Biology Unit 5 evolution

false idea of evolution

• Lamarckism

• Inheritance drives evolution

• acquired traits cause heritable changes in species

• Traits are gained and lost by use and disuse

Lamarckism was shifted to natural selection

A paradigm shift occurred when people changed to natural selection

In a population

variation exists and this variation is heritable

overproduction of offspring

• is common in many species

• this leads to competition for resources meaning not all offspring will survive

• density independent factors may also affect survival (like temperature)

adaptations

• individuals who are better adapted tend to survive and produce offspring

• allow for individuals to be better suited to their environment

• must be heritable therefore encoded in the DNA

• poorly adapted tend to die and produce less offspring due to selective pressures (biotic and abiotic)

natural selection

increases the frequency of characteristics that make individuals better adapted, leading to changes within a species.

terms of natural selection

• can only occur if there is variation among members of the same species

• mutation give rise to new traits

• meiosis and sexual reproduction increase variation between individuals of the same species

Antibiotic resistence (natural selection and evolution in bacteria)

• there are many germs in the body but only some are drug resistant

• antibiotics kill the bacteria causing the illness as well as the good bacteria protecting the body from infection

• the drug-resistant bacteria are now able to grow and take over

• some bacteria can give their drug resistance to others

• some bacteria examples are MRS or Tuberculosis

gene pool

• consists of all the genes and their different alleles present in an interbreeding population

• evolution requires that allele frequencies charge with time in populations

• the variation id determined by alleles present at a given time

• environmental changes alter the selective pressure

• the allele frequency will change in the population

directional selection

Disruptive selection

stabilizing selection

the harty- Weinberg principle

• provides a baseline used to predict allele frequency and determine if a population is evolving

what unrealistic assumptions are made for the Harty-Weinburg principle

1. no mutation in the gene pool

2. no migration of alleles

3. no natural selection

4. mating is random

5. large population

   • this helps assume that the alleles don’t change over generations yet if they do then one of these are at work

equation number 1

equation number 2

5.2 evolution and speciation

species

can be interbreed and produce fertile offspring

speciation

• occurs due to reproductive isolation

• allopathic speciation and sympatric

allopatric speciation

• is when this isolation is due to a physical barrier

• occurs in different geological regions

• the population lose the ability to interbreed, forming two distinct species

Sympatric speciation

• occurs in the same geographical area

temporal isolation

• the time of reproduction between populations is incomplete

behavioral isolation

populations are separated by specific behaviors (like the blue bobied and their mating dance)

polyploidy

• having more than two sets of chromosomes

• haploid=n diploid=2n triploid=3n

• different number cannot pair up properly therefore successfully reproduce

• to produce fertile gametes the chromosomes must form homologous pairs

• triploid offspring would be infertile at one pair

5.3 diversity and classification

the biological species concept is imperfect but still used to group organisms based on similarities and evolutionary history.

• speciation is slow and an endpoint is not always clear

• diverging, non-breeding populations might be in the process of speciation

• distinguishing between non-breeding population

morphology

• group together on a shared physical traits

binomial nomenclature

• two names a Genus species

• italicized and only the Genus is capitalized

Linnaean taxonomy

• a hierarchical classification

• based on physical traits

  Domain

  kingdom

  phylum

  class

  order

  family

  genus

  species

modern classification

• relies on physical traits, behaviors (breeding or non-breeding), and genetic similarities

• reproductive incompatibility lies in the different chromosomes

whole genome sequencing

• determines every base in a genome

• used to research differences within and between species

• tests hypothetical evolutionary relationship based on physical characteristics

single nucleotide polymorphism

• single base substitution (this is the reason humans are .1% genetically different

• different species have different genome sizes

• plants are (can be) polyploid and have greater genome

genome sequencing

• personalized medicine, species identification using a barcode

bacteria are difficult to classify because….

cladogram

terminal branch- most recient species in a lineage

node-hypothetical common ancestor

root- common ancestor of all clades represented on the cladogram

clade- group of organisms that share a common ancestor

• molecular evidence is used to construct and or correct cladograms

the molecular evidence that can be used to figure out the cladograms include

• rRNA as highly conserved species need it, and there are slight differences between species

• Protein analysis fins the similarities in amino acids, yet some proteins are better predictions then others

• DNA sequencing can show that some sequences are conserved between species.

5.2 evolutionary change

Convergent evolution

• species do not share recent common ancestors

• similar selective pressure causes a similarity in morphology

• analogous structures and similar function but different evolutionary history.

• examples: wings in both birds and bats

Divergent evolution

• shared ancestry with changes over time due to differences in selective pressure

• evidence of adapted radiation

homologous structures

• similar features even if function has changed

• examples: pentadactyl limbs within different animals

adaptive radiation

• one species becomes into species, a new ecologist’s niche would appear

• evolutionary history shows period of little change (stasis) punctuated by periods of adapted radiation

sexual selection as selective pressure

• sexually dimorphic= sexual selection

• physical and behavioral traits can be interpreted as a sign of overall fitness

• this in turn provides a reproductive advantage

• lacking these qualities presents a unique type of selective pressure that changes the species over time

• behaviors must be heritable

birds of paradise

• small islands in Papua Guinea

• low predation

• adaptive radiation

• elaborate courtship rituals

artificial selection

• selective breeding changes species

• humans choose desirable triats that may or may not increase survival or reproductive advantage

• shows how rapid evolution can occur

• Examples: Dog breeds and plant varieties

Bacteria resistance

• bacteria have evolved resistance to antibiotics due to human activity

• resistance is considered natural selection because the bacteria are responding to selective pressure, and humans are not intentionally selecting the trait.