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Biodiversity

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Biology

Earth is home to a vast array of different plants, animals, and microorganisms battling to survive in conditions ranging from the dense rainforests in the tropics to barren Sub-Saharan deserts. Biodiversity encompasses the multitude of ecosystems worldwide and the diversity within and between the different species that reside in them. Greater global biodiversity is beneficial to Earth's population as over a third of the world's population rely on marine or coastal biodiversity for their employment; it provides the world with sustained food security and also provides vital information for medical research (25% of drugs used in modern medicine are derived from rainforest plants!).

Biodiversity

Biodiversity measures the variation in different species and genetics. Greater biodiversity (a wide range of different species, habitats and gene pools) results in thriving communities and ecosystems. It has a beneficial impact on the health of the planet, as many species and habitats depend on other species to prosper.

A community is a group of organisms that live in the same habitat and interact.

Communities are often mistaken for ecosystems: an ecosystem describes the community as well as the physical environment the organisms reside in.

These are some key terms that are important when considering biodiversity. Let's go through some definitions.


Species diversity is the variety of species and abundance of each of these species in a particular community. This can be measured using a diversity index, which provides information about the distribution and rarity of a certain species in an area.

Genetic diversity - refers to the variation and size of the gene pool in a community.

Ecosystem diversity is the variation in habitats offered to the species in a certain area.

Background extinction rate - the expected number of the species that would go extinct over a certain period due to natural causes; Human interaction has severely augmented this rate.

Mass extinction events - events in which a large number and variety of species become extinct because of a catastrophic occurrence.

An example of an extinction event is the Cretaceous-Paleogene extinction when the entirety of earth's dinosaur population became extinct.

Keystone species are species that have a substantial effect on the rest of the community relative to their numbers.

Species richness refers to the number of different species in a particular area at any given time.

Endemic species - is a certain species population growing in geographical isolation, for example on an island.


Loss of biodiversity

There are many threats to biodiversity; these include habitat change, pollution, natural disasters and others.

Habitat change

The habitats that these species rely on can change suddenly and gradually, by natural causes and human impacts. Seasonal changes often affect the habitat due to changes in rainfall, causing flooding, droughts, and migration of prey or species with mutually beneficial relationships.

One interesting example of a mutually beneficial relationship between organisms in an ecosystem is the symbiotic relationship between the coral polyps which build up the calcareous exoskeleton of the coral reef and the zooxanthellae (dinoflagellate algae) which are attached to them. The zooxanthellae contain a coloured pigment while also providing the coral polyps with essential nutrients to build up the structure of the reef. Overheating of the coral from sweltering warm seasons causes the coral polyps to expel the zooxanthellae because of this thermal stress, decolouring the coral and causing the exoskeleton to be more fragile. This phenomenon is referred to as coral bleaching.

Biodiversity a coral reef some parts show bleaching zooxanthellae expulsion StudySmarterFigure 1. A coral reef. Some parts show bleaching. Source: wirestock, Freepik.com.

Natural disasters

Natural disasters can occur in many parts of the world, like earthquakes, hurricanes, forest fires or tornados. Habitats can also be decreased by human development around these areas.

Deforestation, mining and agricultural processes all heavily impact ecosystems worldwide by destroying their habitats.

Foreign species introduced into a community can have detrimental effects on many species. This could be because of new competition for food, a new predator or even a species carrying disease.

An example of this is the European rabbit introduced in 1800 into Australia. This species quickly went under a population explosion. They lacked predators, which allowed this prey species to thrive. There was even a disease, called myxoma which was released to control the population.

The increased use of fertiliser by farmlands can reduce biodiversity in the surrounding fields. Nitrogen and phosphorus runoff can also cause eutrophication in nearby rivers, which is harmful to most wildlife.

Eutrophication is the excessive increase in the nutrient content of bodies of water. This increase results in the surging of aquatic plant populations, which use up the dissolved oxygen in the water.

Atmospheric nitrogen can also damage rivers and lakes through eutrophication, sulphur can lead to excessive acid in lakes, ozone damages plant leaves, and heavy metal compounds emitted from cars can accumulate in both plants and animals.

