Isolation and characterization of polymorphic microsatellites for the bastard sole (Microchirus azevia)

The bastard sole (Microchirus azevia) is a species of commercial interest in Spain. Nevertheless, little information is currently available about the genetic characteristics of wild populations. In this survey, we have developed eight new microsatellites using an enriched genome library protocol. Primers were screened on a total of 54 individuals from two wild populations (Mediterranean and Atlantic) from the south coast of Spain, revealing six to 18 alleles per locus with expected heterozygosities ranging from 0.51 to 0.94. These markers can potentially be useful tools for use in population genetic studies.     

Multiple selection pressures influence Trinidadian guppy (Poecilia reticulata) antipredator behavior

Animals alter their behavior to avoid a variety of differenttypes of predators. Trinidadian guppies (Poecilia reticulata)have been an important system for examining the evolution ofantipredator behavior because geographically isolated populationsexperience different amounts of aquatic predation. Althoughthe influence of aquatic predators has been well documented,selective pressures from other types of predators are less wellunderstood. We examined the response of wild-caught individualsfrom upstream and downstream populations to an aquatic predatorand a simulated aerial predator. As previously documented, fishfrom the downstream population responded more strongly to theaquatic predator than did fish from the upstream population,inspecting for longer periods of time. Guppies also exhibiteda strong behavioral response to the potential aerial predator.Although both populations displayed a similar magnitude of response,they differed in the specific behaviors used. Upstream fishtended to freeze on the tank bottom, whereas downstream fishtended to hide under shelter. Field observations suggest thatthese strategies are related to habitat features specific toeach site. The behaviors used against aerial predators differedsubstantially from the behaviors used against aquatic predators,suggesting that different types of predators exert conflictingselection pressures. This research demonstrates the importanceof considering multiple selection pressures acting on an organismwhen trying to understand the evolutionary history of behavioraland morphological traits.     

Isolation and characterization of highly polymorphic microsatellites in the chokka squid, Loligo reynaudii

The chokka squid, Loligo reynaudii, is the target of a commercially valuable fishery in South Africa, but little information is available on population structure and mating system. We developed 11 polymorphic microsatellite markers using both standard nonenrichment and enrichment protocols. Numbers of alleles per locus ranged from 11 to 30, and levels of expected heterozygosity ranged between 0.77 and 0.98. Three loci developed using an enriched library displayed significant departure from Hardy-Weinberg genotype proportions suggesting high frequencies of null alleles. The remaining loci should prove useful for population and parentage studies.     

Mechanisms underlying shoal composition in the Trinidadian guppy, Poecilia reticulata

Free-ranging groups are frequently assorted by phenotypic characters. However, very little is known about the underlying processes that determine this structuring. In this study, we investigate the mechanisms underlying the phenotypic composition of shoals of guppies ( Poecilia reticulata ) in a high-predation stream in Trinidad's Northern Mountain Range. We collected 57 entire wild shoals, which were strongly assorted by body length. Shoal encounters staged within an experimental arena showed shoal fission (but not fusion) events to be an important mechanism in generating phenotypic assortment. In the wild, fission and fusion between guppy shoals occurred extremely frequently and thus are unlikely to constrain the opportunities for shoal assortment. However, fission and fusion processes occur under the restrictions imposed by the distribution of individuals within the environment. We observed size specific segregation within the habitat in three dimensions, providing a passive mechanism that contributes to the maintenance of the observed homogeneity of group composition. Furthermore sex differences were found in social behaviour. Individual male guppies switched between shoals more frequently than females and left a shoal more often than females. We argue that shoal composition is determined by habitat segregation on a medium spatial scale and by fission/fusion processes on a small spatial scale (with sex-specific shoal dynamics adding a additional layer of complexity).     

Isolation and characterization of 43 microsatellite DNA markers for guppy (Poecilia reticulata)

Thirty‐nine polymorphic microsatellite DNA markers were isolated from the guppy (Poecilia reticulata) genomic library. All of the loci showed moderate allelic variation ranging from two to seven alleles, with observed heterozygosities from 0.000 to 0.938. The microsatellite DNA markers isolated will be available for use in analysis of quantitative trait loci in breeding programmes and for population genetic studies on experimental fish.     

