L9 - Tropical forests - cradles or arks? Flashcards
why is biodiversity not equally distributed across the globe
Some biomes are more diverse than others; for example, tropical rainforests cover only 7% of the world’s surface but are home to over half of terrestrial species
what is conservation biogeography, and when was it defined?
Conservation biogeography is a discipline that addresses the spatial distribution of organisms and factors influencing their distribution, defined by Robert Whittaker in 2005
why is biogeography valuable for conservation
It helps understand ecological and historical processes that generate and maintain biodiversity, enabling the design of effective conservation strategies
who is considered the father of biogeography
Alfred Russel Wallace, who studied the distribution and diversity of plants and animals, particularly in Southeast Asia
what is Wallace’s contribution to biogeography realms
Wallace identified geographic barriers that marked species’ ranges and established biogeographic realms based on vertebrate family distributions
how did Holt et al. update Wallace’s biogeography realms
They used large-scale phylogenetic information to identify 20 zoogeographic regions nested within 11 larger realms
what regions have the highest biogeographic uniqueness
Australia has the highest concentration, followed by Africa and South America.
what are the 3 major types of biogeographic distributions
- Cosmopolitan: Found almost anywhere, e.g., brown rat.
- Endemic: Unique to specific locations, e.g., lemurs in Madagascar
- Disjunct: Gaps in distribution, e.g., alligators in North America and China
what is an ecological niche
It is the set of environmental and biotic conditions necessary for a species’ existence
what is phylogenetic niche conservatism
It is the tendency of closely related species to be ecologically similar, such as tropical tree frogs being less diverse in temperate zones
how does extinction affect geographic distributions
Extinction removes populations or species, reshaping their range, e.g., the horse family in North America
what is dispersal and how does it influence species distribution
Dispersal is the movement of species to new areas via favorable habitats or barriers, seen in events like the Great American Interchange
what is vicariance and how does it lead to speciation
Vicariance occurs when populations are separated by barriers, leading to divergence and speciation, e.g., ratites after Gondwanaland’s breakup
what is the difference between allochthonous and autochthonous taxa
- Allochthonous: Originated elsewhere, e.g., mountain lions in South America.
- Autochthonous: Evolved in the region, e.g., lungfishes in South America
what are the 4 types of tropical forests
- Tropical moist broadleaf forests: High rainfall, high biodiversity.
- Tropical moist deciduous forests: Seasonal dry periods, heavily logged.
- Tropical dry forests: Long dry seasons, dominated by deciduous trees.
- Tropical and subtropical coniferous forests: High altitude, low biodiversity.
what is the latitudinal biodiversity gradient (LBG)
It is the pattern where biodiversity is highest in the tropics and decreases toward the poles
what are the 3 hypothesis for the LBG?
- Cradle hypothesis: Higher speciation rates in the tropics
- Ark hypothesis: Lower extinction rates in the tropics
- Out-of-the-tropics: High speciation, low extinction, and species migration out of the tropics
how did glacial cycles during the Pleistocene influence species distributions?
Many northern species migrated south during glacial periods and moved back north as glaciers receded
why are tropical rainforests so biodiverse
heir long-term stability, even during cooling periods, has allowed high speciation rates and the persistence of ancient ecosystems
what are key research implications for the future of biodiversity
- Enforcing environmental regulations.
- Continued monitoring and research.
- Engaging communities in conservation efforts.
- Training skilled personnel to protect ecosystems
