Ricklefs Notes: Chapter 20 - Global Diversity

1,500,000 plants and animal species have been identified and given Latin names
Ecological Diversity – variations among plants and animals
Genetic Diversity – the genetic change, or evolution, responsible for ecological diversity
Phylogenetic Diversity – takes into account the degree of relationship among organisms considering they are all genetically connected with a common ancestor
Adaptive Radiation – the evolutionary convergence and diversification of a species from a recent common ancestor
Endemic – species whose distributions are limited to small areas
Endemism – regions with large numbers of endemic species (ex: oceanic islands)

Identifying areas that are rich with biodiversity can be called an ecological hotspot.

Value of biodiversity can be dependent on social, economic, and ecological considerations.
- Moral responsibility
- Economic benefits – including eco-tourism
- Indication of environmental quality
o Predatory birds being poisoned by DDT
- Maintenance in ecosystem function
o Species have roles in ecosystem and human activities that influence those species can have unintended impacts (i.e. less predators, more deer, more car accidents and denuded forests)

Extinction is natural but not at present rate
Background extinction – low rate of extinction as a result of ecosystems changes over thousands of years
Mass extinction – the dying off of large numbers of species because of natural disasters
Anthropogenic extinction – extinction caused by human activities
- Habitat loss and fragmentation
- Small population size- by reducing genetic variation in the population
- Overexploitation – often in history, human introduction to a territory has corresponding extinction of certain animals (Australia, North America, Madagascar)
- Species introductions – many diseases can be traced to species introductions, some accidental and some purposeful
o Leading to the globalization of the world’s biota at the expense of endemic species
- Emerging diseases – one that has appeared for the first time or one that existed previously but is rapidly increasing in incidence or geographic range
o Animals and plants can suffer from emerging diseases too
- Vulnerability to anthropogenic extinction
o Species that attract our attention are under greater pressure
o Success or failure may rest on small differences in breeding and longevity
o Most species exist for a million or more years, so they naturally can bounce back from setbacks – but how much?

Reserve Designs:
MVP – Minimal Viable Population is the smallest number of the species that can sustain itself in the face of environmental variation
- Population must be distributed widely enough and yet have some subdivision to protect against disease

What makes an area a critical habitat for conservation?
- Hotspots, habitats and areas of special interest
- Amount we are able to reserve is limited by economic considerations
- In developing countries, successful conservation efforts include local people in the design and management so that the benefits are tangible and economically compelling

Design of Reserve Areas
PVA – Population Viability Analysis – which incorporates demographic information about a particular population into a simulation model to predict the probability that it will avoid extinction within a given period

• Larger is better than smaller
• One large reserve is better than several smaller reserves that add up to the same size
• Corridors connecting isolated reserves are desirable
• Circular reserves are better than elongate ones with much more edge

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