Genetic control of the hypothalamo‐pituitary axis and the effect of hybridization on sexual maturation (<i>Xiphophorus</i>, Pisces, Poeciliidae)

Bao, Isaac Y.; Kallman, Klaus D.

doi:10.1002/jez.1402200305

Cited by 30 publications

(15 citation statements)

References 19 publications

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“…Growth rate was estimated from the slope of the curve of size versus age at an age two-thirds ofthat at maturity, following Travis et al (1990). The use of growth rate at this point ensures that all fish are compared at the same developmental stage within each gender (see Bao and Kallman, 1982).…”

Section: Discussionmentioning

confidence: 99%

PHENOTYPIC PLASTICITY IN THE SAILFIN MOLLY, POECILIA LATIPINNA (PISCES: POECILIIDAE). II. LABORATORY EXPERIMENT

1990

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Abstract. -Field studies indicate that the influence of environmental factors on growth rate and size and age at maturity in sailfin mollies (Poecilia latipinna) is inconsistent over time and suggest that the marked interdemic variation in male body size in this species is the result of genetic variation. However, the role of specific environmental factors in generating phenotypic variation must be studied under controlled conditions unattainable in nature. We raised newborn sailfin mollies from four populations in laboratory aquaria under all possible combinations of two temperatures, three salinities, and two food levels to examine explicitly the influence of these environmental factors. Males were much less susceptible than females to temperature variation and were generally less plastic than females in terms of all three traits. Members of both sexes matured at larger sizes and at later ages in less saline and in cooler environments. Food levels were not sufficiently different to affect the traits we studied. The effects of temperature and salinity were not synergistic. Males from different populations exhibited different average ages and sizes at maturity, but females did not. The magnitudes ofthe effects we found were not substantial enough to account for the consistent interdemic differences in male and female body size that have been observed previously. Our results also indicate that no single environmental factor is solely responsible for the environmental effectsobserved in field experiments on growth and development. These studies, together with other work, indicate that the strongest sources of interdemic variation are genetic differences in males and differences in postmaturation growth and survivorship in females.

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Section: Discussionmentioning

confidence: 99%

PHENOTYPIC PLASTICITY IN THE SAILFIN MOLLY, POECILIA LATIPINNA (PISCES: POECILIIDAE). II. LABORATORY EXPERIMENT

1990

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“…37 In several Continued D of these cases, substantial linkage mapping has been used within such hybrid crossing schemes for the purposes of localizing disease loci (reviewed by Naim et al 4 ). In addition, microsatellite loci have recently been developed and used in mapping studies in a cross between X. maculatus (Jp 163 B) and X. andersi.…”

Section: Overall Marker Availability In Xiphophorusmentioning

confidence: 99%

The Genetic Map ofXiphophorusFishes Represented by 24 Multipoint Linkage Groups

et al. 2004

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Hybrids between distinct Xiphophorus species have been utilized for over 70 years to study melanoma and other neoplasms that can develop spontaneously in hybrid offspring. Genetic linkage mapping has proven to be important in delineating genomic areas that harbor oncogenes and tumor suppressors. Within this report, two parallel backcrosses have been utilized to generate a genetic linkage map for Xiphophorus fishes. Isozyme/allozyme, RFLP and PCR-based mapping techniques, including AP-PCR/RAPDs and microsatellite loci were utilized. The derived linkage map provides a total of 403 mapped polymorphisms distributed among 24 linkage groups, representative of 24 acro- and telocentric chromosome pairs. Genomic coverage is approximately one marker per 5.8 cM. Detailed genotypic analysis of the utilized hybrids revealed two areas of the genome that show significant segregation distortion. Loci within the linkage group harboring the sex determining locus (LG 24) and an autosomal linkage group (LG 21) show highly significant deviations from Mendelian expectations. This phenomenon is not present in a hybrid cross that utilizes a different backcross hybrid progenitor species. The derived map with sequence-tagged markers provides a framework for physical map generation, large-scale genomic sequencing and will further enable cross-genome comparisons of vertebrate genomes.

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“…For platyfish, more than 70 years of research has yielded a body of knowledge about phenotypic effects of many life-history and coloration loci. As a result, both genetic variation at the P-locus and physiological consequences of P-alleles have been characterized (Bao & Kallman 1982). For platyfish, the opposing effects of a generation time advantage and a reduced predation-risk advantage probably contribute to maintaining the P-locus polymorphism.…”

Section: Discussionmentioning

confidence: 99%

Evolution of pleiotropic alleles for maturation and size as a consequence of predation

Basolo

2008

Biol. Lett.

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Understanding life-history evolution requires knowledge about genetic interactions, physiological mechanisms and the nature of selection. For platyfish, Xiphophorus maculatus, extensive information is available about genetic and physiological mechanisms influencing lifehistory traits. In particular, alleles at the pituitary locus have large and antagonistic effects on age and size at sexual maturation. To examine how predation affects the evolution of these antagonistic traits, I examined pituitary allele evolution in experimental populations differing in predation risk. A smaller size, earlier maturation allele increased in frequency when predators were absent, while a larger size, later maturation allele increased in frequency when predators were present. Thus, predation favours alleles for larger size, at the cost of later maturation and reproduction. These findings are interesting for several reasons. First, predation is often predicted to favour early reproduction at smaller sizes. Second, few studies have shown how selection acts on alleles that affect age and size at sexual maturation. Finally, many studies assume that trade-offs between these life-history traits result from antagonistic pleiotropy, with alleles that positively affect one trait negatively affecting another, yet this is rarely known. This study unequivocally demonstrates that genetically based trade-offs affect life-history evolution in platyfish.

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Genetic control of the hypothalamo‐pituitary axis and the effect of hybridization on sexual maturation (Xiphophorus, Pisces, Poeciliidae)

Cited by 30 publications

References 19 publications

PHENOTYPIC PLASTICITY IN THE SAILFIN MOLLY, POECILIA LATIPINNA (PISCES: POECILIIDAE). II. LABORATORY EXPERIMENT

PHENOTYPIC PLASTICITY IN THE SAILFIN MOLLY, POECILIA LATIPINNA (PISCES: POECILIIDAE). II. LABORATORY EXPERIMENT

The Genetic Map ofXiphophorusFishes Represented by 24 Multipoint Linkage Groups

Evolution of pleiotropic alleles for maturation and size as a consequence of predation

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