ET1 - Biodiversity and how to study it Flashcards
Convention on biological diversity definition of biodiversity
“the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity between species and of ecosystems.”
How many scientifically described species are there?
Why is this number uncertain?
There are thought to be 1.2-2 million scientifically described species.
This is uncertain due to synonymy (duplicate descriptions of species) and homonymy (‘Hidden diversity’ where multiple species are all thought to be the same).
What is synonymy?
2 examples
Duplicate descriptions of species, thought to make up ~18% of named species.
What is homonymy?
2 examples
Hidden diversity due to similar species being categorized as the same species.
Example: Xingu scale-backed antbirds and common scale-backed antbirds considered same species until vocal recordings show significant song variation between the two.
Appletans et al estimated there is a 100 year lag between categorization and realisation of homonymy.
How can you calculate total species numbers?
3 main ways
MACROECOLOGICAL PATTERNS
- Body size frequency distributions (10-50mil. animals)
- Latitudinal gradients of species (3-5mil. large)
- Species area relationships (~10mil. deep sea species)
DIVERSITY RATIOS
- Ratios between taxa (1.6mil fungal species)
- Host-specificity and spatial ratios (30mil. arthopods in the tropics).
- Known-unknown ratios (1.84-2.57mil. insects globally)
TAXONOMIC PATTERNS
- Time-species accumulation curves (~19,800 marine fish)
- Authors-species accumulation curves (13-18% angiosperms undiscovered).
- Expert estimations (~5mil. insects)
What is the consensus estimate of total species?
The consensus of species estimates varies between 5-8 million species.
How many new species are described each day?
36 new species are described each day.
- 130-160 new fish species per year.
- 95 amphibian species per year.
- 6-7 bird species per year.
Costello et al 2011 species estimate
2.2 million eukaryotic species.
up to 31% of marine species are unknown.
up to 29% of terrestrial species are unknown.
More et al 2011 species estimate (prefered to Costello)
Using accumulation curves at higher taxonomic levels to infer species relationships (better than species accumulation curves).
8.7 million eukaryotic species.
up to 91% of marine species are unknown.
up to 84% of terrestrial species are unknown.
How do we measure biodiversity?
Species richness (organism diversity). Index of diversity (Species number and rel. abundance).
Including underlying patterns and structure is an important incorporation into indices of diversity.
Why are diversity indices important?
Indices of diversity aim to capture the richness and evenness of a community in a single number. This is never fully possible but indices can be useful indicators.
How can a rank abundance curve categorize a community?
Rank abundance curves have a long tail of rare species because most species are rare, especially in diverse ecosystems. Degraded ecosystems tend to lose this long tail and have a steeper curve as a result.
How can species accumulation curves be used to categorize a community?
Accumulation curves can be used to calculate the total number of species in a given area.
More biodiverse areas will have a steeper gradient and flatten more slowly.
What is beta diversity?
Beta diversity is a measure of species diversity between locations.
What is alpha diversity?
Alpha diversity is a measure of local diversity.
