Week 21 Flashcards
What does biodiversity refer to?
Variety and variability of life on Earth
Encompassing all levels s of natural variation from molecular and genetic levels, to species level, and beyond to variation at the landscape level.
Why is biodiversity and conservation important?
Helps us use science to prioritize or conservation efforts
Roughly, how many species and plants are on earth?
~12 million species (<15% described)
Estimation of fungal species o earth?
1.5 million of which 100,000 are known
(molecular tools reveal vast diversity of microbes - >10,000 genetically distinct prokaryotes in handful of sil)
What is the most diverse group of land plants?
The flowering plants (angiosperms), also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 416 families, approx. 13,164 known genera and a total of c. 295,383 known species
What di the spatial patterns of biodiversity reveal?
Its possible to observe that there is a longitudinal gradient of species richness from poles to the tropics
It has been long recognised that the number of species in most taxonomic groups is ______ in the poles and_____ towards the tropics (Huston 1994).
Lowest
Increases
Cross-taxon oceanic average species richness peaks at what temperature?
~30 degrees latitude North or South in all oceans
Example of reverse latitudinal patterns?
Seabirds, lichens, microbes
What do seabirds show reverse latitudinal patterns of species richness?
greatest abundance and diversity at high latitudes (high productivity of northern oceans) :
Antarctic – 17 species flightless penguins
Sub-arctic – 22 species non-migratory Auks, Murrs, Puffins
What do lichens show reverse latitudinal patterns of species richness?
maximal diversity in dry/cold regions and Boreal forest
What do microbes show reverse latitudinal patterns of species richness?
They are cosmopolitan
Abundance of free-living microbes (< 1mm) so large that their dispersal is rarely (if ever) restricted by geographical barriers.
One third of the global diversity of soil protozoa present within single patch of grassland in Scotland.
What are the four main hypotheses that explain why there may be so many more species in the tropics than poles?
- Geographic Area hypothesis: larger area more species, the shape of the planet means more area in the tropics.
- Energy-species hypothesis: the availability of resources and climate dictates number co-existing species in given area (i.e. more available energy in the tropics);
- Rapoport’s Rule: suggests that the geographic range of species decreases as move poles – tropics;
- Evolutionary speed hypothesis: the tropics have had long time stability and faster rates of evolution.
(And a combination of all of them)
What does the geographic area hypothesis of biodiversity state?
There is a general positive relationship between area of land and the number of species that can leave on it.
More area of the planet in the tropics.
What does the energy-species richness hypothesis of biodiversity state?
Energy availability dictates number co-existing species in given area (I.e. more available energy tropics: due to water availability, light, temperature, etc)
What is potential evapotranspiration (PET)?
the sum of evaporation and plant transpiration from the Earth’s land and ocean surface to the atmosphere.
What does actual evapotranspiration do versus PET?
AET = water availability (plant measurement)
PET = species richness of animals
What does energy-species richness hypothesis of productivity hypothesis state?
Availability of resources dictates number co-existing species in given area :
More resources (solar energy and nutrients) for plants, (plant biomass) for herbivores and (prey) for carnivores.
What does energy-species richness hypothesis: ambient energy hypothesis state?
Availability of high temperature and water dictates number co-existing species in given area
Physiological response of organism to temperature
- Low temperature = reduce population growth, lower survival
- Low water availability = reduce plant growth and animal survival
Where is temperature the main limiting factor of? What about rainfall?
Rainfall = most of thw world
Temperature = Only north
What does Rapoport’s rule hypothesis state?
The Rapoport rule is a biogeographic principle that postulates that, as latitude decrease (towards the tropics), a decrease in the geographical extent of both animal and plant species can be observed.
Three explanations to Rapoport’s rule of biodiversity?
Climatic variability = greater at high latitudes
Glaciation = species with high dispersal ability repopulate north
Competition between species = Tropics: hight competition due to restricted habitat. Poles: less competition due to limited environmental factors
What does evolutionary speed hypothesis state?
3 traits characterise species-rich tropics:
- long evolutionary history (more generations)
- relatively stable existence (lack of glaciation)
- constantly warm temperatures
Evidence of quicker evolution in tropics eg on Galapagos Islands in bird species
How do we measure biodiversity?
Species richness/diversity (Alpha-diversity)
Species composition (Beta-diversity)
Phylogenetic diversity
Functional diversity
