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

2006 ◽  
Vol 39 (3) ◽  
pp. 865-872 ◽  
Author(s):  
Ulrike Strecker
Keyword(s):  
Genetic Differentiation ◽  
Reproductive Isolation ◽  
Fish Species ◽  
Species Flock

scholarly journals Speciation in the Cladophorales species flock of ancient Lake Baikal

2021 ◽  
Author(s):  
◽  
Sergio Diaz Martinez
Keyword(s):  
Population Genetics ◽  
Genetic Variation ◽  
Reproductive Isolation ◽  
Lake Baikal ◽  
Species Delimitation ◽  
Sympatric Speciation ◽  
Species Flock ◽  
Ancient Lake ◽  
Data Set ◽  
Dispersal Abilities

<p>Understanding speciation is one of the great challenges in evolutionary biology as many of the processes involved in speciation, as well as the forces leading to morphological and genetic differentiation, are not fully understood. Three main modes of speciation have been described: allopatric, parapatric and sympatric. Sympatric speciation is the most enigmatic mode because in the absence of physical barriers, disruptive selection, assortative mating and hybridization play central roles in reproductive isolation. Although it is accepted that sympatric speciation is possible, only a few examples of this process exist to date. Another common method of speciation in plants and algae is via polyploidization. Recently, a promising system to study speciation in sympatry was discovered: the endemic Cladophorales species flock in ancient Lake Baikal, Russia. The flock consists of sixteen taxa grouped in four genera: Chaetocladiella, Chaetomorpha, Cladophora and Gemmiphora. In spite of their morphological diversity, recent molecular analyses have shown that this is a monophyletic group with low genetic variation and nested within the morphologically simple genus Rhizoclonium. Due to their high number of species, endemism and sympatric distribution, many interesting questions have arisen such as what processes are involved in speciation, and whether this group might be a novel example of sympatric speciation. In this study, we analysed the population genetics of the endemic Baikalian Cladophorales to infer the processes shaping the evolution of the group. First, a set of microsatellites was designed using high-throughput sequencing data. Second, species delimitation methods based on genetic clustering were performed. Third, the population genetics of three widely distributed species was analysed looking for evidence of panmixia, a common criteria to support sympatric speciation. A total of 11 microsatellites that mostly cross-amplify between most species were obtained. The genotyping revealed that most loci had more than two alleles per individual indicating polyploidy. As such, the analyses required a different approach which consisted in coding the genotypes as ‘allelic phenotypes’, allowing the use of individuals of different ploidy levels in the same data set. The species delimitation of 15 operative morphotaxa and 727 individuals supported reproductive isolation of five morphotaxa and two hypotheses of conspecificity. However, some morphotaxa showed unclear assignments revealing the need of further research to clarify their reproductive limits. Finally, the population genetics of Chaetomorpha moniliformis, Cladophora compacta and Cl. kursanovii revealed patterns of genetic variation and structure that suggest different reproductive strategies and dispersal abilities. This demonstrates that contrasting biological characteristics may arise in closely related lineages: Chaetomorpha moniliformis with dominant asexual reproduction and long dispersal abilities; Cladophora compacta with high genetic diversity, no population structure and likely to reproduce sexually; Cl. kursanovii with a structure congruent with geographic distribution and more restricted dispersal. The results suggest that polyploidy, rather than speciation with gene flow, is the force driving the reproductive isolation and evolution of this flock. Although many questions remain to be studied, this research provides the first insights into the diversification of this Cladophorales species flock and contributes to the understanding of speciation in freshwater algae.</p>

scholarly journals Reproductive isolation and patterns of genetic differentiation in a cryptic butterfly species complex

2013 ◽  
Vol 26 (10) ◽  
pp. 2095-2106 ◽  
Author(s):  
V. Dincă ◽  
C. Wiklund ◽  
V. A. Lukhtanov ◽  
U. Kodandaramaiah ◽  
K. Norén ◽  
...  
Keyword(s):  
Genetic Differentiation ◽  
Reproductive Isolation ◽  
Species Complex ◽  
Butterfly Species

