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1.
Tobler M Palacios M Chapman LJ Mitrofanov I Bierbach D Plath M Arias-Rodriguez L de León FJ Mateos M 《Evolution; international journal of organic evolution》2011,65(8):2213-2228
We investigated replicated ecological speciation in the livebearing fish Poecilia mexicana and P. sulphuraria (Poeciliidae), which inhabit freshwater habitats and have also colonized multiple sulfidic springs in southern Mexico. These springs exhibit extreme hypoxia and high concentrations of hydrogen sulfide, which is lethal to most metazoans. We used phylogenetic analyses to test whether springs were independently colonized, performed phenotypic assessments of body and gill morphology variation to identify convergent patterns of trait differentiation, and conducted an eco-toxicological experiment to detect differences in sulfide tolerances among ecotypes. Our results indicate that sulfidic springs were colonized by three different lineages, two within P. mexicana and one representing P. sulphuraria. Colonization occurred earlier in P. sulphuraria, whereas invasion of sulfidic springs in P. mexicana was more recent, such that each population is more closely related to neighboring populations from adjacent nonsulfidic habitats. Sulfide spring fish also show divergence from nonsulfidic phenotypes and a phenotypic convergence toward larger heads, larger gills, and increased tolerance to H(2) S. Together with previous studies that indicated significant reproductive isolation between fish from sulfidic and nonsulfidic habitats, this study provides evidence for repeated ecological speciation in the independent sulfide spring populations of P. mexicana and P. sulphuraria. 相似文献
2.
L Sola A R Rossi V Iaselli E M Rasch P J Monaco 《Cytogenetics and cell genetics》1992,60(3-4):229-235
Chromosomes of Poecilia mexicana mexicana, one of the bisexual species involved in the hybrid origin of the unisexual teleost fish species P. formosa, were analyzed by several staining techniques. Sex-specific, differential heterochromatin, found in other congeneric species, was not observed in P. m. mexicana. Nucleolar organizer regions were polymorphic among individual specimens within a given population sample. A single specimen exhibiting intraindividual variability of chromosome pair 1 and a specimen with a triploid karyotype are also described. 相似文献
3.
Introduction of exotic fishes into Hawai'ian streams has resulted in the simultaneous introduction of exotic parasites. Camallanus corti (Nematoda) and Bothricephalus acheilognathi (Cestoda) are the most prevalent and abundant fish helminths in Hawai'ian streams. The population structure and host specificity of C. cotti and B. acheilognathi in exotic poeciliids were examined during May and June 1995 in Waianu Stream, O'ahu, Hawai'i. Prevalence and mean abundance of C. cotti were significantly different among Poecilia reticulata (65.2%, 1.05), Poecilia mexicana (49.0%, 0.87), and Xiphophorus helleri (32.3%, 0.44). Prevalence of B. acheilognathi was significantly higher in P. mexicana (6.1%) than in P. reticulata (2.1%) and X. helleri (1.6%). However, tapeworm differences in mean abundance were not significant among P. mexicana (0.08), P. reticulata (0.04), or X. helleri (0.03). Nematode and tapeworm prevalence and mean abundance were not significantly different with regard to fish sex. Camallanus cotti prevalence and mean abundance increased as P. mexicana body size increased (r2 = 0.84 and r2 = 0.72, respectively), whereas B. acheilognathi displayed no significant trend with respect to poeciliid body size. 相似文献
4.
Comparisons based upon morphological features and cytochemical staining properties of chromatin, nucleoli, and the ooplasm were used in the present analysis of ovarian maturation in wild-caught Poecilia mexicana and its related gynogenetic diploid and triploid' species'. Using an empirically derived ovarian maturation index, seasonal and collection site differences were found between the unisexual and bisexual forms. These fish seem equally suited to their environments. However, our data indicate that differences in microhabitat can have a profound influence on oocyte development. Although females of Poecilia spp. have asynchronous cycles of ovarian maturation, we could not detect any peculiar cytological events associated with the gynogenetic mode of reproduction. Sperm were found in ovaries of both unisexual and bisexual forms indicating that the unisexuals can compete effectively with females of P. mexicana for matings with males of this species. The methods employed in this study provide a sensitive measure of reproductive potentials in sympatric species. 相似文献
5.
