and are transmitted from insect to insect via a juvenile stage propagule that is free-living in the soil. Here, we tested whether the two species differed in the effects of age by examining the mortality of insect hosts infected with young or old transmission stage nematodes of each species. We also performed mixed infections, where an equal ratio of both species was simultaneously exposed to a host, to determine the effect of age on competitiveness. One species showed reduced performance with age, as older propagules were slower at inducing host mortality. In contrast, the other species increased in killing speed with age. In competition, insect mortality rate was predictive of competitive outcome, such that if one species induced considerably faster host death in a single-species infection, it was competitively dominant in the coinfection. Accordingly, we found a shift in the competitive relationship between the two species with age. Our work demonstrates that species differences in the effects of aging can lead to dramatic shifts in reproductive success. As these effects are realized solely in a competitive environment, both spatial patchiness and temporal niche partitioning may be important for promoting coexistence.
Data from: Herbivore resistance in congeneric and sympatric Nothofagus species is not related to leaf habit
Premise of the study Two fundamental hypotheses on herbivore resistance and leaf habit are the resource availability hypothesis (RAH) and the carbon-nutrient balance hypothesis (CNBH). The RAH predicts higher constitutive resistance by evergreens and the CNBH predicts higher induced resistance by deciduous species. Although support for these hypotheses is mixed, they have rarely been examined in congeneric species. Methods We compared leaf constitutive and induced resistance (as leaf polyphenols and tannin concentrations, and damage level in non-choice experiments) and leaf traits associated with herbivory of coexisting Nothofagus species using 1) a defoliation experiment, and 2) a natural defoliation caused by an outbreak of a common defoliator of Nothofagus species. Key Results In the defoliation experiment, polyphenol and tannin concentrations were similar between deciduous and evergreen species; regardless of leaf habit, polyphenols increased in response to defoliation. In the natural defoliation survey, N. pumilio (deciduous) had significantly higher herbivory, lower C/N ratio and leaf mass per area, and higher nitrogen and phosphorous concentrations than N. betuloides (evergreen); N. antarctica (deciduous) had intermediate values. Polyphenol concentrations and herbivore resistance indicated by the non-choice experiment were lower in N. pumilio than in N. antarctica and N. betuloides, which had similar values. Conclusions Higher herbivory in N. pumilio was associated with a higher nutritional value and a lower level of leaf C-based defenses compared to both the evergreen and the other deciduous species, indicating that herbivore resistance in Nothofagus species cannot be attributed to only leaf habit as predicted by the RAH or CNBH. Please be aware that if you ask to have your user record removed, we will retain your name in the records concerning manuscripts for which you were an author, reviewer, or editor. In compliance with data protection regulations, you may request that we remove your personal registration details at any time. (Use the following URL: https://www.editorialmanager.com/ajb/login.asp?a=r) Please contact the publication office if you have any questions.
Data from: Reproductive isolation and introgression between sympatric Mimulus species
Incompletely isolated species provide an opportunity to investigate the genetic mechanisms and evolutionary forces that maintain distinct species in the face of ongoing gene flow. Here, we use field surveys and reduced representation sequencing to characterize the patterns of reproductive isolation, admixture and genomic divergence between populations of the outcrossing wildflower Mimulus guttatus and selfing M. nasutus. Focusing on a single site where these two species have come into secondary contact, we find that phenological isolation is strong, although incomplete, and is likely driven by divergence in response to photoperiod. In contrast to previous field studies, which have suggested that F1-hybrid formation might be rare, we discover patterns of genomic variation consistent with ongoing introgression. Strikingly, admixed individuals vary continuously from highly admixed to nearly pure M. guttatus, demonstrating ongoing hybridization and asymmetric introgression from M. nasutus into M. guttatus. Patterns of admixture and divergence across the genome show that levels of introgression are more variable than expected by chance. Some genomic regions show a reduced introgression, including one region that overlaps a critical photoperiod QTL, whereas other regions show elevated levels of interspecific gene flow. In addition, we observe a genome-wide negative relationship between absolute divergence and the local recombination rate, potentially indicating natural selection against M. nasutus ancestry in M. guttatus genetic backgrounds. Together, our results suggest that Mimulus speciation is both ongoing and dynamic and that a combination of divergence in phenology and mating system, as well as selection against interspecific alleles, likely maintains these sympatric species.
