Related Experiment Video
Updated: Jun 18, 2026
04:10
Visually Sexing Loggerhead Shrike (Lanius Ludovicianus) Using Plumage Coloration and Pattern
Published on: March 8, 2020
Characterizing dispersal patterns in a threatened seabird with limited genetic structure
Laurie A Hall1, Per J Palsbøll, Steven R Beissinger
1Moss Landing Marine Laboratories, CA 95039, USA.
Molecular Ecology
|November 17, 2009
Summary
Genetic assignment methods successfully identified dispersal patterns in marbled murrelets (Brachyramphus marmoratus). This study found seasonal and demographic biases in migration, with more young females migrating in winter.
Area of Science:
- Ecology
- Population Genetics
- Conservation Biology
Background:
- Genetic assignment methods are valuable for studying dispersal but traditionally require high genetic differentiation and large sample sizes.
- Previous studies often assumed significant genetic differentiation was a prerequisite for robust dispersal analysis.
Purpose of the Study:
- To rigorously test the applicability of genetic assignment methods for characterizing dispersal in a moderately differentiated population.
- To investigate seasonal and demographic patterns of dispersal in the marbled murrelet (Brachyramphus marmoratus).
Main Methods:
- Utilized coalescent simulations to establish an appropriate significance threshold for genetic assignment, balancing Type I and II errors.
- Applied genetic assignment to 589 marbled murrelets genotyped at 13 microsatellite loci to determine origins.
- Analyzed dispersal patterns across breeding, post-breeding, and winter seasons.
Main Results:
- Successfully identified a population of origin for individuals, demonstrating method efficacy even with moderate genetic differentiation (F(ST) ≈ 0.03).
- Observed the highest proportion of migrants during winter (83%), significantly lower during breeding (6%) and post-breeding (8%) seasons.
- Dispersal showed a bias towards younger and female individuals, with few parent-offspring pairs among migrants.
Conclusions:
- Genetic assignment methods can be reliably used to study dispersal in populations with moderate genetic differentiation and larger sizes than previously thought.
- Seasonal variation in migration is pronounced, with winter exhibiting the highest influx of individuals.
- Dispersal patterns suggest limited contribution of migrants to local breeding success, with biases in age and sex.
Related Concept Videos
00:54Distribution and Dispersion
Ecology is the study of how organisms interact with their environment and with one another. An important aspect of ecology is understanding where species are found and how individuals are distributed within those areas. The geographic range of a species refers to the total area where its members are located, while dispersion describes the pattern of spacing of individuals within that range.Geographic Range and Dispersion PatternsWithin a species’ geographic range, individuals may be distributed...
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.
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
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...
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...