Topic 4.1 Flashcards
Biodiversity
Variety of living organisms in an area
Species diversity
Number of different species (species richness) and the abundance of each species in an area (species abundance)
Genetic diversity
Variation of alleles within a species
Endemism
When a species is unique to a single place (isn’t naturally found anywhere else in the world)
-> endemic species are very vulnerable to extinction due to their limited range
Variety of life
Natural selection leading to adaptation and evolution has increased biodiversity on earth over time, but human activities are reducing species diversity
-> some of these human activities include:
. Hunting
. Deforestation
. Climate change
. Agriculture
. Overexploitation
Hábitat
Place where an organisms live
-> it is important to measure species adversity in order to compare different habitats or to study how a habitat has changed over time
Measuring species diversity: 2 ways
- Calculate species richness -> count number of different species in an area
- Calculate species abundance -> count number of different species and the number of individuals in each species and then use index of diversity (D)
Sampling
- Choose area to sample randomly -> makes results more reliable (less bias)
- Count number of individuals of each species in sample area
. For plants: use a quadrant
. For flying insects: use a sweep net
. For ground insects: use a pitfall trap
. For aquatic animals: use a net - Repeat the process as many times as possible -> makes results more representative of whole habitat
- Use results to estimate total number of individuals or total number of different species (species richness) in the habitats studied
Genetic diversity within a species:
Individuals of the same species vary because they have different alleles, so genetic diversity within a species refers to the variety of alleles in the gene pool
Genetic diversity within a species: gene pool
Complete set of alleles in a species (or population) - the greater the gene pool, the greater the genetic diversity
-> its importante to measure genetic diversity to investigate how populations of the same species show different diversity or to show how the genetic diversity of a population change over time
Measuring genetic diversity: phenotype
The larger the number of different phenotypes within a species, the greater the genetic diversity (greater variety in alleles present in species)
Measuring genetic diversity: genotype
The larger the number of different alleles present within a species, the greater the genetic diversity.
-> to look at similarities and differences of alleles within a species you can sequence DNA of individuals of the same species
Heterozygosity index
Heterozygotes are individuals that have two different alleles at a particular locus, and a higher proportion of heterozygotes in a population means that the population has a greater genetic diversity
-> this proportion of heterozygotes in the population can be found with the heterozygosity index (H)
Niche
Role of a species within its habitat -> each species will have its own niche
-> this includes:
. It’s interactions with other living organisms
. It’s interactions with the non-living environment
-> if two species try to occupy the same niche they will compete with each other, and one species will be more successful than the other until only one of the species is left
Adaptation
Features which increase the organisms chances of survival and reproduction
-> these features include
. Behavioural adaptations
. Physiological adaptations
. Anatomical adaptations
- Adaptations become more common in populations of species because of evolution by natural selctio
Organism adaptations to their niche: behavioural adaptations
Ways an organism acts that increase its chances of survival
Examples:
-> possums ‘play dead’ to avoid being detected by predators and attract prey
-> scorpions dance before mating to attract the best partner of species
Organism adaptations to their niche: physiological adaptations
Processes inside an organisms body that increase its chances of survival
Example:
-> brown bears hibernate in winter to slow down their metabolism to conserve energy as there’s less prey available
Organism adaptations to their niche: anatomical adaptations
Structural features of an organisms body that increase its chances of survival
Example:
-> whales have thick layer of blubber to keep them warm in cold water where they can catch prey
Evolution: mutations
These can introduce new alleles into a population causing individuals within a population to show their variation in their phenotypes
-> some of these alleles determine phenotypes that can make the individual more likely to survive
Evolution: selection pressure
These are changes in the environment that create struggle for survival
Evolution: competition
Individuals without advantageous allies don’t survive so there’s fewer individuals and less competition for resources
Evolution: survival and reproduction
Individuals with better adaptations are more likely to survive, reproduce and pass on their advantageous alleles to offspring
Evolution: over time
Number of individuals with advantageous alleles increase
Evolution: over generations
Evolution happens as frequency of the advantageous alleles in the population increases and the favourable adaptations become more common
Speciation
Development of new species
-> species: group of similar organisms that can reproduce to give fertile offspring
-> speciation occurs when populations of the same species become reproductively isolated due to random mutations or geographical isolation which prevent individuals from successfully breeding together
Random mutations
Random mutations can produce new alleles, new phenotypes, and so the following changes
- seasonal changes
- mechanical changes
- behavioural changes
Random mutations: seasonal changes
Individuals from the same population develop different flowering or mating seasons (become sexually active at different times of the year)
Random mutations: mechanical changes
Structural changes to the genitalia in some individuals prevent them from successfully mating with main population
Random mutations: behavioural changes
Group of individuals develop courtship rituals that aren’t attractive to main population
Geographical isolation
- Population is divided by a physical barrier
- There’s different conditions and selection pressures on either side of the barrier
- Natural selection takes place due to the different environments on either side to make advantageous characteristics more common