Data from: Evidence for two sympatric sirenian species (Mammalia, Tethytheria) in the early Oligocene of Central Europe
The early Oligocene (Rupelian) sirenian Halitherium schinzii Kaup, 1838, which represents the type species of the genus Halitherium Kaup, 1838, is revised herein based on a morphological re-evaluation of skeletal material originally assigned to this taxon. This study provides new and comprehensive information on the cranial and postcranial anatomy and allows the distinction of two sympatric species. Following a recent approach on the invalidity and subsequent rejection of H. schinzii Kaup, 1838, Kaupitherium gruelli new genus new species is established on the basis of a nearly complete holotype. The second taxon resembles K. gruelli n. sp. in a number of skeletal features, such as reduced nasals and absence of the canines, but can be clearly distinguished mainly by the post-canine dental formula and the supraoccipital morphology. The diagnostic skullcap of a species formerly synonymized under "H. schinzii" is re-validated as the holotype of K. bronni (Krauss, 1858). On the basis of paleoecological implications, a hypothesis is established to explain the overlapping stratigraphic and biogeographic occurrences (i.e., sympatry of both taxa). A diagnosis and up-to-date synonymy complement the taxonomical information. The revision of "H. schinzii" provides new data on the past sirenian diversity and forms the basis for a taxonomic and systematic re-evaluation of species originally grouped in the genus "Halitherium."
Data from: Dissecting functional components of reproductive isolation among closely related sympatric species of the Anopheles gambiae complex
Explaining how and why reproductive isolation evolves and determining which forms of reproductive isolation have the largest impact on the process of population divergence are major goals in the study of speciation. By studying recent adaptive radiations in incompletely isolated taxa, it is possible to identify barriers involved at early divergence before other confounding barriers emerge after speciation is complete. Sibling species of the Anopheles gambiae complex offer opportunities to provide insights into speciation mechanisms. Here we studied patterns of reproductive isolation among three taxa, An. coluzzii, An. gambiae s.s. and An. arabiensis, to compare its strength at different spatial scales, to dissect the relative contribution of pre- versus post-mating isolation, and to infer the involvement of ecological divergence on hybridization. Because F1 hybrids are viable, fertile, and not uncommon, understanding the dynamics of hybridization in this trio of major malaria vectors has important implications for how adaptations arise and spread across the group, and in planning studies of the safety and efficacy of gene drive as a means of malaria control. We first performed a systematic review and meta-analysis of published surveys reporting on hybrid prevalence, showing strong reproductive isolation at a continental scale despite geographically restricted exceptions. Second, we exploited our own extensive field datasets collected at a regional scale in two contrasting environmental settings, in order to assess: i) levels of pre-mating isolation; ii) spatio/temporal and frequency-dependent dynamics of hybridization, iii) relationship between reproductive isolation and ecological divergence, and iv) hybrid viability penalty. Results are in accordance with ecological speciation theory predicting a positive association between the strength of reproductive isolation and degree ecological divergence, and indicate that post-mating isolation does contribute to reproductive isolation among these species. Specifically, only post-mating isolation was positively associated with ecological divergence, whereas pre-mating isolation was correlated with phylogenetic distance.
Data from: Divergence in drought-response traits between sympatric species of Mimulus
Differential adaptation to local environmental conditions is thought to be an important driver of speciation. Plants, whose sedentary lifestyle necessitates fine-tuned adaptation to edaphic conditions such as water availability, are often distributed based on these conditions. Populations occupying water-limited habitats may employ a variety of strategies, involving numerous phenotypes, to prevent and withstand desiccation. In sympatry, two closely related Mimulus species – M. guttatus and M. nasutus – occupy distinct microhabitats that differ in seasonal water availability. In a common garden experiment, we characterized natural variation within and between sympatric M. guttatus and M. nasutus in the ability to successfully set seed under well-watered and drought conditions. We also measured key phenotypes for drought adaptation, including developmental timing, plant size, flower size, and stomatal density. Consistent with their microhabitat associations in nature, M. nasutus set seed much more successfully than M. guttatus under water-limited conditions. This divergence in reproductive output under drought was due to differences in mortality after the onset of flowering, with M. nasutus surviving at a much higher rate than M. guttatus. Higher seed set in M. nasutus was mediated, at least in part, by a plastic increase in the rate of late-stage development (i.e., fruit maturation), consistent with the ability of this species to inhabit more ephemeral habitats in the field. Our results suggest adaptation to water availability may be an important factor in species maintenance of these Mimulus taxa in sympatry.
FIGURES 36 in A sympatric species pair: Spogostylum ocyale (Wiedemann, 1828) and S. griseipenne Macquart, 1850 (Diptera: Bombyliidae)
FIGURES 36. Genitalia of Spogostylum species. 3. S. ocyale (Wiedemann), phallosome. 4. S. griseipenne (Macquart), phallosome. 5. S. ocyale, bulb of spermatheca. 6. S. griseipenne, bulb of spermatheca. Scale bars = 0.2 mm.
