Biodiversity Concepts and Measures

Study Notes

Biodiversity Overview

Biodiversity refers to the variety of organisms present in a specific area, assessed locally or globally.
Species richness indicates the number of different species in a community.
Index of diversity calculates biodiversity by considering both species richness and individual species counts using the formula:
- Index of diversity = (N(N – 1))/(Σn(n-1))
- N = total organisms of all species
- n = total organisms of each species

Impact of Farming Techniques on Biodiversity

Farming practices like monoculture, herbicide and pesticide usage, hedgerow removal, and woodland clearance negatively impact biodiversity.
Conservation strategies include:
- Legal protection for endangered species.
- Establishment of protected areas.
- Programs such as the Environmental Stewardship Scheme.
Achieving a balance between agricultural development and biodiversity conservation is essential.

Investigating Diversity

Genetic diversity can be assessed through:
- Frequency of measurable/observable traits.
- DNA base sequence.
- mRNA base sequence.
- Protein amino acid sequence.
Gene technology has evolved the investigation methods beyond observable traits.
Variation in organisms arises from both genetics and environmental influences.

Quantitative Variation Analysis

To analyze variation quantitatively:
- Random sampling reduces bias.
- Calculate mean values and standard deviations from samples.
- Mean variations indicate differences between populations.
- A large standard deviation reflects high variation within a population.

Causes of Genetic Variation

Genetic variation can result from mutations, which modify the DNA sequence.
Types of gene mutations include:
- Substitution: A nucleotide is replaced, possibly not changing the resulting amino acid due to the genetic code being degenerate.
- Insertion/Deletion: Addition or removal of nucleotides, often resulting in frameshift mutations.
Mutagenic agents can elevate mutation rates.
Chromosome mutations involve structural or numerical changes to chromosomes, such as non-disjunction during meiosis.
Meiosis creates genetic diversity by producing four genetically distinct daughter cells.

Mechanisms of Genetic Variation in Meiosis

Meiosis involves:
- Separation of homologous chromosomes in meiosis 1.
- Separation of sister chromatids in meiosis 2.
Independent segregation and crossing over contribute to genetic variation.
Random fertilization combines haploid gametes, increasing genetic diversity.

Genetic Diversity and Evolution

Alleles represent different forms of the same gene; genetic diversity measures the range of alleles in a population.
Genetic diversity is crucial for natural selection, the process by which more well-adapted individuals survive and reproduce.
In natural selection:
- Random mutations generate new alleles; while many can be detrimental, advantageous alleles can enhance reproductive success.
- Beneficial alleles become more common over generations due to inheritance.

Types of Selection

Directional selection: Favors extreme traits; e.g., antibiotic resistance enhanced by powerful antibiotics.
Stabilizing selection: Favors intermediate traits; e.g., human birth weight, with extreme weights associated with higher mortality.
Disruptive selection: Favors extreme phenotypes; e.g., fur color in a landscape, which can lead to speciation.

Description

Test your knowledge on the concepts of biodiversity, species richness, and how farming techniques impact ecological variety. This quiz will explore the index of diversity and its components, emphasizing the importance of maintaining biodiversity in ecosystems.