-> Different characteristics will be advantageous so allele frequencies will change in each population
-> Mutations will take place independently in each population changing the allele frequencies - Different allele frequencies will make the populations more genetically distinct and will lead to different phenotype frequencies arising on each side
- New species is formed eventually as they aren’t able to reproduce with one another to produce fertile
offspring
Allele frequency
How often an allele occurs in a population
-> The frequency of an allele in a population changes over time due to gene mutations and this leads to evolution
-> Hardy-Weinberg equations can be used to calculate allele frequencies and to see if a population has changed over time
Hardy-Weinberg principle
Predicts that the frequencies of alleles in a population won’t change from one generation to the next
-> this is only true under certain conditions:
. Large population
. No immigration
. No mutations
. No natural selection
. Random mating
-> if allele frequencies do change in a large population then immigration, emigration, mutations or natural selection have happened
Hardy-Weinberg equations
P + q = 1
(P: frequency of dominant allele)
(Q: frequency of recessive allele)
P^2 + 2pq + q^2 = 1
(P^2: frequency of homozygous dominant genotype)
(2pq: frequency of heterozygous genotype)
(Q^2: frequency of homozygous recessive genotype)
Taxonomy
Science of classification which involves naming organisms and organising them into groups based on similarities and differences
Classification
Classification of organisms is based in their phenotypes, genotypes and how related they are to
. Early classification systems: only used observable phenotypes to place organisms into groups
. New technologies: organisms are classified based on their DNA base sequence
The 8 taxonomic groups
. Domain
. Kingdom
. Phylum
. Class
. Order
. Genus
. Species
Binomial system
First the genus with a capital letter and then the species with lower case in italics
What are the 5 kingdoms
Prokaryotes, protoctista, fungi, plantae, animalia
Prokaryotes
Prokaryotic cells, unicellular, no nucleus, less than 5 nanometres
Eg. Bacteria
Protoctista
Eukaryotic cells, usually live in water, single-celled or simple multicellular organisms
Eg. Algae, Protozoa
Fungí
Eukaryotic cells, chitin cell walls, saprotrophic
Eg. Moulds, yeast, mushrooms
Plantae
Eukaryotic cells, multicellular, cellulose cell walls, can photosynthesise, contain chlorophyll, autotrophic
Eg. Mosses, ferns, flowering plants
Animalia
Eukaryotic cells, multicellular, no cell walls, heterotrophic
What is done to new scientific data
New data is evaluated by other scientists to change the classification system or how an organisms is classified
-> the validity of of the research is checked through the study method/design, and then the research is published in scientific journals where its peer reviewed beforehand
New three domain classification system proposed
This has been proposed after new data on molecular phylogeny
. Phylogeny: study of the evolution of organisms
. Molecular phylogeny: study of similarities and differences in DNA and proteins between different organisms
Old classification VS new classification system
Old classification: all organisms were directly classified into 5 kingdoms
New classification: all organisms are first classified into 3 domains
. Organisms in prokaryote kingdom are separated into two domains: Bacteria and Archaea
. The other four kingdoms are placed into the third domain: Eukaryota
Conservation
Protection and management of endangered species
-> methods of conservation of endangered species to prevent loss of genetic and biodiversity
Methods for conservation of endangered species
. Seed banks
. Captive breeding programmes
. Reintroduction programmes
. Zoos
. Education
. Scientific research
seed banks
Store seeds from endangered plants
-> these conserve genetic diversity by storing a range of seeds with different alleles and different phenotypes which increases survival chances
Seed banks: conditions required
. Collect seeds, sterilise them and dry them out
. Store in a cool (-20 degrees) and dry place -> prevents from germinating
Advantages of seed banks
. Cheaper to store seeds than fully grown plants
. Larger number of seeds can be stores as they need less space
. Less work required to take care of seeds
. Seeds can be stored anywhere as long as its cool and dry
. Seeds are less likely to be damaged by disease, vandalism or natural disorders
Disadvantages of seed banks
. Testing seeds for viability is expensive and time consuming
. Very expensive to store all types of seeds and test them regularly for viability
. Hard to collect seeds from species in remote collections
Zoos and captive breeding
Zoos can breed endangered species in controlled environments to increase their numbers
Zoos and captive breeding: captive breeding problems
. Difficult to recreate natural environment of organisms in a zoo
. Inbreeding depression -> decreases reproduction and chances of survival
. Ethical concerns surrounding keeping wild animals in captivity
Reintroduction programmes
Organisms from zoos and seed banks can be reintroduced into the wild which increases the number of these organisms in the wild, helping to conserve numbers or bring them back from the brink of extinction
Reintroduction programmes: advantages
. Increases food availability
. Increases population and biodiversity
. Habitats develop
Reintroduction programmes: disadvantages
. Organisms act differently in the wild due to being raised in a zoo
. New diseases
. New competition
Scientific research: seed banks advantages and disadvantage
Advantages:
. Provide knowledge of conditions required for plant growth
. Endangered species can be grown for medical research
Disadvantages:
. Data is limited to small, interbred populations which aren’t representative of wild plants
Scientific research: zoos advantages and disadvantage
Advantages:
. Increases knowledge about the behaviour, physiology and nutritional needs of animals
. Easier to investigate animals in controlled environment
Disadvantages:
. Animals in captivity may act differently to animals in wild
Education
Educating people about endangered species and reduced biodiversity helps to raise awareness and interest in conserving biodiversity
. Zoos: let people get close to organisms increasing their enthusiasm for conservation work
. Seed banks: provide training and set up local seed banks all around the world