Apex predators are some of the fiercest animals at the top of the food chain but can be seriously affected by microplastics! They are at the top of the food chain, so they acquire microplastics from all trophic levels through direct ingestion and trophic transfer. These microplastics can potentially impact animals' behaviour and hormones. Erratic behaviour is not helpful when trying to survive in the wild; predators must be efficient when hunting prey and expending energy.

Climate change has a negative impact on temperature, and weather patterns; therefore, it can potentially decrease diversity through droughts, forest fires, melting of icy habitats, and may even cause some animals to migrate away from their historical habitats in search of cooler areas.

Biodiversity climate change effects on earth StudySmarterFigure 2. Representaton of climate change effects on our Earth. Source: macrovector, Freepik.com.


Conservation of biodiversity

It is important to maintain biodiversity so that the species and habitats in these communities can thrive as they depend on each other. Still, biodiversity affects the world in many other ways:


  • Ecosystems are beneficial to the environment as plants absorb carbon dioxide from the atmosphere and provide humans energy directly (fruit and veg) and indirectly (meat). Microorganisms feed on the abundance of waste produced by animals as well.

  • Morally humans have to protect the planet on which we live. Maintaining biodiversity also preserves the beauty of the world around us.

  • Economically, ecosystems can be beneficial to the world. Plants, fungi and bacteria have been the source of numerous scientific discoveries, and wildlife and national parks are tourist attractions in many countries.

  • Biodiversity is helpful in agriculture as most crops that grow on farms have very low genetic diversity and are susceptible to disease. The wild crops surrounding provide genetic diversity through disease-resistant alleles that are shared through breeding.


Because of the threats to biodiversity that were discussed earlier, biodiversity is decreasing in communities worldwide. Humans can help to rectify this in various ways:


  • Captivity - some species are under such threat and are now at such low numbers that the only way to save them is to breed them in captivity until there is a strong enough cohort to be released into the wild. Botanic gardens are the equivalent as they keep plants in captivity and are invaluable to scientific research.

  • Conserved areas- national parks and marine sites are protected from human interference by law.

European Marine Sites (EMS) are areas at sea situated to protect important habitats and ecosystems. They form a chain of protected areas around Europe that protect many marine species.

  • Reducing invasive species by human causes - invasive species can be brought into an area where they do not belong by vehicles like planes and boats. These species can then out-compete and sometimes even prey on other species.

  • Sustainable living - we can help reduce climate change by living more sustainably, minimising driving, and being more energy efficient in the house. Increasing our carbon footprint also helps to prevent global warming.


Species diversity

Species diversity considers the number of different species in a community, as well as the concentration and spread of these species. Having a greater species diversity helps ecosystems survive unexpected environmental changes and be more equipped to deal with the introduction of a new species of predators or disease-carrying parasites. Species richness is one method of measuring species diversity, but this only tells us the number of different species in a particular area. The population density and spread of each species would also have to be measured to give us an idea of the relationships between different species and how the ecosystem functions.

Rising sea levels and increased water salinity resulting from global warming damage habitats used to breed and nurture offspring, so these species have to migrate.

Species diversity index

Index of diversity measures the number of different species in a community and how they contribute to the survival of the other species that live with them in that community through various mutually beneficial and harmful relationships.

The formula for measuring the index of diversity is as follows:



Where:

d= index of diversity

N= total number of organisms of all species

n= total number of organisms of each species

Σ= sum of

Investigating diversity

The DNA of various species can be extracted and then subsequently analysed by computers to determine the precise sequence of nucleotides.

Investigating diversity in DNA and RNA

The DNA extraction is made easier by each nucleotide being labelled with a different fluorescent coloured band - adenine is green, thymine is red, cytosine is blue and guanine is yellow. We can then compare the genetic sequences of different animals and see how closely related they are:

  • Similar sets of gene sequences tell us that the animals are closely related.

  • A higher percentage of similarity between DNA sequences corresponds to a closer relationship between organisms.

  • This is because animals with the same evolutionary ancestors would have had the same genetic sequence, but mutations over time would change this sequence little by little.

