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offspring: [noun] the product of the reproductive processes of an animal or plant : young, progeny. child.
Jan 29, 2020 · Meiosis is a form of cell division that creates gametes. It is comprised of two divisions that in the end, the resulting cell will contain half the chromosomal number of the parent cell. Know the different stages here... Offspring in the largest biology dictionary online. Free learning resources for students covering all major areas of biology.
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What are offspring in biology?
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In biology, offspring are the young creation of living organisms, produced either by a single organism or, in the case of sexual reproduction, two organisms. Collective offspring may be known as a brood or progeny in a more general way. This can refer to a set of simultaneous offspring, such as the chicks hatched from one clutch of eggs, or to ...
- Overview
- Key points
- Introduction
- The biological species concept
- What keeps species distinct?
- Prezygotic barriers
- Postzygotic barriers
- How do new species arise?
- Allopatric speciation
- Case study: squirrels and the Grand Canyon
What defines a species. How new species can arise from existing species.
•According to the biological species concept, organisms belong to the same species if they can interbreed to produce viable, fertile offspring.
•Species are separated from one another by prezygotic and postzygotic barriers, which prevent mating or the production of viable, fertile offspring.
•Speciation is the process by which new species form. It occurs when groups in a species become reproductively isolated and diverge.
•In allopatric speciation, groups from an ancestral population evolve into separate species due to a period of geographical separation.
•In sympatric speciation, groups from the same ancestral population evolve into separate species without any geographical separation.
•According to the biological species concept, organisms belong to the same species if they can interbreed to produce viable, fertile offspring.
•Species are separated from one another by prezygotic and postzygotic barriers, which prevent mating or the production of viable, fertile offspring.
•Speciation is the process by which new species form. It occurs when groups in a species become reproductively isolated and diverge.
•In allopatric speciation, groups from an ancestral population evolve into separate species due to a period of geographical separation.
On some level, the idea of a species is pretty intuitive. You don't need to be a zoologist to classify organisms like humans, giant pandas, or sunflowers into groups based on their appearance. This method works well when the species in question look very different from one another. You probably wouldn’t mistake a panda for a sunflower—unless you really needed your glasses!
But when we get right down to it, what really make a species a species? Organisms that look alike often belong to the same species, but this isn’t always the case. I for one can't tell the African fish eagle and the bald eagle apart from the photos below. But they are, in fact, different species.
On the flip side, organisms that belong to the same species can look very different from one another. For instance, dogs come in all shapes and sizes—from tiny Chihuahuas to massive Great Danes—but they all belong to the same species: Canis familiaris, the domestic dog.
If appearance doesn’t reliably define a species, then what does? For most eukaryotes—such as animals, plants, and fungi—scientists tend to define a species based on reproductive compatibility. That is, organisms are usually considered to be members of the same species if they can successfully reproduce with one another.
According to the most widely used species definition, the biological species concept, a species is a group of organisms that can potentially interbreed, or mate, with one another to produce viable, fertile offspring.
In this definition, members of the same species must have the potential to interbreed. However, that doesn't mean they have to be part of the same interbreeding group in real life. For instance, a dog living in Australia and a dog living in Africa are unlikely to meet but could have puppies if they did.
In order to be considered to be a single species in the biological species concept, a group of organisms must produce healthy, fertile offspring when they interbreed. In some case, organisms of different species can mate and produce healthy offspring, but the offspring are infertile, can’t reproduce.
For example, when a female horse and a male donkey mate, they produce hybrid offspring called mules. Although a mule, pictured below, is perfectly healthy and can live to a ripe old age, it is infertile and cannot have its own offspring. Because of this, we consider horses and donkeys separate species.
The biological species concept connects the idea of a species to the process of evolution. Because members of a species can interbreed, the species as a whole has a common gene pool, a collection of gene variants.
On the other hand, genes are not exchanged between different species. Even if organisms of different species combine their DNA to make offspring, the offspring will be sterile, unable to pass on their genes. Because of this restricted gene flow, each species evolves as a group distinct from other species.
The biological species concept defines organisms as being, or not being, of the same species based on whether they can interbreed to make fertile offspring. But why is it that different species can't successfully interbreed? This question may seem silly for very different species (like a plant and an animal), but for others like the horse and the donkey above, it's much less obvious.
Broadly speaking, different species are unable to interbreed and produce healthy, fertile offspring due to barriers called mechanisms of reproductive isolation.
Prezygotic barriers prevent members of different species from mating to produce a zygote, a single-celled embryo. Some example scenarios are below:
•Two species might prefer different habitats and thus be unlikely to encounter one another. This is called habitat isolation.
