Related Experiment Video
Updated: Jun 19, 2026
05:41
Genotyping and Quantification of In Situ Hybridization Staining in Zebrafish
Published on: January 28, 2020
Intergenomic epistasis causes asynchronous hatch times in whitefish hybrids, but only when parental ecotypes differ
P J Woods1, R Müller, O Seehausen
1Department of Biology, University of Iceland, Reykjavík, Iceland. pamelajwoods@gmail.com
Journal of Evolutionary Biology
|October 15, 2009
Summary
Ecological speciation in Coregonus lavaretus is driven by coadaptation between egg size and offspring growth rate. This mismatch in hybrids causes selection against interbreeding, supporting ecological speciation theory.
Area of Science:
- Evolutionary Biology
- Speciation Research
- Ichthyology
Background:
- Ecological speciation theory posits that ecological divergence drives reproductive isolation.
- Understanding the role of ecological and genetic factors in hybrid offspring is crucial for speciation research.
- Coregonus lavaretus species flock in Alpine lakes provides a model system for studying ecotype divergence.
Purpose of the Study:
- To investigate how ecological and genetic differences between parental species influence hybrid embryonic development and selection.
- To identify endogenous and exogenous selection pressures acting on hybrids.
- To explore the potential for coadaptation between maternal traits and offspring development in driving reproductive isolation.
Main Methods:
- Common-garden experiment with full-sib crosses of three Coregonus lavaretus species from two ecotypes.
- Analysis of embryonic development, including egg size, embryo size, growth rates, mortality, and hatch timing.
- Assessment of epistasis between maternal and embryonic genomes and selection constraints.
Main Results:
- Embryonic growth rates and egg sizes differed significantly between ecotypes, despite similar hatch timing.
- Hybrid crosses exhibited a mismatch between embryonic growth rate and egg size, indicating epistasis.
- Transgressive, asynchronous hatch times and a strong egg size-to-embryo size constraint were observed in hybrids.
- Evidence suggests coadaptation of maternal egg size with offspring growth rate acts as a selection against hybridization.
Conclusions:
- Coadaptation between maternal egg size and offspring growth rate is a significant factor promoting reproductive isolation between ecotypes.
- Ecological divergence, specifically in traits like egg size, can directly contribute to speciation through selection on hybrid offspring.
- Quantifying early life-history traits is essential for understanding the mechanisms of ecological speciation.
Related Concept Videos
02:29Hybrid Zones
Hybrid zones are narrow regions where two closely related species interact, mate, and produce hybrids. Relative to either parent species, hybrids may possess distinct phenotypic or genetic differences that impact their survival and reproductive success. The genetic variances introduced by hybridization influence species diversity and speciation processes within the hybrid zone.Gene flow and natural selection are evolutionary mechanisms that shape the outcome of a hybrid zone. Gene flow...
02:32Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
01:39Epistasis
In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...
01:09Epistasis Analysis
Although Mendel chose seven unrelated traits in peas to study gene segregation, most traits involve multiple gene interactions that create a spectrum of phenotypes. When the interaction of various genes or alleles at different locations influences a phenotype, this is called epistasis. Epistasis often involves one gene masking or interfering with the expression of another (antagonistic epistasis). Epistasis often occurs when different genes are part of the same biochemical pathway. The...
02:27Background and Environment Affect Phenotype
Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
01:17Understanding Species and Reproductive Barriers
A species is a group of organisms that interbreed and produce fertile offspring. Typically, individuals of the same species appear similar and share common characteristics due to their highly similar genomes. However, not all organisms that look alike are members of the same species. Various mechanisms keep most species discrete. While some mechanisms prevent reproductive behavior and fertilization (pre-zygotic isolation), others prevent the production of fertile offspring after mating has...