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Bio 102 Exam 1 Review Notes
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This is a comprehensive and detailed review note on Exam 1 for Bio 102. *Essential Study Material!!
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Biological diversityBiodiversity-the diversity of life
3 main levels:
-genetic
-species
-ecosystem
Species diversity
-usually quantified in two ways:
1.species richness: is a count of the species present in a defined region
2.Species evenness:measurement of how evenly distributed organisms are among species (the
relative abundance of each species present)
For any given species richness:
Higher species diversity if evenness is high-that is, if all species have a comparable abundance
Lower species diversity:one or just a few species dominate a community
How to measure species diversity
-transects, traps, quadrants, mark-and-recapture techniques
-DNA barcoding: uses a well-characterized gene sequence to identify distinct species.
Sequences of target genes are matched to reference libraries.
Genetic Diversity
-measured as the number and relative frequency of all genes (and their alleles) present in a
species
-key for adapting to changing environments
→how?
-genome sequencing
-environmental sequencing
Ecosystem diversity
-highest level of biodiversity
-the number of different ecosystems on the planet within a given geographic area
Biodiversity can be recognized and quantified on several distinct levels, but it is also dynamic, it
changes through time
Why are biodiversity and ecosystem function important?
-ecosystem function: sum of the biological and chemical processes that are characteristic of a
given ecosystem (primary production, nitrogen cycling, decomposition, and carbon cycling)
-species richness increases aspects of ecosystem function:
-productivity
, -resilience
-resistance
Importance of biodiversity to humans
-human health
-agricultural diversity
-wild food sources
-psychological and moral value
-collectively, all direct and indirect benefits that humans derive from organisms and ecosystems
they compose are called ecosystem service
-ecosystem services have been estimated to have a value of US $125 trillion per year
Mass extinctions are “normal” on Earth
-species are vanishing faster than at virtually any other time in Earth’s history
-modern rates of extinction are 100 to 1000 times greater than average rate
-sixth mass extinction in the history of multicellular life
What can we do to protect it?
-biodiversity hotspots
Problems with hotpots:
-criterion of at least 70% of vegetation lost focuses on cumulative past loss, not current rate of
lost
-does not include places like the Amazon
-hotspots focus on species not ecosystem diversity
Major threats to biodiversity
-habitat destruction and degradation
-invasive species and disease
-overexploitation
-pollution
-climate change
Phylogenetic Analysis
How can we study the history of life?
Phylogeny→ the evolutionary history of a group of organisms
Two major analytical tools to reconstruct the history of life:
1.the fossil record
2.Phylogenetic trees
→ can be used separately or in combination
-Phylogenetic tree:graphical summary of this history
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