Variation in sexual dimorphism and assortative mating do not predict genetic divergence in the sexually dimorphic Goodeid fish Girardinichthys multiradiatus

Abstract Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with large variation between species in sexual dimorphism in body shape. Previously we found an association between variation in morphological sexual dimorphism between species and the amount of gene flow within populations in the Goodeinae. Here we have examined if morphological differentiation within a single dimorphic species is related to assortative mating or gene flow between populations. In the Amarillo fish Girardinichthys multiradiatus studies have shown that exaggerated male fins are targets of female preferences. We find that populations of the species differ in the level of sexual dimorphism displayed due to faster evolution of differences in male than female morphology. However, this does not predict variation in assortative mating tests in the laboratory; in fact differences in male morphology are negatively correlated with assortative mating. Microsatellite markers reveal significant genetic differences between populations. However, gene flow is not predicted by either morphological differences or assortative mating. Rather, it demonstrates a pattern of isolation by distance with greater differentiation between watersheds. We discuss the caveats of predicting behavioural and genetic divergence from so-called proxies of sexual selection.

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Morphometric differentiation and sexual dimorphism in Limnomedusa macroglossa (Duméril & Bibron, 1841) (Anura: Alsodidae) from Uruguay

Acta Herpetologica ◽

10.36253/a_h-8955 ◽

2021 ◽

Vol 16 (1) ◽

pp. 11-25

Author(s):

Valeria De Olivera-López ◽

Arley Camargo ◽

Raúl Maneyro

Keyword(s):

Sexual Selection ◽

Body Size ◽

Sexual Dimorphism ◽

Phenotypic Plasticity ◽

Life History Strategies ◽

Clinal Variation ◽

Size And Shape ◽

Secondary Sexual Characteristics ◽

Sexual Characteristics ◽

Morphological Differences

Intersexual morphological differences within a species occur in many traits, including body size and shape. Many processes that cause geographic variability in morphology have been proposed: population structure, phenotypic plasticity (environmental effects on development), and natural and/or sexual selection. Several hypotheses can explain patterns of sexual dimorphism in anurans, including natural or intra/inter-sexual selection, and differences in life history strategies between sexes. Limnomedusa macroglossa is considered a habitat specialist restricted to rocky outcrops in Brazil, Argentina, Paraguay, and Uruguay. We evaluated the extent of sexual (size and shape) dimorphism in L. macroglossa from Uruguay based on morphometrics and secondary sexual characteristics, while taking into account geographic variation. Sexual dimorphism in body size of adults was found, but multivariate analyses did not demonstrate the existence of significant differences in shape. There were also significant differences in body size and hind leg measurements among six hydrographic basins as a result from the phenotypic plasticity correlated with local temperature, representing a clinal variation along the latitudinal gradient of Uruguay. The sexual dimorphism found in body size is probably the consequence of higher growth rates and/or late sexual maturity in females, which favors larger body size for accommodating larger ovaries, and thus, higher reproductive output.

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Assortative mating, sexual selection, and their consequences for gene flow in Littorina

Evolution ◽

10.1111/evo.14027 ◽

2020 ◽

Vol 74 (7) ◽

pp. 1482-1497

Author(s):

Samuel Perini ◽

Marina Rafajlović ◽

Anja M. Westram ◽

Kerstin Johannesson ◽

Roger K. Butlin

Keyword(s):

Sexual Selection ◽

Gene Flow ◽

Assortative Mating

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Geography, assortative mating, and the effects of sexual selection on speciation with gene flow

Evolutionary Applications ◽

10.1111/eva.12296 ◽

2015 ◽

Vol 9 (1) ◽

pp. 91-102 ◽

Cited By ~ 38

Author(s):

Maria R. Servedio

Keyword(s):

Sexual Selection ◽

Gene Flow ◽

Assortative Mating

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REPRODUCTIVE ISOLATION WITH LITTLE GENETIC DIVERGENCE IN SYMPATRIC POPULATIONS OF BROWN TROUT (SALMO TRUTTA)