PEERING THROUGH THE LOOKING GLASS AT A SEXUAL PARASITE: ARE AMAZON MOLLIES RED QUEENS? 总被引:2,自引:0,他引:2
Dries LA 《Evolution; international journal of organic evolution》2003,57(6):1387-1396
Abstract.— The gynogenetic Amazon molly ( Poecilia formosa ) is a clonal, all-female lineage of livebearing fish that faces an unusual obstacle to evolutionary persistence. Sperm from heterospecific males (either sailfin, P. latipinna , or Atlantic, P. mexicana , mollies) is necessary to trigger embryogenesis. However, none of the male's genes are incorporated into the genome of the gynogenetic offspring. Some investigators have proposed that the evolution of male mate discrimination is a result of this cost, leading to a coevolutionary arms race between male avoidance of P. formosa and P. formosa attractiveness. Given that P. formosa successfully reproduces and has not yet gone extinct, it is clear there are mechanisms by which they attract the sexual attention of males. Although a Red Queen coevolutionary process in typical host/parasite systems has been shown to favor the persistence of sexual species, in this system an arms race has been invoked to explain the reverse. Here I present behavioral data supporting a more parsimonious scenario: that mechanisms of attraction in P. formosa are simply a consequence of its hybrid origin. Poecilia latipinna and P. mexicana males do not discriminate between gynogenetic P. formosa females and first generation sexual hybrid females, and females do not differ in agonistic behaviors associated with competition for mates. Both results contradict predictions from the Red Queen hypothesis. Therefore, coevolution is not necessary to explain the apparent evolutionary persistence of P. formosa. 相似文献
6.
Abstract. 1. Caves are often assumed to be predator-free environments for cave fishes. This has been proposed to be a potential benefit of colonising these otherwise harsh environments. In order to test this hypothesis, the predator–prey interaction of a belostomatid (predator) and a cave fish (prey) occurring in the Cueva del Azufre (Tabasco, Mexico) was investigated with two separate experiments.
2. In one experiment, individual Belostoma were given a chance to prey on a cave fish, the cave form of the Atlantic molly ( Poecilia mexicana ), to estimate feeding rates and size-specific prey preferences of the predator. In the other experiment, population density of Belostoma was estimated using a mark–recapture analysis in one of the cave chambers.
3. Belostomatids were found to heavily prey on cave mollies and to exhibit a prey preference for large fish. The mark–recapture analysis revealed a high population density of the heteropterans in the cave.
4. The absence of predators in caves is not a general habitat feature for cave fishes. None the less predation regimes differ strikingly between epigean and hypogean habitats. The prey preference of Belostoma indicates that cave-dwelling P. mexicana experience size-specific predation pressure comparable with surface populations, which may have implications for life-history evolution in this cave fish. 相似文献
2. In one experiment, individual Belostoma were given a chance to prey on a cave fish, the cave form of the Atlantic molly ( Poecilia mexicana ), to estimate feeding rates and size-specific prey preferences of the predator. In the other experiment, population density of Belostoma was estimated using a mark–recapture analysis in one of the cave chambers.
3. Belostomatids were found to heavily prey on cave mollies and to exhibit a prey preference for large fish. The mark–recapture analysis revealed a high population density of the heteropterans in the cave.
4. The absence of predators in caves is not a general habitat feature for cave fishes. None the less predation regimes differ strikingly between epigean and hypogean habitats. The prey preference of Belostoma indicates that cave-dwelling P. mexicana experience size-specific predation pressure comparable with surface populations, which may have implications for life-history evolution in this cave fish. 相似文献
7.
8.
To monitor the perpetuation of triploid genomes in laboratory-reared progeny of wild-caught females of Poecilia, amounts of DNA-Feulgen staining in scale epithelial nuclei were determined for 58 different fish. Based on estimates of average DNA content, these specimens were readily separated into two groups: (a) diploids, with an average of 1–57 × 10−12 g DNA per cell and (b) triploids, with an average of 2.38 × 10−12 g DNA per cell. These values yield a ratio of 1: 1.5, as would be expected from the presence of an extra chromosome set in putative triploid females. Ploidy status of the latter, based on DNA cytophotometry, was independently confirmed for several specimens by direct cytological examination of chromosome number, by electrophoresis of plasma proteins and by morpho-metric analysis. These findings unequivocally document one case involving the production of triploid offspring from a typical, diploid P. formosa and several instances in which broods of all-female triploid offspring were derived in the laboratory from both wild-caught and laboratory-reared triploid mothers. The relationship and significance of these triploid forms to the breeding complex of P. formosa and P. mexicana in nature are discussed. 相似文献
9.
