Unit 3 - Topic 1: Describing Biodiveristy Flashcards
Biodiversity
Refers to the variety of life. The genetic material that gives organisms their specific characterisits and the ecosystems in which they survive.
Species
a group of similar organisms whose members can interbreed with eachother in their natural environment to produce living fetile offspring.
Ecosystems
biological community of interacting organisms and their physical environment.
Determining Diversity of Species
Richness, Evenness (relative species abundance), percentage cover, percentage frequency, Simpsons diveristy index.
Calculate Species Richness and Evenness
Species Richness (S) = number of different species
Species Evenness = number of individuals of species
Percentage Cover and Frequency
% Cover = proppportion of area covered by an organism
% Frequency = % of the quadrat or samplee sixe species is found in
Simpsons Index (D)
Measures diversity by taking into account richness and evenness
Simpsons Diveristy Index (SDI)
The closer to 1 the higher the diversity, and indicates the probability that 2 individuals from the same sample are different species
Species interactions to compare ecosystems
Predation, competition, symbiosis and disease
Predation
Where an organism (predator) kills another organism (prey). When prey is high, predators increase, reducing numbers of prey species.
Competition
Struggle between same organism for the same sources in an environment. Competition reduces population size increasing risks of extinction.
Symbiosis
Is a close ecological relationship between two organisms. There are 5 types
- mutualism: both benefit from obligaotry interaction
- cooperation: both benefit but not dependent
- commensalism: one benefits other is unaffected
- ammensalism: one inhibits the other
- parasitism: one benefits other is hardmed
Disease
relationship between host and pathogen, mainly focuses on infectious diseases. When there are more individuals in area infectious disease is easier to spread, reducing population size.
Abiotic Factors when comparing ecosystems
Climate, Substrate, Size/depth of area
Climate
Refers to temp, humidity, precipitation, wind and ocean currents etc. A comparison can be done across all climates or within the same area as the temperature, weather and other conditions change over time. (particularly due to man-made climate change)
Substrate
The surface or substance were organisms live. Provide information about the nutrients and composition of the environment, allowing to see which species can survive. Also can be used to detect changes in species diversity and why.
Size/depth of area
How much space the ecosystem occupies. Important when examining deforestation, coral bleaching, or similar destructive events. Also populations that experience expansions.
Explain how environmental factors limit the distribution and abundance of species in an ecosystem.
The distribution of species is limited by their ability to access sufficient food sources and habitats. For example, the different type of soil in an ecosystem limits the type of plants that can grow. This can therefore limit the distribution and abundance of certain plant species in an area. The abundance of species is limited by the abundance of food, water and shelter in the areas with beneficial factors.
Classification Systems
Similarity of physical features (the Linnaean system)
Methods of reproduction (asexual, sexual — K and r selection)
Molecular sequences (molecular phylogeny — also called cladistics)
Linnaean System
Species, genus, family, order, class, phylum, kingdom
Reproduction
K - species that are large, long life span, few young at time, logistic growth. Eg Humans
r - short life spans, generally smaller, many young, expodential growth. Eg Rabbits
Molecular Sequence (Cladistics/Phylogeny)
Evolutionary trees based on species shared traits and common ancestory. Also known as taxonomy
Define the term Clade
a group of organisms that is believed to comrise a common ancestor and all of its evolutionary offspring
Assumptions of Cladistics
- common ancestory - group of organisms related if connected
- bifurication - branching pattern split in 2
- physical change - occur over time in lineage
Importance of mulitiple definition of a ‘species’
some species definitions/concepts cannot be applied to organisms that do not reproduce sexually. For example, many organisms reproduce asexually (producing clones), undergo parthenogenesis (development of female gamete without fertilization ie bees) or can transition between sexual and asexual. Also we simply dont know how fossils used to reproduce so cannot account for them.
Identify one example of an interspecific hybrid that does not produce fertile offspring
Mule = horse and donkey
Ecosystems are composed of varied habitats
Microhabitat - a small habitat that may be different from the surrounding larger habitat
Ecoregion - subdivision of an ecozone, with a geographically distinct community. An ecozones is an large area where organism have been evolving in relative isolation over long periods of time
Explain how the process of classifying ecosystems is an important step towards effective ecosystem management (old growth forest, coral reef, productive soils)
Old Growth Forest
Classifying an old growth forest (based on its dominant tree species and specific old-growth characteristics) is important as it allows people to make informed decisions on how to effectivley manage and interact with the specfic ecosystem. This ensures that we have an understanding of human impact on the old growth foresets, thus determing how poeple interact with it, ie prescribed burning.
Describe the process of stratified sampling in terms of;
Purpose, site selection, choice of ecological surveying techniques, minimising bias, data presentation and analysis
Pupose of Stratified Sampling
- Estimating population means of organisms, including density and distribution or by considering the diversity between different areas
- Consider environmental gradients and profiles, including zonation and stratification, showing the impact of an abiotic factor on a biotic one.
Zonation = breaking biome into habitat zones
Stratification = division of physical environment into smaller components
Site Selection
clealry marked out the site in the area loctation
Ecological Surveying Techniques
Quadrats
- Useful where the area being sampled is uniform: Provides a representation of the entire area.
- Once positioned, collect data by: Density, Frequency, Percentage Cover, Scaling Measure
Transects
- It is used to investigate change over distance in an ecosystem.
* Line transect: Sample everything that touches the line.
* Interrupted line transect: Sample at intervals
* Belt transect: Quadrats placed in a continuous line along the transect.
* Ladder belt transect: Quadrat placed at intervals along the transect.
Minimising Bias
Random sampling and systematic sampling minimise bias by deliberalty ignoring features of the habitat - legitimate conclusions can be drawn from these sampling techniques.
Data presentation and analysis
It can be presented in tables, graphs, transect line or transect profile diagrams.
The information can be used to classify the ecosystem, identify the different sub-habitats within the ecosystem or identify relationships between organisms. Over time, this can provide valuable information that may inform management policies.
