Introduction Flashcards
Why should we conserve biodiversity
To maintain species for intrinsic value to drive the whole planet
How is the variety of life on Earth spread
Not evenly, it’s concentrated in special places
What is causing current amphibian species richness to decline
climate change
Chytridiomycosis (pathogen)
Threat from land use change
What is biodiversity
It generally refers to the variety and variability of life on Earth . It encompasses all levels of natural variations from molecular and genetic levels to species level and beyond to variation at the landscape level
What is the simplest way to measure biodiversity
Species richness (all levels of biodiversity from molecular and genetic to species level)
How many species are on the planet
12 million (only 15% described)
What do molecular tools reveal
Vast diversity microbes
How many prokaryotes are in a handful of soil
More than 10,000 genetically distinct ones
How many species of fungus on the world is there
1.5 million of which only 100,000 is known
What is the most diverse group of land plants
The flowering plant (angiosperms) also known as abgiospermae or magnoliophyta
How many families are in the angiosperms
416
How do we know which parts of the planet species are concentrated
The development of global biodiversity information facility
What does the vertebrate map show
More species near the equator. Spatial patterns shows us that all the biodiversity is concentrated in a specific area. We are seeing a latitudinal pattern/ gradient or species richness from poles to the tropics.
What does Huston say
It has been long recognised that the number of species in most taxonomic groups is lowest in the piles and increases towards the tropics
How much diversity is in the different regions
Little in the polar
More in the alpine
Lots in the forests, meadows, sub-tropics, humid tropics with rainforests
Example of a sub-tropic location
Hawaii
Example of humid tropics
Central Africa
Australia
South America
Asia
What is the 0 latitude
The equator
What is there a sharp increase of as latitude increases
Species richness
When does cross-taxon oceanic average species richness peak
At 30* latitude north or south in all oceans
What is the latitudinal pattern of diversity for sea birds
Greatest abundance and diversity at high latitudes (high productivity of northern oceans) so opposite to the usual pattern of diversity (decreased)
How many species are in the Antarctic
17 species of flightless penguins
22 species of non-migratory Auks, Myers and Puffins.
What is the pattern of diversity for lichens
Maximal diversity in dry/cold regions and boreal forest. In the Uk they are concentrated in the north so it doesn’t follow this rule.
How are microbes cosmopolitan
Abeyance of free living microbes are so large that their dispersal is rarely restricted by geographical barriers
What is present in a single patch of grassland in Scotland
One third of the global diversity of soil Protozoa
What are the four hypotheses about why there are so many species in tropics compared to the poles
Energy species hypothesis
Heterogeneity hypothesis
Rapoports rule
Combination of them all
What is the energy species hypothesis
The availability of resources and climate dictates number co-existing species in given area (ie more available energy in the tropics) energy drives species
What is the heterogeneity hypothesis (not a great hypothesis)
Suggests a general increase in heterogeneity as move towards the tropics. Heterogeneity creates more habitats (macro and micro habitats so more species)
What is the rapoports rule
Suggests that the geographic range of species decreases as it moves poles-tropics. A bio geographic principle that says as latitude decreases a decrease in the geographical extent of both animal and plant species can be observed
How does PET fit in the the energy-species hypothesis
If water is available and not limited this is driven by temperature. If evapotranspiration is higher in tropics with more temperature, there’s less in poles bc it’s colder.
What is PET
Potential evapotranspiration is the sum of evaporation and plant transpiration from the earths land and ocean surface to the atmosphere.
Why is the relationship in North America for animals good
Because the PET is good
What are the two sub-hypotheses for energy-species hypothesis
Productivity hypothesis
Ambient energy hypothesis
What is the productivity hypothesis
Availability of resources dictates number of co-existing species in a given area. Driven by the idea of plants driving the diversity of herbivores and herbivores drives the diversity of plants.
What does the food chain length do in the productivity hypothesis
It is related to energy so reduced energy reduces the species number and food web length
What is the paradox of enrichment in the productivity hypothesis
Diversity often declines when added resources in a community such as algal bloom reduces species and plant communities with N fertiliser reduces biodiversity. Competitive exclusion.
What is the ambient energy hypothesis
Availability of high temperature dictates number co-existing species in a given area
What does low temperature in the ambient energy hypothesis do
Reduces population growth, lower surgical due to the physiological response of organisms to temperature
What is the relationship between PET and species richness like
It’s not linearly positive, found that there’s a point in which increasing PET doesn’t increase species richness, it’s positive but at one point the relationship becomes even negative or stable. This is because we are not taking into account water, PET assumes there’s no limitation of water in the planet but there is.
What is the limiting factor in the north
Temperature (PET)
What is the limiting factor in most of the world besides the north
Distribution of rainfall (AET) (love water availability)
Why is the heterogeneity hypothesis not great
Species richness of North American vertebrates are positively correlated. Not well supported and perhaps amphibians, plants and trees are driven by water and share a common driver but not one diving the other.
What are the two limitations of the heterogeneity hypothesis
Model only supported for a few groups (probably indirect correlations mediated by climate factors at global scale)
Latitudinal patterns of diversity also present in oceans, despite relatively little variations in heterogeneity.
What is the taxa in low latitudes e.g tropics for the rapoports rule
Narrow range, low environmental tolerance. Many species with narrow niches - niche packing.
What is the taxi in high latitudes (poles) in rapoports rule
Wide range and environmental tolerance. Few species with wide niches
What are the three explanations of latitudinal patterns of diversity
Climate variability - greater high latitudes (requires broad niche to survive in the north)
Glaciation - high dispersal species repopulate north (have large geographic range)
Competition between species
Why is there high competition in the tropics
Because of the restricted habitat - small niches are more highly evolved with find adaptations
Why is there less competition in the poles
Limited by environmental factors and broad niches
What 2 traits characterise species-rich tropics
Long evolutionary history (more generations) with relatively stable existence (lack of glaciation).
Constantly high temperatures.
Why is there faster growth/ development and evolution of new species in the fourth hypothesis
More stable climates because no glaciation and more generations and constantly high temperature. Species tend to be limited by low temperature.