[May I see an example?]
•Two species might reproduce at different times of the day or year and thus be unlikely to meet up when seeking mates. This is called temporal isolation.
[May I see an example?]
•Two species might have different courtship behaviors or mate preferences and thus find each other "unattractive". This is known as behavioral isolation.
Postzygotic barriers keep hybrid zygotes—one-celled embryos with parents of two different species—from developing into healthy, fertile adults. Postzygotic barriers are often related to the hybrid embryo's mixed set of chromosomes, which may not match up correctly or carry a complete set of information.
In some cases, the chromosomal mismatch is lethal to the embryo or results in an individual that can survive but is unhealthy. In other cases, a hybrid can survive to adulthood in good health but is infertile because it can't split its mismatched chromosomes evenly into eggs and sperm. For example, this type of mismatch explains why mules are sterile, unable to reproduce4 .
New species arise through a process called speciation. In speciation, an ancestral species splits into two or more descendant species that are genetically different from one another and can no longer interbreed.
Darwin envisioned speciation as a branching event. In fact, he considered it so important that he depicted it in the only illustration of his famous book, On the Origin of Species, below left. A modern representation of Darwin's idea is shown in the evolutionary tree of elephants and their relatives, below right, which reconstructs speciation events during the evolution of this group.
For speciation to occur, two new populations must be formed from one original population, and they must evolve in such a way that it becomes impossible for individuals from the two new populations to interbreed. Biologists often divide the ways that speciation can occur into two broad categories:
•Allopatric speciation—allo meaning other and patric meaning homeland—involves geographic separation of populations from a parent species and subsequent evolution.
•Sympatric speciation—sym meaning same and patric meaning homeland—involves speciation occurring within a parent species remaining in one location.
Let's take a closer look at these forms of speciation and how they work.
In allopatric speciation, organisms of an ancestral species evolve into two or more descendant species after a period of physical separation caused by a geographic barrier, such as a mountain range, rockslide, or river.
Sometimes barriers, such as a lava flow, split populations by changing the landscape. Other times, populations become separated after some members cross a pre-existing barrier. For example, members of a mainland population may become isolated on an island if they float over on a piece of debris.
Once the groups are reproductively isolated, they may undergo genetic divergence. That is, they may gradually become more and more different in their genetic makeup and heritable features over many generations. Genetic divergence happens because of natural selection, which may favor different traits in each environment, and other evolutionary forces like genetic drift.
As they diverge, the groups may evolve traits that act as prezygotic and/or postzygotic barriers to reproduction. For instance, if one group evolves large body size and the other evolves small body size, the organisms may not be physically able to mate—a prezygotic barrier—if the populations are reunited.
The Grand Canyon was gradually carved out by the Colorado River over millions of years. Before it formed, only one species of squirrel inhabited the area. As the canyon got deeper over time, it became increasingly difficult for squirrels to travel between the north and south sides.
Eventually, the canyon became too deep for the squirrels to cross and a subgroup of squirrels became isolated on each side. Because the squirrels on the north and south sides were reproductively isolated from one another due to the deep canyon barrier, they eventually diverged into different species5 .
A unit of heredity that is passed from parent to offspring. Allele. One of different forms of a gene. Genotype. The genetic makeup of an organism (ex: TT) Phenotype. The physical characteristics of an organism (ex: tall) Dominant allele. Allele that is phenotypically expressed over another allele.
- How does the dominant allele mask the recessive one at a molecular level? Does the recessive allele ...There isn't a DNA sequence that tells us why or how the dominant allele masks the recessive allele. When we say that a gene is "expressed" and "not...
- Is it possible for a child to have two eye colors like,one eye blue and the other one green?yes, it is very rare and it is called Heterochromia iridium.
- Can genes be altered after birth ?yes they can be altered after birth by your environment but they can be altered manually like the liver king. to get so buff he got one of his hene...
- Why does the capital letter always have to be the dominate trait?It's the other way around, dominant trait is represted with caps
- Can you destroy the genetic genes in our bodies?You can't make them completely disappear. But there's lots of stuff you can do to harm them (if you really want to). You can eat the destroying ang...
Offspring definition: children or young of a particular parent or progenitor.. See examples of OFFSPRING used in a sentence.
Reproduction is the production of offspring. There are two main forms: sexual and asexual reproduction. In sexual reproduction, an organism combines the genetic information from each of its parents and is genetically unique. In asexual reproduction, one parent copies itself to form a genetically identical offspring. Sea turtles are an example of an animal that reproduces sexually, a volvox ...