Pyrenothrix mexicana Herrera-Campos, Huhndorf & Lücking spec. nova is described from leaves in the upper montane rainforest of Oaxaca State, Mexico. It is the second species in the genus Pyrenothrix Riddle, established at the beginning of the twentieth century for the single species, P. nigra Riddle, a corticolous lichen restricted to southeastern United States. Both taxa have the same thallus and perithecial morphology and anatomy, but P. mexicana differs by its longer, transversally septate ascospores. The perithecial anatomy of Pyrenothrix is documented and its systematic affinities are discussed, and we conclude that the family Pyrenothrichaceae Zahlbr. should be placed in the order Chaetothyriales. 相似文献
10.
Photophilic behaviour in surface- and cave-dwelling Atlantic mollies Poecilia mexicana (Poeciliidae)
The phototactic behaviour of surface- and cave-dwelling Atlantic mollies Poecilia mexicana was examined. Surface-dwelling Atlantic mollies, as well as light- and dark-reared cave fish showed photophilic behaviour under all light intensities used (620, 50 and 3 lx). 相似文献
11.
The visual pigments of cones and rods in three species of mollies, Poecilia mexicana , Poecilia latipinna and their asexual hybrid Poecilia formosa , were examined using microspectrophotometry. In P. mexicana , populations from extreme photic habitats were used: one population originated from a clear water habitat, one from a milky water habitat and another from a completely dark cave. Ultraviolet-sensitive cones were found in all species. Differences in the λmax values of the visual pigments were small between species and among the three P. mexicana populations, but dark-reared cave fishes showed appreciably higher variance. The hybrid species P. formosa showed a highly variable long wavelength cone absorbance, ranging from 528·9 to 598·5 nm, suggesting multiple opsin expression or chromophore mixing. 相似文献
12.
Changes in glucose-6-phosphate dehydrogenase (G6P DH; EC 1.1.1.49) activity caused by infection of tobacco ( Nicotiana tabacum L.) leaves with potato virus Y (PVY), cucumber mosaic virus, potato virus X, tobacco rattle virus and turnip mosaic virus, the subcellular localisation of G6P DH isozymes in mesophyll protoplasts derived from healthy and PVY-infected tobacco leaves, as well as G6P DH control and the relationship of its isozymes with the degree of tobacco resistance to PVY multiplication, were studied. The activities of G6P DH were markedly increased in locally and systemically infected leaves and the time courses of the activity linearly correlated with those of virus multiplication. In leaves infected with PVY, the activity time courses of the crude and the partially purified G6P DH were coincident. This probably indicates the involvement of coarse regulation of the enzyme. PVY content linearly correlated with enhanced G6P DH activity in leaf discs derived from susceptible, tolerant and resistant cultivars of tobacco. The increased activity of the enzyme in infected protoplasts and plant tissues was predominantly caused by the increased activity of chloroplastic isozymes. This was confirmed by the specific staining of isozymes after electrophoretic separation of chloroplastic proteins of tobacco leaves. These findings enable the degree of resistance to virus multiplication to be quantified for the use of gene manipulation and breeding. 相似文献
13.
《Journal of morphology》2017,278(12):1667-1681
The structure of the ovary and oogenesis of Poecilia mexicana from an active sulfur spring cave is documented. Poecilia mexicana is the only poeciliid adapted to a subterranean environment with high hydrogen sulfide levels and extreme hypoxic conditions. Twenty females were captured throughout one year at Cueva del Azufre, located in the State of Tabasco in Southern Mexico. Ovaries were processed with histological techniques. P. mexicana has a single, ovoid ovary with ovigerous lamella that project to the ovarian lumen. The ovarian wall presents abundant loose connective tissue, numerous melanomacrophage centers and large blood vessels, possibly associated with hypoxic conditions. The germinal epithelium bordering the ovarian lumen contains somatic and germ cells forming cell nests projecting into the stroma. P. mexicana stores sperm in ovarian folds associated with follicles at different developmental phases. Oogenesis in P. mexicana consisted of the following stages: (i) oogonial proliferation, (ii) chromatin nucleolus, (iii) primary growth, subdivided into: (a) one nucleolus, (b) multiple nucleoli, (c) droplet oils‐cortical alveoli steps; (iv) secondary growth, subdivided in: (a) early secondary growth, (b) late secondary growth, and (c) full grown. Follicular atresia was present in all stages of follicular development; it was characterized by oocyte degeneration, where follicle cells hypertrophy and differentiate in phagocytes. The ovary and oogenesis are similar to these seen in other poeciliids, but we found frequent atretic follicles, melanomacrophage centers, reduced fecundity and increased of offspring size. 相似文献
14.
