Description of a new species from Laguna Chichancanab,Yucatan, Mexico: <Emphasis Type="Italic">Cyprinodon suavium</Emphasis> (Pisces: Cyprinodontidae)

Cyprinodon suavium is a new species that belongs to the endemic species flock from Laguna Chichancanab, Yucatan, Mexico, which is proposed to have evolved by sympatric speciation in the lake during the last 8000years. C. suaviumis distinguished from all other known Cyprinodon species by a flattened and concave inter- and postorbital skull roof and a terminal mouth with distinctive thickened lips. The short gut length and dietary items found in the gut indicate that C. suavium is one of the carnivorous members of the flock.     

A test for conspecific cueing in two sympatric species of pupfish (<Emphasis Type="Italic">Cyprinodon beltrani</Emphasis>, <Emphasis Type="Italic">C. simus</Emphasis>)

In many fishes, individuals prefer to associate with phenotypically similar or conspecific individuals (conspecific cueing). Such phenotypic segregation can be an important evolutionary driver, for example, in intralacustric sympatric speciation processes. I examined conspecific cueing in two species of sympatric pupfish from Laguna Chichancanab in southern Mexico: the little shoaling and highly territorial Cyprinodon beltrani and the highly shoaling but non-territorial C. simus. Females were tested for shoal species preferences in two testing scenarios: (1) a sequential choice test where shoals of four conspecific or four heterospecific (Cyprinodon sp. or Poecilia reticulata) females were presented in succession, and (2) a simultaneous choice test where female shoals of both Cyprindon species were presented concurrently. Overall, higher shoaling in C. simus was corroborated in this study. In the sequential test, no effect of the type of stimulus shoal (con- or heterospecific) on shoaling behavior was detected. In the simultaneous tests, C. beltrani, but not C. simus females showed a preference for the conspecific shoal. It seems possible that C. simus females did not evolve species recognition mechanisms because no other Cyprinodon species in the Laguna Chichancanab shows equally high shoaling, which automatically leads to the formation of single-species (i.e., C. simus-) shoals. C. simus males do not establish long-term territories, but rather spawn within shoals, whereas C. beltrani females approach males in their breeding territories to spawn. I discuss that this behavioral difference still provides a powerful reproductive isolation mechanism even in the absence of conspecific cueing in C. simus.     

Genetic differentiation and reproductive isolation in a Cyprinodon fish species flock from Laguna Chichancanab, Mexico

The Cyprinodon species flock from Laguna Chichancanab, aged 8000 years, provides another potential case of sympatric speciation. The flock consists of seven morphologically distinct species, each within partially different trophic niches, and a group of specimens which cannot unequivocally be assigned to one of these species. Genetic analyses, based on mtDNA and five microsatellite loci, revealed significant genetic differentiation of one species, C. maya, from other members of the species flock, providing strong evidence for reproductive isolation. For the remaining members of the flock significant genetic structuring was detected, with some evidence of gene flow with the most abundant species C. beltrani. These analyses suggest that speciation proceeds with ongoing hybridisation, and further suggest that the morphologically unidentifiable specimens found in the lake are probably hybrids. I propose that in the Cyprinodon species flock besides disruptive selection sexual selection plays an important part in achieving and maintaining reproductive isolation.     

Mating preferences in a species flock of Mexican pupfishes (Cyprinodon, Teleostei)

Female mating preferences were examined in three members of an evolutionarily young Cyprinodon lineage from Laguna Chichancanab, Yucatan, Mexico. In separate experiments, females of C. beltrani and C. labiosus , and C. beltrani and C. maya were simultaneously presented with conspecific and heterospecific males and given the opportunity to spawn with either or both. These three species showed different degrees of conspecific mate recognition: complete for C. maya , intermediate for C. labiosus , and indiscriminate for C. beltrani. We conclude that only C. maya is reproductively isolated and that C. beltrani and C. labiosus still hybridize in nature. Whereas between C. beltrani and C. maya mate choice is symmetric, it is asymmetric between C. beltrani and C labiosus. The results of the mating trials are consistent with mitochondrial DNA data which indicate that C. maya is genetically the most distinct species in the flock. They are also supported by experiments on visually and chemically mediated mate preferences.     

