4.2.1 biodiversity

what is biodiversity?

a measure of variation found in the living world.

\-about the structural and functional variety in the living world.

habitat

where an organism lives

what is habitat diversity

the range of habitats in which different species live

what are some common habitats found in the uk?

\-sand dunes

\-woodland

\-meadows

\-streams

etc

what is a species

a group of organisms that can freely interbreed to produce fertile offspring

what is a fertile offspring

an offspring that can breed to give rise to more offspring

what is genetic biodiversity

the variation between individuals belonging to the same species.

why do we have genetic biodiversity

to ensure that we all don’t look identical.

how do you sample a habitat

\-select a small portion and study it carefully

\-then multiply up the numbers of individuals of each species found, to estimate the number in the whole habitat

\-ensure that sample is representative

what are the different types of samples

random

non-random include:

opportunistic

stratified

systematic

species richness

a measure of how different species are present

species evenness

a measure of how evenly represented the species are

allele

an alternative version of a gene

locus

the position of that gene on a chromosome.

Polymorphic gene locus

a locus that has more than two alleles

what kind of habitat would be more diverse?

a habitat in which there are even numbers of individuals in each species than where individuals of one species outnumber all the others.

more species evenness= more diversity

how would you measure species richness

\-by counting all the species present in the habitat.

how would you measure species evenness

\-carry out quantitative survey.

how would you survey the frequency of plants?

\-use sampling techniques

\-record percentage cover of each plant species.

(large plants) -count the number of individuals per unit area

what does measuring the density of animals in a habitat mean?

calculating how many animals of each species there are per unit area of the habitat.

\-larger ones counted by observation

\-smaller ones by sampling techniques

how would you work out the population in soil

take a sample of soil and sift through it to find all the individuals and count them.

How would you sample in water and estimate population size density

Use a net to sample in the water

\-sift through the mud at the bottom

what is simpson’s index of diversity.

A measure of the diversity of a habitat.

\-takes into account both species richness and species evenness.

what does a high value of Simpson’s index indicate?

shows a diverse habitat

\-a habitat provides a place for many different species and many organisms to live in.

what happens if there is a small change in the environment

could effect one species

\-if it is small, then the total number of individuals affected is a small proportion of the t

what does a low value for diversity suggest?

a habitat dominated a few species.

what could a small change in an environment do to a species?

it could damage or destroy the whole habitat.

give an example of a small change

disease

predator

human’s actions

how would genetic diversity be for isolated population

genetic diversity would be limited

what can measuring the genetic diversity do?

it can help asses the value of that population as a resource for conservation

Where is genetic diversity found?

where there is more than one allele for a particular locus

how would you asses the genetic diversity?

By looking at the observable features of the individuals.

what does genetic diversity lead to

this will lead to variations between individuals that may be easily observable

\-it means that there will be more genetic differences between the gametes produced by member

if there is a large number of different habitats with an area, what would be the biodiversity? Give an example

it would have a high biodiversity.

e.g- coral reef (lots of microhabitats)

if there are only one or two different habitats within an area, what would the biodiversity be like? Give an example

\-low biodiversity

\-large sandy deserts have low biodiversity as the conditions are the same throughout the whole area

what does it mean when there is a greater number of species in an ecosystem?

\-the more evenly distributed the number of individuals from each species, the greater the species diversity

why are ecosystems with a high species diversity considered more stable than those with lower species diversity? Give an example.

as they are more resilient to environmental changes.

e.g Pine forests of Florida

the ecosystems is dominated by one of two tree species. If a pathogen targets one of the two dominant species of trees, then the whole population could wipe out and the ecosystem would collapse.

Can there be genetic difference between populations of the same species and why?

Yes

\-because the two populations occupy different ranges in their habitat, so they are get different selection pressures that affect the allele frequency in their population.

why is genetic diversity important?

it can help the population adapt to, and survive changes in the environment

what does inbreeding in a small, isolated populations lead to?

* a high proportion of individuals being homozygous
* results in lower genetic diversity
* also means that genetic diseases caused by recessive alleles can become more common in these populations

what is a sample?

a method of investigating the abundance and distribution of species and populations

what is random sampling?

the positions of the sampling points are completely random or due to chance

give one advantage of using random sampling

* there will be no bias by the person carrying out the sample as it could affect results.

what is non-random sampling?

