Did you know that there are currently around 7.9 billion people living on our planet? That's a lot of people! But what exactly is population and why is it important to understand? Let's explore this topic and see what we can learn.

What makes a population?

When we talk about populations, we're referring to groups of individuals from the same species that are living in the same area at the same time. It's important to note that two groups of different species living in the same area are not considered a single population, because they are different species. And if two groups of the same species are living in different areas, they are also considered separate populations. Populations can vary in size, depending on the organism. Some endangered species have very small populations, while the human population is a whopping 7.8 billion individuals! Microorganisms like bacteria typically exist in very dense populations too. But remember, population and species are not the same thing.

Species in a population

Defining a species can be quite tricky, and it involves looking at a range of factors such as physical characteristics, genetic makeup, and the ability to produce offspring that can reproduce. This can be especially challenging when different species have very similar appearances. But in general, a species is considered to be a group of organisms that share enough similarities to be classified together and can reproduce to create fertile offspring.

Why can’t members of different species produce viable offspring?

When it comes to interbreeding between different species, it's usually not possible for them to produce viable offspring. Even when closely related species are able to produce offspring, these offspring are often sterile and unable to reproduce themselves. This is because different species have different numbers of chromosomes, and organisms must have an even number of chromosomes to be viable.

For example, mules are the sterile offspring of a male donkey and a female horse. Donkeys have 62 chromosomes, while horses have 64, so mules end up with 63 chromosomes which can't divide evenly during meiosis. However, there are some cases where interspecies crosses produce fertile offspring. For instance, ligers - the offspring of male lions and female tigers - have 38 chromosomes, the same number as their parents. As a result, ligers have been known to produce offspring with other felids.

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An ecosystem is made up of all the living and non-living components in a particular environment, and each species within that ecosystem unique role play temperature, water availability, and competition can all affect the size of a population within that ecosystem. The carrying capacity of an ecosystem is the maximum number of individuals it can support, and population growth is typically represented by a sigmoid curve, which includes a lag phase, log phase, S-phase, stable phase, and decline phase. Population size can be estimated using methods such as randomly placed quadrats, belt transects, or mark-release-recapture. Finally, the population growth rate is the rate at which the number of individuals in a population increases over a specific period of time, and it can be calculated by dividing the difference in population size by the initial population size. Populations - Key takeaways A species is a group of similar organisms that are able to reproduce and create fertile offspring. Most of the time, members of different species cannot produce viable or fertile offspring. This is because when parents do not have the same number of chromosomes, the offspring will have an uneven number of chromosomes. A population is a group of individuals of the same species that occupies a particular space at a particular time, whose members can potentially interbreed and produce fertile offspring. Both abiotic and biotic factors affect the size of a population. Interspecific competition is between species whereas interspecific competition is within a species.

Populations

How do you calculate the population size in biology?

It can be estimated using either percentage cover, frequency or the mark-release-recapture method. 

What is the definition of population?

A population is a group of individuals of the same species that occupy a particular space at a particular time, whose members can potentially interbreed and produce fertile offspring.

How do you calculate population growth rate?

Using the equation: ((New population - original population)/ original population) x 100

What are the different types of population? 

Lag phase, Log phase, S-Phase, Stable Phase and Decline Phase

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