IB biology: option C (IV)

what are indicator species?

species that are sensitive to specific environmental conditions and consequently have a limited range of tolerance

what are examples of indicator species? (3)

lichen, tubifex worms, mayfly larva

what is the purpose of a biotic index?

compare the relative frequency of indicator species and provide an overall assessment of environmental health

what is the biotic index calculation?

biotic index = (total number of individuals of species x total tolerance rating of species) / total number of individuals collected

what dose a high biotic index mean?

indicates the presence of many pollution-sensitive organisms, denoting an unpolluted environment

what does a low biotic index mean?

indicates a polluted environment, due to a relative abundance of pollution-tolerant organisms

what is biodiversity?

the variety and variability of all living organisms within a given ecological area

what are the two main factors that contribute to biodiversity?

species richness and species evenness

what is species richness?

the number of different species present in an area (more species = greater richness)

what is species evenness?

the relative abundance of the different species in an area (similar abundance = more evenness)

how do we calculate Simpson’s Biodiversity Index?

DI = total individuals (total individuals - 1) / total number of individuals of species (number of individuals of species -1)

what does a high Simpson’s biodiversity index mean?

a stable site with many different niches and low competition (high richness and evenness)

what does a low Simpson’s biodiversity index mean?

a site with few potential niches where only a few species dominate (low richness and evenness)

what are factors that affect biodiversity?

habitat size,

edge vs centre of habitat

why is there a difference in biodiversity at the edges of an ecosystem compared to the centre?

ecology at the edges of ecosystems is different from central areas; the edge effect

compare biodiversity at edges of habitat and centre of habitat

edges tend to have greater biodiversity, as different habitats with different abiotic factors exist in close physical proximity,

edges tend to have more competition than central regions, which may restrict survival prospects of certain species

how does size of habitat affect biodiversity?

larger habitats have a greater biodiversity than smaller habitats

how does island size affect biodiversity?

larger islands>smaller islands;

support a greater range of habitats, can sustain higher populations of species, have greater productivity at each trophic level

what is conservation?

the protection and maintenance of natural resources – such as trees, water and wildlife

what are the two types of conservation?

in situ conservation and ex situ conservation

what is in situ conservation?

the preservation of plant and animal species within their natural habitat

what are examples of in situ conservation?

designated protected areas as nature reserves or national parks

what are benefits to in situ conservation?

- allows species to live in the environment to which they are adapted

- maintains the animal's normal behaviour

- provide a place for scientific study and developing public awareness

what is ex situ conservation?

the preservation of plant and animal species outside their natural habitats - typically required for critically endangered species when urgent intervention is required

what are benefits to ex situ conservation?

- greater control of essential conditions

- improve the changes of successful breeding by artificial methods, IVF

what are the disadvantages to ex situ conservation?

- methods do not prevent the potential destruction of natural habitats

- species raised in captivity are less likely to be successfully reintroduced into the wild

- increases inbreeding by restricting gene pool

what are examples of ex situ conservation?

captive breeding (animals raised and bred in containment), botanical gardens (areas devoted to cultivation and display of variety of plant species), seed banks (secure sites that store seeds to preserve genetic diversity)