C10/11 Flashcards
Homologous structure
A structure that appears superficially different (and may preform different functions) in different organisms but has same underlying structure.
Homologous structure example
The pentadactyl limb of vertebrates (many different functions but basic structure very similar)
How does the presence of homologous structures provide evidence for evolution
Evidence for divergent evolution (describes how from common ancestor, different species have evolved, each with different set of adaptive features). This type evolution occurs when adapt new habitat (loss or migrate).
Convergent evolution example
Marsupial and Placental Mole
Both burrow through soft soil to find worms and grubs
Both have streamlined body shape and modified forelimbs for digging
Both have velvety fur (allows for smooth movement through soil)
Differ in fur colour (marsupial orangish, placental grey).
Human influence on Biodiversity (explanation):
Human population growing dramatic rate
To create enough space for housing, industry and farming, humans severely disrupting the ecology of many areas
Deforestation (definition):
Permanent removal of large areas of forest (provide wood for buildings and fuel, and create space for roads, buildings and agriculture)
Agriculture (definition)
Increasing amount land has to be farmed in order feed increasing population. Result large amounts land cleared and in many causes planted with a single crop (monoculture).
Climate change (definition)
Evidence that the release of carbon dioxide and other pollutants into atmosphere from burning fossil fuels increasing global temperature.
Deforestation affects on Biodiversity (4)
Occurs naturally, however most deliberately from human actions.
- Directly decreases the number trees in area
- If only specific tree type is felled, the species diversity is reduced
- It reduces number of animal species, destroying their habitat
- Animals forced to migrate (may increase the biodiversity of neighbouring areas).
Aesthetic reasons for maintaining biodiversity (3)
- Different plants and animals in environments enriches our lives
- Natural world provides inspiration for people (musicians, writers) in turn provide pleasure to others.
- patients recover more rapidly from stress and injury when supported by plants and relatively natural environment.
Economic reasons maintain biodiversity (8)
If biodiversity in an ecosystem is maintained, levels of long-term productivity are higher.
- soil erosion and desertification may occur due to deforestation (reduce ability to grow crops).
- need to conserve all organisms that we use to make things (furniture), result in collapse ,any industries.
- species with potential economic importances may become extinct before even discovered (I.e chemical/ medical uses).
- Continuous monoculture results in soil depletion (reduction diversity of soil nutrients).
- Promotes tourism
- High biodiversity provides protection against abiotic stresses and disease (if not maintained change in conditions or disease can destroy entire crops).
- Plant varieties needed for cross breeding
- Higher the chance of producing different products in the future (medicines).
Ecological reasons for maintaining biodiversity (2)
- All organisms independent on others to survive. Removal of one species may have significant effect on others.
- Some species play a key role in maintaining the structure of an ecological community (“keystone species”).
Agriculture affect on biodiversity
Deforestation Removal of hedgerows Pesticides Herbicides (kill weeds, unwanted plants) Monoculture
Climate change affects biodiversity
- Melting of polar ice caps (extinction of animals and plants)
- Rising of sea levels (melting ice caps and thermal expansion of oceans, flooding low-lying land (salt water will also flow up rivers and contaminate fresh waters).
- Higher temperature and less rainfall (plant species falling to survive effects animals).
- Insect life cycle and populations will change.
If climate change is slow species may have time to adapt. New food source or migrate.
What creates genetic biodiversity
All members of species share same genes, but may have different variations of these genes (alleles ).
What determines how genetically biodiverse a population is
The more alleles present in population, the more genetically biodiverse the population is.
Species that contain greater biodiversity are more likely to…
Adapt (not become extinct), some organisms carry an advantage allele, allows them to survive in the altered conditions.
Factors effecting (an increase in) genetic biodiversity
For it to increase, the number of possible alleles in a population most also increase;
- Mutations
- Interbreeding between different populations
Factors that decrease genetic biodiversity (7)
Selective breeding ( artificial selection)
Captive breeding programmes in zoos and conservation centres
Artificial cloning (asexual reproduction)
Natural selection
Genetic bottlenecks (where few individuals survive an event or change, narrowing gene pool)
The founder effect (small number of individuals create new colony)
Genetic drift (due to random nature of alleles being passed on from parents to their offspring, the frequency of occurrence of an allele varies).
How do we measure genetic biodiversity
By measuring polymorphism (polymorphic genes have more than one allele). Most genes are monomorphic (ensuring the basic structure of individuals in a species remains consistent).
What does the locus/loci of a gene refer to
The position of the gene on a chromosome. The greater the proportion of polymorphic gene loci, the greater the genetic biodiversity within the population.
Equation for the proportion of polymorphic genes loci
Number of polymorphic gene loci/ total number of loci
What is Student T-test used for?
This is used to compare the means of data values of two populations
What are the 2 types of student T-tests
Unpaired T-test: is there a difference between 2 groups (different groups)
Paired T-test: is there a difference in a group between two points in time (variable). One group, the same group being tested.
What is Simpsons index of diversity used for
It’s a measure of biodiversity, that takes into account both species richness and species evenness.
Use the formula to calculate biodiversity.
Spearman’s rank
A method of testing the strength and direction (positive/ negative) of the correlation between two variables
Identify if there’s any relationship between two sets of data