Isolation and characterization of polymorphic microsatellite loci for the northern flicker (Colaptes auratus; Aves)

To investigate the mating system of northern flickers (Colaptes auratus), we developed primers for 14 microsatellite loci and screened them in 68 unrelated adults and their offspring. All markers were highly polymorphic with 9 to +36 alleles per locus. One marker was Z‐chromosome linked; one marker exceeded the size standard range and could not be analysed further. We checked the other 12 markers for Mendelian inheritance in 36 broods for which the social parents were known. Seven markers showed evidence for the presence of null alleles, and three of those showed significant deviation from Hardy–Weinberg equilibrium. Markers were generally unlinked.     

Direct and indirect ecosystem effects of evolutionary adaptation in the Trinidadian guppy (Poecilia reticulata)

Ecological and evolutionary processes may interact on the same timescale, but we are just beginning to understand how. Several studies have examined the net effects of adaptive evolution on ecosystem properties. However, we do not know whether these effects are confined to direct interactions or whether they propagate further through indirect ecological pathways. Even less well understood is how the combination of direct and indirect ecological effects of the phenotype promotes or inhibits evolutionary change. We coupled mesocosm experiments and ecosystem modeling to evaluate the ecological effects of local adaptation in Trinidadian guppies (Poecilia reticulata). The experiments show that guppies adapted to life with and without predators alter the ecosystem directly through differences in diet. The ecosystem model reveals that the small total indirect effect of the phenotype observed in the experiments is likely a combination of several large indirect effects that act in opposing directions. The model further suggests that these indirect effects can reverse the direction of selection that direct effects alone exert back on phenotypic variation. We conclude that phenotypic divergence can have major effects deep in the web of indirect ecological interactions and that even small total indirect effects can radically change the dynamics of adaptation.     

Intrinsic reproductive isolation between Trinidadian populations of the guppy, Poecilia reticulata

Although Trinidadian populations of the guppy, Poecilia reticulata, show considerable adaptive genetic differentiation, they have been assumed to show little or no reproductive isolation. We tested this assumption by crossing Caroni (Tacarigua River) and Oropuche (Oropuche R.) drainage populations from Trinidad's Northern Range, and by examining multiple aspects of reproductive compatibility in the F1, F2 and BC1 generations. In open-aquarium experiments, F1 males performed fewer numbers of mating behaviours relative to parental population controls. This is the first documentation of hybrid behavioural sterility within a species, and it suggests that such sterility may feasibly be involved in causing speciation. The crosses also uncovered hybrid breakdown for embryo viability, brood size and sperm counts. In contrast, no reductions in female fertility were detected, indicating that guppies obey Haldane's rule for sterility. Intrinsic isolation currently presents a much stronger obstacle to gene flow than behavioural isolation, and our results indicate that Trinidadian populations constitute a useful model for investigating incipient speciation.     

Isolation and characterization of polymorphic microsatellites in the Potato Tuber Moth Tecia solanivora (Povolny, 1973) (Lepidoptera: Gelechiidae)

Nine polymorphic microsatellite markers were isolated from Tecia solanivora, one of the most serious pests of potato tubers in Central and South America. As found in other studies of Lepidoptera, development of microsatellites is a difficult task: in our case, despite the large number of clones sequenced (796), of which 70 were unique, only nine loci were found to be both variable, and in Hardy-Weinberg equilibrium, No null alleles were detected. The loci were tested in three other co-occurring Gelechiidae species, one of which was variable. These loci will be used to provide a greater understanding of the genetic changes occurring during the invasive process in this species.     

Population differentiation in Trinidadian guppies (Poecilia reticulata): patterns and problems

Populations of the guppy, Poecilia reficulata , in N. Trinidad exhibit marked population differentiation in allozyme frequencies. Here we investigate six further populations electrophoretically at 25 enzyme-coding loci to examine patterns in geographical structuring, genotypic distributions and genetic diversity. With one exception, possibly related to an experimental introduction, populations divided broadly (dendrogram of Nei's mean genetic identity, Ī) in accordance with proposed ancestral colonization. Most populations were in Hardy Weinberg equilibrium, though some significant deficits in heterozygotes were detected. Incorporating information from published data, markedly hjgher levels of genetic diversity (mean observed heterozygosity, _o) were recorded in lowland [_o= 0.0382 ± k0406 ( s.e .), n = 9] compared with upstream populations [_o= 0.0112 ± 00034 (S.E.), n = 9]. Patterns are discussed in relation to historical and present-day evolutionary forces.     