Relationships between spatio-temporal environmental and genetic variation reveal an important influence of exogenous selection in a pupfish hybrid zone

The importance of exogenous selection in a natural hybrid zone between the pupfishes Cyprinodon atrorus and Cyprinodon bifasciatus was tested via spatio‐temporal analyses of environmental and genetic change over winter, spring and summer for three consecutive years. A critical influence of exogenous selection on hybrid zone regulation was demonstrated by a significant relationship between environmental (salinity and temperature) and genetic (three diagnostic nuDNA loci) variation over space and time (seasons) in the Rio Churince system, Cuatro Ciénegas, Mexico. At sites environmentally more similar to parental habitats, the genetic composition of hybrids was stable and similar to the resident parental species, whereas complex admixtures of parental and hybrid genotypic classes characterized intermediate environments, as did the greatest change in allelic and genotypic frequencies across seasons. Within hybrids across the entire Rio Churince system, seasonal changes in allelic and genotypic frequencies were consistent with results from previous reciprocal transplant experiments, which showed C. bifasciatus to suffer high mortality (75%) when exposed to the habitat of C. atrorus in winter (extreme temperature lows and variability) and summer (abrupt salinity change and extreme temperature highs and variability). Although unconfirmed, the distributional limits of C. atrorus and C. atrorus‐like hybrids appear to be governed by similar constraints (predation or competition). The argument favouring evolutionary significance of hybridization in animals is bolstered by the results of this study, which links the importance of exogenous selection in a contemporary hybrid zone between C. atrorus and C. bifasciatus to previous demonstration of the long‐term evolutionary significance of environmental variation and introgression on the phenotypic diversification Cuatro Ciénegas Cyprinodon.     

Mate recognition systems in a species flock of Mexican pupfish

The pupfishes of Lake Chichancanab (Mexico) provide a unique opportunity to study the evolution of premating reproductive barriers. This group of endemic species is of recent origin and the lineages differ in morphological traits indicating trophic specialization, but show very little genetic change. We studied the function of visual and chemical cues in the mate recognition system of three morphospecies, Cyprinodon beltrani, C. labiosus and C. maya. Only in C. maya, which is genetically the most distinct member of the group, do females show the ability to identify males of their own type, both visually and chemically. C. labiosus females discriminated between their own and C. beltrani males based on chemical but not visual cues. C. beltrani, which is morphologically the least differentiated member of the group, showed no interspecific mate recognition. Females responded more strongly to the visual and chemical cues of their own males than to their own females, but they did not discriminate between their own males and those of the other two morphospecies based upon either type of cue. These results suggest that different levels of behavioural isolation have been established: most isolated is C. maya, and the least is C. beltrani. C. labiosus has an intermediate position. The results also suggest that species recognition cues based on different sensory modalities do not necessarily evolve together, and may evolve at different rates.     

Trophic differentiation in the phylogenetically young Cyprinodon species flock (Cyprinodontidae, Teleostei) from Laguna Chichancanab (Mexico)

Analysis of the gut contents of six syntopic Cyprinodon species from Laguna Chichancanab, Mexico, shows that the supposed basal form, C. beltrani , feeds on detritus and has the longest gut. All other species have significantly shorter guts. Whereas C. simus exclusively ingests detritus despite short gut length, all other species additionally rely on different benthic invertebrates. Each species has developed specific preferences: C. labiosus (amphipods), C. verecundus (bivalves), C. maya (ostracods and gastropods) and C. esconditus (ostracods and chironomid larvae). However, all of them ingest a minimum of c. 40% detritus. According to Schoener's index, pairwise niche overlap varies from c. 40% to over 95% in the species flock. Contrary to this, there is almost no overlap between the members of the flock and the only other native fish species, Gambusia sexradiata , which feeds nearly exclusively on terrestrial arthropods dropping on the water surface. Recently, the cichlid genus Oreochromis and the characid Astyanax fasciatus gained access to the lake. The cichlids show moderate to high niche overlap, whereas in A. fasciatus it is low. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 125–134.     

