Describing Biodiversity Flashcards
Define species richness
Species richness (S) is the number of species within a defined region. The species richness of a region is obtained through sampling or via a census.
Define Biodiversity
the variety of plant and animal life in the world or in a particular habitat, a high level of which is usually considered to be important and desirable.
Define species evenness (relative species abundance)
Species evenness takes into account the number of species and the relative abundance of species in a community
Define percentage cover and how it is calculated
Percent cover is an efficient means of understanding the relative abundance and contribution to the ecosystem made by different plants. Percent cover is a measure of influence, how much space a plant is taking up.
The quadrat is divided into 100 smaller squares. The number of squares the species is found in is equivalent to its percentage cover in that quadrat.
For example, if grass is found in 89 out of 100 squares in the quadrat then it has a percentage cover of 89%
Defne percentage frequency
The quadrat is divided into 100 smaller squares. The number of squares the species is found in is equivalent to its percentage cover in that quadrat.
For example, if grass is found in 89 out of 100 squares in the quadrat then it has a percentage cover of 89%
Describe Simpsons Diversity Index and how to interpret its results
Simpson’s Diversity Index is a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species. As species richness and evenness increase, so diversity increases. n = the total number of organisms of a particular species.
What are the 4 types of species interactions
- Predation
- Competition
- Symbiosis
- Disease
What are some examples of abiotic factors
- climate
- Substrate
- size/depth of area
Differentiate between spatial and temporal scales
Spatial scales are the area that you are looking at and measuring whereas temporal scales are about the season/time of year
How do environmental factors limit the distribution and abundance of species in an ecosystem?
Abiotic Factors: Physical and non-living elements such as temperature, water availability, soil composition, and sunlight play a crucial role in determining where species can survive and thrive. Extremes or scarcity in these abiotic factors can limit the distribution of species.
Biotic Factors: Living components, such as competition for resources, predation, and symbiotic relationships, influence the distribution of species. These interactions can either restrict or favor the abundance of particular species.
Habitat Fragmentation: Human activities or natural occurrences can break down ecosystems, leading to smaller, isolated habitat patches. This fragmentation restricts the movement of species and reduces the available area for populations to live, impacting their distribution and abundance.
Climate Change: Alterations in temperature, precipitation patterns, or severe weather events can disrupt ecosystems, forcing species to move to more suitable habitats. This can lead to shifts in the distribution and abundance of species.
Pollution and Toxins: Environmental pollutants or toxins, including chemical substances, noise, light, or air pollution, can disturb the behavior, health, and reproduction of species, influencing their distribution and abundance within an ecosystem.
Describe the classification systems for the Linnaean system, methods of reproduction and cladistics
Linnaean system - similarities in physical features
Methods of reproduction - Asexual/sexual
Cladistics - DNA and phylogeny
Define Clade
a group of organisms believed to comprise all the evolutionary descendants of a common ancestor.
What are the 3 common assumptions of cladistics
- common ancestry
- bifurcation
- physical change
Why do we need multiple definitions of species?
Multiple species definitions exist due to the complexity of biological diversity. Various concepts—biological, morphological, ecological, and evolutionary—reflect diverse perspectives and practical needs, accommodating the intricacies of interbreeding, genetics, ecology, and evolution within different organisms.
What is an example of an interspecific hybrid that does not produce fertile offspring
Mules: Cross between a male donkey and a female horse. Though they are sterile, they’re commonly used for work due to their strength and endurance.
Ligers and Tigons: Ligers result from a male lion and a female tiger, while tigons come from a male tiger and a female lion. Both hybrids are usually sterile.
Zeedonk or Zonkey: Offspring of a zebra and a donkey. These hybrids tend to be sterile.
What are the varied habitats within an ecosystem?
Microhabitats exist within habitats, which are part of biome types found within realms or ecozones and further organized into ecoregions, all forming a hierarchy of ecological classifications
Describe the process of stratified sampling
- Purpose (estimating population, density, distribution, environmental gradients and profiles, zonation and stratification)
- Site selection
- choice of ecological surveying technique
- minimizing bias
- methods of data presentation and analysis
Describe the 5 methods of minimising bias
- size and number of samples
- random-number generators
- counting criteria
- calibrating equipment
- noting associated precision
What are the limitations of different definitions of species?
Linnaean System (Based on Morphology):
Limitation: Relies on physical characteristics to classify species. It might not accurately represent genetic or evolutionary relationships, leading to misclassification of cryptic or morphologically similar species that are genetically distinct. It can’t encompass asexual organisms or those with variable morphology across populations.
Mode of Reproduction System:
Limitation: Primarily focuses on interbreeding capability to define species. This doesn’t apply to asexual species, making it inadequate for categorizing such organisms. It also faces challenges in hybrid zones where distinct species can interbreed and produce viable but infertile offspring, blurring species boundaries.
Cladistics System (Based on Evolutionary Relationships):
Limitation: While it aims to define species based on evolutionary relationships and shared ancestry, it can be limited by incomplete knowledge of evolutionary history or by gradual changes in species over time. Determining appropriate cutoffs for defining distinct lineages can be arbitrary, especially when dealing with incomplete fossil records or when transitional forms exist.