FIGURE 1 in Four new sympatric species of Tethya (Demospongiae: Hadromerida) from Abrolhos Archipelago (Bahia State, Brazil)
FIGURE 1. Distribution of Tethya brasiliana sp. nov. (13), Tethya cyanae sp. nov. (2), Tethya ignis sp. nov. (1) and Tethya rubra sp. nov. (1, 2) in Abrolhos Archipelago, Bahia State, Brazil.
FIGURE 5 in Four new sympatric species of Tethya (Demospongiae: Hadromerida) from Abrolhos Archipelago (Bahia State, Brazil)
FIGURE 5. Tethya ignis sp. nov. A, preserved holotype (MNRJ 5322A); B, architecture of the ectosome and choanosome; C, strongyloxea; D, spheraster; E, oxyaster and tylaster; F, oxyaster. B – C, LM; D – F, SEM.
FIGURE 6 in Four new sympatric species of Tethya (Demospongiae: Hadromerida) from Abrolhos Archipelago (Bahia State, Brazil)
FIGURE 6. Tethya rubra sp. nov. A, preserved holotype (MNRJ 5316); B, architecture of the ectosome and choanosome; C, strongyloxea; D, E, spherasters; F, oxyaster; G, oxyaster and tylasters; H, tylaster. B – C, LM; D – H, SEM.
FIGURE 2 in Four new sympatric species of Tethya (Demospongiae: Hadromerida) from Abrolhos Archipelago (Bahia State, Brazil)
FIGURE 2. In situ closeups of three species of Tethya from Abrolhos Archipelago, Brazil. A, B, Tethya brasiliana sp. nov. (paratypes); C, Tethya ignis sp. nov. (holotype); D, Tethya rubra sp. nov. (holotype).
FIGURE 4 in Four new sympatric species of Tethya (Demospongiae: Hadromerida) from Abrolhos Archipelago (Bahia State, Brazil)
FIGURE 4. Tethya cyanae sp. nov. A, preserved holotype (MNRJ 6723); B, architecture of the ectosome and choanosome; C, strongyloxea; D, spheraster; E, spheraster and tylaster; F, oxyaster and tylaster; G, tylaster; H, microoxyaster and tylasters. B – C, LM; D – H, SEM.
FIGURE 3 in Four new sympatric species of Tethya (Demospongiae: Hadromerida) from Abrolhos Archipelago (Bahia State, Brazil)
FIGURE 3. Tethya brasiliana sp. nov. A, preserved holotype (UFRJPOR 4670A); B and C, architecture of the ectosome and choanosome; D, strongyloxea; E, spherasters and strongylasters; F, microspheraster; G, strongylaster and microoxyaster; H, microoxyaster. B – D, LM; E – H, SEM.
FIGURES 8–15 in Phylogenetic studies of the subgenus Petrophilus Chaudoir (Coleoptera: Carabidae: Pterostichus), with description of a new species sympatric with P. thunbergi Morawitz
FIGURES 8–15. Endophalli of Petrophilus (8–13) and outgroup species (14, 15) (left lateral view, right lateral view). 8. P. j u n g e n s; 9. P. m a i c h e n s i s; 10. P. thunbergi (Ônuma-kôen); 11. P. thunbergi (Mt. Hirayama); 12. P. tuberifer (Mt. Hirayama); 13. P. tuberifer (Akisato-ikku); 14. P. creper; 15. P. vermiculosus. Numbers in square brackets indicate characters in Appendix 1. Scale: 1.0 mm.
FIGURE 16 in Phylogenetic studies of the subgenus Petrophilus Chaudoir (Coleoptera: Carabidae: Pterostichus), with description of a new species sympatric with P. thunbergi Morawitz
FIGURE 16. Phylogeny and possible character evolution of the subgenus Petrophilus based on the 50% majority consensus tree obtained by the successive-weighting analysis. White circles indicate nodes not shared by the strict consensus tree of the successive-weighting analysis, and black circles indicate nodes shared by the strict consensus tree resulting from the equal-weighting analysis. Numbers below branches indicate bootstrap values in the equal-weighting analysis (where>50%), Bremer support in the equal-weighting analysis, and bootstrap values in the successive-weighting analysis (where>50%). Numbers in the squares indicate characters in Appendix 1, and numbers above the squares indicate character-state changes. Black squares indicate unambiguously optimized characters. White squares indicate characters optimized with ACCTRAN and DELTRAN optimizations (marked with '(a)' and '(d)', respectively). The taxonomies from Kryzhanovshij et al. (1995) and Bousquet (1999, 2003) are presented for comparison. Species with asterisks are described after their studies, and species with two asterisks are not included in Kryzhanovshij et al. (1995).
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