Identification and characterization of eight microsatellite loci in Machilus pseudokobu (Lauraceae), an endemic species of the Bonin Islands

Eight microsatellite loci were identified and characterized for the endangered Machilus pseudokobu (Lauraceae), an endemic tree species of the Bonin Islands. The observed number of alleles at each locus ranged from 1 to 20 with an average of 6.2, and the expected heterozygosity ranged from 0.00 to 0.83 with an average of 0.47. All eight loci were screened in cross-amplification tests for two other endemic Machilus species that also inhabit the Bonin Islands. All loci were successfully amplified in these species.     

Microsatellite markers for Kleinia neriifolia,an endemic Asteraceae species on the Canary Islands

• Premise of the study: Microsatellite makers were developed in Kleinia neriifolia, an endemic Asteraceae species on the Canary Islands, for investigation of the population genetic structure and colonization history of this insular species. • Methods and Results: Seventeen polymorphic and seven monomorphic microsatellite loci were isolated and characterized from K. neriifolia using the protocol of Fast Isolation by AFLP of Sequences COntaining repeats (FIASCO). At the population level, the number of alleles detected per locus varied from two to 16, and the observed and expected heterozygosities were 0.105–1.000 and 0.100–0.923, respectively. • Conclusions: These highly informative loci are potentially useful to obtain a deeper understanding of the evolutionary process of K. neriifolia.     

Additional microsatellites for Sparus aurata and cross‐species amplification within the Sparidae family

Six new microsatellite loci were isolated and characterized in 32 individuals from a farm population of gilthead seabream (Sparus aurata). Expected heterozygosity at all loci was high, ranging from 0.835 to 0.958 with between 10 and 27 alleles per locus. A multiplex polymerase chain reaction protocol was developed using four of the loci. Cross‐species amplification of the loci was tested in six species of the Sparidae family and four loci were successfully amplified in two or more related species.     

Polymorphic microsatellite markers for the Iberian rock lizard species,Iberolacerta cyreni,and cross‐species priming in other Iberolacerta species

Eight polymorphic microsatellite loci are described for the Iberian rock lizard species, Iberolacerta cyreni. Loci were isolated from a partial genomic library that had been enriched for AAAG repeat sequence. Number of alleles per locus ranged from two to 13 in a sample of 24 individuals from the Sierra de Guadarrama (central Spain). Observed heterozygosity ranged from 0.13 to 0.96. At least three loci were amplified and polymorphic in four other Iberian rock lizard species: Iberolacerta monticola, Iberolacerta bonnali, Iberolacerta aranica and Iberolacerta aurelioi. These markers will be used to study mating strategies and reproductive success in I. cyreni.     

Two new species of Heptapterus (Siluriformes: Heptapteridae) from the Uruguay River basin,Brazil

As part of an ongoing taxonomic revision of the genus Heptapterus from the Laguna dos Patos and Uruguay River drainages and Atlantic coastal streams of southern Brazil and Uruguay, two new species closely related to Heptapterus mustelinus were identified. Both species are endemic to small tributaries of the Uruguay River. The two new species are distinguished from each other and from other species of Heptapterus by arrangement of cephalic and trunk laterosensory systems, number of vertebrae and number of dorsal, pectoral and anal-fin rays. Phylogenetic analyses of mitochondrial DNA (coI and cytb) sequence data further supports distinctiveness of the two new species.     

Isolation of microsatellite loci and cross‐species amplifications in three gobiid fish of the genus Pomatoschistus

Gobiids of the genus Pomatoschistus are increasingly being investigated as models for adaptation to coastal environments and for mating system studies. Among the dozen currently analysed species, microsatellite primers have been characterized only for Pomatoschistus minutus. This paper describes seven new polymorphic loci isolated from Pomatoschistus marmoratus and Pomatoschistus microps, two species that hybridize. Cross‐species amplification was tested for these new loci, together with seven already published P. minutus loci. Systematic amplification of samples of each of the three species provided a first indication of their polymorphism.     

Development and characterization of 11 novel microsatellite loci for the roundscale spearfish Tetrapturus georgii and their cross‐species amplification among other istiophorid species

Eleven novel polymorphic microsatellite loci were developed and characterized for the recently validated roundscale spearfish Tetrapturus georgii. Characterization of these markers, based on 35 roundscale spearfish from the western North Atlantic, revealed two to 21 alleles per locus with an average expected heterozygosity (H_E) of 0·09–0·94, and all loci conformed to Hardy–Weinberg expectations. Cross‐amplification of these 11 loci against all other eight known istiophorid species indicates promising prospects for the utility of these markers for istiophorids in general.     