Genetics ◽

10.1093/genetics/92.1.247 ◽

1979 ◽

Vol 92 (1) ◽

pp. 247-262

Author(s):

Nils Ryman ◽

Fred W Allendorf ◽

Gunnar Ståhl

Keyword(s):

Gene Flow ◽

Lactate Dehydrogenase ◽

Brown Trout ◽

Genetic Divergence ◽

Salmo Trutta ◽

Morphological Differentiation ◽

Ecological Perspective ◽

Mountain Lake ◽

Sympatric Populations ◽

Brown Trout Salmo Trutta

ABSTRACT Two reproductively isolated demes of brown trout coexist in a small Swedish mountain lake, Lake Bunnersjoarna. We electrophoretically examined 102 specimens from that lake for 27 enzymes encoded by 54 loci. The two demes are fixed for different alleles at a lactate dehydrogenase locus (LDH-1); statistically significant allele frequency differences at five other loci further support the complete lack of gene flow between these demes. There are significant differences in growth rates between fish in the two demes, but no further morphological differentiation has been detected.——In light of these findings, the genetic distance between these populations is surprisingly small (NEI'S I=0.975). These demes represent one of the least genetically divergent, reproductively isolated sympatric pair of vertebrate populations that have been identified. The results are discussed from both an evolutionary and ecological perspective.

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Pairing dynamics and the origin of species

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.1549 ◽

2011 ◽

Vol 279 (1731) ◽

pp. 1085-1092 ◽

Cited By ~ 25

Author(s):

Oscar Puebla ◽

Eldredge Bermingham ◽

Frédéric Guichard

Keyword(s):

Sexual Selection ◽

Gene Flow ◽

Mate Choice ◽

Assortative Mating ◽

Evolutionary Biology ◽

Population Genetic Analysis ◽

Flow Through ◽

Individual Based Simulation ◽

The Stability ◽

Standing Question

Whether sexual selection alone can drive the evolution of assortative mating in the presence of gene flow is a long-standing question in evolutionary biology. Here, we report a role for pairing dynamics of individuals when mate choice is mutual, which is sufficient for the evolution of assortative mating by sexual selection alone in the presence of gene flow. Through behavioural observation, individual-based simulation and population genetic analysis, we evaluate the pairing dynamics of coral reef fish in the genus Hypoplectrus (Serranidae), and the role these dynamics can play for the evolution of assortative mating. When mate choice is mutual and the stability of mating pairs is critical for reproductive success, the evolution of assortative mating in the presence of gene flow is not only possible, but is also a robust evolutionary outcome.

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Morphological distinction and sexual dimorphism in divergent clades of Neurergus kaiseri (Amphibia: Salamandridae)

Basic and Applied Herpetology ◽

10.11160/bah.102 ◽

2018 ◽

Vol 32 ◽

pp. 5-17

Author(s):

Hadi Khoshnamvand ◽

Mansoureh Malekian ◽

Yazdan Keivany

Keyword(s):

Sexual Selection ◽

Body Size ◽

Sexual Dimorphism ◽

Principle Component Analysis ◽

Morphological Differentiation ◽

Taxonomic Revision ◽

Morphological Characters ◽

Head Width ◽

Morphological Distinction ◽

Ecological Differences

Morphological differentiation and sexual dimorphism in the two genetically distinct clades (Northern and Southern clades) of the Lorestan newt, Neurergus kaiseri, was evaluated for 72 live specimens, using five body- and nine head-related characters and eight calculated ratios. Principle component analysis of morphological characters confirmed that the Lorestan newt populations are well separated into two distinct groups, suggesting that a taxonomic revision in N. kaiseri may be required because of significant molecular, morphological and ecological differences between these clades. Sexual dimorphism in N. kaiseri includes body size and shape. Females were clearly larger than males in most body- and head-related variables and males had relatively greater head width and eye length. Sexual dimorphism in this species may be linked to sexual selection and ecological differences between sexes. However, many aspects of the ecology and reproductive biology of this species remain unknown.