  • Two organisms with similar genetic sequences must have evolved fairly recently to form new species.

  • Evolutionary family trees can easily be produced from this information, so DNA analysis is extremely useful in finding out about the evolutionary history of organisms and the relationships between them.

  • Studying mitochondrial DNA is very beneficial to scientists due to the minimal crossing over in Mt DNA, so the evolutionary patterns are much clearer.

  • Mitochondrial RNA is often used in DNA analysis because it is so easy to extract and can be used to produce a complementary DNA (cDNA) strand, the same as the original template strand of the DNA. This cDNA can then be used to make another complementary strand that is identical to the coding strand of the original DNA.


The role of observable characteristics on diversity

The original method of comparing species is to observe their characteristics. This is quite unreliable as the genetic differences can only be assumed using this technique, as we now know that animals exhibit specific characteristics thanks to several different genes and alleles situated on these genes. Even the environment they live in can impact these characteristics over time. The main problem is that many species have similar characteristics, so more research needs to be conducted to differentiate between them.

Examples of these characteristics include:


  • Number and type of limbs

  • Number of petals, leaves, seeds and branches

  • Fur/fins/wings/antennae

  • Patterns on body/stem/petals/leaves

  • Colour

  • The habitat they reside in

  • Emigrational patterns

  • Eating habits

Investigating the amino acid sequence

Analysing the amino acid sequences for the same protein in different animals can show us how closely related they are. These differences in amino acid sequence will cause the protein to function differently, which could be vital in helping the species survive.

Mutations can lead to the species being better adapted to its environment (survival of the fittest). Therefore, the more similar two amino acid sequences between two animals are, the more closely related they are.

Results collected from amino acid extraction are much more useful than DNA extraction as there are 20 different amino acids compared to only four different bases, and non-coding sections of the DNA can lead to insignificant results. In addition to this, the sequence of amino acids evolves at a much slower rate than that of DNA: in closely related species, the protein will continue to function in the same way; therefore, the sequence will not change.

Quantitative investigation used in calculating biodiversity

Quantitative investigation gathers and analyses numerical data, displayed in graphs and tables, and subsequently observed or put through various statistical tests to test relationships, draw hypotheses, and make predictions for larger populations.

Hypotheses

There are three types of hypotheses: null, one-tailed and two-tailed.

Null hypothesis predicts that there will be no difference between specific populations. Any differences are due to experimental or sampling error.

One-tailed hypothesis predicts the results going in one direction, the result is either greater or lower.

Two-tailed hypothesis: predict that there will be an impact of a variable; however, it does not specify if the effect is, for example, greater or lower.

Let's use a hypothetical example of moss beds. The research question for this is as follows: the study aims to investigate if the moss beds in Lithuanian forests are declining or expanding over time.

So what are the hypotheses?

  • Null hypothesis: There is no change in the area of the moss beds (meaning no expansion or decline).
  • One-tailed: Moss beds are expanding over time.
  • Two-tailed: The area of moss beds will change.

Pearson's chi-squared test is used to deduce a significant difference between the expected values and observed values from a categorical data set.

Types of quantitative research


  • Correlational research is the comparison of the variables that you study to discern any relationship between them.

Biodiversity investigating biodiversity correlation StudySmarterFigure 3. 1: Close correlation between y and x; 2: Loose correlation between y and x; 3: No correlation between y and x. Source: StudySmarter Originals.

  • Descriptive research produces an overall summary of the variables studied rather than an in-depth analysis.
  • In experimental research, hypotheses and cause and effect relationships between variables are tested systematically.

  • Causal-comparative research is used to see if any causal relationship exists between two variables.


Qualitative research

Qualitative research concerns non-numerical data, such as interviews, documents and observations. Qualitative research results are used to better understand peoples' opinions, relationships, behaviours, and psychological states.


Advantages of quantitative research over qualitative research


  • Comparison - studies can be conducted on various samples, and then the results can be compared to test relationships between different groups.

  • Exact replication - identical experiments can be carried out thanks to the regimented nature of quantitative research, increasing the reliability of results.