Primers for 12 polymorphic microsatellite DNA loci from the guppy (Poecilia reticulata)

Twelve polymorphic microsatellite DNA loci were isolated from genomic guppy DNA. We assessed the level of genetic diversity for these loci using individuals from five native Trinidadian populations. All the loci were polymorphic although there were considerable differences among loci and populations in allele frequencies. Within populations, the number of alleles ranged from 1 to 22 and observed heterozygosities ranged from 0.000 to 0.990. Allele frequencies differed substantially between populations suggesting divergence.     

Aerial Jumping in the Trinidadian Guppy (Poecilia reticulata)

Many fishes are able to jump out of the water and launch themselves into the air. Such behavior has been connected with prey capture, migration and predator avoidance. We found that jumping behavior of the guppy Poecilia reticulata is not associated with any of the above. The fish jump spontaneously, without being triggered by overt sensory cues, is not migratory and does not attempt to capture aerial food items. Here, we use high speed video imaging to analyze the kinematics of the jumping behavior P. reticulata. Fish jump from a still position by slowly backing up while using its pectoral fins, followed by strong body trusts which lead to launching into the air several body lengths. The liftoff phase of the jump is fast and fish will continue with whole body thrusts and tail beats, even when out of the water. This behavior occurs when fish are in a group or in isolation. Geography has had substantial effects on guppy evolution, with waterfalls reducing gene flow and constraining dispersal. We suggest that jumping has evolved in guppies as a behavioral phenotype for dispersal.     

Isolation and characterization of polymorphic microsatellites from Asian green mussel (Perna viridis)

Asian green mussels (Perna viridis) belonging to the family Mytilidae are native to the coastal and tropical marine waters of the Indo‐Pacific region. Ten polymorphic microsatellites were isolated and their polymorphisms were determined in 36 individuals. The average allele number of the 10 microsatellites was 11.7/locus with a range of two to 24 and the expected heterozygosity averaged at 0.69, ranging from 0.18 to 0.94. Eight out of 10 microsatellites agreed with the Hardy–Weinberg equilibrium and showed independent segregation. These microsatellites will facilitate the studying of the genetic diversity and population structure of the green mussel in and outside of the Indo‐Pacific region of Asia.     

Isolation and characterization of 17 polymorphic microsatellites in grass carp

Here we report the isolation and characterization of 17 polymorphic loci isolated from a partial genomic DNA library of grass carp (Ctenopharyngodon idellus) enriched for CA repeats. We tested variability of these microsatellites on 24 unrelated individuals collected in China. All microsatellites were polymorphic. The average allele number was 7.9 per locus, ranging from four to 13. The observed heterozygosity was from 0.46 to 0.88 with an average of 0.71, whereas the average expected heterozygosity was 0.78. Sixteen of the 17 microsatellites conformed to Hardy–Weinberg equilibrium, and inherited independently. These microsatellites can be used to study genetic diversity and population structure of wild populations, and facilitate selective breeding of cultured broodstocks.     

Cross-generational environmental effects and the evolution of offspring size in the Trinidadian guppy Poecilia reticulata

Abstract The existence of adaptive phenotypic plasticity demands that we study the evolution of reaction norms, rather than just the evolution of fixed traits. This approach requires the examination of functional relationships among traits not only in a single environment but across environments and between traits and plasticity itself. In this study, I examined the interplay of plasticity and local adaptation of offspring size in the Trinidadian guppy, Poecilia reticulata. Guppies respond to food restriction by growing and reproducing less but also by producing larger offspring. This plastic difference in offspring size is of the same order of magnitude as evolved genetic differences among populations. Larger offspring sizes are thought to have evolved as an adaptation to the competitive environment faced by newborn guppies in some environments. If plastic responses to maternal food limitation can achieve the same fitness benefit, then why has guppy offspring size evolved at all? To explore this question, I examined the plastic response to food level of females from two natural populations that experience different selective environments. My goals were to examine whether the plastic responses to food level varied between populations, test the consequences of maternal manipulation of offspring size for offspring fitness, and assess whether costs of plasticity exist that could account for the evolution of mean offspring size across populations. In each population, full‐sib sisters were exposed to either a low‐ or high‐food treatment. Females from both populations produced larger, leaner offspring in response to food limitation. However, the population that was thought to have a history of selection for larger offspring was less plastic in its investment per offspring in response to maternal mass, maternal food level, and fecundity than the population under selection for small offspring size. To test the consequences of maternal manipulation of offspring size for offspring fitness, I raised the offspring of low‐ and high‐food mothers in either low‐ or high‐food environments. No maternal effects were detected at high food levels, supporting the prediction that mothers should increase fecundity rather than offspring size in noncompetitive environments. For offspring raised under low food levels, maternal effects on juvenile size and male size at maturity varied significantly between populations, reflecting their initial differences in maternal manipulation of offspring size; nevertheless, in both populations, increased investment per offspring increased offspring fitness. Several correlates of plasticity in investment per offspring that could affect the evolution of offspring size in guppies were identified. Under low‐food conditions, mothers from more plastic families invested more in future reproduction and less in their own soma. Similarly, offspring from more plastic families were smaller as juveniles and female offspring reproduced earlier. These correlations suggest that a fixed, high level of investment per offspring might be favored over a plastic response in a chronically low‐resource environment or in an environment that selects for lower reproductive effort     