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Assortative mating, sexual selection and their consequences for gene flow in Littorina

10.1101/2020.01.28.922658 ◽

2020 ◽

Author(s):

Samuel Perini ◽

Marina Rafajlović ◽

Anja M. Westram ◽

Kerstin Johannesson ◽

Roger K. Butlin

Keyword(s):

Sexual Selection ◽

Gene Flow ◽

Natural Selection ◽

Reproductive Isolation ◽

Assortative Mating ◽

Small Male ◽

Mating Pattern ◽

Barrier Effects ◽

Divergent Natural Selection ◽

Coastal Marine

AbstractWhen divergent populations are connected by gene flow, the establishment of complete reproductive isolation usually requires the joint action of multiple barrier effects. One example where multiple barrier effects are coupled consists of a single trait that is under divergent natural selection and also mediates assortative mating. Such multiple-effect traits can strongly reduce gene flow. However, there are few cases where patterns of assortative mating have been described quantitatively and their impact on gene flow has been determined. Two ecotypes of the coastal marine snail, Littorina saxatilis, occur in North Atlantic rocky-shore habitats dominated by either crab predation or wave action. There is evidence for divergent natural selection acting on size, and size-assortative mating has previously been documented. Here, we analyze the mating pattern in L. saxatilis with respect to size in intensively-sampled transects across boundaries between the habitats. We show that the mating pattern is mostly conserved between ecotypes and that it generates both assortment and directional sexual selection for small male size. Using simulations, we show that the mating pattern can contribute to reproductive isolation between ecotypes but the barrier to gene flow is likely strengthened more by sexual selection than by assortment.

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The size of signal detection and emission organs in a synchronous firefly: sexual dimorphism, allometry and assortative mating

PeerJ ◽

10.7717/peerj.10127 ◽

2020 ◽

Vol 8 ◽

pp. e10127

Author(s):

Tania López-Palafox ◽

Rogelio Macías-Ordóñez ◽

Carlos R. Cordero

Keyword(s):

Sexual Selection ◽

Sexual Dimorphism ◽

Assortative Mating ◽

Sexual Communication ◽

Operational Sex Ratio ◽

Mating Season ◽

Mating Period ◽

Communication Signals ◽

Eye Size ◽

Trade Offs

The size of the organs responsible for emitting and detecting sexual communication signals is a likely target for selection. Communication via bioluminescent signals in synchronous fireflies is a promising model to test hypotheses regarding differences between males and females in the effect of the size of signal emission and detection organs on fitness components. Synchronous firefly species congregate in large numbers during the mating season, displaying bioluminescent signals aimed at potential mates during relatively short nightly periods. Operational sex ratios are male-biased and, thus, the so-called typical sex roles (indiscriminate males and choosy females) are expected to evolve. We studied the synchronous firefly Photinus palaciosi, a species that during the mating season congregates in forests of central Mexico offering a magnificent natural show that attracts numerous tourists. P. palaciosi females have reduced wings (brachyptery) and cannot fly. Our field study tested the hypothesis that the male-biased operational sex ratio and the short daily mating period result in strong male-male competition that selects for males with larger lanterns and larger eyes, and against male mate choice, whereas female-female mate competition is absent and, thus, no selection on lantern or eye size is expected. Even though lantern, eye or body size do not predict the probability of being found in copula for either sex, sexual dimorphism in these features, along with allometric slopes of lantern size and assortative mating in terms of relative lantern size, support not only the hypothesis of intense sexual selection among males, but the possibility of subtle mechanisms of sexual selection among females. Trade-offs between investment in signaling (lanterns) versus detection (eyes) structures, or with pressures different from sexual selection such as those imposed by predators, are also likely to be important in shaping the evolution of sexual signaling in these fireflies.

