Name: reproductive barriers in speciation
Uploaded: 2026-06-01T06:28:06.189Z
Duration: 2 min 16 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Biology

Biological Evolution- Unity and Diversity

LS.Bio.9.1

Genetics of Speciation

Speciation is the process by which populations evolve reproductive isolation and become distinct species. It happens when populations build up genetic differences over time.Genetic changes can affect traits like body features, behavior, or the timing of reproduction. Over time, these differences can build barriers that reduce interbreeding.For example, changes in a major pigment gene can shift flower color&#x2014;and that can change which animals visit the flowers.If different pollinators prefer different colors, then plants with different flower colors get fewer chances to cross, so gene flow drops.Some Petunia species attract bees, others attract hummingbirds, and others attract hawkmoths&#x2014;often linked to color, scent, and nectar traits.Another genetic barrier, especially in plants, is polyploidy, where an organism has extra sets of chromosomes.For example, the interbreeding&#x2014;or hybridization&#x2014;of different species of Tragopogon plants led to the formation of new Tragopogon species. Because these hybrids have more than two sets of homologous chromosomes, they can&#x2019;t reproduce with either parent species, even though they are fertile.In some animals, interactions between the host genome and it

genetics of speciation

Speciation is the evolutionary process resulting in the formation of new, distinct species&#x2014;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 reduce the viability, or reproductive capacity, of the hybrid offspring.For example, pre-zygotic mechanisms act early in the life cycle of an organism, imposing the strongest impediment to gene flow, and preventing unfavorable mating combinations. Some mating combinations produce hybrid individuals. Natural selection can work against the production of hybrids with low fitness, thereby increasing reproductive isolation between two species.Post-zygotic reproductive barriers can be due to the intrinsic inviability of hybrids. Genetic complications resulting from aberrant ploidy levels, different chromosomal arrangements, or gene incompatibilities where the alleles do not function properly contribute to different genetic makeup and alternative developmental pathways in hybrids. These genetic alterations affect both plants and animals, leading to post-zygotic isolation and speciation.Epistasis, or non-allelic gene interactions, is a distinctive feature contributing to speciation. The effect of a gene variant is dependent on the genetic background in which it appears. For example, an allele giving rise to a normal phenotype in members of the same species may function poorly in the genetic environment of hybrids. This hybrid weakness can also lead to reproductive isolation and speciation.

https://cloudfront.jove.com/files/ftp_upload/11126/11126_article_thumb_11126.jpg

Education

JoVE Core

Evolution

Speciation and Diversity

KEY TERMS AND CONCEPTS

reproductive barriers in speciation

Reproductive barriers drive speciation by stopping gene flow between populations. Speciation is the evolutionary process that forms new, distinct species, which are groups that cannot freely reproduce with one another. The genetics behind this process focuses on traits and isolating mechanisms that keep populations reproductively isolated.

Some barriers act before a zygote forms, and these are called pre-zygotic mechanisms. They prevent fertilization and create the strongest block to gene flow because they act early in the life cycle. By stopping unfavorable mating combinations, they reduce the chance that hybrids will be produced.

Other barriers act after fertilization and are called post-zygotic mechanisms. These barriers lower the viability or reproductive ability of hybrid offspring. Natural selection can then act against hybrids with low fitness, which can strengthen reproductive isolation between two species.

Post-zygotic isolation can come from intrinsic hybrid inviability. Genetic problems such as abnormal ploidy levels, different chromosome arrangements, or alleles that do not work well together can disrupt development. These changes can affect both plants and animals and send hybrids down alternative developmental pathways.

Epistasis also plays a role in speciation. Epistasis means non-allelic gene interactions, or cases where the effect of one gene depends on the genetic background around it. An allele may work normally within one species but function poorly in a hybrid, and this hybrid weakness can help create reproductive isolation.

Reproductive Barriers in Speciation

understanding species and reproductive barriers

How Species Stay Genetically Separate

Species stay genetically separate through reproductive barriers that limit mating, fertilization, or the survival of offspring. A species is a group of organisms that can interbreed and produce fertile offspring. Members of the same species often look alike because they share very similar genomes. Even so, some organisms that look similar are not the same species. Variation within a species is common. The common wall lizard, Podarcis muralis, has six morphs that differ in throat and underbelly...

formation of species

How New Species Form

Speciation is the process that creates new species from one original species or from multiple original species. The new species become separate from the parent species, and barriers to reproduction usually develop. The main routes are allopatric speciation, which happens with geographic isolation, and sympatric speciation, which happens without it. In allopatric speciation, gene flow between two populations is blocked by a geographic barrier such as a mountain range or habitat fragmentation.

Reproductive barriers drive speciation by stopping gene flow between populations. Speciation is the evolutionary process that forms new, distinct species, which are groups that cannot freely reproduce with one another. The genetics behind this process focuses on traits and isolating mechanisms that keep populations reproductively isolated. Some barriers act before a zygote forms, and these are called pre-zygotic mechanisms. They prevent fertilization and create the strongest block to gene flow...

speciation rates

Two Paths to New Species

Speciation can happen at different speeds, and evolutionary biologists describe those patterns with gradualism and punctuated equilibrium. Both models explain how new species arise. They also show that evolutionary change comes from heritable variation in a population, with natural selection often favoring traits that help survival and reproduction in a given environment. Gradualism is the slow, steady path to speciation. Small changes build up over many generations. In one example, birds on...

hybrid zones

How Hybrid Zones Shape Species Change

Hybrid zones are narrow regions where two closely related species meet, mate, and produce hybrids. Hybrids can show different traits or genes from either parent species. Those differences can affect survival and reproductive success. Because of this, hybridization can change species diversity and influence speciation within the hybrid zone. Gene flow and natural selection shape what happens in a hybrid zone. Gene flow moves genes between populations and can spread, blend, and preserve genetic...

key terms and concepts

Learn how pre-zygotic and post-zygotic barriers, hybrid weakness, and epistasis help populations become new species through reproductive isolation.