Isolation and characterization of eight polymorphic microsatellite loci in the rainforest canopy tree,Syzygium sayeri (Myrtaceae)

Eight polymorphic microsatellite loci were isolated from the rainforest canopy tree, Syzygium sayeri, in order to study parentage and subsequently pollen dispersal among individuals in wild populations. Screening of one natural population (n = 64) mapped in a 500 × 500 m area at Cape Tribulation, north Queensland, Australia, yielded two to 11 alleles per locus with observed levels of heterozygosity ranging from 0.07 to 0.70. One locus was significantly out of Hardy–Weinberg equilibrium after Bonferroni correction for multiple tests. These loci should provide a useful tool in further understanding the dispersal patterns of this species.     

Isolation and characterization of polymorphic microsatellite markers for peacock wrasse (Symphodus tinca)

Eight polymorphic microsatellite loci were isolated and characterized for the peacock wrasse (Symphodus tinca), a labrid fish inhabiting the Mediterranean and Black seas. Characterization of 35 individuals from the western Mediterranean indicated a relatively high allelic diversity (mean = 12.4, range 9–17), and observed heterozygosity ranging from 0.65 to 0.91. We found no evidence of linkage disequilibrium between pairs of loci. Two loci showed significant departure from Hardy–Weinberg equilibrium. These polymorphic markers can be useful in most basic population genetic applications.     

Cloning of highly polymorphic microsatellites in the horse

We have isolated equine microsatellites by screening a genomic library with (TG)n and (TC)n probes. TG microsatellites were found to be more abundant than TC repeats, with an estimated frequency of one per 100,000bp. Sequence analysis of eight TG-positive clones revealed varying structures of the repeat regions; perfect stretches of TG repeats, imperfect stretches of TG repeats and compound regions of TG and TC repeats. Five loci were analysed by PCR and showed extensive polymorphism; three to seven alleles and heterozygosities of 0.40-0.76 were observed when screening 20-30 unrelated individuals. The high degree of polymorphism, their abundance and the possibility of automating the typing procedure make these loci ideal for standardized paternity testing in the horse. Furthermore, we demonstrate that single hairs can be used as starting material for the PCR analysis.     

Beauty in the eyes of the beholders: colour vision is tuned to mate preference in the Trinidadian guppy (Poecilia reticulata)

A broad range of animals use visual signals to assess potential mates, and the theory of sensory exploitation suggests variation in visual systems drives mate preference variation due to sensory bias. Trinidadian guppies (Poecilia reticulata), a classic system for studies of the evolution of female mate choice, provide a unique opportunity to test this theory by looking for covariation in visual tuning, light environment and mate preferences. Female preference co‐evolves with male coloration, such that guppy females from ‘low‐predation’ environments have stronger preferences for males with more orange/red coloration than do females from ‘high‐predation’ environments. Here, we show that colour vision also varies across populations, with ‘low’‐predation guppies investing more of their colour vision to detect red/orange coloration. In independently colonized watersheds, guppies expressed higher levels of both LWS‐1 and LWS‐3 (the most abundant LWS opsins) in ‘low‐predation’ populations than ‘high‐predation’ populations at a time that corresponds to differences in cone cell abundance. We also observed that the frequency of a coding polymorphism differed between high‐ and low‐predation populations. Together, this shows that the variation underlying preference could be explained by simple changes in expression and coding of opsins, providing important candidate genes to investigate the genetic basis of female preference variation in this model system.