L4: Global patterns of biodiversity Flashcards
Species richness
Number of species per unit area
Endemic species
Pertaining to a taxon that is restricted to the geographic area specified, such as continent, lake, biome, or island.
Cosmopolitan (or widespread species)
Occurring essentially worldwide, as on all habitable landmasses or in all major oceanic regions.
Body size and Bergmann’s rule
Bergmann’s Rule (1847): Body size increases with latitude. Within a given group of organisms, those with larger body sizes will be found at higher latitudes.
Therefore, animals tend to be larger in cold areas than in tropical ones.
What is Allen’s rule
For example…
Animals in colder climates have shorter appendages (ears) than their close relatives in warmer climates.
Lepus in north America show a decline in the length of their ears with decreasing temperature.
Gloger’s rule of colour in species
•More darker forms tend to be found in more humid environments, e.g. near the equator. To avoid UV
•In cold environments the color of the species tend to be lighter. Easy to hide in snow.
Floral pigmentation patterns provide an example of Gloger’s rule in plants (Koski, 2015)
Latitudinal gradients
Species diversity decreases with increasing latitude.
Increasing species diversity from the poles to the Equator.
What is Rapoport’s rule?
(Rahbek, 1997)
Rapoport’s rule is an ecogeographical rule that states that latitudinal ranges of plants and animals are generally smaller at lower latitudes than at higher latitudes.
Latitudinal gradients
How is species diversity affected by increasing latitude?
Species diversity decreases with increasing latitude.
Increasing species diversity from the poles to the Equator.
What is endemism?
Endemism is the restriction of a species range to a circumscribed area.
Australia, for instance has the highest number of endemic mammal species.
Effect of elevation on species diversity
Decrease in species diversity with increase in elevation.
The climate after a certain height is less suitable for majority of species.
(Vertaas and Grytnes, 2002).
What are the main processes in shaping the pattern of non endemic species richness?
Dispersal
Climatic filtering along elevational gradients
Human land use
What is Sclater’s classification of marine biogeographic regions?
The use of tracking seals to observe broad biogeographic regions.
Why are environments complex?
The latitude and altitudinal differences vary in biomes (e.g snow/ice, tundra, evergreen forest, temperate forests)
Differences in an environmental parameter such as aridity, e.g going from rainforest to desert.
What is a climograph?
Diagram quantifying some aspects of the relationship between climate and vegetation types.
What other traits can be related to latitude, elevation and different environmental gradients?
Body size
Dispersal capacity
Colour
What was the observed relationships between the percentage of Single Island Endemics and elevation?
Strong pattern of increasing number of endemic species on top of the mountains.
Steinbauer et al, 2016
What did Nogue et al., 2013 find about the richness of non endemic species with increasing elevation?
Decreases
What are the rules you need to remember?
Bergmann’s Rule: Body size increases with latitude
Allen’s rule: Animals in colder climates have shorter appendages (ears) than their close relatives in warmer climates.
Gloger’s rule: More darker forms tend to be found in more humid environments, e.g. near the equator. To avoid UV
Rapoport’s Rule: The idea that latitudinal ranges of plants and animals are smaller at lower latitudes than higher latitudes
What is a sink habitat?
A habitat that is a net importer of individuals, because local reproduction is not sufficient to balance local mortality.
