Diversity of Organisms Flashcards
Challenges to BSC Part 2
Asexual Reproduction’s lack of interbreeding provides a challenge as BSC relies on interbreeding to define species
Bacteria with HGT allows gene sharing between distinct species which contradicts the idea of reproductive isolation as a species boundary
Variation
Genetic: Variation in genotype between individuals
Environmental: Difference between environments of individuals
Morpholohical Strengths and Weaknesses
Easy to apply and straight forward with observation and measurement of traits
May miss cryptic species and confused by variation within species
Phylogenetic Strengths and Weaknesses
Applies to all organisms including asexual and accounts for evolutionary history
Requires detailed phylogenetic information and can lead to a large number of species
Two Species with Chromosome Numbers Reproduce
Gametes will be unable to fuse due to differences in chromosome number and structure
If fertilization occurs, resulting zygote may have an uneven number of chromosomes which leads to developmental problems and often death
If surviving offspring gets produced, they will be infertile because mismatched chromosomes wont pair up correctly during meiosis to produce viable gametes
Variation Between Species VS Variation Within Species
Significant differences
Minor differences
Accumulation of mutations over long time
Natural genetic variations within population
Drives unique traits that distinguish species
Contributes to genetic diversity
Challenges of Speciation
It is gradual and a slow accumulation of differences in traits which makes it hard to pinpoint the moment where two groups diverge enough to be called different species
It’s also arbitrary as there’s no clear line in the continuous process of divergence
Challenges of Morphological Species Concept
Some individuals within a species have a lot of variation which makes it difficult to define boundaries off morphology alone (polymorphism)
Males and females of the same species look very different which can lead to misclassification (sexual dimorphism)
Some species are morphologically similar but have distinct genetic differences and therefore can’t interbreed (cryptic species)
Speciation
Process where two related populations diverge into separate species
When two populations of a species become geographically separated they will likely experience different ecological conditions, leading to them evolving independently and having different mutations which leads to genetic divergence
Classification Pyramid
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Specus
Biological Species Concept
A species is a group of organisms that can interbreed and produce fertile offspring
Chromosome 2 Fusion Hypothesis and Proof
Claims that human chromosome 2 is the result of a fusion of chimpanzee chromosome 12 and 13
Chromosome length of human 2 is the same as chimpanzee 12 and 13 combined
Centromere position of human 2 is similar to the one of 12 and 13 indicating that they are homologous
Human 2 has one centromere where 12 is which gives hypothesis that 13 centromere was inactive
Telomeres are found in human 2 chich indicates that the ends of two chromosomes fused together and sequence found in middle was proof
How are Karyograms Arranged
Length where chromosomes are arranged from tallest to shortest
Banding patterns which are unique patterns of light and dark bands produced by staining
Centromere position which can be in the middle, off center or near one end
Ecological Strengths and Weaknesses
Connecs species to environment and adaptations
Some species can occupy multiple niches
Population
Group of individuals that live in the same area and can interbreed
Whole Genome Sequencing and Uses
Tool that determines complete DNA sequence of an organism’s genome
Can be used to trace evolutionary lineages, study evolutionary relationships and identify genes responsible for specific traits
Morphological Species Concept
Species is a group of organisms with shared traits based on their observable physical characteristics
Importance of Chromosome Numbers
Can e useful to distinguish and identify species
Can provide clues to how species relate
Change in chromosome number contributes to reproductive isolation
Diversity of Genome Within Species
SNP: small genetic variations at a single nucleotide position in DNA sequence which leads to differences in traits and variation
Mutation: insertion and deletion of entire genes or segments of DNA can have significant impact on phenotype and increase variation
Variation Patterns
Organisms inherit traits form ancestors which can be modified over time
Organisms with better suited traits are more likely to survive and reproduce which leads to a change in the gene pool
Organisms that share a more recent common ancestor tend to have higher amount of similar genes
Binomial Naming System
Genus name is uppercase
Specus name is lowercase
Usually underlined
Provides a universal language to name organisms in different countries, and reflects evolutionary relationships as species with the same genus share common ancestor
Discontinuous and Continuous Variation
Results in limited number of phenotypes with no intermediates, and is usually controlled by one gene and unaffected by environment.
Results in range of phenotypes with intermediates, and is usually controlled by multiple genes and affected by environment.
Challenges in Distinguishing Populations and Species
Populations diverge gradually which lead to intermediate forms that share traits with both parent populations
Diverging populations can look similar which makes it hard to differentiate them morphologically
Diverging population can still share same genetic makeup as parent ancestors, making it hard to tell difference
Importance of Variation
Results in different survival rates of an organism, which leads to reproductive success and failure.
Organism with more suitable traits and better adapted to environment has a survival advantage and has a higher chance of reproduction to increase number of offspring
eDNA Process
eDNA Collection
DNA Extraction
PCR Amplification
DNA Sequencing
Species Identification
Challenges of BSC
Asexual reproduction is inapplicable with BSC
Fossil species that are extinct can’t have BSC applied to them
Some closely related species can interbreed and produce fertile hybrids (Lion and Tiger) (Hybridization)
Populations that are geographically isolated may evolve differently and become distinct species over time