Isolation and characterization of simple sequence repeat loci in Rubus hochstetterorum and their use in other species from the Rosaceae family

The identification of microsatellite loci in Rubus hochstetterorum provides an important tool for the characterization and conservation of wild populations of this species. Cross‐species amplification of markers may be of particular interest for the study of other Rubus species. In this study, 41 simple sequence repeat markers were identified in a genomic library of R. hochstetterorum. Fifteen of the identified microsatellite loci were characterized in a set of 30 samples and revealed to be polymorphic with three to 19 alleles per locus. All the identified markers allowed cross‐species amplification in at least one of the other three tested species from the Rosaceae family.     

Microsatellite loci in the Propertius duskywing,Erynnis propertius (Lepidoptera: Hesperiidae), and related species

Fifteen polymorphic dinucleotide microsatellite loci were characterized for Erynnis propertius using an enrichment protocol. The number of alleles varied from nine to 28 for a sample of 24 individuals. Observed heterozygosities ranged from 0.25 to 0.96. Homozygote excess was detected for 10 loci. Twelve markers successfully amplified in related Erynnis species and eight loci were polymorphic in at least one other species.     

Isolation and characterization of the first microsatellite loci from the order Psocoptera in the economically important pest insect Liposcelis decolor (Pearman) and cross‐species amplification

A total of 11 microsatellite loci from the invasive insect pest Liposcelis decolor were isolated and characterized of which six loci were polymorphic. A population survey involving a total of 30–192 individuals per locus from five populations revealed a range of four to seven alleles per locus and moderate observed heterozygosities (0.183–0.565), highlighting the utility of these loci in further population genetic studies. Cross‐species amplifications were successful for two to 11 loci in five other Liposcelis species also of international economic importance.     

Reproductive isolation among endemic pupfishes (Cyprinodon) on San Salvador Island,Bahamas: microsatellite evidence

Three pupfish (Cyprinodon) morphotypes (two endemic) occur in some of the young (6000 ypb) saline lakes on the Bahamian island of San Salvador. The ‘normal’ morph, a detritivore/omnivore, is not different in its general features from Cyprinodon variegatus from other Bahamian islands. ‘Bulldog’ is a scale‐eater/piscivore that preys upon normal pupfish, and ‘bozo’ is a specialized molluskivore. Reproductive isolation among these morphs is not predicted by the evolutionary biology of congeneric species because sympatry of even morphogically and ecologically quite divergent pupfishes has usually resulted in hybridization/introgression. Survey of variation at eight microsatellite loci reveals that sympatric normal and bulldog populations are genetically distinctive by several criteria, and are therefore likely reproductively isolated. The bulldog morph in Crescent Pond is markedly divergent from those in Little Lake and Osprey Lake, a finding consistent with, although it does not prove, separate parallel origins of this morphotype. The data also suggest that the bulldogs in the latter two lakes did not evolve by intralacustrine speciation from the current sympatric normal populations. Some of the genetic data suggest that the bozo morph may also be reproductively isolated from the other two pupfishes, but only a small, pooled sample of this rare morphotype was available, and the issue is not resolved. Isolating mechanisms between bulldog and normal morphs are of special interest because of the possibility that they arose as a consequence of a predator–prey relationship. A strong correlation between reproductive isolation and predator–prey interactions could provide an important example of ecological speciation via direct selection against heterotypic interactions. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 566–582.     

Characterization of polymorphic microsatellite loci in the aphid species Macrosiphum euphorbiae (Hemiptera: Aphididae)

Fourteen microsatellite loci were isolated and characterized in the potato aphid, Macrosiphum euphorbiae Thomas, by screening a genomic library with the oligonucleotide probes (GA)₁₀ (GT)₁₀ and (GATA)₄. Allelic diversity was estimated in samples collected from potato fields in Tunisia. Ten loci displayed polymorphism that ranged from two to four alleles per locus and the observed heterozygosity ranged from zero to one. These markers could be used to study the population genetic structure of this polyphagous aphid species.