Reproductive Barriers in Speciation | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

LS.Bio.10.1

Pennsylvania State Academic Standards

Life Science

interdependent-relationships-in-ecosystems

Interdependent Relationships in Ecosystems

3.1.9-12.V

Natural Selection and Evolution

3.1.9-12.X

Louisiana Student Standards for Science

High School

Life Sciences

Biological Evolution: Unity And Diversity

HS-LS4-5

Environmental Science

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions, Energy And Dynamics

HS-LS2-7

Virginia  Standards of Learning

HIgh School

LS.11

LS.11.a

Minnesota Academic Standards in Science

4.1.1 9L.4.1.1.1

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Biological Evolution: Unity and Diversity

Next Generation Science Standards

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS4-3

Florida Department of Education

SC.912.L.15

SC.912.L.15.9

Texas Essential Knowledge and Skills

BIO.10

BIO.10.C

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

B-LS4-2.

B-LS4-5.

new-york-state-science-learning-standards

New York State Science Learning Standards

HS-LS4-1.

HS-LS4-3.

HS-LS4-5.

Georgia Standards of Excellence

Ecology

SEC3.

SEC3.d

SB6.b

Development of Antibiotic Resistance

Antibiotic resistance is a major public health concern that arises when bacteria evolve mechanisms to withstand the effects of antibiotic treatments. This ...

Understanding 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 ...

Formation 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 ...

Speciation Rates

Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and ...

Speciation is the evolutionary process resulting in the formation of new, distinct species&#x2014;groups of reproductively isolated populations.The ...

Hybrid Zones

Hybrid zones are narrow regions where two closely related species interact, mate, and produce hybrids. Relative to either parent species, hybrids may ...

What is Natural Selection?

Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become ...

Types of Selection

Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural ...

Frequency-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 ...

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly ...

Natural Selection

Fitness
Widespread variation of phenotypes in natural populations provides the raw material for evolution, which is the change in the inherited traits of ...

Simulating Natural Selection
ExpandTo prepare for the lab, set out workstations for each student pair containing 6 white, 6 black, and 13 gray 12 inch ...

Simulating Natural Selection
ExpandTo begin, cut the white, black, and gray pipe cleaners into quarters, which should produce a total of 100 pieces that ...

Artificial Selection

Natural Selection and Adaptive Evolution
In natural settings, adaptive evolution takes place by natural selection, a process in which differences in ...

Observing Artificial Selection in Plants
ExpandTwo weeks before beginning the pollination experiments, collect a sufficient amount of small pots with a ...

Observing Artificial Selection in Plants 
ExpandTo begin the experiment, collect five two-week old grown plants from the generation one population that ...

Analyze and interpret data to summarize how various factors such as geographic isolation, pesticide resistance, antibiotic resistance can influence natural selection.

Phylogenetic Trees

Phylogenetic trees come in many forms. It matters in which sequence the organisms are arranged from the bottom to the top of the tree, but the branches ...

Conditions on Early Earth

Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen ...

The Colonization of Land

Changes in the environment of the early Earth drove the evolution of organisms. As prokaryotic organisms in the oceans began to photosynthesize, they ...

What is Evolutionary History?

Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and ...

The Evidence for Evolution

Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of ...

The Fossil Record

The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms ...

Convergent Evolution

Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure ...

Gene Evolution - Fast or Slow?

The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain ...

genome-size-and-the-evolution-of-new-genes

Genome Size and the Evolution of New Genes

While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major ...

Gene Families

Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes ...

types-of-genetic-transfer-between-organisms

Types of Genetic Transfer Between Organisms

Genetic transfer occurs when genetic information is passed from one organism to another. It occurs via two mechanisms: vertical gene transfer and ...

Ribozymes

The term ribozyme is used for RNA that can act as an enzyme. Ribozymes are mainly found in selected viruses, bacteria, plant organelles, and lower ...

Construct an explanation to illustrate how common ancestry and biological evolution are supported by multiple lines of empirical evidence.

LS.Bio.9.2

Use models to illustrate the conditions required for natural selection, including the overproduction of offspring, inherited variation, and the struggle to survive.

LS.Bio.9.3

Construct an explanation to explain how natural selection leads to adaptations within populations.

LS.Bio.9.4

Extinction

The History of Life on Earth
Fossils of organisms that were different from anything alive today had been documented as early as the 17th century, but it ...

Diversity and Extinction during the Paleogene Epoch
ExpandFirst, familiarize yourself with the extinction reading supplement for the background on what ...

Diversity and Extinction during the Paleogene Epoch
ExpandBegin this procedure by reading the extinction reading supplement that has been printed out for ...

Construct explanations to illustrate how varying environmental conditions may result in: changes in the number of individuals of a species, the emergence of new species over time, or the extinction of other species.

Synteny and Evolution

John H. Renwick first coined the term &#8220;synteny&#8221; in 1971, which refers to the genes present on the same chromosomes, even if they are not ...

Multi-species Conserved Sequences

Next-generation sequencing technologies have created large genomic databases of a variety of animals and plants. Ever since the human genome project was ...

Taxonomy

Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics. It uses a hierarchy of increasingly ...

Phylogeny

Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon ...

Use models (including dichotomous keys, scientific nomenclature, cladograms, phylogenetic trees) to identify organisms and exemplify relationships.

LS.Bio.10.2

Understand natural selection as a mechanism for biological evolution.

Reproductive Barriers in Speciation

Description

Transcript

Tags

More videos by Standards