Replication, integration and stable germ-line transmission of foreign sequences injected into early zebrafish embryos 总被引:26,自引:0,他引:26
To generate stable lines of transgenic fish, early zebrafish embryos were injected with high concentrations of a linear bacterial plasmid. After injection, the foreign DNA was converted into a high molecular weight form and then amplified approximately tenfold during the initial rapid cleavages characteristic of the early embryo prior to gastrulation. While most of this DNA was subsequently degraded during gastrulation, some of the foreign sequences survived the gastrula stage and could be found in most of the injected fish at 3 weeks of age. Only about 5% of fish analysed 4 months after the injection retained foreign DNA in their fins, usually at less than one copy per cell. One of these fish was also found to contain about 100 copies per cell of foreign DNA in a fraction of its germ cells. Approximately 20% of the F1 offspring from this germ-line-positive parent inherited the foreign DNA, whereas 50% of F2 progeny obtained from an identified F1 individual inherited these sequences. The 50% transmission rate in F2 progeny was as expected for a single, heterozygous genomic insert. These observations indicate that injected DNA can be integrated into the fish genome, that the resulting transgenic fish are mosaic and that some of these mosaic individuals give rise to stable lines of transgenic fish. 相似文献
15.
Tanaka D Takahashi A Ueno K 《Journal of experimental zoology. Part A, Ecological genetics and physiology》2009,311(1):11-19
Nuclear transplants of loach were produced by transplantating blastula cell nuclei into nonenucleated unfertilized eggs, using recipient eggs and donor cells distinguished by different polymorphic microsatellites. Of the total of 2,847 operated eggs, 143 hatched and 119 developed to the feeding larval stage. For 15 nuclear transplants (i.e., 11.1-year-old fish and 4.2-year-old fish) that survived up to the adulthood, DNA analysis and karyotype analysis were performed. Results showed that, of the 15 fish, 14 had only a nucleus derived from the donor; moreover, 12 were diploids, 1 was a triploid, 1 was a tetraploid, and 1 was a diploid-tetraploid mosaic with both donor and recipient nuclei. For the 12 fish with only a 2n donor nucleus, morphometric analysis was performed, and two female fish and two male fish were mated with normal fish. The fish with only a 2n donor nucleus were determined to be morphometrically identical to normal fish: they had normal gametogenesis and were able to reproduce. Currently, nuclear transplantation technology is beginning to be adopted in fisheries. Biological information on nuclear transplants obtained in this study can be used in the development of nuclear transplantation technology. 相似文献
16.
Three previously introduced parasitoids (Acerophagus papayae Noyes and Schauff, Anagyrus loecki Noyes and Menezes, and Pseudleptomastix mexicana Noyes and Schauff [Hymenoptera: Encyrtidae]) of the mealybug Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae) were studied for their host instar susceptibility and sex ratio, host instar selection, and interspecific competition in the laboratory. All three parasitoids were able to develop in the second instars, third-instar females, and adult females of P. marginatus. No progeny emerged from first-instar mealybugs. The proportion of female emergence was increased with increasing host size. Parasitoids selected their host instars for oviposition when they had a choice. Between second- and third-instar hosts, A. papayae and P. mexicana had significantly higher parasitism in second-instar mealybugs, whereas A. loecki had higher parasitism in the third-instar mealybugs. When competed with either one or two parasitoid species, A. papayae was significantly more successful in second-instar hosts and A. loecki was significantly more successful in third-instar mealybugs. P. mexicana was significantly less competitive when with A. papayae in both second and third instars, with A. loecki in third instars and with both A. papayae and A. loecki in second and third instars. Overall, A. papayae provided a better control of the host, when present singly or with the other two parasitoids. This information is important in evaluating the efficiency of A. papayae, A. loecki, and P. mexicana and understanding the outcome of their recovery and establishment in field studies conducted in Florida. 相似文献
17.
