Concepts on Patterns of Distribution and Biodiversity

Baldeo, Cortez, Delos Santos, Olivar,

Concepts on Patterns of Distribution

1. No two species are identical in their patterns of distribution

Both species occupy the same tree. (A) Apteryx australis occupies the floor (B) Rhipidura fuliginosa occupies the canopy branches

(A)

(B)

MICROHABITAT concept

Global patterns of terrestrial vertebrate diversity analyzed in the study. Each of the 32 bioregions is colored by its vertebrate species richness (amphibian, reptile, bird, mammal richness combined; dark green represents the lowest values and dark red represents the highest values) (Jetz & Fine, 2012)

2. Causes of pattern vary according to the taxonomic level

Distribution of the Asteraceae Family

Distribution of the Helianthus genus

3. Causes of patterns also vary with the spatial scale

4. Factors in patterns of distribution

Geological history

Climate

Availability of food Chemistry of Environment

Competition

5. Species introduction led to new patterns of distribution

Macropus eugenii was thought to be extinct in Australia for 100 years. But it has been rediscovered in an island in New Zealand (2000 species) where a former governor of that country introduced the species in 1862.

Introduction of mahogany species in the Philippines led to hectares of biodiversity-dead zones.

6. Spatial and temporal isolation leads to speciation

7. Migration constitutes a special kind of dynamic pattern

Ancient human migration patterns as derived from mitochondrial DNA analysis

Concepts on Patterns of Biodiversity

8. Biodiversity means the full range of life on earth

Genetic Diversity

Ecosystem Diversity

Species Diversity

9. Knowledge on global diversity must be established to appreciate the increasing extinction rate of species

• Since there is no absolute idea on how many species existed in the first place, extinction rates are vaguely estimated

• Little is known about extinction rates of microorganisms• We can rarely be sure that a species is actually lost, that no

isolated members remain

10. Out of the 30 million species on Earth, only 1.8 million species have been described

(Groombridge, 1992)

11. The tropics have the highest species diversity

Latitudinal gradients of species richness for swallow tail butterflies in three parts of the world. (Collin & Morris, 1985)

High species diversity is due to:a. high productivity and food availabilityb. high biomass and hence complex structurec. past patterns of evolutiond. survival of fragments of habitats through the cold episodes of the last 2 million yearse. degree of small-scale disturbance mosaic of successional processes

12. Diversity involves species richness and evenness and generally increases during the course of succession

Increasing diversity

13. Biodiversity in a community is dynamic but there are also stabilizing forces at work

• Neutral Theory of Biodiversity (Hubbell, 2001)– Chance plays a great a great part in determining what

species are present in the ecosystem

• Chaos Theory– Very small chance events can determine the ultimate

outcome of the ecosystem

14. There is a tendency for human populations to be dense in biodiversity hotspots.

The Crete Island in Greece a. supported human populations ever since the Neolithic ageb. only 245 km long by 50 km wide and isolated for 5.5 million yearsc. human population reaching 1 million yet supports a highly diverse

community (10% of the species are endemic to the island)

Anthropogenic activities lead to HABITAT DIVERSIFICATION which promotes an increase in biodiversity. There is evidence that biological diversity and human population density are positively related over the less extreme density range. (Cox & Moore, 2005)