How many species total are there?
between 5-40 million
How many named species so far are there?
1.5-1.8 million
- half are insects
~ 300,000 are beetles
How many species of mammals are there?
4500
How many living creatures are present per square foot of one inch of top soil?
1356
What is a definition of biological diversity?
variability among living organisms from all sources including inter alia, terrestrial, marine and other aquatic environments, and the ecological complexes of which they are a part
Including:
- diversity within species
- diversity between species
- diversity of ecosystems
What is a definition of biodiversity?
variability among living organisms from all sources including land based and aquatic ecosystems, and the ecosystems of which they are a part
including:
- within species
- between species
- between ecosystems
* diversity is the key to ensuring continuance of life on Earth
What are the 3 kinds of biodiversity?
- habitat/ecosystem diversity
- genetic diversity
- species diversity
*the survival of each is linked to the health of the other two parts, comprising the wealth of ecosystems
What is habitat/ecosystem diversity?
- variety of habitats available on a local, regional, and global scale
- local or regional habitats may have many or few similar habitats or niches within it
- a local habitat with little biodiversity may contribute to the biodiversity of regional or global habitats if it provides unique characteristics
what is genetic diversity?
- genetic variation within a species
- demonstrated by many alleles of a given gene or a lot of the population being heterozygous
- indicator of the genetic resources available for adaptation
What is a consequence of a lack if genetic diversity?
- may lead to inbreeding depression
- increases susceptibility to pandemics
What is the population size difference of cheetahs between 1900 and now?
- 100,000 cheetahs in 1900
- 12,000 now
What did the experiment involving skin grafting of a cheetah discover?
the cheetah population is genetically homogenous
- low rate of genetic diversity
What can cause populations like the cheetah to become genetically homogenous?
genetic bottleneck/founder effect:
- when a population is reduced to a few individuals (usually <7) and then recovers
= many individuals, little genetic diversity
What is special about apply seeds?
- each apply contains 5 seeds, which will each produce a distinctly different apple tree
How are trees normally grown?
via cuttings, scions, and grafts
What is species diversity?
- number of species present within a given habitat
- measured in terms of richness and evenness
What is richness?
the number of species present in a given area/habitat
What is evenness?
the comparative number of individuals of a species in relation to the total/other species.
Who is E.O. Wilson?
- professor of entomology at Harvard
- career stems from his research in myrmecology (study of ants)
What does E.O. Wilson believe?
- humans have an innate love of diverse life forms (biophillia)
- religious naturalist who speaks of evolution and diversification of life within which humans find meaning
Why is biodiversity valuable according to E.O. Wilson?
1) each species is a masterpiece of evolution
2) by reducing the diversity of life, also reducing the productivity and stability of natural ecosystems, which the preservation of some natural habitats depend upon.
3) the loss of natural products through extinction of species that produced them is extraordinary
4) need healthy, natural ecosystems with the biodiversity in them operating as independent units. need them for the air, soil renewal, watersheds, carbon sinks
Why is biodiversity valuable according to Michael Pollan in The Botany of Desire?
- limiting sexual reproduction can limit genetic variability, inflicting maximal damages to crops from bacteria, fungi, etc. Causing farmers to use pesticides :(
- preserving the biodiversity of domesticated species is as important as for wild species if we are to avoid over dependence on chemical protection for crops
What are some of the challenges of biodiversity?
- conceptual problems with types of organisms and habitats, including potential biases toward natural and native
- how big of an area should be used to assess biodiversity
- which types of diversity are of greatest value to keep in existence
(deep time - a being that is a biological relic) vs (characteristics of special value - genetic resources)
What is a species from 1700-1800s?
- a type
- this fixity of species worked well with the idea of a static created order established by God.
- species as divinely ordained made it easy to assign values