Sexual selection by female choice can maintain male traits that are counter selected by natural selection. Alteration of the potential for sexual selection can thus lead to shifts in the expression of male traits. We investigated female mate choice for large male body size in a fish (Poecilia mexicana) that, besides surface streams, also inhabits two caves. All four populations investigated, exhibited an ancestral visual preference for large males. However, only one of the cave populations also expressed this female preference in darkness. Hence, the lack of expression of female preference in darkness in the other cave population leads to relaxation of sexual selection for large male body size. While P. mexicana populations with size-specific female mate choice are characterized by a pronounced male size variation, the absence of female choice in one cave coincides with the absence of large bodied males in that population. Our results suggest that population differences in the potential for sexual selection may affect male trait variation. 相似文献
18.
Hall GS 《Mycopathologia》1997,140(3):141-147
Using the mitochondrial DNA miniprep technique, the identity of sixteen morphologically unusual cultures allocated to Phytophthora
nicotianae, Phytophthora mexicana or Phytophthora porri was determined by comparison with a library of mtDNA band patterns
obtained from reference cultures. Seven cultures were identified as Phytophthora nicotianae (including those assigned to Phytophthora
mexicana and Phytophthora porri), six as strains of Phytophthora palmivora with small, ovoid, weakly caducous sporangia, and
one as Phytophthora citrophthora. Some cultures of P. nicotianae had a low percentage of caducous sporangia. Percentage sporangium
caducity, but not sporangium L : B ratio, is considered a useful taxonomic criterion for separating species morphologically
similar to Phytophthora nicotianae. One culture from tobacco in New Zealand had a highly unusual morphology and a unique DNA
band pattern, but was not identifiable. One culture from Acacia mearnsii in South Africa had a unique DNA band pattern which
was identical to that of an isolate from Annona squamosa from Australia previously identified as Phytophthora palmivora, the
precise identity of which is still unclear. The identity of most isolates from diseased durian was found to be Phytophthora
palmivora, confirming its role as the main pathogen, but P. nicotianae was also identified from this host.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
Van Wynsberghe NR Canto-Lara SB Damián-Centeno AG Itzá-Ortiz MF Andrade-Narváez FJ 《Memórias do Instituto Oswaldo Cruz》2000,95(5):595-600
In the State of Campeche, Mexico, zoonotic cutaneous leishmaniasis is mainly due to Leishmania (L.) mexicana. The parasite population is maintained in a mammalian species, a reservoir in which the ideal course of infection should be long and relatively nonpathogenic. The objective of the present study was to document the retention of L. (L.) mexicana in 29 naturally infected rodents. These cricetids lived in captivity for up to two years and were tested monthly for the presence of the parasite, by cultures of needle aspirates from the base of the tail. Peromyscus yucatanicus and Ototylomys phyllotis were incriminated as the primary reservoir hosts. The finding that the multiplication of parasites in P. yucatanicus might be triggered by temperature, suggests that this animal would be a good choice for further research on L. (L.) mexicana. 相似文献
20.
E M Flores 《Revista de biología tropical》1975,23(1):29-52
The leaf anatomy of two Bromeliaceae, Hechtia glomerata Zucc., a terrestrial xerophyte of arid zones, and Acehmea mexicana Baker, a tropical moist forest epiphyte, is compared; these species show adaptations to different extremes of adverse environmental conditions as to water uptake. The leaves of A. mexicana have more water storage tissue than those of H. glomerata; on the other hand, H. glomerata is capable of root absorption. In A. mexicana, modified nonfunctional stomata increase transpiration resistance. Also, this species shows more specialized foliar trichomes which permit the uptake of water and possibly of nutrients. The balance between transpiration and absorption rates is regulated in both species by the combined presence of peltate scales and stomata. The degree of adaptation to drought presented by epiphytic species is more complicated than that shown by terrestrial species. Epiphytic plants like A. mexicana may be derived from xerophytic species that have undergone readaptation to a humid climate. The conspicuous negative geotropism in the leaves of A. mexicana causes the formation of basal deposits of water, which play an important functional role in survival. 相似文献