* sampling the positions of the sampling points completely random of due to chance

give one weakness of non-random sampling

* there is a chance that the person choosing could show bias towards certain areas.
* they may deliberately place quadrats in areas with the least species as its easier
* Unrepresentative

when is the best time to use random sampling

\-when a sample area is reasonably uniform or has no clear pattern

what does the distribution of a species mean?

describes how it spread throughout the ecosystem.

what does the abundance of species mean?

the number of individuals of that species.

what is a quadrat?

\-square frames made of wood or wire

\-placed on the ground and the organisms within them are recorded.

they can be used to measure the distribution and abundance of plants or slow-moving animals.

how do you avoid sampling bias when using quadrats?

by placing it randomly in the area

describe how you would use a quadrat in an experiment

* convert sampling area into a grid format and labelling each square on the grid with a number
* the use a random generator to pick the sample points
* the abundance of all the different species present can be recorded

what are sweeping nets?

* large, strong nets with a fine material used to catch flying insects and insects that live in long grass by sweeping the net back and forth through the grass

what are pitfall traps?

* cans or jars that are buried in the ground that used to catch ground insects as they fall into the trap.

what are pooters?

small plastic containers with two tubes sticking out that are used to suck up small insects

* first tube is placed over the insect and the second tube is used by the scientist to create suction

what is a tullgreen funnel?

* funnels with a light bulb above and a container below used to collect invertebrates to move down until the drop into the container

what is kick-sampling?

This technique is used to catch freshwater invertebrates living in streams or rivers

* net placed on the stream-bed so that water can flow into it
* and the steam bed just above the net is churned by the scientist for a set period of time
* invertebrates carried by the stream into the net

how would you use a line transect?

* lay out a measuring tape in straight line across the sample area
* at equal distances along the tape, record the identity of the organisms that touch the line e.g every 2m
* produces quantitative data

how would you use a belt transect

* place quadrats at regular intervals along the tape and record the abundance of each species within a quadrat
* produces quantitative data

what is the gene pool 

 all the alleles of all the genes within a species

why can there be genetic differences or diversity between populations of the same species which increases the size of the gene pool

* This may be because the two populations occupy slightly different ranges in their habitat and so are subject to slightly different selection pressures that affect the allele frequencies in their populations

why is diversity in a species important?

it creates a larger gene pool which can help the population **adapt**, and survive **changes in the environment**

what could be changes in the environment that help the population adapt

**biotic factors** such as new predators, pathogens and competition with other species

 **abiotic factors** like temperature, humidity and rainfall

how can genetic diversity be assessed?

* The **proportion of polymorphic gene loci**
* The number of loci that have two or more alleles

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* The **proportion of the population that is heterozygous** for any specific gene locus
* **Allele richness**
* The number of different alleles that exist for specific genes

how can phenotypes be used to identify the presence of multiple alleles

when each **different allele** is expressed in the phenotype of an individual they produce **observable differences**

what do you do if some genes with different alleles don’t produce an observable change in the phenotype

**the DNA sequences or the protein products of the alleles must be examined and compared**

what is genetic polymorphism 

 when there are two or more alleles present at a single loci

what is a monomorphic locus

is one that does not have multiple alleles

what is a polymorphic locus

that has multiple alleles

* The most common allele must have a frequency less than 95% or 99%how

how do you assess the genetic diversity of a species population

* They identify how many of these gene loci are polymorphic
* The number of polymorphic gene loci is then divided by the total number of loci being investigated

what is the equation for calculating the proportion of polymorphic gene loci (*P*)

***P*** **= number of polymorphic gene loci ÷ total number of loci investigated**

what are limitations of proportion of polymorphic genetic loci

does not illustrate the allele richness of a breed or species

what can you do instead of using the proportion of polymorphic genetic loci

Comparing the **amino acid sequences** of proteins

* This is a useful method when investigating allozymes
* Comparing **DNA sequences**
* Due to the fact that the genetic code is degenerate, the amino acid sequence of two alleles could be the same but their DNA base sequence could be different

why has there been an exponential growth?

