1 Definition of Biodiversity Biodiversity The variety of life on Earth Can refer to Species diversity variety of species in an area Genetic diversity variation of genes within a species Habitat diversity variety of ecosystems in a region Differences among species e g birds vs mammals insects vs plants 2 Levels of Biodiversity Between species Leads to species richness Within species Genetic concepts Gene Segment of DNA coding for a trait Allele Different versions of a gene A gene is like an instruction in your body for a trait like eye color An allele is a version of that instruction like blue eyes vs brown eyes Genotype Set of genes in an individual Phenotype Observable trait of an individual Genomics Study of all genes in an organism 3 Number of Species on Earth Named species 1 5 2 million Estimated total millions to tens of millions Most species are unknown to science Variation among individuals of the same species Traits differ due to genotype genes and phenotype expression of traits influenced by genes and environment Example Differences in human height 4 Species Concepts Species Traditionally defined as a group that can interbreed Limitations Some organisms e g bacteria reproduce asexually Some species are only partially separated e g coyote and wolf Species can be identified by Form morphology DNA sequences Behavior and habitat 5 Classification of Species Linnaean System Hierarchical classification created by Linnaeus Binomial nomenclature Two part species name Genus capitalized species lowercase Examples Homo sapiens Canis familiaris 6 Patterns of Biodiversity Global patterns Higher species richness in tropical regions Lower species richness in polar and temperate regions Mountains and wet areas often increase diversity Species richness Number of species in a community Species diversity Includes both richness and evenness how equally species are represented 7 Evolution and Phylogeny Evolution Change in genetic makeup of organisms over time Produces biodiversity through branching patterns One species can split into multiple species Phylogenetic tree shows evolutionary relationships and branching Example Tree squirrels vs ground squirrels 8 Ecosystems and Ecosystem Services Ecosystem All organisms in an area abiotic environment air water soil Ecosystem services Benefits humans receive from ecosystems e g Oxygen Food Freshwater Biophilia Human attraction to nature plants and animals 9 Measuring Biodiversity Species richness Number of species in a community Evenness How equally individuals are distributed among species Diversity Combination of richness and evenness Can compare communities using these measures 10 Genomics and Biodiversity Genomics allows researchers to Study many genes at once Compare genetic variation across individuals and species Understand the basis for biodiversity Genetic differences alleles are fundamental to variation within species 11 Human Impact Humans are causing a sixth mass extinction Habitat loss and degradation Pollution Invasive species Exploitation of wildlife Climate change Extinction rates are 10 100 times higher than natural rates Biodiversity exists between species within species and among habitats Genetic diversity underlies differences in phenotype Tropical regions have the highest biodiversity Evolution and branching speciation generate diversity Humans are currently a major threat to global biodiversity Key Takeaways
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