Related Experiment Video
Updated: Jul 12, 2026
07:24
In Situ Hybridization Techniques for Paraffin-Embedded Adult Coral Samples
Published on: August 31, 2018
Introgression versus immigration in hybridizing high-dispersal echinoderms.
Fiona M Harper1, Jason A Addison, Michael W Hart
1Department of Biology, Dalhousie University, Halifax, NS, Canada. fharper@rollins.edu
Evolution; International Journal of Organic Evolution
|August 24, 2007
Summary
Larval dispersal across oceans is a more significant driver of gene flow than hybridization between species. This study found that marine larvae are more effective gene flow vectors than gametes, even between closely related sea urchins and sea stars.
Area of Science:
- Marine biology
- Population genetics
- Evolutionary biology
Background:
- Phylogeographic studies often reveal interspecific gene flow (introgression) through hybridization.
- Understanding introgression's impact on population genetic structure is crucial.
- The trans-Arctic interchange provides a context for studying marine gene flow.
Purpose of the Study:
- To quantify and compare gene flow across oceans versus across species boundaries.
- To assess the relative influence of introgression versus dispersal on genetic structure.
- To investigate the role of hybridization and backcrossing in marine populations.
Main Methods:
- Analysis of mitochondrial DNA (mtDNA) sequences from four species of sea urchins and sea stars.
- Quantification of gene flow rates between sympatric species and across oceanic barriers.
- Comparison of gene flow via heterospecific gamete interactions versus larval dispersal.
Main Results:
- Gene flow between sympatric species was significantly lower than gene flow across oceans.
- Rates of gene flow via heterospecific gamete interactions were small.
- Dispersal of planktonic larvae proved to be a more effective vector for gene flow.
Conclusions:
- Larval dispersal is a more significant driver of gene flow than interspecific hybridization in these marine invertebrates.
- Gametes are less effective vectors of gene flow compared to larvae, even between closely related species.
- Oceanic dispersal plays a dominant role in shaping marine population genetic structure over interspecific interactions.
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...
02:39Gene Flow
Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.
01:31Formation of Species
Speciation describes the formation of one or more new species from one or sometimes multiple original species. The resulting species are discrete from the parent species, and barriers to reproduction will typically exist. There are two primary mechanisms, speciation with and without geographic isolation—allopatric and sympatric speciation, respectively.Allopatric SpeciationIn allopatric speciation, gene flow between two populations of the same species is prevented by a geographic barrier, like...
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...
01:07Speciation Rates
Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
02:16Genetics of Speciation
Speciation is the evolutionary process resulting in the formation of new, distinct species—groups of reproductively isolated populations.The genetics of speciation involves the different traits or isolating mechanisms preventing gene exchange, leading to reproductive isolation. Reproductive isolation can be due to reproductive barriers that have effects either before or after the formation of a zygote. Pre-zygotic mechanisms prevent fertilization from occurring, and post-zygotic mechanisms...