4C Biodiversity and conservation

The main factors affecting biodiversity today are

• Habitat destruction

• Overexploitation

• Hunting

• Agriculture

• Climate change

Habitat destruction

• Habitat loss 

• Habitat fragmentation habitats are divided into small areas - populations living within are more likely to suffer from inbreeding or local extinction

• Deforestation - forest habitats often have the highest levels of biodiversity

Overexploitation

natural resources exploited by humans are actually being used up faster than they can be replaced

Hunting

many wild, non-farmed species are removed more quickly than their wild populations can be replenished

Agriculture features

• Farms became more specialised so they grew only one crop or raised one type of livestock (monoculture)

• Fields were made bigger to accommodate machinery via the removal of hedgerows/stonewalls

• More land was made arable by draining wetland/filling in ponds

• Use of fertilisers and pesticides increased

Agriculture cons

• Monocultures support much lower levels of biodiversity

• Hedgerows represent an important habitat for many insects, small mammals and birds, which can nest there

• Fertilisers can leach into waterways, causing eutrophication

• Pesticides used on crops kill insect pests but also kill many non-target species

Climate change

• It is feared that climate change is now occurring too fast for many species to be able to adapt to these changes, which could lead to extinction

• Increasing atmospheric CO₂ is leading to more CO₂ dissolving in seawater - negatively affecting organisms that require calcium carbonate for shells

• Increased ocean temperatures have also led to an increased frequency of coral-bleaching events, where the tiny organisms that live inside corals and help keep them alive leave due to temperature stress. Without these organisms, the corals die and are broken down

Biodiversity

a study of all the variation that exists within and between all forms of life

it is very important for the resilience of ecosystems

How can biodiversity be assesed?

• The number/range of different ecosystems  and habitats

• The number of species and their relative abundance

• The genetic variation within each species

Species richness

the number of species within an ecosystem

Genetic diversity

the diversity of alleles and genes in the genome of species

Endemism

Certain species only occur in one particular area of the world - more at risk of extinction

why is species richness a limiting way to measure species diversity?

as it does not take into account the number of individuals of each species

Species abundance

a measure of the relative number of individuals of the same species within a given area

Heterozygosity index

H = number of heterozygous / number of individuals in the population

An index of diversity

a measurement that describes the relationship between the number of species present and how each species contributes to the total number of organisms that are present in that community

The index of diversity formula

ΣN(N-1)  /  n(n-1)

• n = total no. of organisms for a single species in the community

• N = total no. of organisms in the community

• Σ = sum of

niche

The role that a species plays within its habitat including:

The biotic interactions of the species (e.g. the organisms it feeds on and the organisms that feed on it)

The abiotic interactions (e.g. how much oxygen and carbon dioxide the species exchanges with the atmosphere)

Adaptations to abiotic and biotic conditions

• Anatomical, structural features such as horns, claws or feathers, that increase an organism's chances of survival

• Behavioural, behaviours such as courtship of defensive behaviours, that increase an organism's chances of survival

• Physiological, processes inside the body, such as venom production or the ability to digest cellulose, that increase an organism's chances of survival

Hardy-Weinberg Principle

states that if certain conditions are met, the allele frequencies of a gene within a population will not change from one generation to the next

What are the conditions or assumptions that must be met for the Hardy-Weinberg principle to hold true?

• Mating must be random between individuals

• The population is infinitely large

• There is no migration, mutation or natural selection

p + q = 1

• Whole population = 1

• The letter p represents the frequency of the dominant allele (B)

• The letter q represents the frequency of the recessive allele (b)

p² + q² + 2pq = 1

• The chance of an individual being homozygous dominant is p²

• The chance of an individual being heterozygous is 2pq

• The chance of an individual being homozygous recessive is q²

Reasons for changes in allele frequency

mutation and natural selection

Mutations

• The primary source of genetic variation is mutation

• Results in the generation of new alleles

• which may be advantageous/disadvantageous/expressed or not

Natural selection

the advantageous alleles increase in frequency over time and generations due to selection pressure

Reproductive isolation occurs when

changes in the alleles and phenotypes of some individuals in a population prevent them from successfully breeding with other individuals in the population that don't have these changed alleles or phenotypes

Seasonal changes

May develop different mating or flowering seasons

Mechanical changes

may develop changes in their genitalia that prevent them from mating successfully

Behavioural changes

changes in their courtship behaviours, meaning they can no longer attract individuals of the opposite sex for mating

Conservation of species

protecting and managing them for future generations

Seed banks

conserves plant diversity by drying and storing seeds in a temperature-controlled environment

advantages of seed banks

• more cost effective to store seeds than fully grown plants

• take up less space so more can be stored rather than plants

• less labour intensive

• can be stored anywhere as long as its cool and dry

• are less vulnerable to disease, natural disaster or vandalism

disadvantages of seed banks

• testing seeds for viability is expensive/time consuming

• cost would be high to store all types of seeds

• challenging to collect seeds from plants growing in remote habitats

captive breeding programmes

breed individuals of a species so their offspring can be released into the wild

advantages of captive breeding programmes

• Scientists are able to closely study animal’s genetics, behaviours and habitat needs

• leads to a greater understanding of species’ needs

• scientist’s can carry out studies that would be difficult to carry out in the wild

• zoos can educate the public abt endangered spices

disadvantages of captive breeding programmes

• Captive breeding of small species populations can reduce genetic diversity

• Certain animal species will not breed in captivity

• Not all zoos can provide adequate habitats for animals with specific needs

• Many people question the ethics of keeping animals in captivity

• Animals in zoos may not behave the same way they would in the wild, therefore isn’t reliable

Benefits of reintroduction back into the wild

• Will help prevent them from going extinct in the wild

• Organisms that rely on these plant/animals for food/habitat may benefit from their presence

• Contributes toward restoring lost or degraded habitats

Disadvantages of reintroduction back into the wild

• These organisms may carry new diseases that will harm other organisms living in that habitat

• Reintroduced animals may lack the ability to find food or communicate effectively with members of their own species