Evolution and Biodiversity

Genetics: study of heredity

Genes: Chuck of DNA

Alleles: different forms of the same gene.

• Two copies of each gene = two alleles

  • , one from mom, one from dad

• 23 pairs of chromosomes. XX= female. YY= Male.

Evolution: change in allele frequency in a population over time.

How do Populations Evolve?

Mutation: change in DNA sequence.

• Advantageous- Codes for a new trait that increases fitness

• Deleterious- Codes for new trait that reduces fitness

• Neutral: Neither change nor affect fitness

*Creates genetic diversity in a population.

Gene flow: introduces new individuals with different allele frequencies.

Genetic drift: Randomness in gametes and survival.

• Gametes- sex cells (egg and sperm)

• Bottleneck effect- results from a drastic reduction in population size.

Natural selection: some traits help survival and increase in frequency.

• Unfit- traits removed from the gene pool don’t survive.

• Fit- traits pass on to the offspring and survive.

Evolutionary adaptation: a population increase in frequency of traits to suit the environment. Slow process.

What is a Species?

Group of individuals that can interbreed and produce fertile offspring.

Speciation: one species splits into two species

• Allpactic- physical barrier separating the population

• Sympatric- same area, different habitats.

*Needs reproductive isolation.

Gametic: Species whose gametes cannot fuse.

Mechanical: species whose genital openings cannot align.

The Fossil Record

Transitional forms: link the past and present.

Biogeography: the study of the geographic distribution of species

Comparative anatomy: the comparison of body structure between different species.

• Same structure but, a new function.

  • Ex. Human arm and bat wing.

  • Animals share common ancestors with these bones.

• Vestigial Structures:

  • leftover structures from ancestors.

  • Once functional, now has only marginal, if any, importance.

Comparative embryology: early stages of development are similar