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Patterns of Mitochondrial Variation Within and Between African Malaria Vectors, Anopheles gambiae and An. arabiensis, Suggest Extensive Gene Flow

Genetics ◽

10.1093/genetics/147.4.1817 ◽

1997 ◽

Vol 147 (4) ◽

pp. 1817-1828 ◽

Cited By ~ 4

Author(s):

Nora J Besansky ◽

Tovi Lehmann ◽

G Thomas Fahey ◽

Didier Fontenille ◽

Lawrence E O Braack ◽

...

Keyword(s):

Gene Flow ◽

Anopheles Gambiae ◽

Genetic Divergence ◽

Isolation By Distance ◽

Haplotype Diversity ◽

Introgressive Hybridization ◽

Sub Saharan Africa ◽

Malaria Vectors ◽

Amino Acid Difference ◽

Mtdna Sequence

Abstract Anopheles gambiae and An. arabiensis are mosquito species responsible for most malaria transmission in sub-Saharan Africa. They are also closely related sibling species that share chromosomal and molecular polymorphisms as a consequence of incomplete lineage sorting or introgressive hybridization. To help resolve these processes, this study examined the partitioning of mtDNA sequence variation within and between species across Africa, from both population genetic and phylogeographic perspectives. Based on partial gene sequences from the cytochrome b, ND1 and ND5 genes, haplotype diversity was high but sequences were very closely related. Within species, little or no population subdivision was detected, and there was no evidence for isolation by distance. Between species, there were no fixed nucleotide differences, a high proportion of shared polymorphisms, and eight haplotypes in common over distances as great as 6000 km. Only one of 16 shared polymorphisms led to an amino acid difference, and there was no compelling evidence for nonneutral variation. Parsimony networks constructed of haplotypes from both species revealed no correspondence of haplotype with either geography or taxonomy. This trend of low intraspecific genetic divergence is consistent with evidence from allozyme and microsatellite data and is interpreted in terms of both extensive gene flow and recent range expansion from relatively large, stable populations. We argue that retention of ancestral polymorphisms is a plausible but insufficient explanation for low interspecific genetic divergence, and that extensive hybridization is a contributing factor.

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Morphological and genetic analysis in morphologically divergent river and lake specimens of the freshwater crayfish Samastacus spinifrons (Philippi, 1882) (Decapoda, Parastacidae)

Crustaceana ◽

10.1163/15685403-00003560 ◽

2016 ◽

Vol 89 (8) ◽

pp. 877-899 ◽

Cited By ~ 4

Author(s):

Erich Rudolph ◽

Nelson Colihueque ◽

Miguel Yañez

Keyword(s):

Genetic Divergence ◽

Morphological Variability ◽

Morphological Differentiation ◽

Coi Gene ◽

Genetic Constitution ◽

Freshwater Crayfish ◽

Morphological Variations ◽

Genetic Level ◽

Morphological Differences ◽

Degree Of Differentiation

Samastacus spinifrons (Philippi, 1882), is the only South American parastacid that inhabits both rivers and lakes. The literature on this species reports certain morphological differences between representatives of lake and river populations. The aim of this study was to analyse the degree of differentiation of these morphological variations through multivariate analysis, and to explore the possible causes at a genetic level, by undertaking genetic divergence analysis using 18S and 28S ribosomal DNA molecular markers, and the mitochondrial cytochrome c oxidase subunit I (COI) gene. The material analysed was collected from five populations of central-southern Chile, two of which were lake and three were river populations. Our results show that marked morphological differences exist between lake morph and river morph individuals. These differences are related with the size of the rostrum, cephalothorax, chelae of the first pair of pereopods (P1) and phallic papillae. The lake specimens present a larger body size, a longer rostrum and more elongated, less thick P1 chelae and longer phallic papillae. Similarly, their body spinulation is significantly more prominent. Nevertheless, this level of morphological differentiation did not correlate positively with the genetic divergence analysis, since only scarce genetic differentiation was observed between representatives of the lake and river morphs of S. spinifrons. These results suggest that the morphs analysed would emerge as a consequence of the phenotypic plasticity phenomenon. Thus, this morphological variability could be explained by the adaptation of S. spinifrons specimens of a similar genetic constitution, to limnic environments with very different dynamics.

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