Related Concept Videos
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...
01:21Frequency-dependent Selection
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
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...
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.
02:39Predator-Prey Interactions
Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.
02:37Gene Duplication and Divergence
The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
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08:33
Determination of Photoreceptor Cell Spectral Sensitivity in an Insect Model from In Vivo Intracellular Recordings
Published on: February 26, 2016
Polyphenism in insects.
Stephen J Simpson1, Gregory A Sword, Nathan Lo
1School of Biological Sciences, The University of Sydney, NSW 2006, Australia. stephen.simpson@sydney.edu.au
Current Biology : CB
|October 1, 2011
Summary
Polyphenism, where one genotype yields multiple phenotypes, is key to insect adaptability. This study explores environmental triggers, epigenetic mechanisms, and the adaptive significance of insect polyphenism.
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Genetics
Background:
- Polyphenism, the production of multiple phenotypes from a single genotype, is a significant driver of insect success.
- It enables life-history partitioning, adaptation to environmental changes, and social organization.
Purpose of the Study:
- To survey current research on prominent examples of insect polyphenism.
- To examine environmental cues, mediating pathways, and epigenetic mechanisms underlying polyphenism.
- To discuss the adaptive and life-history significance of polyphenism.
Main Methods:
- Review of existing literature on insect polyphenism.
- Analysis of environmental triggers, neurochemical and hormonal pathways.
- Investigation of molecular genetic and epigenetic mechanisms.
- Assessment of adaptive and life-history significance.
Main Results:
- Polyphenism allows insects to optimize life stages (larval feeding vs. adult reproduction).
- Seasonal and dispersal morphs enhance adaptation to environmental variability.
- Caste polyphenism facilitates labor division in eusocial insects.
- Epigenetic mechanisms play a crucial role in initiating and maintaining polyphenic traits.
Conclusions:
- Insect polyphenism is a multifaceted phenomenon with significant adaptive advantages.
- Common themes across different polyphenic systems are emerging.
- Future research should focus on comparative analyses and uncovering novel epigenetic regulators.