Genetic Differentiation among Populations of the Northern Redbelly Dace (Phoxinus eos) in Ontario

1994 ◽  
Vol 51 (6) ◽  
pp. 1218-1228 ◽  
Author(s):  
C. Anna Toline ◽  
Allan J. Baker
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Fish Species ◽  
Protein Electrophoresis ◽  
The Other ◽  
Population Divergence ◽  
Average Heterozygosity ◽  
Weinberg Equilibrium ◽  
Hardy Weinberg Equilibrium ◽  
Population Substructuring

Eighteen populations of northern redbelly dace (Phoxinus eos) from three regions in Ontario were examined genetically using protein electrophoresis. Differentiation among regions was greater (FST = 0.100) than within them (FST = 0.045–0.064), suggesting that levels of gene flow are high enough to prevent differentiation through drift only within regions. Levels of heterozygosity, percent polymorphic loci, and number of alleles per locus are high relative to other fish species, which suggests that populations of dace in this study have not been subject to severe bottlenecks. Thus, population divergence has apparently occurred gradually over the last 10 000 yr. Average heterozygosity was not correlated with pond area. Thus, populations in Algonquin Park are not more prone to the effects of drift than those in the other two regions. Populations from the Sudbury region were genetically differentiated from those in Algonquin Park and from near Kingston, a result consistent with the historical biogeography of Ontario. Despite relatively high levels of heterozygosity, observed levels in this study deviated significantly from those expected from Hardy–Weinberg equilibrium. The breeding biology of P. eos and other fish suggests that our results may be explained by the presence of population substructuring in the localities sampled.

scholarly journals Genetic Divergence between Two Sympatric Ecotypes of Phalaenopsis pulcherrima on Hainan Island

Diversity ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 446
Author(s):  
Xiangyu Hu ◽  
Siren Lan ◽  
Xiqiang Song ◽  
Fusun Yang ◽  
Zhe Zhang ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Genetic Differentiation ◽  
Reproductive Isolation ◽  
Hainan Island ◽  
Nutrient Content ◽  
Soil Conditions ◽  
Island Population ◽  
Ecological Differentiation ◽  
Ecotypic Differentiation ◽  
High Level

Ecotypes are the result of ecological differentiation at the early stages of speciation. Adaptation to soil conditions offers arguably the best examples of local adaptation in plants. Two sympatric ecotypes, with either a red or green abaxial leaf surface, were found without clear geographical isolation in Phalaenopsis pulcherrima, a Southeast Asia endemic and endangered orchid. The soil of the red leaf ecotype has a higher water content and nutrient content than the green ecotype. What is the genetic structure of the two ecotypes? Is there complete or partial reproductive isolation between the two ecotypes? In this work, leaf reflection of the two ecotypes in P. pulcherrima were compared, to illustrate their difference in leaf color. The genetic differentiation between two ecotypes was examined, using ISSR and SRAP markers to determine the genetic structure of the populations. Our results showed that the green ecotype had reflectance spectrum peaks at 530 nm and 620 nm, while in the red ecotype, the peak at 530 nm was absent. A total of 165 ISSR and SRAP loci showed a high level of genetic diversity within the green ecotype, and analyses of the population structure revealed two genetic clusters that corresponded to the red and green ecotypes. The percentage of variation between the two ecotypes (24.55%) was greater than the percentage of variation among the populations (16.54%)—indicating partial reproductive isolation, high genetic differentiation, and that ecological differentiation has been more important than geographical barriers among populations within ecotypes. Most pairwise FST values between the populations within either ecotype on Hainan Island were less than 0.15; however, the FST between both the Thai and Malaysian populations and the Hainan Island population was greater than 0.25, due to South China sea isolation. Ecotypic differentiation is an important part of speciation; therefore, we must take into account the axes along which lineages sort, when formulating protection strategies.

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