* **Improved technology** leading to an **abundance of food** = increase in birth rate
* **Improved medicine, hygiene and health care** = decrease in death rate

what happens as the human population increases

countries become more economically **developed**, our requirement for these **natural resources** also **increases causes a harmful effect on the environment**

why is there a conflict between human needs and a conservation of biodiversity

* The damage to these ecosystems is negatively impacting the **species** and **habitats** contained within them

what are the main factors affecting biodiversity today

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* Habitat destruction
* Overexploitation
* Hunting
* Agriculture
* Climate change

what happens when land is cleared for human need such as agriculture and industry

* **Habitat loss** (plant and animals completely lose their habitats)
* **Habitat fragmentation** (habitats are divided into small areas - populations living within these **separated habitat fragments** are more likely to suffer from **inbreeding** or **local extinction**)

why is deforestation one of the most damaging forms of habitat destruction

the **highest levels of biodiversity**

how are marine habitats also being destroyed

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* **Coral reefs** (some people use dynamite as an extreme way to catch fish, which damages corals)


* **Sea beds** (fishing practices such as trawling, where nets are dragged along the sea bed, destroy this important habitat)

how is natural resources being overexploited

they are being used up **faster** than they can be replaced

why are trees being overexploited

much deforestation is **unsustainable**

as trees are **removed** but are **not replaced** by replanting. Even if they are replanted, the **rate at which trees are being removed** far **exceeds** the **rate at which they are growing back**

how is hunting a form of overexploitation

many **wild, non-farmed species** of animals are being hunted and removed **more quickly** than their wild populations can be **replenished**

give an example of hunting being overexploitation

hunting of animals for 'bush meat' in developing countries (including the hunting of primates such as monkeys and chimpanzees, as well as other mammal and reptile species)

what modern farming techniques have had a major negative impact on the level of biodiversity?

* farms raised a monoculture-
* pesticides used on crops, kill insect pests but also kill many non-target species
* fields were made bigger, removal of hedgerows and stonewalls biodiversity removed
* fertilisers- leach into waterways causing eutrophication-leads to the death of fish species

why are bumblebees in decline?

* bumblebees require habitats with a large number of flowering plants to ensure a supply of pollen all year round e.g hedgerows

use of pesticides to the decline of bumblebees why?

* The **monoculture** of crops **reduces plant diversity** for bumblebee habitats, has a negative impact on pesticides

what two factors that make farming economically viable?

* high yield- measure of how useful a product is obtained
* profit

why is it difficult to find balance between conservation and farming

* it can be expensive and time-intensive to maintain biodiversity
* it can reduce the yield of crops and livestock

what is climate change

* weather patterns to change and frequency of extreme weather to events to increase

how does climate change affect biodiversity

* climate change is happening too fast for species to adapt to these changes, result in many species becoming extinct and a major decline in biodiversity

how is global warming causing decrease in biodiversity

* species move to poles and may not be able to compete with the species already present in these habitats
* some species may not be able to move or change their distributions fast enough to adapt

global warming is threatening marine biodiversity

* increasing the atmospheric CO2 leads to more co2 in seawater, decreasing the pH, negatively affects organisms that require calcium carbonate for shells
* increased ocean temperatures-led to an increased frequency of coral-bleaching events, tiny organisms that live inside help keep them alive leave due to temperature stress

what are some reasons for maintaining biodiversity

* ecological
* Economic


* Aesthetic
* Social
* Moral/ethical
* Environmental
* Agricultural

why does biodiversity have a major effect on the stability of an ecosystem

* a more diverse ecosystem is better able to survive and adapt to environmental changes or threats

give an example on how biodiversity have a major effect on the stability of an ecosystem

if the temperature of a species-rich lake rises due to global warming:

* Some species of fish in the ecosystem are unable to cope with the change while others can

what are keystone species?

they have a larger impact on the ecosystem than others

give an example as to what happens when keystone species are lost

* Bush elephants in the savannah graze in a very extreme way, knocking over and eating several species of tree
* This destruction of vegetation actually helps to maintain the ecosystem

What are some economic reasons to maintain biodiversity

* ecotourism- a major source of income for many countries
* Many tourists travel to and spend money in National parks so they can see wildlife
* Increased tourism in a country contributes to the economy and provides jobs
* contributions to the field of **science and technology**
* The specific enzyme used in DNA sequencing was first discovered in thermophilic bacterium found in a hot spring in Yellowstone National Park, USA

how are aesthetics reasons to maintain biodiversity

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* **pleasure in the beauty of nature** 
* It provides **inspiration** for creatives such as photographers, poets, musicians and artists
* There is a strong argument for preserving biodiversity because of its aesthetic benefits

what are social reasons to maintain biodiversity

people like watching environments which may be lost if they are not conserved, with the loss of the social benefits that they can bring