C.4 Conservation of biodiversity

Question 1

What are indicator species?

Answer 1

Indicators species are sensitive to specific environmental conditions and consequently have a limited range of tolerance
- Their presence or absence can be used as a indicator of environmental conditions.

Examples: mayfly larvae require high levels of dissolved oxygen in water

Question 2

Calculating biotic indices

Answer 2

• Relative numbers of an indicator species can be used to calculate the value of a biotic index
• Biotic indices compare the relative frequency of indicator species and provide an overall assessment of environmental health
  Biotic index = (Σ(n x a))/N
  n = number of individuals in a species
  a = tolerance rating of the species
  N = total number of individuals collected
• A low biotic index indicates a polluted environment
• A high biotic index indicates the presence of many pollution-sensitive organisms, denoting an unpolluted environment

Note: a change in the biotic index over time marks a change in the environmental conditions within a given ecosystem

Question 3

What does biodiversity refer to?

Answer 3

Biodiversity describes the variety and variability of all living organisms within a given ecological area.
- Biodiversity can be used to refer to the number of species, their genetic diversity or habitat variety (ecological variations)

Question 4

What are the two components that contribute to biodiversity?

Answer 4

1. Species richness: describes the number of different species present in an area (more species = greater richness)
2. Species evenness: describes the relative abundance of the different species in an area (similar abundance = more evenness)

Question 5

Using Simpson’s reciprocal index of biodiversity to analyze the biodiversity of communities

Answer 5

The Simpson’s reciprocal index (D) can be used to measure the relative biodiversity of a given community
- It takes into account both the number of species present (richness) and the number of individuals per species (evenness)
- A higher index value is indicative of a greater degree of biodiversity within the community

D = (N(N-1))/(Σn(n-1))
N = total number of individuals collected
n = number of individuals of a species

Simpson’s reciprocal index can be used to compare communities to identify intrinsic qualities:
- A high index value suggests a stable site with many different niches and low competition (high richness and evenness)
- A low index value suggests a site with few potential niches where only a few species dominate (low richness and evenness)

Note: the index value may change in response to an ecological disturbance (such as human intervention or natural disasters)

Question 6

What are biogeographic factors and how can these be applied in natural reserves?

Answer 6

Size:
- Larger habitats tend to promote biodiversity better than smaller habitats (more available niches = less competition)

Edge effect:
- Habitats with less “edge” are better
- Ecology at the edges of ecosystems is different from central areas (e.g. more sunlight, more wind, etc.)
- This is known as the edge effect, whereby species distribution is influenced by the divergent environmental conditions
- Edges tend to have greater biodiversity, as different habitats with different abiotic factors exist in close physical proximity
- However edges tend to have more competition than central regions, which may restrict survival prospects of certain species

Clustered reserves:
- Clustered reserves are better than fragmented and isolated reserves

Corridors:
- Habitat corridors between parts of a fragmented habitat can connect disparate regions to improve genetic diversity

Question 7

Island size/edge effect and biodiversity relationship

Answer 7

Size:
The biodiversity of an island is typically proportionate to island size (i.e. larger islands have greater biodiversity) - positive relationship
- Larger islands support a greater range of habitats (and hence more available niches for species to occupy)
- Larger islands can sustain higher population numbers for each species (increases species evenness)
- Larger islands have greater productivity at each trophic level, leading to longer and more stable food chains

Edge effect:
The diversity of species within a given environment changes with proximity to the ecosystem’s boundaries (edge effect)
- Biodiversity may be greater at the border between two ecosystems as different abiotic factors favour certain species
- However certain species may not be able to thrive under these conditions and instead must occupy more central regions
- The effect of edges on biodiversity will be greatly influenced by the particular conditions caused by the ecological disturbance

Question 8

Different strategies for the conservation of endangered species

Answer 8

in situ and ex situ

Question 9

In situ conservation

Different strategies for the conservation of endangered species

Answer 9

In situ conservation is the preservation of plant and animal species within their natural habitat
- This typically involves the designation of protected areas of land as either nature reserves or national parks

Advantages:
- It allows species to live in the environment to which they are adapted and to occupy their natural position in the food chain
- It maintains the animal’s normal behaviour (offspring usually aquire skills from parents and peers around them)
- Retaining the natural habitat prevents its eventual loss and ensures it remains available for other endangered species
- Such areas provide a place to return animals from breeding programs as they provide realistic conditions for reintegration
- Reserves in different areas can share information and provide a place for scientific study and developing public awareness

Question 10

Ex situ conservation

Different strategies for the conservation of endangered species

Answer 10

Ex situ conservation involves the preservation of plant and animal species outside their natural habitats
- Ex situ conservation may typically be required for critically endangered species when urgent intervention is required

Advantages:
- It allows for greater control of essential conditions (e.g. climate control, dietary intake, veterinary care, etc.)
- It can improve the chances of successful breeding by utilising artificial methods (e.g. embryo transfer, IVF, etc.)

Disadvantages:
- Such conservation methods do not prevent the potential destruction of their natural habitats
- Species raised in captivity are less likely to be successfully reintroduced into the wild (loss of autonomous survival)
- Ex situ conservation increases inbreeding by restricting the gene pool and restricts the evolution of the species

Types of ex situ conservation methods:
- Captive breeding
- Botanical gardens
- Seed banks

Question 11

Case study of the captive breeding and reintroduction of an endangered animal species: the red wolf

Answer 11

• The red wolf in Native to the Southerneastern USA
• Threats during the 1900s: hunting/predator control programs (deemed to be a pest), destruction / alteration of habitat
• The red wolf was designated an endangered species in 1967 and declared extinct in the wild in 1980.
• U.S. Fish and Wildlife Service initiated a captive breeding program enabled the species to be reintroduced.
• As of 2010, the reintroduced population of red wolves was thought to total around 130 individuals.