  • Large samples - data can be collected from large samples in quantitative research. In contrast, collecting large samples in qualitative research is more difficult as the results are more subjective and long-winded.

  • Statistical analysis - the use of established hypothesis testing procedures and various statistical analysis formulae, we can better understand the relationship between variables.



Biodiversity - Key takeaways

  • Biodiversity is the measure of the abundance and spread of different species, as well as the size of their gene pool and the habitats available to them.

  • Greater biodiversity is important in maintaining ecosystems worldwide and positively impacts the environment and the human population.

  • The diversity between species can be investigated through the index of diversity calculations, the study of observable characteristics, DNA sequence and amino acid sequences.

  • Quantitative research is the gathering of numerical data which is then analysed and inputted into tables and graphs to deduce if any relationship exists between variables.


Biodiversity

Biodiversity is a culmination of species, genetic and ecosystem diversity to give an idea of the abundance, variance and gene pool of species in a certain area.


Genetic diversity is the size of the gene pool in a population, and the amount of different alleles within this gene pool.

You can compare various observable characteristics, but also if you have the correct technology you can compare the DNA, RNA and amino acids of different organisms.

Deforestation has a detrimental effect on biodiversity because it kills the habitats of various species which live in the trees, as well as killing some of the organisms in the process.

There are many ways to measure biodiversity, such as measuring species richness, inputting data into the index of diversity formula or using quadrats and transects.

Overfishing has a huge impact on global aquatic biodiversity and climate change resulting from human development leads to the degradation of aquatic habitats such as coral reefs.

Species diversity is important in maintaining mutualistic relationships and even competitive relationships between species in order to maintain a stable ecosystem.

Species diversity concerns the number and spread of different species within a community, whereas genetic diversity concerns the gene pool of a community.

Quantitative research concerns numerical, objective data, whereas qualitative research entails more subjective data such as opinions, behaviours and beliefs.

Index of diversity is the measure of the number of different species in a community and how they affect other species in the community.

Final Biodiversity Quiz

Question

How does ecosystem stability relate to species diversity?

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Answer

Mutualistic, competitive, and predator-prey relationships all help to maintain a stable ecosystem.

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Question

What is species diversity?

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Answer

Species diversity is the amount of different species in an area, their abundances, and the spread of each species.

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Question

Why is biodiversity important?


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Answer

Greater biodiversity results in thriving communities, more stable ecosystems and is beneficial to the health of the planet.

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Question

How is genetic diversity measured?


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Answer

By measuring the amount and variance of alleles in a population.

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Question

What is low genetic diversity?


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Answer

When there is low genetic variation between a population.

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Question

Why is genetic diversity important?


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Answer

High genetic variation allows populations to adapt to changes in conditions as there is a higher probability of a suitable allele being present.

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Question

How does crossing over affect genetic diversity?

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Answer

How does crossing over affect genetic diversity?

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Question

What is quantitative research study?


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Answer

It is the gathering and analysis of numerical data, which can then be observed in tables and graphs to discern any relationships between variables.

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Question

What are the 4 types of quantitative research?


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Answer

Correlational, descriptive, experimental and causal-comparative.

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Question

What are some of the threats to biodiversity?

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Answer

Climate change, nutrient loading, invasive species, pollution.

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Question

How are human activities affecting aquatic biodiversity?

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Answer

Overfishing has a huge impact on global aquatic biodiversity and climate change resulting from human development leads to the degradation of aquatic habitats such as coral reefs.

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Question

Why is species diversity important?


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Answer

Species diversity is important in maintaining mutualistic relationships and even competitive relationships between species in order to maintain a stable ecosystem.

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Question

How are species diversity and genetic diversity different?


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Answer

Species diversity concerns the number and spread of different species within a community, whereas genetic diversity concerns the gene pool of a community.

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Question

What is the difference between quantitative and qualitative investigation?


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Answer

Quantitative research concerns numerical, objective data, whereas qualitative research entails more subjective data such as opinions, behaviours and beliefs.

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Question

What is the index of diversity?


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Answer

Index of diversity is the measure of the number of different species in a community and how they affect other species in the community.

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